A 5.6 GHz Balanced Colplitts QVCO With Back-gate Coupling Technique

A 5.6 GHz quadrature voltage-controlled oscillator (QVCO) designed with balanced Colpitts topology and coupled with back-gate coupling technique is presented. The use of back-gate of the core transistor as coupling terminals removes the noise contributed from the coupling transistor of conventional QVCO and reduces power consumption. The prototype is implemented using TSMC standard 0.18 mum 1P6M CMOS process technology. With 1.8 V power supply, the phase noise of the QVCO is -113 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 5.6 GHz, and tuning range is 330 MHz. The figure of merit is -174.6 dB. Power consumption is 21.6 mW.

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