Pulse_Load - Keithley 4200A-SCS Reference Manual

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Model 4200A-SCS Parameter Analyzer Reference Manual

pulse_load

This command sets the output impedance for the load (DUT).

int pulse_load(int instr_id, long chan, double load);

Standard, Full Arb, Segment Arb

DUT impedance can be independently set for each pulse card channel. The DUT impedance can be

set from 1 Ω to 10 MΩ, depending on the programmed pulse high and low values.

Maximum power transfer is achieved when the DUT impedance matches the output impedance of the

pulse card. For example, if the DUT impedance is set to 1 MΩ, the voltage output settings will change

to account for the higher DUT impedance, ensuring that the voltage at the DUT will not be double the

voltage setting (caused by reflection due to load mismatching).

The purpose of setting the DUT load to a value other than 50 Ω is to simplify the calculation of the

output levels. For example, if the DUT load is set to 50 Ω, but the actual DUT load has a high

impedance of 1 MΩ, setting a voltage level of 2 V will result in a 4 V pulse at the DUT. Setting the

DUT load to 1 MΩ will permit the set voltage to match the actual voltage, so setting a 2 V level will

result in a 2 V pulse, with the pulse card taking the DUT impedance into account.

pulse_load(VPU1, 1, 100)

Sets the output impedance of pulse card channel 1 to 100 Ω.

4200A-901-01 Rev. C / February 2017

The instrument identification code of the pulse card, such as VPU1 or VPU2

Channel number of the pulse card: 1 or 2

Output impedance (in ohms): 1 to 10e6 (default 50)

Section 13: LPT library function reference