Second order active filters

Abstract

A second order active filter comprises an input terminal, an output terminal, and a common terminal, a capacitive T-network comprising three capacitors and, in parallel therewith, a resistive T-network comprising three resistors, the terminals of the T-networks being connected respectively via a first amplifier to the output terminal, via a buffer to the input terminal, and to the common terminal, a potential divider between the output and common terminals, and a second amplifier having an input coupled to a tapping point of the potential divider and an output coupled via a resistor to the central junction of the capacitive T-network and via a capacitor to the central junction of the resistive T-network. In different configurations of the filter, the component coupled to the common terminal may be omitted from one of the T-networks, or from both of the networks with another potential divider coupled between the input and common terminals and a third amplifier coupling its tapping point to one of the networks.

Dependencies are inferred from the claim text.