JAJSE34I September 2017 – October 2021 OPA189 , OPA2189 , OPA4189
PRODUCTION DATA
Zero-drift amplifiers such as the OPAx189 use switching on the inputs to correct for the intrinsic offset and drift of the amplifier. Charge injection from the integrated switches on the inputs can introduce short transients in the input bias current of the amplifier. The extremely short duration of these pulses prevents the pulses from amplifying, however the pulses may be coupled to the output of the amplifier through the feedback network. The most effective method to prevent transients in the input bias current from producing additional noise at the amplifier output is to use a low-pass filter such as an RC network.