Programmable Error Amplifier
This switched capacitor circuit enables use of a low resolution, fast ADC (for example 6 bit flash) to monitor the whole range of output voltage with a high accuracy. A digitally controlled switched capacitor network sets the reference voltage at the level equal to the desired or expected value. The difference between this reference voltage and actual measured voltage is captured and amplified by a switched capacitor amplifier. The actual output voltage is reconstructed by combining the reference voltage and the measured value representing the difference. This difference for the purposes of feedback regulation can be considered a regulation error. In this way a very simple, low cost, 6 bit flash ADC can be used to monitor the output voltage with 10-12 bit resolution and a high speed. The advantage of this technique comes from the fact that during normal operation a high frequency regulation is required only in a relatively narrow range around the equilibrium point. Full range feedback information can be fetched at a slower rate.