Agilent Technologies 4294A Specifications download pdf (Page 104)

5-13. DC bias voltage enhancement

DC biased impedance measurement is popularly used to evaluate the characteristics of the device

under the conditions where the device actually operates in circuits. The internal DC bias function

of the impedance measurement instruments is normally designed to apply a bias voltage to capaci-

tor DUTs. It is suited to DC biased capacitor measurements.

Maximum applicable bias voltage is different for instruments. The internal bias source can typically

output a variable bias voltage of up to ± 40 V through the Hc terminal. An external DC voltage

source is required to apply a DC bias voltage that must exceed the limits of the internal DC bias

function.

Some instruments have a DC bias input terminal for connecting an external DC voltage source. Use

an external bias fixture or adapter for other instruments with no internal DC bias and for DC bias

requirements that exceed the maximum voltage of the bias input terminal. Table 5-5 lists the avail-

able bias fixture and adapters.

Table 5-5. External bias fixture and adapters

Note: Applicable DUT types for the 16065C and 16200A depend on the test fixture connected.

Use the 16065A external voltage bias fixture, which has a built-in protection circuit, for leaded

devices and high voltage DC bias of up to ± 200V. Figure 5-40 shows the setup for a + 200 V DC

biased measurement. Since the 16065A is equipped with a bias monitor output, a digital voltmeter

is used to monitor the DC bias voltage actually applied to the DUT. The 16065C external voltage

bias adapter is designed to apply a bias voltage of up to ± 40 V from an external voltage source. This

adapter can be connected between any 4-terminal pair test fixture and instrument’s UNKNOWN ter-

minals, thus allowing the use of an appropriate test fixture that accommodates the DUT. The

16200B external DC bias adapter operates specifically with the RF I-V measurement instruments

and the 4294A with the 42942A. This adapter resolves both voltage bias and current bias needs.

When used for capacitor measurements, it allows a bias voltage of up to 40 V DC across the DUT by

using an external DC voltage source.

5-30

Model Product

Applicable Maximum

Usable Applicable

number type

instrument bias voltage

frequency DUT type*

and current range

16065A Bias fixture 4-terminal ± 200 V, 50 Hz to Leaded

pair 2 mA 2 MHz

16065C Bias adapter 4-terminal ± 40 V, 50 Hz to Leaded and

pair 20 mA 2 MHz SMD

16200B Bias adapter RF I-V ± 40 V, 5 A 1 MHz to Leaded and

4294A+ 1 GHz SMD

42942A

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Agilent Technologies 4294A Specifications Page 104