Active RC circuit for telecommunication filters - has four pole network feeding inverting amplifier with two feedback circuits

摘要

The active resistor-capacitor circuit, as a building block for telecommunications filters, consists of a chain of a 4-pole network (2) and an inverting amplifier (3). The 4-pole input is connected via a first 2-pole (5) to the circuit input (1). The amplifier output is the circuit output (4) and is also connected over a second 2-pole (6) to the input of the 4-pole and over a third 2-pole (7) to a node inside the 4-pole. This basic structure can be altered, e.g. by using a non-inverting amplifier, to give various characteristics.