Circuitry for an implantable neurostimulator device having a plurality of electrodes and for providing a stimulation pulse having at least first and second stages between a first and second of the plurality of electrodes, comprising: a first multiplexer configurable to select a first voltage from voltages at the plurality of electrodes, wherein the first voltage comprises a voltage at the first electrode; a second multiplexer configurable to select a second voltage from voltages at the plurality of electrodes, wherein the second voltage comprises a voltage at the second electrode; and holding circuitry for receiving the first voltage and the second voltage and for producing a first input and a second input, wherein the holding circuitry comprises a first and a second capacitor, and wherein the holding circuitry is configurable to store a difference between voltages at the first and second electrodes on the first capacitor during a first stage of the stimulation pulse as the first input, and to store a difference between voltages at the first and second electrodes on the second capacitor during a second stage of the stimulation pulse as the second input. 5644049_1 (GHMatters) P93071.AU.1 SARAHW 7/08/2014 rr r LUj LU - C) LU LU r Ln LUj coo N D' C) ~
Sample and hold circuitry for monitoring voltages in an implantable neurostimulator