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Silicon-based kinetic energy converters employing variable capacitors, also known as electrostatic vibration energy harvesters, hold promise as power sources for Internet of Things devices. However, for most wireless applications, such as wearable technology or environmental and structural monitoring, the ambient vibration is often at relatively low frequencies (1–100 Hz). Since the power output of electrostatic harvesters is positively correlated to the frequency of capacitance oscillation, typical electrostatic energy harvesters, designed to match the natural frequency of ambient vibrations, do not produce sufficient power output. Moreover, energy conversion is limited to a narrow range of input frequencies. To address these shortcomings, an impacted-based electrostatic energy harvester is explored experimentally. The impact refers to electrode collision and it triggers frequency upconversion, namely a secondary high-frequency free oscillation of the electrodes overlapping with primary device oscillation tuned to input vibration frequency. The main purpose of high-frequency oscillation is to enable additional energy conversion cycles since this will increase the energy output. The devices investigated were fabricated using a commercial microfabrication foundry process and were experimentally studied. These devices exhibit non-uniform cross-section electrodes and a springless mass. The non-uniform width electrodes were used to prevent pull-in following electrode collision. Springless masses from different materials and sizes, such as 0.5 mm diameter Tungsten carbide, 0.8 mm diameter Tungsten carbide, zirconium dioxide, and silicon nitride, were added in an attempt to force collisions over a range of applied frequencies that would not otherwise result in collisions. The results show that the system operates over a relatively wide frequency range (up to 700 Hz frequency range), with the lower limit far below the natural frequency of the device. The addition of the springless mass successfully increased the device bandwidth. For example, at a low peak-to-peak vibration acceleration of 0.5 g (peak-to-peak), the addition of a zirconium dioxide ball doubled the device's bandwidth. Testing with different balls indicates that the different sizes and material properties have different effects on the device's performance, altering its mechanical and electrical damping. [ABSTRACT FROM AUTHOR]

The detection of gaseous refrigerants, necessary for industrial control and environmental monitoring, is explored using rotational spectroscopy in the THz wave region. Rotational absorption spectra for two widely used commercial hydrofluorocarbon (HFC) refrigerants, 1,1,1,2-tetrafluoroethane (R-134a or HFC-134a) and 2,3,3,3-tetrafluoropropene (R-1234yf or HFO-1234yf), are characterized in the 220–330 GHz frequency range at room temperature (297 K) and modest pressures (0.25–8 Torr) using a compact microelectronics-based THz wave spectrometer. The absorption spectra illustrate complex, broad, and repeating structures that result from the blending of hundreds of pressure-broadened rotational lines. The unique and distinct spectra for R-134a illustrate potential for its detection in the present frequency region with estimated detection limits approaching 15 ppm per meter path length in 1 atm of air. The spectra for R-1234yf are less distinct than those for R-134a and illustrate complex structured rotational absorption features in combination with an underlying quasi-continuous absorption that increases in strength to higher frequencies. To our knowledge, this is the first experimental characterization for the spectra of R-134a and R-1234yf in this frequency region. [ABSTRACT FROM AUTHOR]

Featured Application: Gas Sensing. Gas sensing for dimethyl sulfoxide (DMSO) based on rotational absorption spectroscopy is demonstrated in the 220–330 GHz frequency range using a robust electronic THz-wave spectrometer. DMSO is a flammable liquid commonly used as a solvent in the food and pharmaceutical industries, materials synthesis, and manufacturing. DMSO is a hazard to human health and the work environment; hence, remote gas sensing for DMSO environmental and process monitoring is desired. Absorption measurements were carried out for pure DMSO at 297 K and 0.4 Torr (53 Pa). DMSO was shown to have a unique rotational fingerprint with a series of repeating absorption bands. The frequencies of transitions observed in the present study were found to be in good agreement with spectral simulations carried out based on rotational parameters derived in prior work. Newly, intensities of the rotational absorption lines were experimentally observed and reported for DMSO in this study. Measured intensities for major absorption lines were found in very good agreement with relative line intensities estimated by quantum mechanical calculations. The sensor developed here exhibited a detection limit of 1.3 × 1015–2.6 × 1015 DMSO molecules/cm3 per meter of absorption path length, with the potential for greater sensitivity with signal-to-noise improvements. The study illustrates the potential of all electronic THz-wave systems for miniaturized remote gas sensors. [ABSTRACT FROM AUTHOR]

