Electronic filter circuit

摘要

To eliminate the high frequency portion of an input signal while permitting low frequency and DC portions to pass, the electronic filter utilizes an n-1 order active network in combination with a capacitor to generate a shunt current, thereby providing a low pass filter having n-order operating characteristics. Included in the active network is an active element, such as an operational amplifier, which responds to an input signal by creating a voltage across the capacitor, resulting in a shunt current that in turn provides the desired filter characteristics. In certain special cases the n-order active filter can utilize a differentiating element in combination with n-2 order active network along with the capacitor to achieve n-order operating characteristics.