AD9877

The AD9877 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 and dual 8-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 upsampling factors of 12* or 16* with an output signal bandwidth as high as 5.8 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 dB to 7.5 dB in 0.5 dB steps is available to preserve SNR when reduced output levels are required.

The 12-bit ADC has excellent undersampling performance, allowing it to typically deliver better than 10 ENOBs with IF inputs up to 70 MHz. The 12-bit IF ADC can sample at a rate up to 33 MHz, allowing it to process wideband signal inputs. Two programmable - DACs are available and can be used to control external components, such as variable gain amplifiers (VGAs) or voltage-controlled tuners.

The AD9877 integrates a CA port that enables a host processor to control the AD8321/AD8325 or AD8322/AD8327 programmable gain amplifier (PGA) cable drivers via the MxFE SPORT.

The AD9877 is available in a 100-lead MQFP package. It offers enhanced receive path undersampling performance and lower cost compared to the pin-compatible AD9873. The AD9877 is specified over the extended industrial (−40°C to +85°C) temperature range.