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ABSTRACT In this paper, a new frontend for 5G receivers is proposed. In the presented work, a new bandwidth enhancement technique for low‐noise transconductance amplifiers and for wireless frontends has been proposed. The proposed frontend achieves low noise figure (NF) by using a noise cancelation scheme in the newly proposed LNTA. The linearity of the frontend is also improved by increasing the DC gain and the bandwidth of the opamp used in the transimpedance amplifier and by exploiting a linearity improvement method for the LNTA. The frontend has been implemented in a standard 0.18 μm CMOS process. The post‐layout simulation results prove the gain of 38 dB with less than 3 dB deviation in the pass‐band over a 6.5 GHz bandwidth. The results also show that NF is less than 8 dB, the worst‐case IIP3 is −2 dBm, the maximum S11 is equal to −9.5 dB while the frontend consumes 9.95 mW DC power from a single 1.8‐V supply, and the occupied area is 0.813 mm2. [ABSTRACT FROM AUTHOR]

This paper presents the development of a wireless data acquisition system for a wearable health sensor designed to measure glucose levels, pulse rate, and body temperature. The method emphasizes non-invasive and continuous monitoring to provide timely healthcare interventions. The designed system prioritizes wearability, flexibility, compactness, and low power consumption for user comfort and convenience. A transimpedance amplifier is designed to increase the glucose sensor signal with optimal gain and bandwidth, utilizing modeling tools for accurate signal processing. Filters, amplifiers, analog-to-digital converters, and a microcontroller for data processing and wireless transmission were used to create an integrated multi-input readout circuit for all three sensors. The work aims to develop a small and efficient circuit consuming less than 100 mW and occupying less than 6 cm2. This research extensively covers the design and optimization of a transimpedance amplifier, the development of an integrated multi-input readout circuit, and the incorporation of low-power Bluetooth data transfer for a wearable health sensor system. The biosensor's 10 uA signal range was effectively amplified to a voltage level that is readable, guaranteeing a minimum gain of 10,000 and converting it from current to voltage for measurement. An important milestone was achieved by integrating the communication of the amplified signal, heart rate, and temperature characteristics to the host application using Bluetooth. The complete system has been efficiently contained within a compact 6 cm² footprint. [ABSTRACT FROM AUTHOR]

In this paper, a comparative examination of four various transimpedance amplifier (TIA) topologies is performed. Each of the four topologies is precisely designed to fit a diverse range of applications. The discussed topologies are the common source (CS) with resistive feedback, the regulated cascode (RGC), the CMOS inverter with resistive feedback, and the composite cascode with resistive feedback. Each topology was studied in both gate-driven (GD) and body-driven (BD) configurations with a thorough evaluation of its performance characteristics provided. Among these topologies, the composite cascode topology is proposed for use for the first time with TIAs in both the gate-driven and the body-driven configurations. The type of applications that are suitable for specific performance metrics are mentioned. The simulation is performed utilizing 130-nm CMOS technology predictive technology model (PTM) with a power-supply voltage, VDD, of 1.2 V for GD configurations and 0.9 V for BD configurations. Finally, the impact of technology scaling on the performance of the GD and BD configurations are investigated.

In this paper a novel low power wideband CMOS transimpedance amplifier (TIA) with reduced peaking at low supply voltage has been presented. In the proposed TIA, floating gate MOSFET (FGMOS) and flipped voltage follower (FVF) techniques are employed in folded cascade (FC) based TIA. Both FGMOS and FVF techniques make proposed TIA suitable for low voltage operations. Furthermore, to enhance the − 3 dB bandwidth an inductive peaking technique is incorporated which works without affecting the gain. Moreover, this peaking technique does not alter the noise performance of the circuit. Simulation of the proposed TIA design is conducted using Mentor Graphics with CMOS-based TSMC 0.18 µm technology using 0.3 pF input photodiode capacitor. Simulation results of the proposed TIA demonstrate an enhanced -3 dB bandwidth of 13.2 GHz, showing 41% improvement compared to conventional FC-based TIAs and, a transimpedance gain of 50.5 dBΩ. The input referred noise for the suggested TIA is 21.6 pA√Hz. The proposed circuit consumes 3 mW from 1.2 V power supply. [ABSTRACT FROM AUTHOR]

This study presents an integrated analog front-end (AFE) tailored for photoplethysmography (PPG) sensing. The AFE module introduces a novel transimpedance amplifier (TIA) that incorporates capacitive feedback techniques alongside common drain feedback (CDF) TIA. The unique TIA topology achieves both high gain and high sensitivity while maintaining low power consumption. The resultant PPG sensor module demonstrates impressive specifications, including an input noise current of 4.81 pA/sqrt Hz, a transimpedance gain of 18.43 MΩ, and a power consumption of 68 µW. Furthermore, the sensory system integrates an LED driver featuring automatic light control (ALC), which dynamically adjusts the LED power based on the strength of the received signal. Employing 0.35 µm CMOS technology, the AFE implementation occupies a compact footprint of 1.98 mm × 2.475 mm. [ABSTRACT FROM AUTHOR]

