The AD9876 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 supporting 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 AD9876 provides 12-bit converter performance on both the Tx and Rx path.

The TxDAC+ uses a selectable digital 2× or 4× interpolation low-pass or band-pass filter to further oversample transmit data and reduce the complexity of analog reconstruction filtering. The transmit path signal bandwidth can be as high as 26 MHz at an input data rate of 64 MSPS. The 12-bit DAC provides differential current outputs for optimum noise and distortion performance. The DAC full-scale current can be adjusted from 2 to 20 mA by a single resistor, providing 20 dB of additional gain range.

The receive path consists of a PGA, LPF, and ADC. The PGA has a gain range of –6 dB to +36 dB, programmable in 2 dB steps, adding 42 dB of dynamic range to the receive path. The receive path LPF cutoff frequency can be programmed to either 12 MHz or 26 MHz. The filter cutoff frequency can also be tuned or bypassed where filter requirements differ. The 12-bit ADC uses a multistage differential pipeline architecture to achieve excellent dynamic performance with low power consumption.

The AD9876 provides a voltage regulator controller (VRC) that can be used with an external power MOSFET transistor to form a cost-effective 1.3 V linear regulator.

The digital transmit and receive ports are each multiplexed to a bus width of six bits and are clocked at a frequency of twice the 12-bit word rate.

The AD9876 ADC and/or DAC can also be used at sampling rates as high as 64 MSPS in a 6-bit resolution nonmultiplexed mode.

The AD9876 is pin compatible with the 10-bit AD9875. Both are available in a space-saving 48-lead LQFP package. They are specified over the industrial (–40°C to +85°C) temperature range.

APPLICATIONS

• Powerline Networking
• Home Phone Networking
• xDSL
• Broadband Wireless
• Home RF