A combined VCO and divide-by-two for low-voltage low-power 1.6 GHz quadrature signal generation

In this paper we present a transformer-based differential VCO stacked with a divide-by-two for low-voltage low-power 1.6 GHz quadrature signal generation. The VCO adopts Amstrong VCO configuration to alleviate the small headroom and the noise coupling encountered. The start-up condition and the phase noise performance of the proposed local oscillator (LO) circuitry are analyzed using a linearized small-signal model. The LO was fabricated in TSMC 65 nm CMOS technology. It dissipates only 2.6 mW under 1 V supply voltage, while achieving good phase noise performance.