The frequency response of the photocurrent (Iph) generated in perovskite photodetectors is a crucial issue in imaging or telecommunication applications, although it is briefly discussed in the literature. The present work obtains for the first time the complete expression of the Iph generated on MAPbI3 (MA:methylamoniumI) perovskite polycrystalline thin films. A conditioning circuit is used to extract Iph at 1 V of bias voltage under a square‐modulated laser excitation with a sensitivity smaller than 1 nW and a linear dynamic range LDR > 200 dB; It allows an accurate determination of the module of Iph together with the phase, which is not usually reported in photodetector systems. The frequency domain analysis reveals that Iph can be modeled by two fractional poles located at low (10 kHz) and high (39–250 kHz) cut‐off frequencies. Optimum geometrical parameters and excitation fluence are found for the wider response, resulting for the best device on a cut off frequency up to 250 kHz, and the reproduction of square‐modulated optical waves up to 100 kHz. These results represent an important strategy toward the electrical analysis of MAPbI3 (or other perovskite materials) for the design of posterior electronic stages, optimization of devices and determination of their figures of merit. [ABSTRACT FROM AUTHOR]

An optical receiver employs an all-inverter-based front-end design that provides maximum transconductance for a given power supply and allows for ultra-low power consumption. The feedback transimpedance amplifier (TIA) input stage utilizes a multi-stage amplifier to achieve a dramatic increase in feedback resistance and lower input-referred noise. Cascading an inverter-based active inductor continuous-time linear equalizer provides frequency peaking to compensate the input stage TIA that is intentionally designed with a reduced bandwidth to achieve adequate sensitivity at low power. Fabricated in 28 nm CMOS, the 12.5 Gb/s optical receiver achieves - 10.7 dBm OMA sensitivity at 0.11 pJ/bit energy efficiency and occupies only 720 μ m 2 area. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The frequency response of the photocurrent (Iph) generated in perovskite photodetectors is a crucial issue in imaging or telecommunication applications, although it is briefly discussed in the literature. The present work obtains for the first time the complete expression of the Iph generated on MAPbI3 (MA:methylamoniumI) perovskite polycrystalline thin films. A conditioning circuit is used to extract Iph at 1 V of bias voltage under a square‐modulated laser excitation with a sensitivity smaller than 1 nW and a linear dynamic range LDR > 200 dB; It allows an accurate determination of the module of Iph together with the phase, which is not usually reported in photodetector systems. The frequency domain analysis reveals that Iph can be modeled by two fractional poles located at low (10 kHz) and high (39–250 kHz) cut‐off frequencies. Optimum geometrical parameters and excitation fluence are found for the wider response, resulting for the best device on a cut off frequency up to 250 kHz, and the reproduction of square‐modulated optical waves up to 100 kHz. These results represent an important strategy toward the electrical analysis of MAPbI3 (or other perovskite materials) for the design of posterior electronic stages, optimization of devices and determination of their figures of merit.

In this paper, a photodiode (PD)/transimpedance (TIA) interface is presented. The cathode terminal of the PD is AC-coupled to one of the inputs of a pseudo-differential TIA while the anode terminal is DC-coupled to the other input of the TIA. The DC-coupled input provides a path for the low-frequency component of the input signal to reach the output. This component is extracted by a baseline wander compensation scheme (BWCS) and fed to the input to eliminate signal drift after long data runs. Compared with the conventional pseudo-differential receiver, the proposed interface improves the gain, the gain-bandwidth product (GBW), and the signal-to-noise ratio (SNR) by 5dB, $1.37\mathrm {\times }$ and 4.5dB, respectively, while maintaining $209\mathrm {\times }$ smaller low cutoff frequency than the AC coupled receiver. The proposed interface is compatible with any TIA topology. Post-layout simulations and analytical models validate the feasibility of the proposed technique.

Summary: This paper presents an inductorless transimpedance amplifier (TIA) that employs bias feedback technique in a MOS‐based immittance converter (MIC) to achieve high bandwidth. The bias feedback technique is analyzed and explored as a supplementary approach to reduce the input impedance in a current buffer structure. Employing this technique in a MIC‐based TIA structure provides an additional degree of freedom for the design and helps reduce the trade‐off between bandwidth and power. The proposed structure is designed and simulated in 0.18 μm CMOS technology considering a 1 pF photodiode capacitance. The post‐layout simulation results show that the TIA provides a transimpedance gain of 50.9 dBΩ, a bandwidth of 6.1 GHz, and an input‐referred current noise of 9.9 pA/√Hz. The circuit consumes 3.42 mW from a 1.8 V supply and occupies 0.0046 μm2 area. Results are compared with TIAs reported in the literature, which confirms the effectiveness of the proposed modified MIC structure. [ABSTRACT FROM AUTHOR]

This study presents an integrated analog front-end (AFE) tailored for photoplethysmography (PPG) sensing. The AFE module introduces a novel transimpedance amplifier (TIA) that incorporates capacitive feedback techniques alongside common drain feedback (CDF) TIA. The unique TIA topology achieves both high gain and high sensitivity while maintaining low power consumption. The resultant PPG sensor module demonstrates impressive specifications, including an input noise current of 4.81 pA/sqrt Hz, a transimpedance gain of 18.43 MΩ, and a power consumption of 68 µW. Furthermore, the sensory system integrates an LED driver featuring automatic light control (ALC), which dynamically adjusts the LED power based on the strength of the received signal. Employing 0.35 µm CMOS technology, the AFE implementation occupies a compact footprint of 1.98 mm × 2.475 mm.

