Analog Devices' precision instrumentation amplifier front-end

As part of a complete signal chain, the AD8295 in amp works well with a wide range of ADI’s analogue-to-digital converters (ADCs), including the AD7656, AD7763 and AD7690, and multiplexers, such as ADI’s ADG1209.

The AD8295 in amp delivers the highest common-mode rejection (CMR) over frequency in its class. The CMR of competing devices typically falls off at 200 Hz, while the AD8295 maintains a minimum CMR of 80 dB to 8 kHz for all grades at G = 1. High CMR over frequency allows the AD8295 to reject wideband interference and line harmonics, greatly simplifying filter design. The on-board in amp is gain-programmable and uses a single resistor to set the gain from 1 to 1000, delivering 1 ppm/ degrees C maximum gain drift (B grade), 8 nV/√Hz maximum input voltage noise at 1 kHz, and 0.25-μV p-p input noise (0.1 Hz to 10 Hz).

The AD8295 operates on both single and dual supplies and is well suited for applications where ±10‑V input voltages are encountered. The entire chip (in amp and two op amps) uses only 2 mA of total current, allowing for more channel density and lower cost designs. The AD8295 components are arranged in a logical way so that typical application circuits, such as a differential ADC driver or an in amp with output filtering, have short routes and few vias. Unlike most chip-scale packages, the AD8295 does not have an exposed metal pad on the back of the part, freeing additional space for routing and vias.