Bidirectional, offset-free current source for use in bio-impedance measurement system, has negative feedback circuit guiding signal from pole of load resistor to input of filter, where output of filter is connected with input of amplifier

摘要

The current source has poles (P1, P2) formed by outputs of an operational amplifier (OP1). A series connection of a measuring resistor and impedance (Rl) to be measured is connected with one of the outputs of the amplifier. A negative feedback circuit guides a voltage signal at a node point of the measuring resistor and a load resistor to an input of the amplifier. Another negative feedback circuit guides the voltage signal from a pole of the load resistor to an input of a low pass filter (OP2), where an output of the filter is connected with another input of the amplifier.