AD8428:  Low Noise, Low Gain Drift, G = 2000 Instrumentation Amplifier

The AD8428 is an ultra-low noise instrumentation amplifier designed for accurately measuring tiny, high-speed signals. It delivers industry-leading gain-accuracy, noise and bandwidth.

All gain setting resistors for the AD8428 are internal to the part and precisely matched. Care is taken in both interconnects and symmetry. This results in excellent gain drift and quick settling to the final gain value after the part is powered on.

The high CMRR of the AD8428 prevents unwanted signals from corrupting the acquisition. The part’s pin-out is designed to avoid parasitic capacitance mismatches that can degrade CMRR at high frequencies.

The AD8428 is one of the fastest instrumentation amplifiers available. The circuit architecture is designed for high bandwidth at high gain: it uses current feedback topology for the initial pre-amp gain stage of 200, followed by a difference amplifier stage of 10. This results in a 3.5 MHz bandwidth at a gain of 2000, for an equivalent gain-bandwidth product of 7 GHz.

The AD8428 pinout allows access to internal nodes between the first and second stage. This feature can be useful to modify DC and AC parameters between the two amplification stages.

The AD8428 performance is specified over the industrial temperature range of −40°C to +85°C. It is available in an 8-lead plastic SOIC package.

APPLICATIONS

• Sensor interface
• Medical instrumentation
• Patient monitoring