The AD8432 is a dual-channel, low power, ultralow noiseamplifier with selectable gain and active impedance matching.Each channel has a single-ended input, differential output, andintegrated input clamps. By pin strapping the gain setting pins, four accurate gains of G = 12.04 dB, 18.06 dB, 21.58 dB, and 24.08 dB (×4, ×8, ×12, and ×16, respectively) are possible. A bandwidth of200 MHz at G = 12.04 dB makes this amplifier well suited for many high speed applications.

The exceptional noise performance of the AD8432 is madepossible by the active impedance matching. Using a feedback network, the input impedance of the amplifiers can be adjusted to match the signal source impedance without compromising the noise performance. Impedance matching and low noise in the AD8432 allow designers to create wider dynamic rangesystems that are able to detect even very low level signals.

The AD8432 achieves 0.85 nV/√Hz input-referred voltage noise fora gain of 12.04 dB. The AD8432’s ultralow noise, low distortion, gain accuracy, and channel-to-channel matching are ideal for high performance ultrasound systems and for processing I/Qdemodulator signals.

The AD8432 operates on a single supply of 5 V at 24 mA. It isavailable in a 4 mm × 4 mm, 24-lead LFSCP. The LFCSP featuresan exposed paddle that provides a low thermal resistance path to the PCB, which enables more efficient heat transfer and increasesreliability. The operating temperature range is −40°C to +85°C.

Applications

• CW Doppler ultrasound front ends 
• Low noise preamplification 
• Predriver for I/Q demodulators and phase shifters 
• Wideband analog-to-digital drivers

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.