An electrostatic field mill (EFM) is widely used to measure the strength of electrostatic fields, the main drawback of which is the occurrence of large measurement errors (up to 15 % in the range from 0 to 1 kV/m). This paper examines the aspects of using transimpedance amplifiers (TIAs) for the tasks of converting the current received from the EFM sensor into voltage, which will make it possible to reduce the instrumental error and ensure the linearity of the atmospheric electrostatic field strength measurement. In the general case, for the functional circuits of the electrostatic field mill, which include a differential transimpedance amplifier, there is the use of two TIA circuits, which are connected in parallel. Despite the simplicity of implementation, such a configuration contains a number of disadvantages and is not optimal. In the paper, a comparative analysis of a typical circuit of a differential TIA and a circuit of an ungrounded differential transimpedance amplifier with zero voltage drop proposed by the authors is carried out. As a result of the analysis, it was established that the designed authentic circuit of the ungrounded differential transimpedance amplifier with zero voltage drop has better parameters of linearity and interference resistance, in contrast to the generally accepted one. The value of the signal-to-noise ratio for the proposed scheme improved by 42 % on average compared to the typical one. The main difference of the proposed scheme is that the stability of the amplification factor is ensured, the influence of the bias parameters of the operational amplifier is leveled, and the overall noise level is reduced. The use of the designed scheme of an ungrounded differential transimpedance amplifier with zero voltage drop could make it possible to increase the accuracy of the measurement of the electrostatic field strength. [ABSTRACT FROM AUTHOR]

In this paper, the design methodology of a high-linearity wide-band transimpedance amplifier (TIA) for cable television (CATV) application is addressed. A simple four-stage topology is proposed to maintain a well-balanced linearity over a wide operating band. The regulated cascode (RGC) input stage is used to match an input impedance of 75 Ω, followed by a gain stage with enhanced bandwidth. The high-linearity output stage is able to drive the 75 Ω load directly with high output swing under a high supply voltage. The prototype is implemented with a standard 0.11μm CMOS process while occupying the silicon area of 0.034 mm2. The measurement results for the prototype show a peak gain of 76.6 dBΩ over a 3-dB bandwidth of 1.1 GHz with a considerably small gain ripple and an OIP3 of 20.4 dBm. The whole test chip consumes 447 mW DC power and the measured average input-referred noise current spectral density is 7.9 pA Hz−1/2 up to 1 GHz. [ABSTRACT FROM AUTHOR]

This paper presents the design and testing of an ultra-low-noise transimpedance amplifier (TIA) for low-frequency noise measurements on low-impedance (below 1 kΩ) devices, such as advanced IR photodetectors. When dealing with low-impedance devices, the main source of background noise in transimpedance amplifiers comes from the equivalent input voltage noise of the operational amplifier, which is used in a shunt–shunt configuration to obtain a transimpedance stage. In our design, we employ a hybrid operational amplifier in which an input front end based on ultra-low-noise discrete JFET devices is used to minimize this noise contribution. When using IF3602 JFETs for the input stage, the equivalent voltage noise of the hybrid operational amplifier can be as low as 4 nV/√Hz, 2 nV/√Hz, and 0.9 nV/√Hz at 1 Hz, 10 Hz, and 1 kHz, respectively. When testing the current noise of an ideal 1 kΩ resistor, these values correspond to a current noise contribution of the same order as or below that of the thermal noise of the resistor. Therefore, in cases in which the current flicker noise is dominant, i.e., much higher than the thermal noise, the noise contribution from the transimpedance amplifier can be neglected in most cases of interest. Test measurements on advanced low-impedance photodetectors are also reported to demonstrate the effectiveness of our proposed approach for directly measuring low-frequency current noise in biased low-impedance electronic devices. [ABSTRACT FROM AUTHOR]

In this work, we experimentally analyze the periodic oscillations that take place in staircase APDs with separate absorption and multiplication regions when operating under continuous laser light. These oscillations increase in frequency when the APD gain increases. We have verified that they are not affected by the parameters (gain and bandwidth) of the transimpedance amplifier, and thus originate inside the APD. The phenomenon is analyzed systematically by considering devices with different thicknesses of the absorption region. Possible physical interpretations related to the flux of holes generated by impact ionization are provided. [ABSTRACT FROM AUTHOR]

This paper presents three different types of on-chip avalanche photodiodes (APDs) realized in a TSMC 180 nm 1P6M RF CMOS process, i.e., a P+/N-well (NW) APD for its high responsivity and large bandwidth by excluding slow diffusion currents; a P+/Deep N-well (DNW) APD for its improved near-infrared (NIR) sensitivity; and a P+/NW/DNW APD for its capability to prevent premature edge breakdown and improve NIR sensitivity. Thereafter, a conventional voltage-mode optoelectronic receiver (V-OER) was realized to confirm the feasibility of the three on-chip APDs. However, the measured results of the V-OER demonstrate a very narrow dynamic range. Therefore, we propose a current-mode optoelectronic receiver (C-OER) realized in the same CMOS process for the applications of short-range LiDAR sensors, where current-conveyor input buffers are exploited to deliver the photocurrents with no significant signal loss to the following inverter cascode transimpedance amplifier, hence resulting in an extended dynamic range. The optically measured results of the C-OER with an 850 nm laser source demonstrate large output pulses. The C-OER chip consumes 47.8 mW from a 1.8 V supply and the core occupies 0.087 mm2. [ABSTRACT FROM AUTHOR]