The panel sessions at this year's IEEE International Microwave Symposium (IMS) Week, scheduled during lunches, cover a broad range of topics and events spanning the week. Panel sessions are (co)sponsored by the IEEE Radio Frequency Integrated Circuits (RFIC) Symposium, the IEEE Microwave Theory and Techniques Society's (MTT-S) IMS, and the Automatic Radio Frequency Techniques Group (ARFTG) Microwave Measurement Conference. The various sessions are briefly described. [ABSTRACT FROM AUTHOR]

This article presents a 148-GHz coupled loop fundamental oscillator with a quad-feed octagonal slot antenna. The proposed loop configuration with a multi-feed antenna leads to each oscillator experiencing multiple injected signals. An analysis is performed to explain the dynamics of the coupled loop oscillator in the presence of multiple signal-injection paths. It is shown that the proposed oscillator configuration will only operate with $- \pi /2$ phase between the adjacent oscillators. This phase difference is necessary for the quad-feed antenna to combine and radiate the output power from the four single-ended oscillators in the loop. The output from each oscillator is ac coupled to the following oscillator stage using a phase compensating capacitor, whose value is selected to enhance the oscillation frequency of the coupled loop. The use of buffer stages is avoided in favor of a passive power feed network for extraction of the output power from each oscillator. The proposed oscillator is fabricated in a 22-nm FDSOI process and has a 0.5-mm2 chip area. The measured peak effective isotropic radiated power (EIRP) of the oscillator is 9.7 dBm with a corresponding dc-EIRP efficiency of 34.3% when operating from a 0.8-V supply. To the authors’ knowledge, this dc-EIRP efficiency is the highest among reported oscillators to date operating between 100 and 200 GHz. [ABSTRACT FROM AUTHOR]

In this paper, a twin-FET (field effect transistor) THz detector monolithically integrated with a dual-feed antenna is presented. The antenna-detector configuration can be extended for ’N’ FET elements to relax the input impedance requirement for the detector readout circuitry while maintaining good responsivity. A dual-feed octagonal slot antenna is used to couple THz radiation and provide differential excitation to the twin-FET detector. The multi-feed antenna-FET detector interface can be designed for an arbitrary phase excitation of one or more FET elements. Fabricated in Global Foundries 22nm FD-SOI process, the proposed detector covers a measured frequency range from 220 GHz to 300 GHz. Such bandwidth is sufficiently wide to capture reliable spectral information for distinguishing a number of gases in a mixture. The absorption spectra of pure methanol, chloromethane and acetonitrile are measured using a rotational spectroscopy setup incorporating the twin-FET detector. Detection of a small concentration of acetonitrile, at 4 Torr pressure, is demonstrated in a binary mixture with predominantly chloromethane. Detection of ethanol and methanol in their binary mixture is also demonstrated at 4 Torr pressure. This is a significant step towards the development of all-electronic THz spectroscopy for the detection of volatile organic compounds (VOCs) in the presence of contaminants with a strong THz absorption signature at >1 Torr pressure. [ABSTRACT FROM AUTHOR]

This paper studies the effect of amplitude and phase mismatch on the power conversion efficiency of differentially-drive rectifiers employing cross-coupled MOSFETs. The analysis begins by defining the different operational regions of the differential rectifier and how the common-mode interference resulting from amplitude and phase mismatches affects the symmetrical operation of the rectifier. A mathematical model is developed to estimate the output voltage and the power conversion efficiency under such mismatching conditions. Simulation and measurement results are provided to validate the mathematical model through the design of a three-stage differential rectifier in 0.13 μ m CMOS technology. Modification to the original rectifier design using a tail load topology is also proposed to reduce the effect of mismatches. [ABSTRACT FROM AUTHOR]

This study presents a push--push oscillator architecture based on differential gate equalisation to enhance the oscillation frequency while providing relatively high output power with ultra-compact layout form factor. The frequency enhancement is derived as a function of the equivalent RLC model of the oscillator's main constituents. The proposed principle is applied to a terahertz oscillator in the 200-300 GHz range to mitigate the excessive substrate and skin effect losses in standard digital 65-nm complementary metal--oxide--semiconductor technology at such high frequencies. The design concept is validated using two single-stage push--push oscillators. The first oscillator shows -8.1 dBm output power at 250 GHz oscillation frequency and -106.8 dBc/Hz phase noise at 10 MHz offset while consuming 76 mW power from 1.5 V DC supply voltage. The chip area is 200 x 250 μm². The second oscillator provides -14.8 dBm output power at 285 GHz and -106 dBc/Hz phase noise at 10 MHz offset with 80 mW power consumption from 1.5 V DC supply. The chip area is 200 x 200 μm². [ABSTRACT FROM AUTHOR]

