Reducing impact of degradation on analog circuits by chopper stabilization and autozeroing

This paper shows that chopper stabilization and autozeroing, commonly used to eliminate offset and low frequency noise, can also significantly reduce the effects of transistor degradation caused by hot carrier and BTI stress in analog circuits. An open loop amplifier circuit designed in a 32nm high-κ, metal gate technology is investigated by circuit simulation and sensitivity analysis. This analysis was conducted using DC stress which can cause high offset for asymmetric input signals. Aging due to negative and positive bias temperature instability, conducting and non-conducting hot carrier injection is taken into consideration. The aging contributions of these effects on the individual transistors in the circuit and on the amplifier offset are evaluated and a drastic reduction of the output offset is obtained by chopping and autozeroing.