Specifications

5.13 DC bias voltage enhancement
DC biased impedance measurement is popularly used to evaluate the characteristics of the device
under conditions where the device actually operates in circuits. The internal DC bias function of
impedance measurement instruments is normally designed to apply a bias voltage to capacitor
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 ±200 V. Figure 5-45 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 4TP test fixture and the instrument’s UNKNOWN terminals,
thus allowing the use of an appropriate test fixture that accommodates the DUT. The 16200B exter-
nal 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 exter-
nal DC voltage source.
5-34
Model Product Applicable Maximum Usable Applicable
number type instrument bias voltage frequency DUT type*
and current range
16065A Bias fixture Auto-balancing ± 200 V, 50 Hz to Leaded
bridge 2 mA 2 MHz
16065C Bias adapter Auto-balancing ± 40 V, 50 Hz to Leaded and
bridge 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