A Radiation-Tolerant 25.6-Gb/s High-Speed Transmitter in 28-nm CMOS With a Tolerance of 1 Grad

This article presents a 25.6-Gbit<inline-formula> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>s−1 high-speed transmitter (HST) manufactured using 28-nm CMOS technology. The HST macroblock includes an all-digital phase-locked loop (ADPLL), duty cycle corrector (DCC) circuit, data pattern generator, serializer, and a driver capable of driving the differential 100-<inline-formula> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> line as well as a silicon photonics (SiPh) ring modulator (RM). The design adopts various radiation hardening techniques, such as triple modular redundancy (TMR), physical circuit spacing, and protection against radiation-induced leakage. The circuit achieves a total ionizing dose (TID) tolerance above 1 Grad, which aligns with the future large hadron collider (LHC) detector upgrade requirements. In this article, the architecture of the HST based on the LC-tank-based ADPLL, half-rate serializer, and the source-series-terminated (SST) output driver included in the prototype chip is described. The experimental results are reported, including general evaluation as well as the radiation characterization of the HST.