Abstract-A wide-range voltage-and-frequency clock synchronizer (WRCS) for maintaining synchronization during dynamic voltage-and-frequency scaling was developed. The key feature of the WRCS is short-range skew measurement based on a predictive-delay-adjustment (PDA) scheme. The short-range skew measurement results in reduction of the area of the WRCS by 77%, that is, the area of the fabricated WRCS in a 40-nm CMOS process is only 5.65 × 10^-3 mm². In the case of large voltage variation (0.8-1.55 V) and wide frequency range (100 MHz-1 GHz), measured skew is suppressed to the lowest percentage yet reported, namely, less than 6.8% of clock period. Moreover, current consumption of the WRCS is only 0.48 mA under 1.1-V 100-MHz operation.