A programmable speech circuit suitable for telephone transducers

To satisfy the differing requirements of various telecommunication administrations and to accommodate the characteristics of different transducers, a number of electronic speech circuits have been developed. To avoid this proliferation of types, a new programmable speech circuit, based on an improved bipolar process, has been developed. This speech circuit is suitable for many transducer types-dynamic, piezoceramic, and electret microphones-and provides 6 dB of programmable gain in both directions to compensate for line length.