Design of push-push and triple-push oscillators for reducing 1/f noise upconversion

In this paper, 1/f noise upconversion in push-push and triple-push oscillators is studied, and the design requirements for minimizing 1/f noise upconversion are presented. In push-push oscillators, the presence of the large second harmonic components may degrade the waveform symmetry of the oscillation waveforms, leading to the significant 1/f noise upconversion. To minimize 1/f noise upconversion in push-push oscillators, the phases of Fourier coefficients of all harmonics need to be equal. In triple-push oscillators, the waveform symmetry can easily be achieved by eliminating all even harmonic components. The experimental results show that around 15-dB phase-noise improvement at 100-kHz offset frequency can be obtained by satisfying the waveform symmetry condition in push-push and triple-push oscillators.