Advanced Analysis Of CMRR/PSRR Frequency Response And Slew Rate Properties For Operational Amplifiers

This thesis proposes a method for analyzing the CMRR/PSRR frequecny response of the two-side input single-ended output amplifiers--the gain perturbation method.In a two-side input single ended output amplifier,a differential pair with current-mirror load is often used to convert a two-side signal to a single-ended signal,and this structure is asymmetric.The differential pair with current-mirror load combine two currents caused by the input signal to one current at the output port.Because of the asymmetric structure,there is a little difference in the size of the two currents.As for computing the common-mode gain,this little difference is critical,but the existing symbolic tools have difficulty analyzing this difference.The gain perturbation method emphasizes the difference between the two currents.Compared with the results computed by using the symbolic tool directly,the results of gain perturbation method is simpler.Inspired by the computation of CMRR,the gain perturbation method is applied to compute PSRR.The single-ended input sigle-ended output stages have no effect on CMRR,whereas every stage of the opamp affects PSRR.The proposed gain perturbation method is a preliminary exploration in analyzing CMRR/PSRR automatically.This method including partitioning the circuit,generating intermediate signals,and establishing formal formulas.The slew rate of the folded cascode opamp is analyzed seperately in different situations,according to the difference in relative sizes between the biasing current of the input transistor and the biasing current of the commongate transistor.