Abstract: A 4.224GHz quadrature voltage-controlled oscillator (QVCO) applied in MB-OFDM UWB synthesizers is implemented in 0.18μm RF-CMOS technology.An improved structure of the QVCO is presented for better phase noise.A novel configuration of a MOS varactor is designed for good linearity of Kvco, as well as a new digital capacitor controlled array topology with lower parasitic capacitance and lower Ron.Measurement results show a phase noise of -90.4dBc/Hz at 100kHz offset and -116.7dBc/Hz at 1MHz offset from a carrier close to 4.224GHz.The power dissipation is 10.55mW from a 1.8V supply.

Key words: UWB, quadrature VCO, phase noise, varactor, DCCA, quadrature performance