Fully Integrated Analog Telephone

The design of a CLSI for analog subset applications is presented. The MIP (Maximum Integrated Phone) combines extended signalling and speech functions in a single integrated circuit using a 2.4 micron CMOS technology. A loudspeaker amplifier included in the receive path permits on hook dialing and group listening. A synthesized high impedant current source extracts the power available on the line terminals. The noise requirements of -72 dBVp with 50 dB gain could be achieved by implementing a low noise preamplifier and with integration of a background noise reduction circuit in the transmit path. Packaged in a 40 pins DIL the MIP-device offers a cost effective solution for future low-, medium- and high-end subset applications.