AD8331ARQZ

Overview

The AD8331ARQZ is a single-channel ultralow noise variable gain amplifier (VGA) from Analog Devices, housed in a 20-lead QSOP package. It integrates an LNA with 19 dB fixed gain and an X-AMP VGA providing 48 dB of linear-in-dB control range. The device operates on a single 5 V supply, consuming 125 mW per channel. Key electrical parameters include a 120 MHz bandwidth, 0.74 nV/√Hz input voltage noise, and a typical output-referred noise of 48 nV/√Hz. Gain scaling is 50 dB/V over a 0 to 1 V control voltage range.

Feature Summary

• Integrates an ultralow noise preamplifier with programmable input impedance matching for source optimization without compromising noise performance.
• Features an X-AMP variable gain amplifier with precise linear-in-dB scaling and excellent part-to-part gain matching.
• Includes a selectable gain postamplifier with adjustable output limiting to prevent overload in subsequent stages.

Applications

• Ultrasound and sonar time-gain controls
• High performance automatic gain control systems
• I/Q signal processing
• High speed dual ADC drivers

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to ensure correct packaging and tape-and-reel specifications. Confirm that the component meets all required environmental standards and RoHS compliance levels before finalizing procurement orders.

Selection Notes

Select this component when a single-channel solution with integrated low-noise amplification is required. Ensure the application utilizes a single 5 V supply and requires a 120 MHz bandwidth. Verify that the 20-lead QSOP package dimensions fit the target PCB layout constraints.

Part Context

This device belongs to the AD8331/AD8332/AD8334 family of ultralow noise VGAs. While the AD8332 offers dual channels and the AD8334 provides quad channels, the AD8331 is specifically designed as a single-channel unit. All variants share the same core X-AMP technology and signal path architecture.

Replacement Considerations

Direct functional replacements within the same family include the AD8332 and AD8334, though these offer different channel counts and pin configurations. Verify pin compatibility and thermal requirements when substituting with higher-density variants.

FAQ

How is the input impedance of the AD8331 adjusted?

The input impedance can be adjusted using a single external resistor connected to the RIZ pin, allowing matching to various signal sources while maintaining optimal noise performance.

What is the function of the HILO pin?

The HILO pin selects between two gain ranges: LO mode (-4.5 dB to +43.5 dB) and HI mode (7.5 dB to 55.5 dB), optimizing the gain range and output noise for specific applications.