In this work real‐time ultraviolet photodetectors are realized through metal‐semiconductor‐metal (MSM) structures. Amorphous indium gallium zinc oxide (a‐IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an allenhancement a‐IGZO thin film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES and a good noise equivalent power value NEP. [ABSTRACT FROM AUTHOR]

The recording and analysis of biomagnetic fields have widespread applications in medical research and diagnostics. Wearable magnetic field sensors offer a noncontact and portable method for sensing biopotentials. This article presents a readout circuit in 180-nm CMOS for strain-modulated multiferroic vector magnetic field sensors. By utilizing a demodulator-first architecture, the circuit bandwidth and dynamic range requirements are greatly reduced allowing for a low power consumption of 5.9 mW. The circuit bandwidth is from 76 mHz to 2.2 kHz, allowing for measurement across the range of interest for biomagnetic signals. Utilizing a modulation noise cancellation technique, the noise performance of the sensor system is significantly improved, and the sensor modulation amplitude can be increased, resulting in improved sensor sensitivity. Measurements for the sensor-readout system demonstrate a 144 pT/ $\surd $ Hz magnetic noise floor at 1 kHz. The noise and power consumption are significantly lower than alternative magnetic sensor systems of similar volume.

This paper presents a 2.4/5 GHz dual-band low-noise and highly linear receiver (RX) for IEEE 802.11a/b/g/n/ac/ax applications. The RX employs an RF front-end architecture composing a balun-low-noise transconductance amplifier, current-mode passive mixers, and transimpedance amplifiers (TIAs) to achieve compactness, low noise, and high linearity. A novel power-efficient feedforward operational amplifier architecture was also implemented in the TIA design to achieve the target RX error vector magnitude (EVM) of less than −35 dB with modulation and coding scheme 11 and 1024 quadrature amplitude modulation. Fabricated in a 22-nm SOI CMOS process, the RX achieved noise figures of 2.1/4.2 dB, in- band input-referred third-order intercept points of −11.8/−7.5 dBm, EVMs of −46.4/−44.6 dB for the 2.4/5 GHz bands, respectively. It drew a bias current of 21 mA from a nominal supply voltage of 0.8 V. The active die area was 0.65 mm2.

This paper presents a highly linear and wideband transimpedance amplifier (TIA) suitable for 5G Sub-6 GHz surface acoustic wave (SAW) filter-less receivers (RX). It is known that for the baseband TIA in a SAW-less RX, the high out-of-band (OOB) linearity is necessary to cope with huge OOB blockers. In other words, the input impedance ( $Z_{in}$ ) of the TIAs should be as low as possible, which in turn necessitates high-gain, large-bandwidth (BW) operational transconductance amplifiers (OTA). In this work, a pseudo-differential two-stage OTA with 46 dB open-loop gain and 1 GHz unity-gain loop bandwidth (UGLB) is designed at low supply voltage (Vdd). To stabilize the differential mode (DM) loop, the phase margin (PM) is compensated with the zeros generated by the series of resistors and capacitors (R-C), and the gain margin is improved by the feed-forward technique. To stabilize the common mode (CM) loop without the degradation of the DM gain, a wideband common mode rejection (CMR) technique named cascode negative resistance (CNR) is proposed. This TIA prototype is implemented in a 40 nm low-power (LP) CMOS technology. The measured results show that the TIA achieves 56 MHz BW and 29.5 dBm OOB IIP3. The input impedance is below $29 \Omega $ in the concerned frequency range and the in-band (IB) input referred noise (IRN) is $120 uV_{RMS}$ . The total chip power consumption is around 8.5 mW at 1.2 V supply voltage and the core area is as small as $0.015 mm^{2}$ .

This work presents the development of an automatic and customized measuring system employing sigma-delta analog-to-digital converters and transimpedance amplifiers for precise measurements of voltage and current signals generated by microbial fuel cells (MFCs). The system can perform multi-step discharge protocols to accurately measure the power output of MFCs, and has been calibrated to ensure high precision and low noise measurements. One of the key features of the proposed measuring system is its ability to conduct long-term measurements with variable time steps. Moreover, it is portable and cost-effective, making it ideal for use in laboratories without sophisticated bench instrumentation. The system is expandable, ranging from 2 to 12 channels by adding dual-channel boards, which allows for testing of multiple MFCs simultaneously. The functionality of the system was tested using a six-channel setup, and the results demonstrated its ability to detect and distinguish current signals from different MFCs with varying output characteristics. The power measurements obtained using the system also allow for the determination of the output resistance of the MFCs being tested. Overall, the developed measuring system is a useful tool for characterizing the performance of MFCs, and can be helpful in the optimization and development of sustainable energy production technologies. [ABSTRACT FROM AUTHOR]

