Analog Front End for an ANSI Standard ISDN Transceiver

This paper describes the analog front end of a two-chip U-interface transceiver based on the American National Standard Institute (ANSI) 2B1Q line code. The companion digital signal processing chip is described elsewhere. The ultimate system performance of the transceiver is determined to a large extent by the performance of the analog front end. The main limiting factors are nonlinear distortion, the resolution of the data converters and noise. The chip described here achieves about 75dB linearity in the transmitter and 13 bit resolution in the receiver ADC.