A 1.88-NEF 3-kHz Current-Reuse Common-Gate Amplifier Featuring Resistorless High-Pass Filtering

Vagus nerve electroneurogram (VENG) signals have recently emerged as markers for the detection of epileptic seizures. However, these signals present a low amplitude and a large bandwidth, making them sensitive to the intrinsic noise of acquisition circuits and to interference from nearby muscles, which must be filtered out before amplification. To properly retrieve the useful signals, both the input filter and the instrumentation amplifier of the acquisition chain require an optimal noise-current trade-off. To tackle these issues, this work presents a common-gate current-reuse amplifier featuring resistorless high-pass filtering, prototyped on a 22-nm fully depleted silicon-on-insulator chip. The measured amplifier consumes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${2.38}\ {\mu} \mathrm{A}$</tex> with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${1.7}\ {\mu}\mathrm{V}_{\text{RMS}}$</tex> input-referred noise, resulting in a noise efficiency factor (NEF) of 1.88 with a bandwidth from 300 Hz to 3 kHz.