A low-phase-noise 61 GHz push-push VCO with divider chain and buffer in SiGe BiCMOS for 122 GHz ISM applications

This paper presents a 61 GHz push-push VCO with an integrated divide-by-eight divider and an output buffer in a 130 nm SiGe BiCMOS process. The VCO core features a differential Colpitts topology with coupled inductors to improve phase noise performance. Eight sub-bands are realized by three digital tuned varicaps, which are placed in parallel with the analog tuned varicap. Its tuning range is 60.85-63.65 GHz with a measured output power of above 10 dBm. The measured phase noise is -106 dBc/Hz at 1 MHz offset with an overall VCO/buffer power dissipation of 93.6 mW. The VCO/buffer has achieved an efficiency of 14%, a figure-of-merit including output power (FOM_P) of 193.1 dBc/Hz and an ITRS FOM of 185.6 dBc/Hz.