AD8321AR

Overview

The AD8321 is a digitally controlled variable gain amplifier optimized for coaxial line driving applications. It operates from a single +9 V supply and features an SPI-compatible interface for gain control over a 53.4 dB range with 0.7526 dB/LSB resolution. The device maintains a constant 75 Ω output impedance during power-up and power-down conditions, eliminating the need for external transformers. It supports differential or single-ended inputs and delivers low distortion performance.

Feature Summary

• Digitally programmable gain via SPI-compatible serial interface
• Maintains constant 75 Ω output impedance in all operational states
• Integrated reverse amplifier for low-power standby mode
• Optimized for driving low-distortion signals into 75 Ω loads

Applications

• Gain programmable line drivers for cable modems
• HFC high-speed data modem upstream paths
• Interactive CATV set-top boxes
• CATV plant test equipment
• General purpose IF variable gain blocks

Procurement Notes

Verify component status as the datasheet indicates OBSOLETE. Confirm availability of equivalent replacement parts if current stock is limited. Ensure ordering suffixes match required packaging options such as reel or tube formats. Check for lead-free (Z) variants if environmental compliance is mandatory for the specific application design.

Selection Notes

Select this component for applications requiring precise digital gain control in RF signal chains. It is suitable for designs needing a fixed 75 Ω output impedance without external matching networks. Consider the single-supply operation and power-down functionality for battery-sensitive or energy-efficient systems. Verify input signal levels against the specified AC voltage output requirements.

Part Context

Manufactured by Analog Devices Inc., the AD8321 belongs to the family of gain-programmable amplifiers designed for cable television infrastructure. It serves as a critical component in hybrid fiber-coaxial networks, specifically handling upstream data transmission. The device integrates attenuator cores, power amplifiers, and digital logic into a single 20-lead SOIC package.

Replacement Considerations

Public documentation identifies the AD8326 as a related high-output power variant within the same product family. Designers should evaluate the AD8326 if higher output power capabilities are required while maintaining similar interface characteristics. No other direct public substitutes are confirmed in the provided source material.