A low reference spur phase-locked loop realized with dynamic current injection charge pump

Abstract

A dynamic current injection charge pump (DCI-CP) is proposed to obtain perfect dynamic current match in this paper. In the proposed DCI-CP, dynamic injection current which includes positive injection current and negative injection current is generated to compensate the dynamic current mismatch. To verify the proposed DCI-CP, a CPPLL is fabricated in SMIC 0.18-µm CMOS process. Measurement results show that it synthesizes frequency from 0.6 to 1.3 GHz with a supply voltage of 1.8 V, consuming 4.7 mW. Simulation results show the dynamic current mismatching of proposed DCI-CP is as low as 4 nA even in the worst case. The measurement reference spur achieves −74 dBc at 1.1 GHz oscillation frequency, of which the maximum and minimum reduction are 9 dB and 3 dB, respectively. The phase noise achieves −98.5 dBc/Hz @1 MHz offset. The core occupies a die area of 0.154 mm² totally.