A Single-Event-Transient Hardened Phase Locked Loop for Clock and Data Recovery

A radiation-hardened phase-locked loop is proposed for phase interpolator clock and data recovery purposes. A sensitive node-compressed charge pump and multi-node cross coupling voltage-controlled oscillators are proposed in this phase-locked loop with the goal of achieving good jitter performance and improving anti-SET (SET, single-event transient) capability. The root mean square (RMS) jitter of the phase-locked loop is reduced from 3.7 ps to 2.58 ps at 2 GHz, while the laser threshold is improved from 120 pJ to 370 pJ compared to the unhardened phase-locked loop. The hardened phase-locked loop also does not lose its lock state from linear energy transfers (LETs) of 3.3 to 37.3 MeV·cm²/mg.