A 2.5mW Fully-Passive 2^nd-Order Noise-Shaping Bang-Bang PLL with Adaptive DCO Gain Controller Achieving 305-fs_rms Jitter and –246.3 dB FoM

A fully-passive second-order noise-shaping bangbang phase-locked loop with adaptive DCO gain controller is introduced. The proposed noise shaping technique effectively reduces the quantization noise generated by the bang-bang phase detector, which is a major influence on the integrated root-mean-square(rms) jitter. The proposed noise-shaping PD adopts a compact timing and fast-response circuit structure, which reduces the loop latency and ensures the loop stability with limited power consumption. In addition, the proposed automatic gain calibration, operating in background manner, optimizes the loop bandwidth and reduces the in-band phase noise by 6 dB. The proposed phase-locked loop is fabricated in 65 nm process with a core area of 0.12 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. The power consumption of the core circuit is 2.50 mW at an output frequency of 4.8 GHz, and it achieves 305 fs rms jitter. The figure of merit (FoM) reaches –246.3 dB.