Most analog circuits need a current reference generator to provide a stable biasing point for the transistors. Given the limited voltage headroom in advanced node technologies, there would be notable restrictions on the tolerance of the reference current deviation. Use of off-chip reference generators adds to the size of the system while the on-chip reference current generators are still partially dependent on the on-chip resistor values which is prone to technology variations. We propose an on-chip reference generator with a fully off-chip resistor which has less sensitivity to process variations. Monte-Carlo simulation results shows that the proposed has 31% more precision compared to the conventional on-chip reference generator. Measurement results in$0.18~{{\mu }}\text{m}$CMOS shows that the chip produces a stable reference current that is defined based on an off-chip resistor. The proposed structure consumes the same current as conventional and does not add to the power consumption.

Chronic disease is one of the most pressing health challenges facing the United States (and an increasing set of other countries). The onset or progression of diseases like obesity, diabetes, and metabolic disorder are strongly related to eating behavior, and scientists are still trying to fully understand the complex mixture of diet, exercise, genetics, sociocultural context, and physical environment that lead to these diseases. Health science, however, has no effective means for automatically measuring eating behavior in free-living conditions. The Auracle aims to be a wearable earpiece that detects eating behavior, to be fielded by health-science researchers in their efforts to study eating behavior and ultimately to develop interventions useful to individuals striving to address chronic disease related to eating.

In this paper, a high frequency read-out channel for electrical impedance imaging is presented. The channel comprises an instrumentation amplifier (IA), automatic gain control (AGC), high-resolution delta sigma analog-to-digital converter (ADC), mixer, and ADC buffer. Design details of the channel are described, and the performance of the ADC and the entire channel are reported, based on simulation results from a 0.18 μm CMOS technology. The power consumption of the proposed read-out channel is 7.6 mW.

In this paper, we present a microphone preamplifier that adapts its power consumption according to the input signal's instantaneous bandwidth. The preamplifier's dynamic range and gain keep reasonably constant, regardless of the power consumption. The preamplifier was fabricated with a 0.5-μm CMOS process. The measurement results show it has over 79.5-dB dynamic range with 53.4% power saving compared to its non-adaptive counterpart.

We analyze the dynamics of a logarithmic transimpedance amplifier that are not explainable from its small-signal model. The amplifier was used both to measure pixel currents in an imager as well as currents from a floating gate array for accurate programming. We explain the marked asymmetry between the up-going and down-going current steps intuitively using circuit concepts and then based on phase-plane analysis. This analysis also helps develop a method of reducing the huge delay to down-going current steps.

An analog sinusoidal oscillator usually involves some form of amplitude-limiting mechanism. We examine OTA nonlinearity as a choice for amplitude limiting, and introduce a general method for its use in OTA-C oscillators. We illustrate our discussion with an example design that we fabricated and tested. Our results show that OTA nonlinearity yields low-distortion oscillators at practically no power- or area cost

In this paper, we propose a novel bandpass filter design that incorporates automatic gain control (AGC). The gain control in the filter reduces the performance requirements of a wide-band AGC, and allows for low-power multichannel compression. The filter achieves up to15dB of compression on a65dB input dynamic range and is tunable over the audio frequency range, withμW power consumption and< 5%harmonic distortion.

We have developed a field programmable analog array (FPAA) that can be configured to synthesis and analyze a vast variety of circuits. This FPAA is a valuable platform for studying nonlinear dynamics in circuits, as it offers close to the flexibility of computer simulation, but with actual experimental results. We present data from a current mirror, a peak detector, and a second-order section