12 - Application notes
Source- Measure considerations
82
SMU4000 Series Instruction Manual
Timing
In addition to the timing controls in the manual setup menu, there are other things that can be
done to optimise the rise and fall time performance of the SMU.
•
Slew rate setting – Ensure slew rate is set to maximum for optimum rise/fall times.
•
High Reactance Setting – Ensure high reactance is set to off for optimum rise/fall times.
•
Ranges – Always select manual ranges for optimum rise/fall times.
•
Load Power level – In modes that utilise the voltage source, higher load levels will result
in a slightly slower response.
•
Voltage Limit – To reduce the risk of limit overshoot, the current source is slewed
slightly based upon the voltage limit set. The voltage limit can be increased to reduce
the amount of slew applied.
•
Current Limit – To reduce the risk of limit overshoot, the voltage source is slewed
slightly based upon the current limit set. The current limit can be increased to reduce
the amount of slew applied. Note that a greater slew is applied on limits <210mV, i.e.,
the 200mV and 20mV ranges.
•
Load reactance – Any load capacitance or inductance can have significant effects on the
output response, potentially affecting both speed and overshoot.
•
High voltage polarity reversal – When the output is changed from a level <-21V to
>+21V or >+21V to <-21V a delay of around 280ms must be incorporated.
•
Setting a limit too close to the desired output level can result in extended source
rise/fall times. The source is slewed slightly when approaching (and predicting to exceed
a limit) in order to enter the limit smoothly.