A new approach to the push–push oscillator based on a differential SIW bandpass filter

Abstract

ABSTRACTA novel push–push oscillator based on a differential bandpass filter (BPF) using substrate integrated waveguide (SIW) technique is presented in this paper. For the first time, the differential SIW BPF is utilized as a frequency stabilization element to provide differential outputs in designing the push–push oscillator. The complex quality factor (Qsc)-peak frequency of the BPF is chosen for the design at approximately half the final output frequency to achieve low phase noise performance. Moreover, two transmission zeros (TZs) below the passband and two TZs above the passband which highly improve the out-of-band rejection are obtained by using both electromagnetic coupling and cross coupling. An SIW power combiner is also designed to obtain the desired signal. A push–push oscillator has been proposed and experimentally demonstrated at 27.8 GHz to verify the above design concept. The measured results show that the output power is −17.3 dBm with a phase noise of 128.6 dBc/Hz at 1-MHz offset.