40-GHz VCO with 10-GHz tuning range in a 90-nm CMOS technology

This paper presents a wide tuning rang mm-wave VCO (voltage controlled oscillator) fabricated in IBM 90-nm CMOS technology. The VCO can be tuned from 31.4 GHz to 42.2 GHz and utilizes a differential tuning mechanism based on varactors and switched capacitors. A switched current source is used to improve the performance of the VCO when an MIM (metal-insulated-metal) capacitor is switched in the LC resonation tank. Without switched capacitor, the VCO core circuit consumes a power of 8.4 mW and exhibits a phase noise of -114 dBc/Hz at 1 MHz offset from resonation frequency, but with switched capacitor, the power is increased to 12.2 mW, and the phase noise is incresed to -104 dBc/Hz.