An ultra-low-noise large-bandwidth transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. The TIA connected with the tip-sample component in CryoSTM is called as CryoSTM-TIA. Its transimpedance gain is as high as 1 GΩ, and its bandwidth is over 300 kHz, but its equivalent input noise current power spectral density is less than 4 (fA)2/Hz at 100 kHz. The low inherent noise for the CryoSTM-TIA is due to its special design: (1) its pre-amplifier is made of a pair of low-noise cryogenic high electron mobility transistors (HEMTs); (2) the noise generated by one HEMT is eliminated by a large capacitor; (3) the capacitance of the cable connected the gate of the other HEMT to the tip is minimized; (4) thermal noise sources, such as the feedback resistor, are placed in the cryogenic zone. The dc output voltage drift of the CryoSTM-TIA is very low, as 5 μV/°C. The apparatus can be used for measuring the scanning tunneling differential conductance spectra, especially the scanning tunneling shot noise spectra (STSNS) of quantum systems, even if the shot noise is very low. It provides a universal tool to study various novel quantum states by measuring STSNS, such as detecting the Majorana bound states. [ABSTRACT FROM AUTHOR]

In this work, real-time ultraviolet photodetectors are realized through metal-semiconductor-metal (MSM) structures. Amorphous indium gallium zinc oxide (a-IGZO) is used as semiconductor material and gold as metal electrodes. The readout of an individual sensor is implemented by a transimpedance amplifier (TIA) consisting of an all-enhancement a-IGZO thin-film transistor (TFT) operational amplifier and a switched capacitor (SC) as feedback resistance. The photosensor and the transimpedance amplifier are both manufactured on glass substrates. The measured photosensor possesses a high responsivity R, a low response time tRES, and a good noise equivalent power value NEP. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reflection fiber temperature sensors functionalized with plasmonic nanocomposite material using intensity-based modulation are demonstrated for the first time. Characteristic temperature optical response of the reflective fiber sensor is experimentally tested using Au-incorporated nanocomposite thin films deposited on the fiber tip, and theoretically validated using a thin-film-optic-based optical waveguide model. By optimizing the Au concentration in a dielectric matrix, Au nanoparticles (NP) exhibit a localized surface plasmon resonance (LSPR) absorption band in a visible wavelength that shows a temperature sensitivity ~0.025%/°C as a result of electron–electron and electron–phonon scattering of Au NP and the surrounding matrix. Detailed optical material properties of the on-fiber sensor film are characterized using scanning electron microscopy (SEM) and focused-ion beam (FIB)-assisted transmission electron microscopy (TEM). Airy's expression of transmission and reflection using complex optical constants of layered media is used to model the reflective optical waveguide. A low-cost wireless interrogator based on a photodiode transimpedance-amplifier (TIA) circuit with a low-pass filter is designed to integrate with the sensor. The converted analog voltage is wirelessly transmitted via 2.4 GHz Serial Peripheral Interface (SPI) protocols. Feasibility is demonstrated for portable, remotely interrogated next-generation fiber optic temperature sensors with future capability for monitoring additional parameters of interest. [ABSTRACT FROM AUTHOR]

Free Space Optic Communication (FSO) is one of the communication systems chosen for 5G + / 6G backhaul. Many works were done to improve signal quality either at emission, transmission channel or at reception through photodetector. The aim of this work is to design a new transimpedance amplifier (TIA) to improve Free Space Optic Communication (FSO) photodetector performance. To achieve our purpose, a negative electrical resistance was introduced into conventional TIA. SPICE software and Kirchhoff's laws were used to design and analyze the circuit. The obtained results show that the new TIA has a better amplitude gain response and lower equivalent noise than conventional TIAs. High bandwidth and flat amplitude response in the pass band characterize our TIA. This characteristic is one of the two criteria for a photodetector to be considered as a quantum device. A 3D gain representation highlights different regions of positive and negative feedback resistors and frequencies to be used or avoided in order to ensure TIA stability.

Summary: This paper proposes an inductorless fully differential transimpedance amplifier (TIA) with a single‐ended photo current to offer high bandwidth for applications of beyond 10 Gb/s optical communications. The presented TIA provides a much lower input impedance by modifying the cross‐coupled regulated cascode (CC‐RGC) configuration. The introduced method is able to enhance the bandwidth in the presence of wide range of input photodiode capacitance from small to large values, with a negligible increase in the peaking of frequency response. The proposed circuit is designed and simulated using the TSMC 130‐nm CMOS technology to validate the proposed technique. The post‐layout simulation results show that the TIA delivers a transimpedance gain of 46.5 dB Ω, a bandwidth of 8.8 GHz, and an input‐referred current noise of 33 pA/√Hz. The circuit occupies an active area of 0.004 mm2 and consumes 9.8 mW from a 1.3 V supply. Furthermore, the robustness of the proposed TIA is verified by means of the Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

A low-noise high-gain large-bandwidth transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. The TIA connected with the tip-sample component in CryoSTM is called as CryoSTM-TIA. The CryoSTM-TIA has a transimpedance gain of 10 G Ω , a bandwidth of over 100 kHz, and an equivalent input noise current power spectral density less than 4 (fA) 2 / Hz at 100 kHz. The low inherent noise of the CryoSTM-TIA is due to its special design: (1) its pre-amplifier (Pre-Amp) is made of the low-noise cryogenic high electron mobility transistors; (2) the cascode-type configuration for the Pre-Amp is used to avoid Miller effect to reduce its input capacitance C A ; (3) the capacitance of the cable connected the Pre-Amp input to the tip, i.e., C I , is minimized; (4) thermal noise sources, such as the feedback resistor, are placed in the cryogenic zone. Its high gain and large-bandwidth are realized together, due to the application of the frequency compensation in the feedback loop, the reduced C A , and the minimized C I . This apparatus can be used for fast high-energy-resolution measurements of scanning tunneling spectra for low conductivity materials, especially for measuring their scanning tunneling shot noise spectra. [ABSTRACT FROM AUTHOR]

