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.
FEATURES
Low cost 3.3 V MxFE™ for DOCSIS-, EURO-DOCSIS-, DVB-, DAVIC-compliant set-top box and cable modem applications
232 MHz quadrature digital upconverter
12-bit direct IF DAC (TxDAC+™)
Up to 65 MHz carrier frequency DDS
Programmable sampling clock rates
16× upsampling interpolation LPF
Single-tone frequency synthesis
Analog Tx output level adjust
Direct cable amp interface
12-bit, 33 MSPS direct IF ADC with optional video clamping input
