A CMOS monolithic amplifier for cardiac EIT applications

Analog Integrated Circuits and Signal Processing - This paper presents a low-noise amplifier (LNA) with superior linearity for ultra-wideband (UWB) purposes. Linearity is a significant parameter...     

An energy-efficient spike encoding circuit for speech edge detection

In speech processing applications, the instantaneous bandwidth of speech can be used to adaptively control the performance of an audio sensor’s analog front end. Extracting the instantaneous bandwidth of speech depends on the detection of speech edges in the time–frequency plane. In this paper, we propose a spike encoding circuit for real-time and low-power speech edge detection. The circuit can directly encode the signal’s envelope information—an important feature to identify the speech edge—by temporal spike density without additional envelope extraction. Furthermore, the spike encoding circuit automatically adapts its resolution to the amplitude of the input signal, which improves the encoding resolution for small signal without increasing the power consumption. We use the nonlinear dynamical approach to design this circuit and analyze its stability. We also develop a linearized model for this circuit to provide the design intuition and to explain its adaptive resolution. Fabricated in 0.5-μm CMOS process, the spike encoding circuit consumes 0.3-μW power and the experimental results are presented.     

Implementing the Lorenz oscillator with translinear elements

Nonlinear processing is often more suitable than the traditional linear approach is for analyzing biological signals. Unfortunately, digital nonlinear operations are computationaly expensive. In contrast, a large variety of nonlinear operations can efficiently be implemented in analog electronics, operating at real-time speeds. The low level of accuracy generally associated with analog processing is not a concern in this scenario, as biological signals themselves typically have low signal-to-noise ratios. One challenge of analog processing is in its apparently-ad hoc design, and the fact that there is very little wide-spread knowledge of systematically implementing analog electronics to perform arbitrary nonlinear computations. Another issue is the integrity of the analog components; the analog properties of electronic devices are prone to a large amount of mismatch. In this paper, we examine multiple-input translinear element (MITE) networks, a class of analog circuits that addresses the two concerns of a structured synthesis procedure and component mismatch. We test the ability of these MITE networks for accurately realizing linear and nonlinear systems with prescribed dynamics by attempting to implement the Lorenz equations. We will present the theoretical procedure, address practical implementation issues, and then show experimental results from a version of the circuit fabricated in a 0.5 μm CMOS technology through MOSIS.     

A microphone readout interface with 74-dB SNDR

A continuous-time (CT) sigma-delta modulator (SDM) for condenser microphone readout interfaces is presented in this paper. The CT SDM can accommodate a single-ended input and has high input impedance, so that it can be directly driven by a single-ended condenser microphone. A current-sensing boosted OTA-C integrator with capacitive feedforward compensation is employed in the CT SDM to achieve high input impedance and high linearity with low power consumption. Fabricated in a \(0.35\) - \(\upmu\) m complementary metal-oxide-semiconductor (CMOS) process, a circuit prototype of the CT SDM achieves a peak signal-to-noise-and-distortion ratio of 74.2 dB, with 10-kHz bandwidth and \(801\) - \(\upmu\) W power consumption.     

A Bandpass Filter With Inherent Gain Adaptation for Hearing Applications

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 to 15 dB of compression on a 55-dB input dynamic range and is tunable over the audio frequency range, with microwatt power consumption and <5% harmonic distortion.     

CircRNA—Protein Interactions in Muscle Development and Diseases

Circular RNA (circRNA) is a kind of novel endogenous noncoding RNA formed through back-splicing of mRNA precursor. The biogenesis, degradation, nucleus–cytoplasm transport, location, and even translation of circRNA are controlled by RNA-binding proteins (RBPs). Therefore, circRNAs and the chaperoned RBPs play critical roles in biological functions that significantly contribute to normal animal development and disease. In this review, we systematically characterize the possible molecular mechanism of circRNA–protein interactions, summarize the latest research on circRNA–protein interactions in muscle development and myocardial disease, and discuss the future application of circRNA in treating muscle diseases. Finally, we provide several valid prediction methods and experimental verification approaches. Our review reveals the significance of circRNAs and their protein chaperones and provides a reference for further study in this field.