[ MOT Two Chip ADSL solution/ADI 5 chip solution ]
......For example, Motorola has announced a two-chip set that provides all the ADSL-specific modem functions: the MC14560 ADSL transceiver and the MC03AX1456CO/RT line driver. The MC14560 ADSL transceiver packs all the basic functions to perform transmit and receive operations in a Category 2 ADSL modem. It can handle data rates up to 8 Mbits/s downstream and 1 Mbit/s full-duplex. When combined with a controller and line-driver interface, it can be configured as either a central-office or remote-terminal ADSL transceiver unit (ATU-C or ATU-R, respectively)
The 14560 uses a digital interface to transfer input and output data. The transceiver can support up to seven independent data streams or bearer services, including four simplex ports and three duplex ports for bidirectional transfers. The digital interface provides framing, data interleaving and deframing trellis encoding/decoding. An on-chip DMT processor sports embedded DSPs and peripherals to perform modulation, demodulation and echo cancellation for the system. This device handles both transmit and receive functions.
The 14560's analog front end performs D/A conversions on the data samples from the DMT processor, as well as the filtering and signal conditioning required for transmission on the line interface. On the receive side, it filters the analog input, performs A/D conversion and provides the samples to the DMT processor. The analog front end also contains a special host-processor interface consisting of an 8-bit data bus, 5-bit address bus, chip select, read-write signal and a single interrupt line. The interface is directly compatible with the 8-bit parallel data and address interface on Motorola microcontrollers. Depending on the application, the host processor could be from Motorola's MC68302, MC68360 or MPC860 families.
Completing the Motorola solution is the MC03AX1456 line driver, a single chip to interface the MC14560 transceiver with the line transformer. The MC03AX1456CO line driver is designed for the central office (ATU-C) and the MC03AX1456RT for the remote terminal (ATU-R). The line driver provides three differential ports: a transmit and a receive port to interface to the transceiver, and a bidirectional line port. The transmit port incorporates a high-pass filter and programmable gain stage, while the receive port provides programmable high-frequency boost, programmable gain and a high-pass filter.
For its part, Analog Devices has announced a five-chip set for implementing an ADSL modem. The AD20mps910 chip set consists of the AD6435 modem interface, the AD6436 DMT coprocessor, the AD6437 analog front end, the AD816 line driver and receiver, and the ADSP-2183 DSP.
The modem-interface device forms the interface between the ADSL chip set and external systems. The ADSL transceiver includes an internal V.35 interface, and Ethernet or ATM interfaces can be implemented.
The DMT coprocessor performs core DSP functions to implement DMT modulation and demodulation. The AD6437 analog front end is a single-chip implementation of all analog and mixed-signal operations required in an ADSL system, including A/D, D/A, filters and amplifiers.
The AD816 incorporates the line driver, receiver and amplifiers to interface to the line interface. Finally, the ADSP-2183 general-purpose 16-bit DSP polishes off a variety of general control tasks, including training (line characterization) and system-control operations.
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