This document discusses some challenges and solutions in the design of instrumentation amplifiers, including capacitor and resistor selection, input bias current matching, DC accuracy, signal-to-noise ratio, etc.
This document addresses a common problem with instrumentation amplifier (in-amp) circuits where failure to provide a DC return path for input bias currents causes the output to saturate at the supply rails. This issue typically arises when inputs are capacitively coupled, causing bias currents to charge coupling capacitors until saturation occurs.
The values should be 0.1 uF or less to keep component size small.
They vary widely but most have maximum values between 1.5 nA and 10 nA.