MODELING OF LOW-LEVEL RECTIFICATION RFI IN BIPOLAR CIRCUITRY

This paper discusses the rectification response exhibited by low-frequency bipolar transistors when microwave energy is injected. A circuit-analysis model for calculating low-frequency small-signal RFI response is outlined and applied in analyzing RFI behavior of a 741 op amp. Principal results from the RFI-device model are 1) RFI is due basically to nonlinearity of the emitter-base characteristic, and also to ac crowding and nonuniformity of gain across the emitter, and 2) there is a distinct inverse relationship between device size (emitter perimeter) and rectification-RFI sensitivity. Model results and comparison with 741 op amp measurements indicate that the rectification sensitivity to 1-GHz power is approximately 3 mV of offset voltage referred to the device input, per microwatt of absorbed power. Copyright © 1979 by the Institute of Electrical and Electronics Engineers, Inc.