Differential oscillator using double-sided paralell-strip line with an inserted conductor plane

A novel differential oscillator using double-sided parallel-strip line (DSPSL) with an inserted ground plane is proposed in this letter. Its two sub-oscillators on the opposite sides of the substrate operate in differential mode, leading to the inherent suppression of the second harmonics at the common DSPSL output port, while the fundamental signals are well combined without additional combiner required. To further enhance the suppression of the second harmonic, the inset length of the ground plane into the DSPSL resonator is optimized to make the second harmonics to be suppressed inside each sub-oscillator.