Integrated circuit having bipolar transistors and field effect

Abstract

An integrated circuit having a first group of semiconductor components which use potentials which are positive with respect to the substrate and a second group of components which use potentials which are negative with respect to the substrate. A negative voltage regulator circuit suitable for use in telephone circuits is described in which the regulated output is produced at the substrate so that noise can be prevented from being capacitatively coupled from the substrate to the input stages of amplifiers in the same integrated circuit. The exemplary circuit is produced by the so-called BIDFET process and use both bipolar and field effect transistors. One semiconductor component described includes an enhancement mode MOSFET with a channel in the surface of an epitaxial layer and a drain region forming the base of a bipolar transistor using the epitaxial layer as a collector region, there being a highly doped buried layer of the same conductivity type as the epitaxial layer at the interface between it and the substrate which is of the opposite conductivity type.