A Micropower CMOS-Instrumentation Amplifier

A CMOS switched capacitor instrumentation amplifier is presented. Offset is reduced by an auto-correlation technique and effects due to charge injection are attenuated by a special amplifier configuration. The circuit which is realized in a 4 μm double poly process has a typical offset (σ) of 370 μV, an RMS input referred integrated noise (0-f
_c
/2) of 79 μV and consumes only 21 μW (f
_c
= 8 kHz, V
_DD
= 3 V).