A Compact V -Band Quad-Core VCO With Coupling-Coexistence and Dual-Filtering Techniques

This paper proposes a compact and low phase noise (PN)V-Band quad-core voltage-controlled oscillator (VCO) in a 28-nm CMOS technology, capable of extracting third-harmonic frequencies forD-band integrated sensing and communication (ISAC) systems. Coupling-coexistence technique based on a tricoupled transformer and dual-filtering technique enhance PN without additional area. A compact snowflake geometry topology is proposed, employing both inductor-sharing and moderejection techniques. The measured quad-core VCO tunes from 49.8 to 53.9 GHz, achieving -94.2 dBc/Hz and -121.1 dBc/Hz optimal phase noise (PN) at 1 MHz and 10 MHz offset, respectively, at 53.6 GHz carrier. The design also achieves the comparable area and power consumption of a single-core oscillator, combined with the PN performance advantages of multi-core oscillators, achieving a high FoMAof -200.1 dBc/Hz.