Stimulation Circuitry in an Implantable Stimulator Device for Providing a Tissue Voltage as Useful During Neural Response Sensing

Stimulator circuitry useable in a stimulator device is disclosed. The circuitry includes biasing circuitry that can be used to generate a voltage to allow any one or more electrode on the device (including the case electrode and lead-based electrodes) to provide a common mode voltage (Vcm) to the tissue. Providing a stable Vcm to the tissue is particularly useful when sensing neural responses to the stimulation that the device provides. Switches are provided to couple each of the electrode nodes to one or more buses. This allows any of the electrodes to be selected to provide bipolar or monopolar stimulation, or to act to provide Vcm to the tissue during relevant pulses phases, including during passive charge recovery.