CIRCUITRY TO ASSIST WITH NEURAL SENSING IN AN IMPLANTABLE STIMULATOR DEVICE IN THE PRESENCE OF STIMULATION ARTIFACTS

Sense amplifier (amp) circuitry for an implantable stimulator device is disclosed useful for sensing neural responses or other voltages in a patient's tissue. The sense amp circuitry comprises a low-voltage and a high-voltage sense amp circuit, either of which may be selected based on an assessment of the magnitude of the voltage at either or both of the inputs connected to selected sensing electrodes. The assessed magnitude, as determined by monitoring circuitry, can be processed by an algorithm to select use of one of the sense amp circuits, selecting the low-voltage sense amp circuit when the magnitude(s) are lower, and the high-voltage sense amp circuit when the magnitude(s) are higher. Furthermore, DC offset compensation circuitry is disclosed to equate the DC levels of the inputs, which may only operate when the high-voltage sense amp is selected.