To overcome light interference, including a large DC offset and ambient light variation, a robust photoplethysmogram (PPG) readout chip is fabricated using a 0.13-μm complementary metal-oxide-semiconductor (CMOS) process. Against the large DC offset, a saturation detection and current feedback circuit is proposed to compensate for an offset current of up to 30 μA. For robustness against optical...

A low-voltage low-power analogue-baseband chain designed for IEEE 802.11a/b/g wireless local-area network (WLAN) receivers is described. It features architecturally a ‘two-step channel selection’ to complement the radio front-end, and a flexible intermediate frequency (IF) reception capability to alleviate the cancellation of frequency and DC-offset. In circuit implementation, a double-quadratu...

A new design technique employing CMOS Current Feedback Operational Amplifier (CFOA) is presented. This design approach applies CFA OTA as input stage cascaded with class AB cross-coupled buffer stage. The performance parameters of CMOS CFOA such as bandwidth, slew rate, settling time are extensively improved compared with conventional CFOA. These parameters are very important in high frequency ...

An electrowetting system with protection against dielectric breakdown is presented. It comprises an electrolyte and a Parylene-C film deposited on an aluminum electrode. The system demonstrates virtually instantaneous self-healing (within 100 ms) after dielectric breakdown under both DC and certain AC electrowetting conditions. DC current response during electrowetting on intentionally damaged ...

Orthogonal frequency division multiplexing (OFDM) systems with direct-conversion architecture suffer from both carrier frequency offset (CFO) and dc offset (DCO). In this paper, we study CFO estimation problem for OFDM systems with time-varying DCO (TV-DCO) caused by gain mode switch of low noise amplifier (LNA). Based on linear approximation of TV-DCO, a blind algorithm is proposed for CFO est...

We describe a general offset-cancelling architecture for analog multiplication using chopper stabilization. Chopping is used to modulate the offset away the output signal where it can be easily filtered out, providing continuous offset reduction which is insensitive to drift. Both square wave chopping and chopping with orthogonal spreading codes are tested and shown to reduce the offset down to...

Biomedical sensors are used to measure a myriad of biopotential signals including electroencephalogram (EEG), electrocardiogram (EKG), electromyogram (EMG), and neural field potential (NFP) signals [1], [2], [3]. Most of the useful information in these signals resides in the frequency range of 0.5 Hz to 1 kHz, allowing ultralow power circuits to be used when processing them. This is critical fo...