Accuracy When Holding A Non-Optimum Range; Bias For The Dut; Internal Bias - IET Labs, Inc. RLC Digibridge 1693 User And Service Manual

3.6.9 Accuracy When Holding a Non-
Optimum Range
The accuracy specifications are valid when the opti-
mum range is used for any given impedance value.
The optimum range is selected by the autoranging
capability. If some other range is selected and held
by the operator, the specified accuracy will be poorer.
This accuracy may be calculated by multiplying the
impedance ratio terms in the accuracy specifications
by factors given in Table 3-11.
Table 3-15: Multiplying Factors for Impedance Ratio Terms

3.7 Bias for the DUT

NOTE Keep the EXTERNAL BIAS switch OFF and
the BIAS ON indicator unlit, for all measurements of
inductors and resistors, and also for capacitors unless
they are to be measured with dc bias applied.

3.7.1 Internal Bias

To measure capacitors with the internally available
2-volt dc bias voltage applied, use the following pro-
cedure. (The FUNCTION can be either MEASURE
or ENTER.)
1. Press [SHIFT][INT BIAS] keys so that the
BIAS ON indicator is lit.
NOTE: This indication, for internal bias, is somewhat
dimmer than the other keyboard indicators.
2. To enable the special shorting routine (see
paragraph 3.7.3):
A. Select ENTER function
B. Press [2][=][SHIFT][SPECIAL][3]
C. Select MEASURE function
Operation
3. Wait at least 1 second before initiating mea-
surement, to allow for settling of internal
circuits.
In the CONTINUOUS mode, disregard displays during
this interval.
This delay is associated with enabling the internal bias;
it applies to each DUT only if internal bias is disabled
for each change of DUT.
4. Observe correct polarity when inserting DUT
into test fixture.
Bias POSITIVE polarity is at the LEFT ("low"
terminals) of the remote test fixture 1689-9600.
Bias NEGATIVE polarity is at the RIGHT.
5. For each DUT, in the CONTINUOUS mea-
sure mode, disregard the first displayed result
and read the second. Notice enough of the
subsequent results to verify that the DUT has
stabilized. Use the stable result.
6. In the TRIGGERED measure mode, each
measurement cycle includes the normal
settling time (7 to 12 ms for 1-kHz mea-
surements), or a programmed delay. See
paragraph 3.5.3. Remeasure enough DUTs
to be sure that they are stabilized in the first
measurement so that any subsequent differ-
ences are well within the error permitted by
your needs. If not, program in a longer delay.
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