A 9-GHz Subsampling-Chopper PLL with Charge-Share Cancelling and Achieving 57.8-fs-rms Jitter with 15dB In-Band Noise Improvement

A 9-GHz sub-sampling (SS) PLL employs a new chopping charge-pump (CP) with controlled pre-charging or pre-discharging to cancel the charge sharing during the chopper's phase swapping, thus eliminating its 1/f noise. Fabricated in 65-nm CMOS, the prototype achieves 57.8-fs rms jitter with −111.9-dBc/Hz in-band noise at 1kHz offset.