A 24.6-29.6GHz Hybrid Sub-Sampling PLL with Tri-State Integral Path Achieving 44fs Jitter and -254.8dB FOM in 28nm CMOS

We present an LC-based hybrid sub-sampling phase-locked loop (PLL). A novel tri-state integral path is applied to reduce the loop filter (LF) area and eliminate ripples on the control signals. The effectiveness of the proposed technique is compared with type-II hybrid PLL and PLL using delta-sigma modulator. The 24.6-29.6GHz PLL instance implemented in 28-nm planar process achieves RMS jitter of 44fs and -254.8dB FOM and consumes power of 17mW from a 0.9/0.95V supply.