Patent ID: 7724081

Claim:
An amplifier front-end circuit, comprising: an input node for receiving a common-mode voltage V cm ; a first differential transistor pair having first and second inputs and first and second outputs; a capacitor; a voltage source which provides a reference voltage V ref ; a switching network arranged to: charge said capacitor to V ref ; couple said capacitor to said first differential pair's first input and couple V ref to said first differential pair's second input such that the voltages at both inputs are ˜V ref ; and couple said input node to said capacitor such that the voltage at said first differential pair's first input is level-shifted to ˜(V cm +V ref ); and an error correction circuit coupled to said first differential pair's first and second outputs and arranged to reduce charge injection error and kT/C noise components that would otherwise be present in said outputs due to said level shift.