Process Sensor Using Current-Steering Logic Inverter based Ring Oscillator

This paper presents a process sensing circuit using current-steering logic (CSL) inverter-based ring oscillators. NMOS and PMOS CSL inverters are used for the ring oscillators for NMOS and PMOS process sensing, respectively. The designed process sensor circuit can distinguish between five different process corners with a sufficient difference. The output is a 6-bit digital output and is stable with a read and reset functionality. The circuit uses a 26 MHz reference clock, and the output is available in 10 µs for all the process corners. The circuit is designed and simulated in 65 nm CMOS technology with a 1 V supply. The layout of the circuit is also presented along with the post-layout results.