Agilent Technologies 5750A Measurement Techniques, Electronic Load, Current-Monitoring Resistor

Verification and Calibration Appendix B

Measurement Techniques

Electronic Load

Many of the test procedures require the use of a variable load capable of dissipating the required power. If a variable resistor is used, switches should be used to either; connect, disconnect, or short the load resistor. For most tests, an electronic load can be used. The electronic load is considerably easier to use than load resistors, but it may not be fast enough to test transient recovery time and may be too noisy for the noise (PARD) tests.

Fixed load resistors may be used in place of a variable load, with minor changes to the test procedures. Also, if computer controlled test setups are used, the relatively slow (compared to computers and system voltmeters) settling times and slew rates of the power supply may have to be taken into account. "Wait" statements can be used in the test program if the test system is faster than the power supply.

Current-Monitoring Resistor

The 4-terminal current shunt is used to eliminate output current measurement error caused by voltage drops in the load leads and connections. It has special current-monitoring terminals inside the load connection terminals. Connect the voltmeter directly to these current-monitoring terminals.

Test Set-up

The following figure illustrates the test set-up used for the verification procedures.

Power Supply

+S +LS -LS -S +V -V

Power Supply	Power Supply
+S +LS -LS -S +V -V	+S +LS -LS -S +V -V

+

DC voltmeter,

scope, or

rms voltmeter

A.	+
	Electronic load
	or resistor

DC voltmeter,+	Current
scope, or
	shunt
rms voltmeter
B.	+
	Electronic load
	or resistor

Load

Resistor

5050

BNCBNC

+Differential amplifier

output

BNC

50ohm

termination

C.

input

Scope or rms voltmeter

Series N5700 User’s Guide 95