1 GHz voltage controlled oscillator using a SSBW/BGW combined mode resonator filter

Results from a 1-GHz voltage controlled oscillator (VCO) stabilized with a novel 3-pole combined mode resonator filter (CMRF) using surface skimming bulk waves and Bleustein-Gulyaev waves are presented. Fabricated on rotated Y-cut quartz, the CMRF can handle more than 2 W of power on a substrate area of 3 mm² has a typical insertion loss of 5-7 dB, a 1-dB bandwidth of 0.17%, and a bandpass ripple within 1 dB. The smooth phase response around its center frequency allows linear tuning of the VCO. Compared to a surface acoustic wave coupled resonator filter (SAWCRF), the CMRF has a 3-4 times larger fractional bandwidth and about 5 times lower group delay, which makes it ideal for wideband FM applications. The CMRF stabilized VCO can transmit more than 200 kb/s when square wave modulated. When sine wave modulated, the 3-dB frequency deviation drop occurs at 100 kHz. Design details are described and possible applications are discussed