Dual low-noise amplifier

5 August 2009 Analogue, Mixed Signal, LSI

Analog Devices has introduced a dual, ultra- low-noise amplifier with selectable gain and active impedance matching.

The AD8432’s combination of selectable gain and low noise enables the amplifier to detect and resolve low-level input signals. Active impedance matching reduces signal reflection by matching signal-source and amplifier-input impedances without compromising input-noise performance. By using the pin-strapping options, designers can select gains of 4, 8, 12 and 16. At a gain of four, the amplifier has a bandwidth of 200 MHz and 0,85 nV/rtHz input referred voltage noise figure.

The device is designed for communications infrastructure and medical ultrasound applications that require up to 200 MHz of bandwidth combined with a high channel count and variable gains. The common die and symmetrical design ensure precise phase matching between channels.

A single-ended-input amplifier, the AD8432 operates on a single 5 V supply and provides a differential output optimised to drive Analog Devices’ AD8333 and AD8339 I/Q demodulators and phase shifters in medical ultrasound CW Doppler applications, as well as a wide range of ADCs such as the AD7679 18-bit, 570 kSps PulSAR converter and AD7952 14-bit, 1 MSps PulSAR converter.

The AD8432 packaging features an exposed paddle that provides a low thermal-resistance path to the PCB (printed circuit board), which enables efficient heat transfer and increases reliability.

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