AD9879

The AD9879 is a single-supply set-top box and cable modem mixed-signal front end. The device contains a transmit path interpolation filter, complete quadrature digital upconverter, and transmit DAC. The receive path contains a 12-bit ADC, a 10-bit ADC, and dual 7-bit ADCs. All internally required clocks and an output system clock are generated by the phase-locked loop (PLL) from a single crystal or clock input.

The transmit path interpolation filter provides an upsampling factor of 16* with an output signal bandwidth as high as 8.3 MHz. Carrier frequencies up to 65 MHz with 26 bits of frequency tuning resolution can be generated by the direct digital synthesizer (DDS). The transmit DAC resolution is 12 bits and can run at sampling rates as high as 232 MSPS. Analog output scaling from 0.0 dB to 7.5 dB in 0.5 dB steps is available to preserve SNR when reduced output levels are required.

The 12-bit and 10-bit IF ADCs can convert direct IF inputs up to 70 MHz and run at sample rates up to 33 MSPS. A video input with an adjustable signal clamping level, along with the 10-bit ADC, allow the AD9879 to process an NTSC and a QAM channel simultaneously.

The programmable - DAC can be used to control external components, such as variable gain amplifiers (VGAs) or voltage controlled tuners. The CA port provides an interface to the AD8321/AD8323 or AD8322/AD8327 programmable gain amplifier (PGA) cable drivers, enabling host processor control via the MxFE SPORT.

The AD9879 is available in a 100-lead MQFP. It offers enhanced receive path undersampling performance and lower cost when compared with the pin-compatible AD9873. The AD9879 is specified over the commercial (−40°C to +85°C) temperature range.