In-situ measurements of ultraviolet (UV) and solar irradiance is very sparse in Nigeria because of cost; it is estimated using meteorological parameters. In this work, a low-cost UV and pyranometer device, using locally sourced materials, was developed. The instrument consists of a UV sensor (ML8511), a photodiode (BPW34) housed in a carefully sealed vacuumed glass bulb, the UV and solar irradiance sensor amplifiers, a 16-bit analog-to-digital converter (ADS1115), Arduino mega 2560, liquid crystal display (LCD) and microSD card for data logging. The designed amplifier has an offset voltage of 0.8676 mV. The sensitivity of the irradiance device is 86.819 Wm-2/mV with a correcting factor of 27.77 Wm-2 and a maximum range of 1200 Wm-2. The instrument validation error is 9.67% and a correlation coefficient of 0.89 when compared with a standard SRS100 pyranometer. The UV sensor showed a close response with a correlation of 0.99 in comparison with a standard Skye instrument. From 08:00 to 16:00 local time (LT), there is a very close agreement between the standard device and the developed counterpart, with marginal differences of about 9.6% observed at the two extremes. [ABSTRACT FROM AUTHOR]

This paper reports on a CMOS fully integrated optoelectronic sensing system composed of a Si photodiode and a transimpedance amplifier acting as the electronic analog front-end for the conditioning of the photocurrent generated by the photodiode. The proposed device has been specifically designed and fabricated for wearable/portable/implantable biomedical applications. The massive employment of sensor systems in different industrial and medical fields requires the development of small sensing devices that, together with suitable electronic analog front ends, must be designed to be integrated into proper standard CMOS technologies. Concerning biomedical applications, these devices must be as small as possible, making them non-invasive, comfortable tools for patients and operating with a reduced supply voltage and power consumption. In this sense, optoelectronic solutions composed of a semiconductor light source and a photodiode fulfill these requirements while also ensuring high compatibility with biological tissues. The reported optoelectronic sensing system is implemented and fabricated in TSMC 180 nm integrated CMOS technology and combines a Si photodiode based on a PNP junction with a Si area of 0.01 mm2 and a transimpedance amplifier designed at a transistor level requiring a Si area of 0.002 mm2 capable to manage up to nanoampere input currents generated by the photodiode. The transimpedance amplifier is powered at a 1.8 V single supply showing a maximum power consumption of about 54 μW, providing a high transimpedance gain that is tunable up to 123 dBΩ with an associated bandwidth of about 500 kHz. The paper reports on both the working principle of the developed ASIC and the experimental measurements for its full electrical and optoelectronic characterizations. Moreover, as case-examples of biomedical applications, the proposed integrated sensing system has also been validated through the optical detection of emulated standard electrocardiography and photoplethysmography signal patterns. [ABSTRACT FROM AUTHOR]

This paper presents the design and testing of an ultra-low-noise transimpedance amplifier (TIA) for low-frequency noise measurements on low-impedance (below 1 kΩ) devices, such as advanced IR photodetectors. When dealing with low-impedance devices, the main source of background noise in transimpedance amplifiers comes from the equivalent input voltage noise of the operational amplifier, which is used in a shunt–shunt configuration to obtain a transimpedance stage. In our design, we employ a hybrid operational amplifier in which an input front end based on ultra-low-noise discrete JFET devices is used to minimize this noise contribution. When using IF3602 JFETs for the input stage, the equivalent voltage noise of the hybrid operational amplifier can be as low as 4 nV/√Hz, 2 nV/√Hz, and 0.9 nV/√Hz at 1 Hz, 10 Hz, and 1 kHz, respectively. When testing the current noise of an ideal 1 kΩ resistor, these values correspond to a current noise contribution of the same order as or below that of the thermal noise of the resistor. Therefore, in cases in which the current flicker noise is dominant, i.e., much higher than the thermal noise, the noise contribution from the transimpedance amplifier can be neglected in most cases of interest. Test measurements on advanced low-impedance photodetectors are also reported to demonstrate the effectiveness of our proposed approach for directly measuring low-frequency current noise in biased low-impedance electronic devices.

Recently published CMOS optical receivers consist of a limited-bandwidth first-stage transimpedance amplifier (TIA) followed by an equalizer. Limiting the TIA’s bandwidth improves the gain and reduces the noise but introduces a significant inter-symbol interference (ISI) that is dealt with by the subsequent equalizer. Continuous-time linear equalizer (CTLE) is a commonly used equalizer in both electrical and optical links. However, recent research reported different findings about CTLE-based optical receivers. Some research papers concluded that CTLEs boost high-frequency noise compared to a full-bandwidth design. Other publications reported that high-frequency noise remains unaffected while white noise is significantly reduced. This work aims to solve this discrepancy by presenting an accurate analysis for CTLE-based optical receivers considering noise, gain, and jitter. We show that the noise performance depends on the pole/zero locations of the limited-bandwidth (LBW)-TIA and the follow-on equalizer. A properly designed CTLE-based receiver achieves a $2.5 \times $ higher gain and a $1.74\times $ better noise than the full-bandwidth design. The CTLE is also compared to the well-known decision feedback equalizer (DFE). The noise performance of the CTLE-based receiver lies between that of finite and infinite impulse response DFE-based receivers but achieves better gain than both architectures.

