A 2.4-GHz low power high performance frequency synthesizer based on current-reuse VCO and symmetric charge pump

This paper presents a low power high performance frequency synthesizer. Based on the current-reuse VCO architecture, the whole system power consumption is significantly saved with excellent phase noise performance. Imbalance amplitude problems caused by the unsymmetrical VCO are solved by the pre-tuning mechanism, which automatically chooses the correct frequency band for the certain frequency channel. Besides, the symmetric charge pump (CP) can minimize the current mismatches and phase offset. The frequency synthesizer is fully integrated in 130-nm CMOS technology consuming 5.8 mW. Measurement results show performance of -130 dBc/Hz at 1 MHz offset phase noise, 450 fs rms jitter. The reference spur is below -75dB, and it operates successfully with 1Mbps GFSK signals as the two-point modulated transmitter.