Digital calibration technique using a signed counter for charge pump mismatch in phase-locked loops

The authors adopt a digital technique to calibrate the current mismatch of the charge pump in phase-locked loops. The proposed digital calibration technique using a signed counter reduces the calibration time up to a minimum of 64% as compared with the other techniques. This technique is designed by a standard 0.18 μm CMOS technology. The calibration time is 32.8 μs, the average power is 6.2 mW at a 1.8 V power supply and the effective area is 0.263 mm².