부산대학교 도서관

This paper presents a GaAs interference suppression MMIC for integration in broadband receiver front ends. The circuit is an interferrometer, with a gain stage in one path, and a gain stage followed by a variable delay line in the other path. The voltage-tunable delay is implemented with discrete inductors and diode-connected transistors. The total time delay of the second path is adjusted by varying the voltage on the varactors to place a spectral notch at different frequencies across the band. The demonstrated prototype circuit is well matched across X-band and the notch can be tuned from 8.2 to 10.8 GHz. For a CW signal in this band, the circuit shows a 10 dB suppression of interference signals 2 GHz away, and over 11 dB suppression for 3 GHz separation. Broadband suppression at the front end can improve the useful dynamic range of digital cancellation.