Accurate transient response model for automatic synthesis of high-speed operational amplifiers

This paper presents an accurate time-domain analysis of operational amplifiers' step response. Both slewing and linear settling phases are investigated in order to correct some discrepancies found in previous literature works. Moreover theoretical results are exploited developing a CAD tool for the automatic synthesis of high-gain highspeed operational amplifiers. Transistor level simulations are performed with MOS lev. 2 and BSIM3v3 models for a telescopic OTA evaluated in the design of a 12-b 200-MS/s pipelined analog-to-digital converter in a 0.35-/spl mu/m BiCMOS technology. The excellent agreement between predicted and simulated results are the consequence of an improved analysis of the slewing-to-linear transition.