Stability Analysis of Current Feedback Amplifiers
High frequency current-feedback amplifiers (CFA) are finding a wide acceptance in more complicated applications from dc to high bandwidths. Often the applications involve amplifying signals in simple resistive networks for which the data sheets provide adequate information to complete the task. Too often the CFA application involves amplifying signals that have a complex load or parasitic components at the external nodes that creates stability problems. This application note covers the discussion of using Bode analysis to determine the gain and phase margin while including external parameters. It discusses how to determine the input buffer gain and its effect on the closed-loop gain. A more appropriate mathematical model is developed for a clearer understanding of the poles and zeros of the CFA amplifier. Finally a summary of how parasitic components influence the frequency and time domain response.