AD9878BSTZ

Overview

The AD9878BSTZ is a single-supply, 3.3 V mixed-signal front end (MxFE) designed for broadband cable applications. It integrates a transmit path with a 12-bit direct IF DAC operating up to 232 MSPS and a quadrature digital upconverter supporting carrier frequencies up to 65 MHz. The receive path features dual 12-bit ADCs and one 10-bit ADC, all sampling at 29 MSPS. Internal clock generation is handled by a PLL derived from a single crystal or clock input. The device includes an auxiliary ∑-∆ DAC and a CA port for interfacing with external PGA cable drivers.

Feature Summary

• Transmit: 12-bit TxDAC+ running at 232 MSPS with programmable analog output level adjustment (0 dB to -7.5 dB).
• Receive: Dual 12-bit and single 10-bit ADCs with video clamp input; 12-bit ADCs deliver >10 ENOBs at IF inputs up to 70 MHz.
• Digital Processing: Integrated DDS for frequency synthesis up to 65 MHz with 26-bit tuning resolution and 16× interpolation filter.
• Interface: Serial control bus and dedicated CA port for direct connection to AD832x family cable driver amplifiers.

Applications

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

Procurement Notes

Verify the package type is the 100-lead LQFP. Confirm the temperature range specification covers extended industrial conditions (-40°C to +85°C). Ensure the ordering suffix matches the required tape and reel or tube configuration if applicable, though specific packaging quantities are not detailed in the datasheet.

Selection Notes

Select this component for designs requiring a unified Tx/Rx solution for DOCSIS, EURO-DOCSIS, DVB, and DAVIC standards. The integrated PLL simplifies clocking requirements by generating internal clocks from a single oscillator. Consider the 12-bit ADC dynamic performance for wideband signal processing needs.

Part Context

The AD9878 is part of Analog Devices' MxFE product line, targeting hybrid fiber-coaxial (HFC) network infrastructure. It consolidates multiple discrete components into a single chip to reduce board space and power consumption in upstream and downstream cable modem architectures.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Designers should consult Analog Devices for current portfolio updates or cross-reference options based on specific interface and performance requirements.

FAQ

What is the maximum sampling rate for the transmit DAC?

The transmit DAC supports a maximum sample rate of 232 MSPS.

How is the internal clock generated?

All internally required clocks and the output system clock are generated by the phase-locked loop (PLL) from a single crystal oscillator or clock input.

Can the AD9878 interface directly with cable driver amplifiers?

Yes, it integrates a CA port that enables a host processor to interface with the AD832x family of programmable gain amplifier (PGA) cable drivers via the MxFE serial port.