Single-, Dual- and Octa-Core Millimeter-Wave VCOs with -190 dBc/Hz FOM T in 22 nm FDSOI CMOS

We present three voltage-controlled oscillators (VCOs) with wide continuous frequency tuning range (FTR) and low phase noise (PN) for mm-wave radar applications. All three VCOs are fabricated in a 22 nm FDSOI CMOS technology and employ a common core optimized for FOM $_T$ using a systematic design methodology introduced in this work. VCO1 is a single-core push-push VCO achieving a FTR of 16.7% centered at 121.8 GHz, with a minimum measured PN of −109.2dBc/Hz at 10 MHz offset and a power consumption of only 3 mW. VCO2 is a dual-core push-push VCO employing a tail transformer (TF) that simultaneously enables tail filtering, multi-core coupling, and non-invasive second-harmonic extraction. As a result, VCO2 achieves a 3 dB improvement of mean PN compared to VCO1. Further PN reduction typically relies on ring- or star-shaped arrangements of four or more coupled cores. However, design rules of many advanced CMOS nodes prohibit arbitrary transistor rotation, limiting practical implementations to at most four cores. As a solution, VCO3 combines multiple coupling mechanisms to enable a robust octa-core (N=8) architecture despite these geometrical constraints. ... mehrAs a proof of concept, VCO3 achieves a continuous FTR of 15.1% centered at 52.7 GHz with a minimum PN of −125.7dBc/Hz, which is competitive to state-of-the-art SiGe VCOs. All three VCOs exhibit a minimum FOM $_T$ of −190 dBc/Hz, confirming successful performance scaling from single-core to dual- and octa-core architectures. To our knowledge, this represents the best reported FOM $_T$ for silicon VCOs with continuous FTR at comparable frequencies.