Dual-Band SiGe HBT Clapp VCOs with a Novel Band-Switching Technique of Controlling a Negative Resistance Bandwidth

A dual-band SiGe HBT Clapp VCO for the next generation multi-band and multi-mode wireless applications is presented. It employs a novel band-switching technique of controlling a negative resistance bandwidth for a fixed dual-band resonator. The negative resistance bandwidth can be switched by controlling a supply bias voltage as well as a shunt inductor of the common-collector HBT. The implemented 0.35-mu m SiGe HBT Clapp VCO has achieved a dual-band performance from 0.666 to 0.674GHz for a V-CC of 4 V and from 1.521 to 1.536 GHz for a V-CC of 2 V. The phase noise at 100kHz offset is -120.2dBc/Hz at 0.67GHz and -112.5dBc/Hz at 1.53GHz. This is the first report on the multi-band SiGe HBT Clapp VCO with oscillation bandwidths switched by a supply bias voltage.