A 19.5-GHz Radiation-Hardened Sub-Sampled PLL With Quad-Core VCO in 16-nm FinFET Achieving Sub-50 fs Jitter

This letter presents a radiation-hardened (rad-hard) subsampled phase-locked loop (SS-PLL) that achieves state-of-the-art jitter performance while incorporating radiation-hardened techniques to mitigate single-event-upsets (SEUs) present in the space environment. Furthermore, rad-hard techniques are incorporated in each core PLL subblock which include a rad-hard charge-pump Gm cell, a pulser circuit with triple modular redundancy (TMR), and a quad-core voltage-controlled oscillator (VCO) with varactor hardening and LC tail filters. Implemented in a 16-nm FinFET process, the PLL consumes 36.5 mW of power and achieves a jitter of 45.82 fs at 19.5 GHz. Testing at a cyclotron facility verifies robust SEU performance up to an LET of 55 MeV $\cdot $ cm2/mg.