Block:AFE Gm-C

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AFE — Gm-C integrator front-end

AC-coupled low-noise front-end built from a transconductance (Gm) stage driving an integrating capacitor, followed by a switched-cap LPF (SC LPF). Sits on top of electrode DC offset and electrochemistry.

Design equation

Mid-band gain: <math>A_v = G_m \cdot R_{out}</math> High-pass corner set by the pseudoresistor network (AC coupling) — see bias / pseudoresistor notes.

Known failure modes

• DC offset overloading the input pair.
• Pseudoresistor corner drifting with process (weak-inversion resistor).
• Gm nonlinearity at large offsets.

Instances

• RC1.9