Semi-automatic measured statistics for demodulation RFI in inverting operational amplifier circuits with and without suppression capacitors

Abstract

A description is given of an investigation to determine statistical variations for radio frequency interference (RFI) demodulation responses in operational amplifier (op amp) circuits. 50% amplitude-modulated (AM) RF signals were injected into the op amp signal input terminal to produce undesired demodulated responses at a 1 kHz AM frequency. The RF frequency was varied over the range 0.1 to 400 MHz. The demodulation RFI was characterized by a nonlinear transfer function H/sub 2/. The two op amp types tested were the 741 and the OP27. The results show that the OP27 has better RFI immunity than the 741 with and without RFI suppression capacitors.<>