Erik Moerman

A four-channel digital signal processor in 1.2- mu m CMOS with on-chip D/A and A/D conversion serving four speech channels in a new-generation subscriber line circuit

The major component for a new-generation line circuit was designed and fabricated in a 1.2- mu m CMOS technology. The circuit includes digital signal processing of receive (RX) and transmit (TX) signals as well as the analog front end of four subscriber lines to a PCM (pulse code modulation) digital exchange. The device operates on a single 5-V power supply. The four-channel digital signal-processor including the analog front ends is fabricated on a 40-mm/sup 2/ 1.2- mu m CMOS die area. The DSP functions, the RX and TX filters, the decimator, the interpolator, and the A/ mu -law transcoder are included as independent data paths, one for the TX and RX filters, one for the decimator, and another for the interpolator, the digital sigma-delta modulator, and the transcoder. The on-chip analog front end contains a notch filter to cancel the 12/16-kHz payphone signal, a switched-capacitor PDM A/D and D/A converter, and smoothing filters. On the first measured samples, the signal-to-distortion ratio is measured to be 33 dB at -45 dBmo for -7 dB gain setting. >

A 4/7 kHz audio bandwidth selectable digital phone interface (DPI) chip with on-chip analog functions and modem

The Digital Phone Interface (DPI) is designed for a new generation of digital telephone terminals for private exchanges. This circuit gives a total solution for all telephone function thereby including DSP functions, voice coding/decoding and analog front end, signal generators for DTMF and ringing, modem for data transfer between terminal and exchange and a multitude of interfaces to communicate to the external world. Besides the normal earpiece micro and speaker, handsfree operation is available by using a selectable input low noise microphone amplifier and an additional 50 ¿ 100mW LS driver. For the handsfree operation an AGC and anti-oscillation (anti-larsen) function is implemented. The line modem generates a modified RTZ (WAL2) code and is able to cover distances to 1.5 km. In addition the component is extensible with external signal processing modules (echo cancelling ..) and is also able to transfer a 7 kHz speech bandwidth. The device is a mixed analog/digital design produced in a 1.2¿m CMOS technology on 46 mm2 die area and consumes 200 mW.

A single chip mixed digital/analog signal processor in 1.2 mu CMOS interfacing 4 analog subscriber lines to the PCM digital System 12 exchange

For the development of a new generation line circuit a 4 channel speech processor was designed and fabricated in a 1.2 mu CMOS technology. The circuit includes digital signal processing for receive and transmit signals as well as the analog frontend interfacing four subscriber lines to a PCM digital exchange. The device is operating on a single 5 V power supply.<<ETX>>