AD9878BST

Overview

The AD9878BST is a single-supply, 3.3 V CMOS mixed-signal front end (MxFE) designed for broadband cable modem and set-top box applications. It integrates a transmit path featuring a quadrature digital upconverter, interpolation filter, and a 12-bit direct IF DAC capable of sampling rates up to 232 MSPS with carrier frequencies up to 65 MHz. The receive path includes dual 12-bit ADCs and one 10-bit ADC, all sampling at 29 MSPS. Internal clock generation is handled by a phase-locked loop (PLL) derived from a single crystal or clock input. The device supports DOCSIS, EURO-DOCSIS, DVB, and DAVIC standards.

Feature Summary

• Integrated 12-bit direct IF DAC with programmable sampling rates up to 232 MSPS and analog output level adjustment.
• Dual 12-bit and single 10-bit ADCs in the receive path, supporting 29 MSPS sampling rates and undersampling performance.
• Complete quadrature digital upconverter with a Direct Digital Synthesizer (DDS) providing up to 65 MHz carrier frequency.
• Internal PLL generates all required clocks from a single oscillator input; includes an 8-bit Σ-Δ auxiliary DAC.

Applications

• Cable set-top boxes
• Cable modems
• Wireless modems

Procurement Notes

Verify that the ordering suffix 'BST' corresponds to the specific package variant and temperature range defined in the official Analog Devices Ordering Guide. Confirm the revision status (Rev. A) matches the design requirements. Ensure compatibility with the 100-lead LQFP package dimensions during PCB layout planning.

Selection Notes

Select this component for broadband applications requiring integrated Tx/Rx signal conditioning. Ensure the host processor can interface via the SPORT serial port for register control. Verify that the external resistor values for FSADJ and REFIO meet the electrical characteristics for desired output current and reference stability.

Part Context

The AD9878 is part of Analog Devices' MxFE family, targeting cable infrastructure. It replaces discrete transmitter and receiver solutions by integrating filters, mixers, and converters. Similar devices include the AD9861 and AD9865, which offer varying levels of integration for baseband transceiver applications.

Replacement Considerations

Check the official Ordering Guide for pin-compatible or functionally equivalent alternatives within the AD98xx series. Verify that any substitute maintains the 100-lead LQFP footprint and 3.3 V supply requirements.