The AD9877 is a single supply Cable Modem/Set Top Box Mixed Signal Front End. The device contains a transmit path interpolation filter, a 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 PLL from a single crystal or clock input.
The transmit path interpolation filter provides upsampling factors of 12x or 16x with an output signal bandwidth as high as 8.4 MHz. The direct digital synthesizer (DDS) can generate carrier frequencies up to 65 MHz with 26 bits of frequency tuning resolution. The transmit DAC resolution is 12 bits and can run at sampling rates as high as 232 MSPS. Analog output scaling from 0 to 7.5 dB in 0.5 dB steps is available to preserve transmit path SNR when reduced output levels are required.
The 12-bit ADC has excellent undersampling performance allowing it to deliver better than 10 ENOBs with IF inputs up to 75 MHz. The 12-bit IF ADC has a sampling rate of up to 33MHz, allowing it to process wideband signal inputs.
Two programmable sigma delta DACs are available which 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/AD8323 or AD8322/AD8327 programmable gain amplifier (PGA) cable drivers through the MxFE SPORT.
The AD9877 is available in a 100-pin MQFP package. It offers enhanced receive path undersampling performance and lower cost, compared with the pin compatible AD9873. The AD9877 is specified over the extended industrial (-40ºC to +85°C) temperature range.
