Work in process: Integrated low phase noise Colpitts quadrature voltage controlled oscillator and mixer with charge-injection for Wimax communications and wireless networking application

A fully integrated, 5.6 GHz low-phase noise Colpitts quadrature voltage-controlled oscillator (QVCO) and broadband CMOS double-balance mixer are presented. This QVCO is a complementary cross-coupled voltage-controlled Colpitts oscillator with a 3-bit switched capacitor array parallel to the inductor to form LC resonant tank. Without buffer circuits, measured results achieve a tunable frequency range from 4.81 GHz to 5.75 GHz, corresponding to 17.8 %, a phase noise of -121 dBc/Hz at 1 MHz offset frequency from 5.64 GHz, while the QVCO draws 3.8 mA current and 6.84 mW consumption respectively. Including pads, the VCO chip area is 1.046 mm² (1.35 mm×0.775 mm). The output power is -10.04 dBm with 50-Ω. termination at the frequency of 5.64 GHz and the calculated FOM (figure of merit) is -187.7 dBc/Hz. Measurement of the CMOS mixer with charge-injection (1.120 by 1.030 mm²) is performed in the 5.6 GHz, input return loss is higher than 8.5 dB. Two chips are implemented in TSMC 0.18 um CMOS technology with 1.8 V supply voltage for Wimax communications and wireless networking application.