A Fully Integrated 64-Channel Recording System for Extracellular Raw Neural Signals

This paper presents a fully integrated 64-channel neural recording system for local field potential and action potential. It mainly includes 64 low-noise amplifiers, 64 programmable amplifiers and filters, 9 switched-capacitor (SC) amplifiers, and a 10-bit successive approximation register analogue-to-digital converter (SAR ADC). Two innovations have been proposed. First, a two-stage amplifier with high-gain, rail-to-rail input and output, and dynamic current enhancement improves the speed of SC amplifiers. The second is a clock logic that can be used to align the switching clock of 64 channels with the sampling clock of ADC. Implemented in an SMIC 0.18 μm Complementary Metal Oxide Semiconductor (CMOS) process, the 64-channel system chip has a die area of 4 × 4 mm2 and is packaged in a QFN−88 of 10 × 10 mm2. Supplied by 1.8 V, the total power is about 8.28 mW. For each channel, rail-to-rail electrode DC offset can be rejected, the referred-to-input noise within 1 Hz–10 kHz is about 5.5 μVrms, the common-mode rejection ratio at 50 Hz is about 69 dB, and the output total harmonic distortion is 0.53%. Measurement results also show that multiple neural signals are able to be simultaneously recorded.

A Novel Rail-to-Rail Input Swing Threshold-Inverter Multi-Bit Quantizer Using Interpolation Technique for Sampled-Data Circuits

In this paper, a novel and simple multi-bit quantizer based on the threshold inverter quantization (TIQ) approach is presented for use in sampled-data circuits. The key part is a front-end signal conditioning circuit with the aid of the interpolation technique that makes it possible to realize a rail-to-rail input range operation over the conventional threshold inverter-based quantizer circuits while maintaining the benefits of the TIQ structure without employing any analog-intensive circuits such as current sources or amplifiers, thus achieving a digital-compatible implementation. Simulation results in TSMC 90-nm CMOS technology at a power-supply voltage of 1[Formula: see text]V confirm the efficient performance of the proposed circuit.

A Sub-1 V Bulk-Driven Rail to Rail Dynamic Voltage Comparator with Enhanced Transconductance

Reduced voltage head room availability for input signal swing is one of the major bottlenecks in the design of circuits operating with low supply voltages which attracts investigations leading to improvement in the input signal dynamic range of such circuits. Employing bulk-driven MOSFETs (BDMOS) at the input section of the circuit is a popular technique used for increasing the input dynamic range, but the smaller bulk transconductance of the bulk-driven MOSFET degrades the performance of the circuit in comparison with that of a conventional gate-driven counterpart. A double tail voltage comparator employing BDMOS technique offering rail-to-rail input dynamic range and capable of operating at sub-1[Formula: see text]V power supply is presented in this paper. A transconductance improvement scheme is employed for the first time in the literature for a voltage comparator to overcome the major drawbacks associated with the reduced bulk transconductance of BDMOS input transistors and double tail topology permits low voltage operation. The performance parameters of the proposed voltage comparator are comparable to that of conventional gate-driven comparators, with an additional advantage of rail-to-rail input dynamic range. Pre-layout and post-layout simulations were performed in Cadence Virtuoso suite with gpdk 90[Formula: see text]nm library at power supply as low as 0.6[Formula: see text]V. The worst case delay of the proposed circuit is 0.71[Formula: see text]ns and the worst case power consumption of the circuit is 15[Formula: see text]uW. The circuit consumes a silicon area of 33[Formula: see text]μm[Formula: see text]46[Formula: see text]μm. An analytical model of the transconductance enhancement technique and delay of the proposed comparator are also presented.

A Low-Power, High-Gain Amplifier with Rail-to-Rail Operating Capability: Applications to Biomedical Signal Processing

low-voltage, low-power, rail-to-rail, two-stage trans-conductance amplifier is presented. The structure exploits body-driven transistors, configured in folded-cascode structure. To reduce the power consumption, the transistors are biased in the subthreshold region. The Specter RF simulation results which are conducted in TSMC 180nm CMOS standard process proves the well-performance of the proposed structure. The performance of the proposed structure against process variations is checked through process corners and Monte Carlo simulations. The results prove the robustness of the proposed amplifier against process uncertainties. Some important specifications of the design derived from circuit simulations are 93.36 dB small-signal gain, 14.4 PV2/Hz input referred noise power, 26.5 kHz unity gain frequency, 20 V/ms slew rate. The proposed structure draws 260 nW power from 0.5 V power supply and is loaded with a 15 pF loading capacitor. The input common mode range of structure is from 0 to 0.5 V.