Agilent Technologies 4294A Specifications download pdf (Page 56)

Figure 4-4. Example of shorting device. (Agilent PN: 5000-4226)

4-2-4. Open, short and load compensations

There are numerous measurement conditions where complicated residual parameters cannot be

modeled as the simple equivalent circuit in Figure 4-3. Open/short/load compensation is an

advanced compensation technique that is applicable to complicated residual circuits. To perform

open/short/load compensation, three measurements are required before measuring the DUT, with

the test fixture terminals opened, shorted, and with a reference DUT (load) connected. These mea-

surement results (data) are used for calculation when the DUT is undergoing measurement. As

shown in Figure 4-5, the open/short/load compensation models the test fixture residuals as a four-

terminal network circuit represented by the ABCD parameters. Each parameter is known if three

conditions are known and if the four-terminal circuit is a linear circuit.

The open/short/load compensation should be used in the following situations:

(1) An additional passive circuit or component (e.g. external DC bias circuit, balun transformer,

attenuator and filter) is connected.

(2) A scanner, multiplexer or matrix switch is used.

(3) A non-standard length test cable is used or the 4TP cable is extended from the standard Agilent

test cable.

(4) An amplifier is used to enhance test signal.

(5) A component handler is used.

(6) A custom-made test fixture is used.

In the cases listed above, open/short compensation will not work effectively and the measurement

result contains some error.

It is not necessary to use open/short/load compensation for simple measurement, like measuring an

axial leaded component using the 16047A test fixture. Open/short compensation is adequate for

such measurements.

4-4

1 2 ... 51 52 53 54 55 56 57 58 59 60 61 ... 125 126

No comments

Agilent Technologies 4294A Specifications Page 56