AD8317ACHIPS

Overview

The AD8317 is a demodulating logarithmic amplifier fabricated using a high-speed SiGe process, designed for RF measurement and power control applications. It operates over a frequency range of 1 MHz to 10 GHz with a typical supply voltage of 3.0 V to 5.5 V and quiescent current of 22 mA. The device provides a 55 dB dynamic range up to 8 GHz with ±3 dB error and maintains high accuracy of ±1.0 dB over temperature. Key electrical parameters include a logarithmic slope of -22 mV/dB, an intercept of 15 dBm, and pulse response times of 6 ns fall and 10 ns rise.

Feature Summary

• Demodulating logarithmic amplifier utilizing progressive compression across a cascaded amplifier chain equipped with detector cells.
• Capable of functioning in both measurement mode for signal amplitude monitoring and controller mode for power amplifier setpoint regulation.
• Features low noise output suitable for precise measurements and rapid pulse response enabling detection of RF bursts at rates exceeding 50 MHz.
• Includes temperature compensation adjustment interface to optimize intercept stability against ambient temperature variations.

Applications

• RF transmitter PA setpoint control and level monitoring
• Power monitoring in radio link transmitters
• RSSI measurement in base stations, WLANs, WiMAX, and radars

Procurement Notes

Verify the specific suffix of the part number against the manufacturer's ordering guide to confirm package type and temperature grade. Ensure the component matches the required RoHS compliance status for your assembly process. Confirm that the datasheet revision aligns with your design specifications, as performance characteristics may be updated between revisions. Cross-reference pin configurations to ensure compatibility with existing PCB layouts.

Selection Notes

Select this component when wide bandwidth up to 10 GHz and high dynamic range are required for RF signal processing. Consider the 2 mm × 3 mm LFCSP package for space-constrained designs. Evaluate the need for external temperature compensation resistors based on the operating frequency and required intercept stability. Ensure the system can accommodate the specified supply voltage range and current consumption during active operation.

Part Context

The AD8317 belongs to Analog Devices' family of demodulating logarithmic amplifiers, sharing design heritage with devices like the AD8318 but offering enhanced speed and reduced footprint. It is distinct from ADCs or accelerometers by its specific function as a log converter for RF signals rather than digital data conversion or motion sensing. The device is optimized for linear-in-dB output representation of input signal amplitudes.

Replacement Considerations

Check the manufacturer's official cross-reference list for verified substitutes. Ensure any replacement maintains the 1 MHz to 10 GHz bandwidth and similar dynamic range specifications. Verify pinout compatibility if direct replacement is intended without PCB redesign.

FAQ

How does the AD8317 handle temperature drift in its output?

The device includes a TADJ pin that allows for the connection of an external resistor to ground. This resistor sets an analog correction coefficient to reduce intercept drift, optimizing stability for specific operating frequencies.

What is the difference between measurement and controller modes?

In measurement mode, VOUT provides a decreasing linear-in-dB representation of the RF input signal amplitude. In controller mode, VOUT regulates the gain of an external amplifier to maintain a setpoint defined by the VSET pin.