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 mm(2) (1.35 mmx0.775 mm). The output power is -10.04 dBm with 50-W 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 mm(2)) 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.