AD9853AS

Overview

The AD9853AS is an obsolete programmable digital QPSK/16-QAM modulator fabricated on an advanced CMOS process. It integrates a high-speed direct-digital synthesizer (DDS), a 10-bit DAC, digital filters, and DSP functions into a single chip. The device supports FSK, QPSK, DQPSK, 16-QAM, and D16-QAM modulation formats with a 41-tap programmable pulse-shaping FIR filter. It operates on a single +3.3 V to +5 V supply, consuming 750 mW at full clock speed. The component features a 6x internal reference clock multiplier, integrated Reed-Solomon FEC, and a serial control bus for configuration.

Feature Summary

• Integrates DDS, 10-bit DAC, and DSP functions for complete digital modulation
• Supports multiple modulation formats including QPSK, 16-QAM, and FSK
• Includes programmable pulse-shaping FIR filters and interpolating filters
• Features integrated Reed-Solomon forward error correction and randomizer

Applications

• HFC network return-channel transmitter applications
• Interactive cable modem systems
• Wireless LAN infrastructure

Procurement Notes

This component is officially classified as obsolete by Analog Devices. Verification of availability requires checking authorized distributors or surplus suppliers for remaining stock. Ensure the specific MQFP package variant matches the target PCB footprint. Confirm that the design can accommodate end-of-life status without requiring immediate redesign.

Selection Notes

Select this part for HFC return-path designs requiring integrated digital modulation. Verify compatibility with the AD8320 cable driver amplifier for optimal signal integrity. Check that the required modulation format and data rates fall within the supported specifications. Consider the surface mount packaging constraints during layout planning.

Part Context

The AD9853AS belongs to the AD9853 series of digital modulators from Analog Devices. It is designed specifically for cost-effective and space-saving implementations in cable modem and HFC network equipment. The AS suffix denotes the Metric Quad Flatpack (MQFP) package option suitable for automated surface mount assembly processes.

Replacement Considerations

No official replacement part numbers are documented in the provided datasheet. As the component is obsolete, alternative solutions may require evaluating newer generation modulators or discrete FPGA-based implementations to replicate the integrated DDS and DAC functionality.