CDM secondary clamp of RX and TX for high speed SerDes application in 40nm CMOS technology

Novel secondary clamp solutions to boost CDM robustness for both RX and TX circuits along with dual diode of 135fF to meet over 6-G bit/s SerDes are presented. For RX circuit, active PMOS clamp with no voltage overshoot is used as secondary clamp to GND. For TX circuit, by constructing a secondary ESD path through the pre-driver and pumping-up the gate node of the main-driver, an additional series resistor deteriorating SerDes performance is not needed for secondary clamp.