4b3t U Interface Circuit

STU2071 (UIC) provides two transparent 64 kbit/s B channels, a transparent 16 kbit/s D channel, a transparent 1 kbit/s service channel and a 1 kbit/s maintenance channel for loop and error mes- sages on subscriber lines. UIC enables full duplex continuous data transmis- sion via the standard twisted pair telephone ca- ble. Adaptive Echo cancellation is used to restore the received data. An equalizer, done with an adaptive Filter restores the data which are dis- torted by the transmission line. The coefficient of the equalizer and echo cancel- ler are conserved during a power down. An all digital PLL performs both bit and frame synchroni- zation. The Analog front end consists of receive path RX and transmit path TX, providing a full duplex ana- log interfacing to the twisted pair telephone cable. Before data are converted to Analog signals, they pass through a digital Filter (TX-filter) to reduce the high frequency components. After D/A con- version the signal is amplified and sent to the hy- brid . By STMicroelectronics