In this paper, a transformer-based bandwidth (BW) extension technique is employed to improve the BW, noise, and silicon area of inverter-based transimpedance amplifiers (TIAs) even when they use inductive peaking. A TIA based on the proposed technique, designed and laid out in a 16-nm FinFET process, demonstrates a 36% increased in BW, a 19% reduction in input-referred noise, and a 57% reduction in silicon area compared to the conventional TIA with inductive peaking. In the proposed TIA architecture, inclusion of a transformer in the forward path compensates partially for the parasitic capacitances of the inverter and relaxes the transimpedance limit of the conventional TIA. The proposed technique also lowers the input-referred current noise spectrum of the TIA. Post-layout in companion with electromagnetic (EM) simulations and statistical analysis are employed to verify the effectiveness of the proposed architecture. Simulation results show that the TIA achieves a transimpedance gain of 58 dB $\Omega $ , a BW of 17.4 GHz, an input-referred noise of 17.4 pA/sqrt (Hz), and an eye-opening of 20 mV at a data-rate of 64 Gbps PAM4 and at a bit-error-rate (BER) of 1E-6. The whole TIA chain is expected to consume 19 mW and occupies an active area of 0.023 mm2.

This article explores the power-sensitivity trade-off in optical receivers aiming to improve the energy-efficiency of the overall link. Optical receivers with field-effect transistor (FET) front-ends (FEs) are usually designed for optimal noise performance by matching the circuit’s input capacitance $\left ({C_{I} }\right)$ to the total input parasitic capacitance $\left ({C_{D} }\right)$ . However, the receiver’s power dissipation is also proportional to the input capacitance $C_{I}$ . Therefore, this paper studies the feasibility of the capacitive matching rule in the context of minimizing the power dissipation of the overall link. For that purpose, design trade-offs for the receiver, transmitter, and the overall link are presented. Comparisons are made to study how much the receiver can be downsized, sacrificing optimal noise performance, before its power reduction is offset by the transmitter’s increase in power. Simulation results show that energy-efficient links require low-power receivers with input capacitance much smaller than that required for noise-optimum performance. As an example, for a 25 Gb/s operation, an optical loss budget of 12.6 dB, and a receiver designed in 65 nm CMOS technology with $C_{D}$ of 200 fF, the overall link dissipates 2.55 pJ/bit when the receiver’s noise is minimized, leading to a receiver with $C_{I}/C_{D}=1.29$ . When optimized for overall link efficiency, the receiver size is significantly reduced to $C_{I}/C_{D}=0.38$ and the link’s energy-efficiency also improves to 1.41 pJ/bit. If the link budget or knowledge of the transmitter side is incomplete, our analysis indicates that maximizing gain with value of $C_{I}/C_{D}=0.5$ is a reasonable choice.

We report on fabricated titanium dioxide (TiO2) thin films along with a transimpedance amplifier (TIA) test setup as a photoconductivity detector (sensor) in the ultraviolet-C (UV-C) wavelength region, particularly at 260 nm. TiO2 thin films deposited on high-resistivity undoped silicon-substrate at thicknesses of 100, 500, and 1000 nm exhibited photoresponsivities of 81.6, 55.6, and 19.6 mA/W, respectively, at 30 V bias voltage. Despite improvements in the crystallinity of the thicker films, the decrease in photocurrent, photoconductivity, photoconductance, and photoresponsivity in thicker films is attributed to an increased number of defects. Varying the thickness of the film can, however, be leveraged to control the wavelength response of the detector. Future development of a chip-based portable UV-C detector using TiO2 thin films will open new opportunities for a wide range of applications. [ABSTRACT FROM AUTHOR]

This article presents a transimpedance amplifier (TIA) design suitable for 1 Gbps operation using a 4-level pulse amplitude modulation scheme. It is aimed toward communication protocols with large-area photodetectors, such as plastic-optical-fiber, visible light communications, and biomedical applications. The TIA leverages a flipped-voltage-follower as well as global current feedback to extend the bandwidth of the TIA and operates up to 400 MHz with a very low static power while driving a very large capacitance. The TIA has a static power consumption of only 1.2 mW at a 1 V supply voltage. Additionally, the fully-differential version of the proposed TIA is introduced in the case of using spatially-modulated light detectors. The design is validated with post-layout simulations employing a commercially available 40 nm CMOS process. Mismatch and corner simulations demonstrate that the proposed TIA can still provide the specifications in the worst-case scenarios. [ABSTRACT FROM AUTHOR]