This brief presents a power-efficient, highly linear front-end (FE) integrated circuit (IC) for electrocardiogram (ECG) acquisition applications. Compared to typical FE architectures, the proposed FE uses only one bandpass instrumentation amplifier (IA) to reduce the chip area and dc power consumption. To achieve high linearity, the bandpass IA is composed of a high-gain two-stage amplifier in a capacitive-feedback configuration. Miller compensation and the class-AB output stage are utilized to incorporate the filtering and buffering functions within the IA without the need for additional circuit stages. The FE IC is fabricated in 0.13- ${ \mu }\text{m}$ CMOS technology, and occupies only a 0.16-mm2chip area. The measured input-referred noise is 3.2 ${ \mu }$ Vrms with a midband gain of 34.6 dB, and a bandwidth that extends from 0.9 to 350 Hz. A total harmonic distortion of −65 dB is measured at an input signal of 5.5 mV $_{{pp}}$ , with a dc power consumption of 1.8 ${\mu }\text{W}$. In a real-time measurement, the proposed FE IC is capable of detecting high-fidelity ECG waveforms. [ABSTRACT FROM AUTHOR]

This letter presents a self-alignment system using a continuous and a proportional-to-position-error correction algorithm. The system is designed to address uninterrupted point-to-point high-speed line-of-sight optical wireless links. The alignment correction employs amplitude detection from a mm2scale CMOS-compatible 4-PD array connected to a 4-channel receiver and followed by digital-processing and feedback toward the receiver lens position. The proposed self-alignment method is validated with a receiver position varying over about 5-cm range and a receiver angle covering around ±10 degree with roughly ×4 field-of-view widening due to the automatic alignment. A 50-Mb/s ON-OFF-keying transmission link is maintained across 4 meters distance using a 650-nm-red light-emitting-diode source with a bit-error-rate below the forward-error-correction limit of 3.8 × 10-3. [ABSTRACT FROM PUBLISHER]

This letter presents an on–off-keying visible-light-communication (VLC) link realized over 6-m distance. The transmitter is implemented with a commercially available red LED source at 650 nm. While most of the reported high-performance VLC links are using p-insulator-n photodetectors, this receiver employs a simple CMOS-compatible p-n photo-detector. A 150-Mb/s optical wireless transmission is measured with a bit-error rate of $1.3\times 10^{{\mathbf {-6}}}$ , which falls below the forward error correction limit of $3.8\times 10^{{\mathbf {-3}}}$ . The second-order L-C-R equalization is used in both the transmitter and the receiver circuits to achieve maximum bandwidth extension. The VLC link is realized with a low illuminance of 250 lux. This power is below the common indoor illumination levels which enables advanced lighting-compatible VLC applications. The receiver and the source circuits consume around 240 and 105 mW, respectively, which represents to our knowledge a record energy-per-bit level of 2.3 nJ/b. [ABSTRACT FROM PUBLISHER]

Design, manufacturing and measurements results for silicon plasma wave transistors based wireless communication wideband receivers operating at 300 GHz carrier frequency are presented. We show the possibility of Si-CMOS based integrated circuits, in which by: (i) specific physics based plasma wave transistor design allowing impedance matching to the antenna and the amplifier, (ii) engineering the shape of the patch antenna through a stacked resonator approach and (iii) applying bandwidth enhancement strategies to the design of integrated broadband amplifier, we achieve an integrated circuit of the 300 GHz carrier frequency receiver for wireless wideband operation up to/over 10 GHz. This is, to the best of our knowledge, the first demonstration of low cost 130 nm Si-CMOS technology, plasma wave transistors based fast/wideband integrated receiver operating at 300 GHz atmospheric window. These results pave the way towards future large scale (cost effective) silicon technology based terahertz wireless communication receivers. [ABSTRACT FROM AUTHOR]

In this paper, the design of a low noise charge sensitive preamplifier, suitable for high capacitance solid-state neutron detector arrays, is described. Noise considerations related to arraying multiple detectors in either series or parallel are also presented. Using the designed preamplifier, an energy resolution of 12 keV FWHM in Si is achieved with 1 nF equivalent detector capacitance and 10~\mu\S shaping time. Additionally, a novel preamplifier topology, which utilizes a capacitance canceling input stage, is presented. Detailed analysis of the capacitance cancelling stage is discussed with special consideration given to its use with a charge sensitive preamplifier. Up to a 15% decrease in noise is demonstrated using the capacitance cancelling technique. [ABSTRACT FROM AUTHOR]

