The AD766 16-bit DSP DACPORT provides a direct， threewire interface to the serial ports of popular DSP processors， including the ADSP-2101， TMS320CXX， and DSP56001. No additional “glue logic” is required. The AD766 is also complete， offering on-chip serial-to-parallel input format conversion， a 16-bit current-steering DAC， voltage reference， and a voltage output op amp. The AD766 is fabricated in Analog Devices’ BiMOS II mixed-signal process which provides bipolar transistors， MOS transistors， and thin-film resistors for precision analog circuits in addition to CMOS devices for logic. The design and layout of the AD766 have been optimized for ac performance and are responsible for its guaranteed and tested 94 dB signal-to-noise ratio to 20 kHz and 79 dB SNR to 250 kHz. Laser-trimming the AD766’s silicon chromium thinfilm resistors reduces total harmonic distortion below –81 dB （at 1 kHz）， a specification also production tested. An optional linearity trim pin allows elimination of midscale differential linearity error for even lower THD with small signals. The AD766’s output amplifier provides a ±3 V signal with a high slew rate， small glitch， and fast settling. The output amplifier is short circuit protected and can withstand indefinite shorts to ground.