In this work, a design of transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. TIA with the tip-sample component in CryoSTM is called as CryoSTM-TIA. With transimpedance gain of 1 GΩ, the bandwidth of the CryoSTM-TIA is larger than 200 kHz. The distinctive feature of the proposed CryoSTM-TIA is that its pre-amplifier is made of a single cryogenic high electron mobility transistor (HEMT), so the apparatus equivalent input noise current power spectral density at 100 kHz is lower than 6 (fA) 2 /Hz. In addition, "bias-cooling method" can be used to in-situ control the density of the frozen DX - centers in the HEMT doping area, changing its structure to reduce the device noises. With this apparatus, fast scanning tunneling spectra measurements with high-energy-resolution are capable to be performed. And, it is capable to measure scanning tunneling shot noise spectra (STSNS) at the atomic scale for various quantum systems, even if the shot noise is very low. It provides a powerful tool to investigate novel quantum states by measuring STSNS, such as detecting the existence of Majorana bound states in the topological quantum systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In this work, we experimentally analyze the periodic oscillations that take place in staircase APDs with separate absorption and multiplication regions when operating under continuous laser light. These oscillations increase in frequency when the APD gain increases. We have verified that they are not affected by the parameters (gain and bandwidth) of the transimpedance amplifier, and thus originate inside the APD. The phenomenon is analyzed systematically by considering devices with different thicknesses of the absorption region. Possible physical interpretations related to the flux of holes generated by impact ionization are provided.

To meet the high time-resolution requirements of a fast ionization profile monitor (IPM), a 64-channel electrical signal acquisition system with a fast response frequency of 1 MHz has been developed. This article initially describes an ultralow noise transimpedance amplifier, which is an analog front-end (AFE) electronics aiming to achieve a balance between the accuracy and bandwidth, as well as to truly reflect the microstructure of short beam pulses. Subsequently, a synchronized multichannel data transmission system based on field-programmable gate arrays (FPGAs) transmits data streaming with the low latency and high throughput, and meanwhile, it provides data homogeneity in time across channels. The system is designed in a modular way to easily extend up to 128 channels. The nonlinearity of the readout electronics is less than 0.2% in the dynamic range of 15 nA– $15~\mu \text{A}$ , and the relative resolution is 0.15% at the input current of 15 $\mu \text{A}$. The spurious-free dynamic range (SFDR) is about 82.43 dB at a fundamental frequency of 1 kHz, and the effective number of bits (ENOB) of the analog-to-digital conversion (ADC) is better than 13 bits. The relative synchronization time discrepancy between channels is better than 2.5% of the sampling cycle. Finally, the system is deployed for the beam profile measurement with an IPM. The obtained peak value shows a good proportionality with the beam intensity increment, and all the electronics properties achieve reasonable and excellent performance. [ABSTRACT FROM AUTHOR]

In this work, it is presented a unified model to integrate a radiation detector on a single chip using TFTs-based amplifiers, to fabricate a low-cost thermal neutron detector system. The model is based on the current-voltage experimental measurements of the CdS/CdTe detector and CMOS Si-Poly TFTs technology. Parameters obtained by $I-V$ and $C$ - $V$ analysis were introduced into Smart SPICE to design the amplifiers. The output voltage was simulated for a neutron capture event. Three amplification topologies were studied, obtaining an output voltage in the range of 180 to 260 mV with a generated photocurrent pulse around 3.5 $\mu \text{A}$ , which is high enough to be interfaced with a microcontroller. The neutron detector is integrated into TFT amplifiers with a gain of around 50 dB and bandwidth of 4.7 MHz at −3 dB. [ABSTRACT FROM AUTHOR]

Aiming at the high complexity of the mathematical model of short channel transistor, a gm/Id method is proposed to describe the short channel transistor model. This method optimizes the circuit performance by establishing the relationship between the circuit index and transistor size. The experiment result shows that the transimpedance amplifier with a photodetector capacitance of 250 fF can achieve a gain of 59.72 dBΩ, a bandwidth of 3.445 GHz, an input referred current noise of 6.209×10-3 nA/sqrt/Hz and equivalent input noise current of 876.0 nA. The design dissipates 7.5 mW from a 1.2 V supply. The test results show that, when 100 μA current is input, the peak to peak data jitter of the circuit is about 64.92 ps, and the output swing is 81.1 mW.

Reflection fiber temperature sensors functionalized with plasmonic nanocomposite material using intensity-based modulation are demonstrated for the first time. Characteristic temperature optical response of the reflective fiber sensor is experimentally tested using Au-incorporated nanocomposite thin films deposited on the fiber tip, and theoretically validated using a thin-film-optic-based optical waveguide model. By optimizing the Au concentration in a dielectric matrix, Au nanoparticles (NP) exhibit a localized surface plasmon resonance (LSPR) absorption band in a visible wavelength that shows a temperature sensitivity ~0.025%/°C as a result of electron–electron and electron–phonon scattering of Au NP and the surrounding matrix. Detailed optical material properties of the on-fiber sensor film are characterized using scanning electron microscopy (SEM) and focused-ion beam (FIB)-assisted transmission electron microscopy (TEM). Airy’s expression of transmission and reflection using complex optical constants of layered media is used to model the reflective optical waveguide. A low-cost wireless interrogator based on a photodiode transimpedance-amplifier (TIA) circuit with a low-pass filter is designed to integrate with the sensor. The converted analog voltage is wirelessly transmitted via 2.4 GHz Serial Peripheral Interface (SPI) protocols. Feasibility is demonstrated for portable, remotely interrogated next-generation fiber optic temperature sensors with future capability for monitoring additional parameters of interest.