Triple-Band Transformer-Coupled LC Oscillator With Large Output Voltage Swing

This letter presents a low phase noise triple-band voltage-controlled oscillator (VCO). The designed circuit consists of a dual-resonance LC-tank VCO and a single-resonance LC-tank VCO. The two sub-VCOs are coupled via transformers and varactors. The net LC resonator has three main resonant frequencies selectable by controlling the bias of varactors. The proposed VCO has been fabricated with the TSMC 0.18 μm 1P6M CMOS technology. The VCO can generate differential signals in the frequency range of 2.80-3.57, 7.43-7.65, and 8.23-8.77 GHz with core power consumption of 3.3, 4, and 4.2 mW at the dc drain-source bias of 0.65 V, respectively. At 3.49, 7.53, and 8.52 GHz phase noises at 1 MHz offset are -123.06 dBc/GHz, -119.62 dBc/Hz, and -118.34 dBc/Hz, respectively. The die area of the triple-band VCO is 0.626 × 0.912 mm ².