INTRODUCTION
The ST70136 ADSL Analog Front End (AFE) chip implements the analog transceiver functions required in a Customer Premise ADSL modem. It connects the digital modem chip with the loop driver and hybrid balance circuits.
The AFE has been designed with high dynamic range in order to greatly reduce the external filtering requirements at the front end.
The AFE chip and its companion digital chip along with a loop driver, implement the complete G.992.2 and G.992.1 DMT modem solution.
The AFE receive path contains a programmable gain amplifier (RxPGA), a low pass anti-aliasing filter, and a 12-bit A/D converter. The RxPGA is digitally programmable from 0 to 31dB in 1dB steps.
The AFE transmit path consists of a 14-bit D/A converter, followed by a programmable gain amplifier (TxPGA). The transmit gain is programmable from 0 to -15dB in 1dB steps.

■ WIDE TRANSMIT AND RECEIVE DYNAMIC RANGE TO REDUCE EXTERNAL FILTERING REQUIREMENTS
■ RECEIVE PROGRAMMABLE GAIN: 0 TO 31dB GAIN IN 1dB STEPS
■ RECEIVE PROGRAMMABLE ATTENUATOR 0,-4dB, -8dB, -12dB
■ 12-BIT A/D CONVERTER IN RECEIVE PATH
■ TRANSMIT PROGRAMMABLE GAIN: 0 TO -15dB IN 1dB STEPS
■ 14-BIT D/A CONVERTER IN TRANSMIT PATH
■ LOW POWER MODE: 10mW IN LISTENING MODE, 250µW IN POWER DOWN
■ TONE DETECTOR: ACTIVITY DETECTION FOR WAKE-UP FUNCTION
■ 64-PIN TQFP PACKAGE
■ 64-PIN LFBGA PACKAGE
■ 0.50µm, 5V BICMOS TECHNOLOGY
■ 3.3V DIGITAL INTERFACE
■ 5V ANALOG INTERFACE