At this time, DMT modulated waveforms are not typically menuselectable items contained within arbitrary waveform generators. Even using AWG software to generate DMT signals, AWGs that are available today may not deliver DMT signals sufficient in performance with regard to MTPR due to limitations in the D/A converters and output drivers used by AWG manufacturers. Similar to evaluating single-tone distortion performance of an amplifier, MTPR evaluation requires a DMT signal generator capable of delivering MTPR performance better than that of the driver under evaluation. Generating DMT signals can be accomplished using a Tektronics AWG 2021 equipped with opt 4, (12/24-Bit, TTL digital data out), digitally coupled to Analog Devices AD9754, a 14-bit TxDAC®, buffered by an AD8002 amplifier configured as a differential driver. See Figure 45 for schematics of a circuit used to generate DMT signals that can achieve down to –80 dBc of MTPR performance, sufficient for use in evaluating xDSL drivers. Note that the DMT waveforms available with the AD8016ARP-EVAL and AD8016ARB-EVAL boards or similar WFM files are needed to produce the necessary digital data required to drive the TxDAC from the optional TTL digital data output of the TEK AWG2021. Copies of these WFM files can be obtained through the Analog Devices website,