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 <tex-math notation="LaTeX">D</tex-math> -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 <tex-math notation="LaTeX">D</tex-math> -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 <tex-math notation="LaTeX">$-$</tex-math> 1.5 dBm ( <tex-math notation="LaTeX">$-$</tex-math> 8 dBm) without buffer and low phase noise of <tex-math notation="LaTeX">$-$</tex-math> 98.7 dBc/Hz ( <tex-math notation="LaTeX">$-$</tex-math> 95 dBc/Hz) and the VCO remains remarkable phase noise performance up to temperatures <tex-math notation="LaTeX">$>$</tex-math> 200 <tex-math notation="LaTeX">∘</tex-math> C.