Sheng-Yu Peng

A Fully Reconfigurable Low-Noise Biopotential Sensing Amplifier With 1.96 Noise Efficiency Factor

A fully reconfigurable biopotential sensing amplifier utilizing floating-gate transistors is presented in this paper. By using the complementary differential pairs along with the current reuse technique, the theoretical limit for the noise efficiency factor of the proposed amplifier is below 1.5. Without consuming any extra power, floating-gate transistors are employed to program the low-frequency cutoff corner of the amplifier and to implement the common-mode feedback. A concept proving prototype chip was designed and fabricated in a 0.35 μm CMOS process occupying 0.17 mm 2 silicon area. With a supply voltage of 2.5 V, the measured midband gain is 40.7 dB and the measured input-referred noise is 2.8 μVrms. The chip was tested under several configurations with the amplifier bandwidth being programmed to 100 Hz, 1 kHz , and 10 kHz. The measured noise efficiency factors in these bandwidth settings are 1.96, 2.01, and 2.25, respectively, which are among the best numbers reported to date. The measured common-mode rejection and the supply rejection are above 70 dB . When the bandwidth is configured to be 10 kHz, the dynamic range measured at 1 kHz is 60 dB with total harmonic distortion less than 0.1%. The proposed amplifier is also demonstrated by recording electromyography (EMG), electrocardiography (ECG), electrooculography (EOG), and electroencephalography (EEG) signals from human bodies.

A fully reconfigurable low-noise biopotential sensing amplifier

In this paper, we present a fully reconfigurable biopotential sensing amplifier, which employs floating-gate transistors for the programming of the low-frequency cutoff corner and for and for common-mode feedback implementation without consuming any extra power. With a supply voltage of 2.5V, the measured midband gain is 40.7dB and the measured input-referred noise is 2.8 μVrms. The chip was tested under several configurations with the amplifier bandwidth being programmed to 100Hz, 1kHz, and 10 kHz. The measured noise efficiency factors in these bandwidth settings are 1.96, 2.01 and 2.25. The measured common-mode rejection and the supply rejection are above 70 dB. The measured dynamic range is 60 dB with total harmonic distortion less than 0.1%.

A Power-Efficient Reconfigurable OTA-C Filter for Low-Frequency Biomedical Applications

A power-efficient operational-transconductance-amplifier-capacitor (OTA-C) filter for biomedical applications is presented with detailed noise analysis. This filter consists of a cascade of biquadratic sections, each of which is configured via a serial-peripheral-interface circuit embedded with non-volatile memories to provide low pass or bandpass response. All filter parameters, including the gains, natural frequency, and quality factor, are orthogonally adjustable by programming charges on floating-gate bias transistors. The reconfigurable biquadratic section is composed of four power-efficient linearized OTAs. Each OTA consists of complementary hextuple-diffusor-quadruple-differential-pairs (HDQDPs) and a floating-gate common-mode feedback scheme. A developed computer algorithm for transistor dimension optimization is adopted to extend the input linear range of the HDQDP based on nonlinearity cancellation. A prototype chip is designed and fabricated in a

A non-invasive material sensing system and its integrated interface circuits

0.35~ \mu {\mathrm{ m}}

Linearity efficiency factor and power-efficient operational transconductance amplifier in subthreshold operation

CMOS process to demonstrate reconfigurability and performance of the proposed filter. Each biquadratic section occupies

A fully reconfigurable low-power floating-gate transistor-capacitor filter

0.12{\mathrm{ mm}}^{2}

A Power-Efficient Reconfigurable Output-Capacitor-Less Low-Drop-Out Regulator for Low-Power Analog Sensing Front-End

with a frequency tuning range more than five decades. Measured spurious-free dynamic ranges (SFDR) at the low pass and bandpass outputs from one of the biquadratic sections are 52.6 and 54.55 dB, respectively, when the natural frequency is programmed at 2 kHz with power consumption of 107.2 nW. A fourth-order Chebyshev low pass and an eighth-order Butterworth bandpass responses are implemented with characterized SFDRs of 50.43 and 48.3 dB, respectively.

OPERATIONAL TRANSCONDUCTANCE AMPLIFIER, RECONFIGURABLE FULLY DIFFERENTIAL VOLTAGE SENSING AMPLIFIER AND RECONFIGURABLE FULLY DIFFERENTIAL CAPACITIVE SENSING AMPLIFIER

In this paper, a resonator-based non-invasive material sensor and its sensor interface circuits are presented. The sensing interface circuits detect the resonant frequency and resonator loss caused by the material under test. The readouts of resonance frequency and resonator loss correspond to the real and the imaginary parts of the sample relative permittivity respectively. The resonant amplitude is maintained constant by injecting different amounts of tail current to the resonator from a current mode digital-to-analog converter (I-DAC). The control bits of this I-DAC indicates the loss of the resonator. The interface circuit employs an integration-and-count approach to digitize the resonance frequency directly. The signal-to-noise ratio increases with the integration interval without being limited by the resolution of a dedicatedly designed analog-to-digital converter. A prototyped chip has been designed and fabricated in a 0.18 μm CMOS process. The preliminary measurement results show that the proposed sensor system can distinguish air, deionized water, and different concentrations of ethanol and methanol.

A Bypass-Switching SAR ADC With a Dynamic Proximity Comparator for Biomedical Applications

A linearity efficiency factor (LEF) is proposed in this paper to quantify the trade-off among linearity, bandwidth, and power consumption in designing differential pair or operational transconductance amplifier (OTA) circuits. The unitless LEF can be used to evaluate the trade-off efficiency of a circuit topology without considering the effects of input attenuation nor the bias current level when all transistors are biased in the subthreshold region. According to this proposed figure of merit, a power-efficient linearized differential pair and a fully differential OTA are proposed and evaluated. The OTA, which is composed of a complementary pair of the linearized differential pairs and a floating-gate common-mode feedback scheme, exhibits 7.8 times better power efficiency than a basic OTA with capacitive input attenuation while achieving the same transconductance and linearity performance.

An 85 dB SNDR third-order ΔΣ modulator for audio applications

This paper presents a fully reconfigurable low-power filter that is composed of a cascade of floating-gate transistor-capacitor (FGT-C) biquadratic sections suitable for biomedical applications. The proposed FGT-C filter provides both the lowpass and bandpass outputs to the following stage with all filter parameters reconfigurable, including the gains, natural frequency, quality factor, DC levels for input and outputs. The filter topology exhibits good modularity so that the biquadratic sections can be cascaded and scaled up to implement high-order frequency responses easily with efficient area and power consumption. A prototype chip has been fabricated in a 0.35μm 2P4M CMOS process and each FGT-C biquadratic filter occupies an area of 0.0313mm2. From measurement results, the filter consumes 118.4nW of power with a dynamic range of 45.5dB while operating at 1.8V power supply with a 10kHz bandwidth.