High-frequency monolithic generalised immittance converter for RCactive filters

Abstract

A monolithic circuit configured to realise a high-quality generalised immittance convertor function at high frequencies is described. A single low-valued external bias resistor is used to set the output drive current limit. An example of a 5th-order elliptic lowpass ladder filter with bandedge at 1 MHz and excellent stopband performance up to 13 MHz is given to illustrate the capability of the device. The circuit can be treated as a 3-terminal floating nullor accompanied by a voltage buffer circuit, and is therefore suitable for generalised wideband amplifier applications.