A 24.5-to-45.2-GHz Dual-Injection Clock Multiplier with Folded-Inductor-Based Magnetic-Flux Cancellation Achieving 32.83-fs_rms Jitter and 0.037-mm² Core Area

We present an injection-locked clock multiplier (ILCM) with an ultra-wide frequency tuning range (TR) and low-jitter, employing a compact folded-inductor-based magnetic-flux cancellation technique. An LC-series dual-mode quadrature ring oscillator (QRO) is co-designed with an edge-combining frequency doubler in mm-wave bands to simultaneously extend the TR and lower the phase noise. Leveraging the differential time-alignment technique, the proposed design achieves an exceptionally large loop bandwidth <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{f}_{\text{BW}})$</tex>. Fabricated in 28-nm, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{HPC}+\text{CMOS}$</tex>, the QRO provides a 59.46% TR (12.25-22.6 GHz), while the doubler's output delivers a frequency range of 24.5 to 45.23 GHz. Occupying a tiny core area of 0.037 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, the proposed ILCM achieves a measured rms jitter of 32.83 fs at 39.5 GHz.