Incremental differentiator including sampling circuit - compares successive samples to determine derivative relative to time

摘要

The incremental differentiator circuit receives a signal (e), a function of time (t) and provides a first derivative (de/dt). The input supplies a sample-and -hold circuit including an electronic switch controlled by a square wave signal at the sampling frequency (fs) provided by a clock. An analogue store holds samples of the input amplitude. This is connected to an operational amplifier having a gain of one. The input also supplies one of the inputs of the difference circuit, the second input being provided by the operational amplifier. The output of the difference circuit provides a signal indicative of the difference between successive samples. By low pass filtering and interpolation the first derivative. (de/dt) is produced.