Ultra-low-noise amp

Comms/medical-application amplifier features selectable gain and broad bandwidth

Analog Devices designed the AD8432 dual ultra-low-noise amplifier for high channel count, wide-bandwidth communications and medical applications. The device features selectable gain and active impedance matching, and provides superior noise performance, lower per-channel cost and nearly three times the bandwidth of comparable products. The 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 while retaining input-noise performance. Designers can select gain of four, eight, 12 or 16, by pin-strapping. At a gain of four, the amplifier has 200-MHz bandwidth, with a 0.85-nV/rtHz input referred voltage noise figure.

A single-ended-input amplifier, the AD8432 operates on a single 5-V supply and provides a differential output optimised to drive ADI’s AD8333 and AD8339 I/Q demodulators and phase shifters in medical ultrasound CW Doppler applications, in addition to a wide range of ADCs (analog-to-digital converters), such as the AD7679 18-bit, 570 ksamples/sec PulSAR converter and AD7952 14-bit, 1 Msamples/sec PulSAR converter.

ADI designed the AD8432 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. Its packaging features an exposed paddle that provides a low thermal-resistance path to the PCB (printed circuit board), which enables more efficient heat transfer and increases reliability. The AD8432 costs $1.99 (1000) and comes in a 4mm x 4mm LFSCP 24-Lead LFCSP.

EDN Europe