An Energy-Efficient Small-Area Configurable Analog Front-End Interface for Diverse Biosignals Recording

We introduce a fully integrated configurable analog front-end (CAFE) sensor intended to accommodate various types of bio-potential signals in this article. The proposed CAFE is composed of an AC-coupled chopper-stabilized amplifier to effectively reduce 1/f noise and an energy- and area-efficient tunable filter to tune this interface to the bandwidth of various specific signals of interest. A tunable active-pseudo-resistor is integrated into the amplifier's feedback to realize a reconfigurable high-pass cutoff frequency and enhance its linearity, while the filter is designed using a subthreshold-source-follower-based pseudo-RC (SSF-PRC) topology to attain the required super-low cutoff frequency without the need for extremely low biasing current sources. Implemented in TSMC 40 nm technology, the chip occupies an active area of 0.048 mm(2) while consuming 2.47 mu W DC power from a 1.2-V supply voltage. Measurement results indicate that the proposed design achieved a mid-band gain of 37 dB, with an integrated input-referred noise (V-IRN) of 1.7 mu V-rms within 1-260 Hz. The total harmonic distortion (THD) of the CAFE is below 1 % with a 2.4(pp) input signal. With a wide-range bandwidth adjustment capability, the proposed CAFE can be used in both wearable and implantable recording devices to acquire different bio-potential signals.