A 10-to-12 GHz 5 mW Charge-Sampling PLL Achieving 50 fsec RMS Jitter, -258.9 dB FOM and -65 dBc Reference Spur
Jiang Gong, Fabio Sebastiano, Edoardo Charbon, Masoud Babaie
Abstract
This paper presents a charge-sampling PLL (CSPLL), that demonstrates the best reported jitter-power FOM of -258.9 dB thanks to its high phase-detection gain and to the removal of the power-hungry buffer driving the phase detector. It also achieves -65 dBc of reference spur by both minimizing the modulated capacitance seen by the VCO tank and reducing the duty cycle of the sampling clock. Without requiring any RF dividers, a 50 μW frequency tracking loop is also introduced to robustly lock the CSPLL to a 100 MHz reference. Fabricated in 40-nm CMOS, the 0.13 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> CSPLL achieves an RMS jitter of 50 fsec at 11.4 GHz while consuming 5 mW.