0.6 V Biopotential Acquisition IC with 28 nW Self-biased Instrumentation Amplifier and Analog Spike Extraction

Abstract: This paper presents an ultralow power 0.6 V biopotential acquisition IC with analog spike extraction. To reduce power consumption, we propose a self-biased current-balancing instrumentation amplifier, which has current consumption of 46.4 nA, noise efficiency factor of 2.00, bandwidth between 115 Hz and 1461 Hz, and input referred noise of 8.84 μVrms. In addition, the passive RC lowpass filter in the amplifier acts as both dc servo loop and self-bias. Furthermore, we implemented a spike detector based on an analog nonlinear energy operator consisting of a low-voltage open-loop differentiator and an open-loop gate-bulk input multiplier. To either merge adjacent spikes within a predefined time window or remove unwanted glitches during spike extraction, we included an adjacent spike merger circuit based on a counter.