An adaptive frequency calibration technique for fast locking wideband frequency synthesizers

A fast response adaptive frequency calibration (AFC) technique for wideband frequency synthesizers is presented. In order to operate in a wideband frequency range, digitally controlled switched-capacitors bank LC VCO is used and a widerange digital logic quadricorrelator (WDLQ) is proposed for frequency detector. The specified VCO tuning range is as wide as 1 GHz (50%) from 1.5 to 2.5 GHz and the VCO gain is 20 MHz/V. The CADENCE Spectre simulation results show that the proposed design can achieve a fast adaptive frequency calibration in less than 25 mus with 10 MHz reference clock, which is shortened by half in comparison with the previous works which used counters for frequency detector