GENERAL DESCRIPTION
●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
●10-bit, 33 MSPS direct IF ADC
●Dual 7-bit, 16.5 MSPS sampling I/Q ADC
●12-bit Σ-∆ auxiliary DAC
●APPLICATIONS
● Cable modem and satellite systems
● Set-top boxes
● Power line modem
● PC multimedia
● Digital communications
● Data and video modems
● QAM, OFDM, FSK modulation
