The SpikeSafe current source has protection circuitry to reduce undershoot at turn-off. It also does not employ a shorting switch that is present in some pulsed current sources. These design features prevent negative currents through the DUT, but they allow the DUT capacitance to remain charged during the off time. So it is normal for the DUT to have a voltage potential across it during the off time. Even though a voltage is present, the current through the DUT is very small or zero during this time. To reduce this voltage, a resistor may be placed across the output + and – terminals. Vektrex current shunt cable includes the resistor and shunts the excess capacitance for 8 individual source channels eliminating excess light output during pulse off.
Vektrex current shunt cable for the SMU (SKU 104464) shunts excess capacitance for a single source channel eliminating excess light output during pulse off.