This paper deals with the susceptibility of analog integrated circuits to radio frequency interferences (RFI) and it concentrates on the effects induced by RFI on the operation of offset compensated chopped CMOS operational amplifiers. The first part of the work explains the causes of the additional output DC offset induced by input RF disturbances in chopped systems. Afterwards, the design of a chopped CMOS operational transconductance amplifier (OTA) is briefly treated and in the final part of the paper the results of some simulations performed on such OTA are presented in order to highlight the concepts discussed in the first and second paragraphs.