AD9975

a FEATURES Low Cost, 3.3 V-CMOS, Mixed Signal, Front End Converter for Broadband Modems 10-Bit D/A Converter (TxDAC+®) 50 MSPS Input Word Rate 2؋ Interpolating Low-Pass Transmit Filter 100 MSPS DAC Output Update Rate Wide (21 MHz) Transmit Bandwidth Power-Down Modes 10-Bit, 50 MSPS A/D Converter Fourth Order LPF with Selectable Cutoff Frequency Dual Mode Programmable Gain Amplifier Internal Clock Multiplier (PLL) Two Auxiliary Clock Outputs 48-Lead LQFP Package APPLICATIONS Powerline Networking Home Phone Networking TXEN RXEN TXCLK RXCLK Broadband Modem Mixed-Signal Front End AD9975 FUNCTIONAL BLOCK DIAGRAM AD9975 10 K 10 TX+ TxDAC+ TX– CLK1 ADIO[9:0] CLK-GEN CLK2 OSCIN XTAL 10 ADC PGA LPF PGA RX+ RX– AGC[2:0] 3 3 SPORT REGISTER CONTROL GENERAL DESCRIPTION The AD9975 is a single-supply, broadband modem, mixed signal, front end (MxFE™) IC. The device contains a transmit path interpolation filter and DAC and a receive path PGA, LPF, and ADC required for a variety of broadband modem applications. Also on-chip is a PLL clock multiplier that provides all required clocks from a single crystal or clock input. The TxDAC+ uses a digital 2× interpolation low-pass filter to oversample the transmit data and ease the complexity of analog reconstruction filtering. The transmit path bandwidth is 21 MHz when sampled at 100 MSPS. The 10-bit DAC provides differential current outputs. The DAC full-scale current can be adjusted from 2 to 20 mA by a single resistor, providing 20 dB ...