A Phase-Change Via-Reconfigurable CMOS $LC$ VCO

This paper demonstrates the efficacy of phase-change (PC) vias in reconfiguring RF front-end circuits for multiband/multi-standard operation. Constructed using two series-connected (SC) GeTe vias, a PC switch can be reversibly transformed between a high ROFF state and a low RON state within 1 μs. Using such PC switches to switch the inductor in a resonator, two LC voltage-controlled oscillators (VCOs) based on: 1) a SC and 2) a coupling-controlled (CC) resonator are developed. Designed and fabricated in 0.13- μm CMOS in conjunction with an in-house GeTe process, the VCOs can switch their operating frequency over widely separated bands. Wide tuning ranges of 2.89-4.23/(4.93-7.79) and 4.80-8.53/(5.28-10.20) GHz were achieved in the off/on state for the SC/(CC) VCOs. The measured phase noise over the entire tuning range was lower than -103.4 and -102.7 dBc/Hz, at a 1-MHz offset frequency, respectively.