The ADA400A Differential Preamplifier allows direct oscilloscope measurements of very low amplitude voltages and signals which are not ground referenced. The high impedance of both inputs eliminates the need to add additional ground points in the DUT, thereby avoiding circulating currents which disturb the measurement or the circuit.
ISIS Electronics Internal Link
Manufacturer's Website: http://www.tek.com/datasheet/ada400a-differential-preamplifier-datasheet#
