A Self-Oscillating Mixer using the Fundamental Oscillation of a FET Without Source Feedback for Low Cost Microwave Receiver

Abstract

ln this paper, design of a novel self-oscillating mixer is presented using a single FET with grounded source. In contrast to conventional designs, RF signal is mixed with the fundamental self-oscillation frequency generated internally utilizing the negative resistance method. No source feedback and extra filtering at RF or IF are used. A self-oscillating mixer with the fundamental self-oscillation frequency fLO = 4.075 GHz is designed for fRF = 4.00 GHz and fabricated in microstrip line technology. It provides a measured conversion gain of 4 dB, IPin1dB of -19 dBm, SSB noise figure of 6 dB with a wide dynamic range of 66 dB. Also it can down-converts a wide range of RF frequency from 2 GHz to 7 GHz.