Test-Fixture Connections; Bias Voltage For The Dut; Internal Bias; External Bias - IET Labs, Inc. RLC Digibridge 1693 User And Service Manual

use of line-voltage regulators between power lines
and the test equipment is recommended as the only
sure way to rule out the effects on measurement data
of variations in line voltage.

2.5 Test-Fixture Connections

An external test fixture or cables are always required,
because connection from the 1693 Digibridge to the
DUT is provided via BNC cables (from connectors
that can be positioned at either front or rear of the
instrument, as described .in Chapter 5). For general
purposes, the recommended test fixture, cable, and
their connections are as follows. Refer to paragraphs
1.4 and 3.2 for more information about accessories.
On 1693 Description
Drive -
IL
Potential -
PL
Potential +
PH
Drive +
IH
COMMENT: It is important that the IL and PL leads
connect to the same end of the DUT (and that PH and
IH connect to the other end). Also, connecting IL/PL
to the test-fixture connectors labeled "+" (and IH/PH
to "-") assures that the test fixture's "+"and "0" labels
agree with the bias polarity.
NOTE: In the cable's color code, RED is associated
with "hot" leads, which have dc voltage, negative
with respect to ground , when bias is used.
Installation
Cable On
Black Band I+
Black and P+
White Band
Red and White P-
Band
Red Band I-

2.6 Bias Voltage for the DUT

2.6.1 Internal Bias

No external connections are required for the internal
2-volt bias. 2V bias is supplied internally by the
instrument.

2.6.2 External Bias

External bias can be provided by connecting a suitable
current-limited, floating dc voltage source, as follows.
• Be sure that the voltage is never more than
60 V, max.
• A current limiting voltage supply is recom-
mended; set the limit at 200 mA, max.
• Be sure that the bias supply is floating; DO
NOT connect either lead to ground.
• A well-filtered supply is recommended. Bias-
supply hum can affect some measurements,
particularly if test frequency is the power
frequency.
• Generally the external circuit must include
switching for both application of bias after each
DUT is in the test fixture and discharge before
it is removed.
• Connect the external bias voltage supply and
switching circuit, using the optional 1658-2450
cable, via the rear-panel EXTERNAL BIAS
connector. Observe polarity marking on the rear
panel; connect the supply accordingly.
1693 RLC Digibridge
9