The influence and modeling of process variation and device mismatch for analog/rf circuit design

Abstract

The influence of local process variation and device mismatch to the electrical characteristics of resistors, capacitors, and MOSFETs is reviewed. The discussion is mainly focus on the device mismatch as it becomes more and more important in analog design utilizing modern CMOS technology. The models to describe the mismatch behavior are also discussed. To reduce the design circle/cost and help improving the circuit yields, physical and accurate statistical modeling approach is needed to predict correctly the circuit behavior with the consideration of local process variation and device mismatch. With including the physical correlations between the independent variable and model parameters such models can predict the measured data well at different bias conditions for devices with wide geometries. For the model to be predictive, besides the well known physical effects such as short and narrow width effects, the influence of new physics effects such as poly-gate depletion and channel quantization to process variation and mismatch should be accounted for to describe the device/circuit behaviors correctly.