VCO Design with Uniformly Low Phase Noise Versus Frequency and Temperature for D-Band Applications

This article presents an approach in the design of voltage-controlled oscillators (VCOs) that aims to provide robust low-noise performance while also being resistant to high-temperature conditions. The proposed design methodology is grounded in the principles of the negative resistance model. For demonstration purposes, a D-band oscillator is realized in a SiGe BiCMOS technology and evaluated, which significantly corroborates the design approach. For frequency doubling, two concepts, the push-push principle (VCO1) and Gilbert cell mixer (VCO2), are implemented and compared with a special focus on load pulling effects. Both realizations target the D-band center frequency of 140 GHz with a tuning range of around 13 GHz. The VCO core draws a current of 40 mA and the on-chip frequency divider 32 mA from a 3.3-V source. A uniform differential output power of about -1.5 dBm (-8 dBm) without buffer and low phase noise of -98.7 dBc/Hz (-95 dBc/Hz) and the VCO remains remarkable phase noise performance up to temperatures >200 °C.