Fully integrated analog telephone

The maximum integrated phone (MIP) combines the signaling and speech functions for analog subset applications in a single integrated circuit using a 2.4- mu m CMOS technology. The device can handle both dual-tone multiple-frequency and decadic dialing. A ten-number repertory and a last-number redial function are included. A loudspeaker amplifier allows call progress monitoring during on-hook dialing. Background-noise-reduction circuitry is included in the transmit path to achieve a noise performance of -72 dBV/sub p/ with 50-dB gain. Power is extracted from the line terminals by a synthesized high-impedance current source. The chip is 17-mm/sup 2/ and is presented in a 40-pin dual in-line package.<
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