Search

This paper presents new applications of low-voltage and low-power multiple-input multiple-output differential difference transconductance amplifier (DDTA). The multiple-input bulk-driven MOS transistor (MIBD MOST) technique provides multiple-input of the active device that simplifies the application’s topology and reduces its power consumption. The proposed DDTA has been used to realize multiple-input single-output shadow filter. Both voltage- and transimpedance-mode filtering functions can be obtained. The natural frequency and the quality factor of the shadow filter can be independently and electronically controlled using DDTA-based amplifiers. The proposed shadow filter has been modified to work as a shadow oscillator. The condition and frequency of oscillation can be controlled independently and electronically. The DDTA is capable to work with 0.5V supply voltage and consumes 218.2 nW. The applications have been designed and simulated in Cadence using $0.18\mu \text{m}$ TSMC CMOS technology.

This paper presents a new application of the multiple-input operational transconductance amplifier (MI-OTA). The MI-OTA has been used to realize a first-order universal filter which shows that the first-order transfer functions such as low-pass, high-pass, and all-pass filters can be obtained easily from a single topology by applying the input signal to the appropriate terminals. Moreover, both non-inverting and inverting transfer functions of all filtering functions can be obtained. The pole frequency of all filters can also be controlled electronically. The first-order all-pass filters have been selected to realize high-quality band-pass filter. For low-voltage supply operation and extremely low power consumption, the proposed MI-OTA is realized by the multiple-input bulk-driven MOS transistor technique with transistors operating in subthreshold voltage region. The circuit has been simulated using the $0.18 \mu \text{m}$ TSMC CMOS technology with 0.5 V of supply voltage and it consumes 29.77 nW of power for 10 nA nominal setting current. The post-layout simulation results show that the applications of MI-OTA agree well with theory.

In this contribution, the realization of a first-order, two-input, single-output voltage-mode multifunction filter employing a second-generation voltage conveyor (VCII) is described. The proposed first-order versatile filter is extremely simple, composed of a single VCII and three passive devices. Because of its low output impedance, the output voltage node can be easily cascaded with other voltage-mode configurations without the requirement of any buffers. In the same circuit topology, the proposed first-order filter provides various filtering functions: inverting and non-inverting low-pass (LPF), inverting and non-inverting high-pass (HPF), as well as inverting and non-inverting all-pass (APF). The digital method allows the selection of output first-order filtering functions without the need for additional circuits such as inverting or double-gain amplifiers. Furthermore, the pass-band gain of the low-pass and high-pass responses can be adjusted by varying the resistance or capacitance values without influencing the pole frequency as well as the phase response. The influence of VCII’s current/voltage gain errors and parasitic elements on filtering performance is also investigated. Moreover, the modification of the proposed lagging phase all-pass filter to achieve electronic controllability is also proposed by replacing the passive resistor with the operational transconductance amplifier (OTA). The $0.18\mu \text{m}$ TSMC CMOS structure of the VCII employed in the proposed filter operates in the subthreshold region and utilizes the bulk-driven technique (BD), enabling it to operate with 0.4V supply voltage and consuming 383 nW of power. The total harmonic distortion (THD) of the LPF with an applied input voltage $V_{inpp}=300$ mV @ 50Hz is -49.5 dB. An application example as a quadrature sinusoidal oscillator realized from the proposed first-order allpass filter and lossless integrator is also included. The performance of the proposed reconfigurable voltage-mode first-order filter is simulated and experimentally tested using a commercially available AD844 IC-based VCII with ±5 V power supply.

This paper presents a new extremely low-voltage low-power bulk-driven (BD) operational transconductance amplifier (OTA) realized for low frequency biosignal processing. The CMOS structure of the OTA utilizes bulk-driven and self-cascode techniques in the subthreshold region, supporting the operation with the supply voltage ( $\text{V}_{\mathrm {DD}}$ ) as the threshold voltage ( $\text{V}_{\mathrm {TH}}$ ) of a single MOS transistor, i.e., $\text{V}_{\mathrm {DD}}$ = $\text{V}_{\mathrm {TH}}$ = 0.5 V, while offering nano power consumption (31.3 nW for 15 nA nominal setting current). Using the extremely low-voltage and low-power OTA in biosignal processing enables extending the lifetime of applications that are powered by battery or energy harvesting sources. The OTA has a 54.7 dB low frequency gain, 6.18 kHz gain bandwidth and 75° phase margin at 15 pF load capacitance. The proposed OTA has been used to realize a bandpass filter (BPF) with adjustable gain for electrocardiogram (ECG) signal processing. The higher cutoff frequency of the BPF is adjustable electronically by a setting current and the BPF’s gain can be adjusted by capacitors value. The total harmonic distortion (THD) of the BPF is −53.56 dB, the input integrated input-referred voltage noise is $17.9 \mu \text{V}_{\mathrm {rms}}$ , the common mode rejection ratio (CMRR) is 75 dB and the power supply rejection ratio (PSRR) is 87.7 dB. The BPF was designed in the Cadence program using $0.18 \mu \text{m}$ CMOS technology from TSMC. The simulation results agree with the presented theory.

Abstract Nano‐electromechanical (NEM) contact switches are extensively studied to suppress the limitations of conventional complementary metal‐oxide‐semiconductor (CMOS) transistors. The attributes of NEM contact switches includes reduced power consumption, reduced off‐state leakage current, and increased on‐state current and sub‐thermal switching. However, unacceptably high pull‐in voltage and low contact lifetime posed a significant challenge for the use of NEM contact switches in energy efficient CMOS applications. Here, graphene‐based electro‐statically actuated NEM contact switches with ultra‐low pull‐in voltage and significant improvement in the contact lifetime are demonstrated. This is achieved by using the graphene on gold electrode as a contact material. The graphene NEM contact switches with graphene as a contact material exhibit an ultra‐low pull‐in voltage of < 0.5 V and high contact lifetime of more than 1.5× 106 cycles. The switches also show an excellent switching performance with high on/off ratio of ≈108, an extremely low off‐state current of ≈100 fA, and small hysteresis window of < 0.1 V.

This paper presents a new electronically tunable universal filter and quadrature oscillator for low frequency biomedical and biosensor applications employing low-voltage differential difference transconductance amplifier (DDTA). The DDTA CMOS structure uses 0.5 V of supply voltage and consumes 277 nW of power. Unlike the previous universal filters, the proposed filter provides many transfer functions of the standard five transfer functions such as low-pass, high-pass, band-pass, band-stop and all-pass with both unity and controlled voltage gains as well as both inverting and non-inverting transfer functions. The natural frequency and the voltage gain of the five standard transfer functions can be controlled electronically. For the band-pass filter, the third intermodulation distortion (IMD3) was 0.37% for 20 mVpp input signal while the output integrated noise was 61.37 $\mu \text{V}$ . The dynamic range (DR) was 53.27 dB for 1% IMD3. The quadrature oscillator has electronically and orthogonal control of the condition and frequency of oscillation. The proposed circuit and its applications were designed and verified via Cadence simulator tool using 0.13 $\mu \text{m}$ UMC CMOS technology. Further, the circuit was evaluated by PSPICE simulation and experiment test using commercial OTA LM13700.