2.4GHz Fast Hopping Frequency Synthesizer

A 2.4GHz frequency synthesizer is proposed as a part of a low cost RF front end for ISM band applications. The frequency synthesizer employed a new dual loop architecture to improve the settling time, while keeping a fine frequency resolution. With a settling time of 30µs, the frequency synthesizer is able to hop at 2k hop/s with less than 10% overhead. When utilized in a digital wireless system, the fast hopping rate is able to improve the efficient of the coding scheme and improve the performance of the system. The frequency synthesizer includes a monolithic LC tank VCO with a phase noise performance of-94.728dBc/Hz,-113.2dBc/Hz and-118dBc/Hz at 100kHz, 600kHz and 1MHz offset respectively, with an innovative varactor design, the VCO is able to achieve a tuning range of 600MHz, from 1.8GHz to 2.4GHz. When designed in a 0.35µm CMOS technology, the synthesizer drew 40mA from a 3V supply.