This letter presents an amplifier-frequency doubler chain in thin digital 65-nm bulk CMOS process. Injection locking is applied to the amplifier to increase the power gain and compensate for the conversion loss in the frequency doubler. The doubler uses a compact low-impedance transmission line (LZ TLine) for effective dc decoupling in the output matching network. Measurement results show a peak output power of 1.5 mW at 194 GHz, and a peak PAE of 0.4% at 196 GHz. The locking range is measured as 8.5 GHz (92.5~101 GHz) with 2-dBm input fundamental power, and can be extended to 15 GHz with 4-dBm input power. [ABSTRACT FROM PUBLISHER]

This letter proposes a low-power energy harvesting circuit (EHC) that performs synchronous energy conversion on a triplate variable capacitor to improve the maximum achievable output power. A triplate macro-scale electrostatic generator with capacitor variation of 405\,\pF to 1.15\,\nF and 405\,\pF to 1.07\,\nF on two complementary adjacent capacitors operating 180^\circ out of phase at 98\,\Hz is fabricated and used in the characterization of the designed EHC. The integrated circuit is fabricated using AMI 0.7-\mu \M high-voltage CMOS process and tested with the triplate capacitor to demonstrate mechanical to electric energy conversion. At steady state, the EHC produces 3.26 \nJ/cycle, including energy flyback losses. This results in a total output power of approximately 308 \nW on a 10- \mu \F reservoir capacitor from a 98- \Hz vibration signal. [ABSTRACT FROM AUTHOR]

This work explores the potential of microwave heating for applications requiring parallel DNA amplification platforms. Device characterization and thermal modeling is performed on 4.1 μl microfluidic chamber fabricated in polycarbonate. Microwave power at 6 GHz is delivered to the chamber via copper transmission line in a microstrip configuration. Microwave power reflection coefficient and temperature measurements are performed to characterize the power coupled to the chamber and rate of change in temperature. Temperatures up to 72 °C are achieved with less than 400 mW power applied at the input of the transmission line. Initial heating and cooling rates measured experimentally are ∼7 and ∼6 °C/s, respectively. These results suggest that microwave heating is an efficient, rapid heating technique suitable for programmable, parallel DNA amplification platforms to be empolyed in future genetic analysis systems. [ABSTRACT FROM AUTHOR]

Gas sensing by THz wave absorption spectroscopy is demonstrated for several volatile organic compounds (VOCs) using a broadband electronics-based THz wave spectrometer. Spectral absorption is characterized in the frequency range from 220 to 330 GHz for seven VOCs and water vapor in a gas cell at room temperature and pressures of 0.5–10 Torr. Amplitude-modulation is applied to the interrogating radiation, and lock-in detection is used to acquire the transmitted frequency-dependent radiation intensity. For methanol, ethanol, n-propanol, formic acid, formaldehyde, acetaldehyde, acetone, and water vapor, measured transition frequencies agree with literature databases, where available. The present work demonstrates the potential for an all-electronic THz gas sensor for conditions where pressure broadening and line blending occur, as would be found in typical industrial, environmental, and biological gas sensing applications. [ABSTRACT FROM AUTHOR]

The potential of THz wave electronics for miniaturized non-intrusive sensors for atmospheric, environmental, and industrial gases is explored. A THz wave spectrometer is developed using a radio-frequency multiplier source and a Schottky-diode detector. Spectral absorption measurements were made in a gas cell within a frequency range of 220-330 GHz at room temperature and subatmospheric pressures. Measurements are reported for pure acetonitrile (CH3CN), methanol (CH3OH), and ethanol (C2H5OH) vapors at 5 and 10 Torr and for methanol dilute in the air (0.75-3.0 mol%) at a pressure of 500 Torr. An absorbance noise floor of 10−3 was achieved for a single 10 s scan of the 220-330 GHz frequency domain. Measured absorption spectra for methanol/air agree well at collisional-broadened conditions with spectral simulations carried out using literature spectroscopic parameters. In contrast to the previous submillimeter wave research that has focused on spectral absorbance at extremely low pressures (mTorr), where transitions are in the Doppler limit, and the present study illustrates the applicability of THz electronics for gas sensing at pressures approaching those found in atmospheric and industrial environments. [ABSTRACT FROM AUTHOR]