A 900-MHz 1-V CMOS frequency synthesizer

A 900-MHz 1-V frequency synthesizer has been fabricated in a standard 0.35-/spl mu/m CMOS technology. The frequency synthesizer consists of a divide-by-128/129 and 64/65 dual-modulus prescaler, phase-frequency detector, charge pump, and voltage-doubler circuit with an external voltage-controlled oscillator (VCO) and passive loop filter. The on-chip voltage-doubler circuit converts the 1-V supply voltage to the higher voltage which supplies the prescaler internally. In this way, the 900-MHz 1-V frequency synthesizer with an external VCO can be achieved. The measured phase noise is -112.7 dBc/Hz at a 100-kHz offset from the carrier, and the synthesizer dissipates 3.56 mW (not including VCOs) from a single 1-V supply when the switching frequency of the on-chip voltage doubler is 200 kHz and the power efficiency of the voltage doubler is 77.8%. The total chip area occupies 0.73 mm/sup 2/.