AD9975 Datasheet | Analog Devices

Features Low Cost, 3.3 V-CMOS, Mixed Signal, Front End Converter for Broadband Modems 10-Bit D/A Converter (Tx DAC+®) 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 10 K 10 TX+ Tx DAC+ TX- CLK1 ADIO[9:0] CLK-GEN CLK2 OSCIN XTAL RX+ RX- AGC[2:0] 3 3 SPORT REGISTER CONTROL GENERAL DESCRIPTION The AD9975 is a single-supply, broadband modem, mixed signal, front end (Mx FE™) 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 Tx DAC+ uses a digital 2× interpolation low-pass filter to oversample the transmit data and ease the plexity 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 m A by a single resistor, providing 20 d B of additional gain range. The receive path consists of a PGA, LPF, and ADC. The programmable gain amplifier (PGA) has two modes of operation. One mode allows programming through the serial port and provides a gain range from - 6 d B to +36 d B in 2 d B steps. The other mode allows the gain to be controlled through an asynchronous 3-pin port and offers a gain range from 0 d B to 48 d B in 8 d B steps with the use of an external gain stage. The receive path LPF cutoff frequency can be selected to either 12...