Abstract
Bio-signal detection needs low-noise while high-gain amplifier. However it will suffer front-end saturation problem if input has a large signal disturbance. Motion artifact is one case for in-vivo tests. To shorter the possible circuit saturation period, we develop a fast recovery loop with the recovery time of 200μs. In low noise amplifier design, this work uses the complementary leakage-balanced structure for 0.1Hz high-pass corner frequency with 60pF input capacitance. The programmable gain is from 460 to 5600. The input equivalent noise from 0.1Hz to 100Hz is 2.3μV. Thanks to the full differential topology, this work achieves PSRR of 74dB and CMRR of 70dB at 10Hz. With a single 1-V supply, the total power of a low-noise amplifier, a low-pass filter, a variable-gain amplifier, and a fast recovery loop, is 17.2μW.