1.5-GHz voltage controlled oscillator with 3% tuning bandwidth using a two-pole DSBAR filter

First results on a novel voltage controlled oscillator (VCO) in the lower gigahertz range, featuring excellent phase noise and high power efficiency are presented. The heart of the VCO is a recently reported novel miniature two-pole decoupled stacked bulk acoustic resonator (DSBAR) filter. With its single 180° phase transition over the 1 dB bandwidth, linear phase, and maximum 1 dB insertion loss, it provides stable single-mode operation over 45 MHz (≈3%) of tuning bandwidth and has negligible heat dissipation when operated at incident power levels of 100 mW or greater. The 1.55-GHz laboratory VCO prototypes operate at 5 V supply voltage, 50 mA supply current, 15 dBm of output power, and >;13% efficiency, demonstrating -84 and <; -180 dBc/Hz phase noise suppression at 1 kHz carrier offset and in the thermal noise region, respectively. VCOs with cascaded DSBAR filters for further phase noise reduction are also demonstrated.