AD8327ARU-REEL

Overview

The AD8327ARU-REEL is a digitally controlled variable gain amplifier optimized for coaxial line driving applications. It operates from a single 5 V supply with a gain range of 48.16 dB, adjustable in 6.02 dB steps via an 8-bit serial interface. The device features a 160 MHz bandwidth and maintains a constant 75 Ω output impedance. Key electrical parameters include a maximum gain of 30 dB, minimum gain of -19.16 dB, and quiescent current ranging from 5 mA in sleep mode to 135 mA at maximum gain.

Feature Summary

• Digitally programmable gain control over a 48.16 dB range using SPI-compatible serial interface
• Maintains constant 75 Ω differential output impedance during both transmit enable and disable states
• Integrated transmit enable and sleep modes for power management and between-burst transient reduction

Applications

• DOCSIS high-speed data modems for upstream transmission
• Interactive cable set-top boxes requiring variable gain amplification
• PC plug-in cable modems designed to MCNS-DOCSIS standards
• General-purpose digitally controlled variable gain blocks in CATV systems

Procurement Notes

Verify component authenticity through authorized Analog Devices distributors or certified secondary market suppliers. Confirm the presence of the REEL suffix indicates tape-and-reel packaging suitable for automated assembly. Check for RoHS compliance status as manufacturing processes may vary by production batch. Ensure storage conditions adhere to ESD sensitivity guidelines to prevent performance degradation prior to installation.

Selection Notes

Select this component for designs requiring precise digital gain control in 5 V CATV environments. The fixed 75 Ω output simplifies PCB layout by eliminating external matching resistors. Consider the 160 MHz bandwidth sufficient for upstream frequencies up to 65 MHz. Evaluate power consumption requirements against the 5 mA sleep mode capability if battery efficiency or thermal management is critical for the target application.

Part Context

This part belongs to the AD8327 family of variable gain amplifiers manufactured by Analog Devices. It is specifically engineered for upstream path transmission in cable modem architectures. The device integrates a low-noise buffer, a digitally controlled attenuator, and a high-power output amplifier into a single 20-lead TSSOP package.

Replacement Considerations

No direct public substitutes are confirmed in the provided documentation. Designers should evaluate alternative variable gain amplifiers that support 5 V operation and 75 Ω output impedance. Verify pin compatibility and serial interface timing requirements when considering cross-reference components for legacy system maintenance.

FAQ

How is the gain adjusted on the AD8327?

Gain is adjusted via an 8-bit serial word loaded through the SDATA, CLK, and DATEN pins. Each major carry results in a 6.02 dB change in gain.

What is the function of the TXEN pin?

The TXEN pin controls the transmit state. Logic 1 enables forward transmission, while Logic 0 disables it, reducing power consumption and maintaining 75 Ω output impedance.

Does the output impedance change during transmit disable?

No, the AD8327 maintains a constant 75 Ω differential output impedance regardless of whether the device is in transmit enable or transmit disable mode.