Patent ID: 9594104
Date: 2017-03-14
CPC Classifications: A61B,G01R

Claim:
1. An apparatus for determining impedance of a plurality of electrodes, comprising: a plurality of channels having a plurality of first channels and a plurality of second channels; at least one reference channel, the reference channel configured as a reference potential for the plurality of channels; a signal generator electrically connected to the plurality of channels, the signal generator configured to provide a plurality of input signals to the plurality of channels, the plurality of input signals includes a first input signal and a second input signal, the second input signal being opposite in phase of the first input signal and generated by means of an inverter connected in parallel with the output of the signal generator; a reference signal generator connected to the reference channel, the reference signal generator configured to provide an input signal to the reference channel; at least one amplifier connected to each of the plurality of channels and the reference channel to amplify the signal through the plurality of channels and the reference channel, each of the plurality of channels connected to a positive terminal of the amplifier and the reference channel connected to a negative terminal of the amplifier; and at least one filter arrangement having a first filter and a second filter, the at least one filter arrangement connected to an output of the at least one amplifier to filter the signal from the at least one amplifier; whereby the impedance of the plurality of channels can be determined from the output signal obtained from the at least one filter arrangement; and wherein the signal generator provides the plurality of inputs to the plurality of channels such that the common mode voltage imposed on the amplifier of each channel is minimized.