A sub-2.5ns frequency-hopped quadrature frequency synthesizer in 0.13-μm technology

This paper presents a fast-hopping frequency synthesizer architecture with quadrature outputs, based on sub-harmonic injection-locking, that is compliant with Wireless-USB/WiMedia specifications. The synthesizer features a cross-coupled quadrature digitally-controlled oscillator, that is injection locked to a sub-harmonic frequency. On-chip mixers have been implemented to measure the quadrature accuracy of the outputs. The overall architecture is a CMOS-only implementation and has been fabricated in 0.13-mum SiGe BiCMOS process. Measurement results indicate lock-times of less than 2.5 ns, a locked phase noise of -114 dBc/Hz at 1 MHz offset and a quadrature accuracy of better than 0.5deg. The frequency synthesizer (excluding output buffers) occupies an area of 0.27 mm² and consumes 14.5 mW of power. The best and worst case spur suppression achieved are 47 and 31 dB, respectively. This is the lowest power fast-hopping quadrature frequency synthesizer that has been reported to date.