V-band push-push VCO using slow-wave CPW resonators for low phase noise reduction

This article presents a design for two fully integrated millimeter-wave V-band push-push voltage-controlled oscillators (VCOs) implemented in a 150-nm pHEMT process is presented. Both use slow-wave coplanar waveguide (CPW) structure transmission line resonators, instead of a lumped LC tank, to provide an extended output frequency range and relatively low phase noise (PN). A LC tank with and without slow-wave features is used in the two VCO circuits. The measured results for manufactured chips are compared. The VCO with the slow-wave feature demonstrates a lower PN of -104.5 dBc/Hz at a 1-MHz offset frequency. A comparison of the designs with and without a slow-wave VCO shows that the VCO design with slow wave demonstrates lower average PN of approximately 8 dBc at an offset frequency of 1 MHz. Varactor adjustment of the oscillation frequencies for the two VCOs gives 53.2 to 57.1 GHz for the VCO without slow wave and 53.8 to 55.4 GHz for the VCO with slow wave. The two VCOs are developed for use in licensed V-band transceiver systems.