LCX_UserManual_en_08_1.pdf - 第62页
Measurement setups R&S ® LCX Series 62 User Manual 1 179.2260.02 ─ 08 6. Set up the measurement of the capacitance as described, e.g. in "Measuring a capacitor" on page 65. 7. T o activate the voltage bias,…
Measurement setups
R&S
®
LCX Series
61User Manual 1179.2260.02 ─ 08
6.3 Configuring BIAS
Referred to as biasing defines the method of superimposing a voltage or current on an
existing voltage/current to shift the operating point of an electronic component to a spe-
cific value.
With the bias function of the R&S LCX, you can predefine a working DC bias that cor-
responds to an expected supply voltage, or (current) in a circuit. The function enables
you to measure the component sample under operating conditions, as expected for the
intended use.
Example: DC dependency of inductors
To measure the current flowing through an inductor under real conditions, e.g., in
power supplies, the current of approximately < 0.1 mA supplied by the R&S LCX is not
sufficient. To achieve higher current, the most common method is to superimpose the
AC with a DC current.
How to: "Setting a current bias" on page 63
Example: DC dependency of capacitors
Some capacitor types, e.g. electrolytic or tantalum capacitors, require a positive volt-
age bias to achieve accurate measurements of the component sample. To add the
bias, you can use either the internal bias source, or supply the bias externally, e.g.
using a power supply.
How to: "Setting an external voltage bias" on page 62
6.3.1 Internal bias voltage
Setting an internal voltage bias
To bias a capacitive component sample:
1. To select the capacitance measurement (DUT component type), press the [C] key.
2. Configure the test signal.
3. To select the parameters for measurement results display:
a) Select the measurement pair softkey in the upper left corner, to open the selec-
tion editor.
b) Select the parameters "Cp-D" (parallel capacitance, dissipation factor).
c) Confirm you selection.
d) Repeat the steps to select the second parameters, e.g. select "Cp-Rp" (parallel
capacitance, parallel resistance).
4. To set the voltage bias value:
a) Press the [Bias Level] key.
b) Enter, e.g. 5 V using the keypad on the screen.
5.
Confirm with
.
Configuring BIAS
Measurement setups
R&S
®
LCX Series
62User Manual 1179.2260.02 ─ 08
6. Set up the measurement of the capacitance as described, e.g. in "Measuring a
capacitor" on page 65.
7. To activate the voltage bias, press the [Bias Enable] key.
The lighting [Bias Enable] key indicates that bias is active.
Deactivating current bias
To turn off current bias:
1. Press the [Bias Enable] key.
The unlit [Bias Enable] key indicates that current bias is deactivated.
2. Remove the component sample.
6.3.2 External voltage bias
Option: R&S LCX-K108
The readback voltage indicated on the "GUI" relies on the external power supply that
must be activated. If the power supply output is deactivated or the connection is open,
both, the test signal voltage monitor and the external bias voltage monitor can be inac-
curate.
Setting an external voltage bias
For safety reasons, the instrument limits the test signal level to 2 V when using exter-
nal voltage bias.
To bias a capacitive component sample with a DC voltage supplied by a power supply
instrument:
1.
NOTICE! Check all cables to make sure that they are not damaged.
Connect the safety sockets of the power supply with the cables of the same color
to the corresponding External Voltage Bias at the rear panel.
Note: The voltage at the + bias input must be positive regarding the - bias input.
Do not apply a negative voltage at the bias input.
The output of the power supply must be floating against ground.
2.
NOTICE! Risk of instrument damage.
Too high external voltage bias can damage the circuitry of the instrument.
Do not apply a voltage higher than the specified 40 V DC to the external voltage
bias inputs.
3.
NOTICE! External BIAS requires a constant voltage. Before applying the voltage,
make sure that you have set the constant voltage mode in the supplying instru-
ment. Refer to the user manual of the power supply.
Set the output voltage of the supplying instrument to constant voltage mode.
Configuring BIAS
Measurement setups
R&S
®
LCX Series
63User Manual 1179.2260.02 ─ 08
4. On the R&S LCX, select the capacitance measurement with the [C] key.
5. Configure the test signal.
6. To select the parameters for measurement results display:
a) Select the measurement pair softkey in the upper left corner, to open the selec-
tion editor.
b) Select the parameters "Cp-Rp" (parallel capacitance, parallel resistance).
c) Confirm you selection.
d) Repeat the steps to select the second parameters, e.g. select "Cp-D" (parallel
capacitance, dissipation factor).
7. To select the external voltage bias:
a) Press the [settings] key.
b) Select the "Measurement" tab.
c) Set the "Voltage Bias" to "Ext.".
8. Press the [home] key to return to the measurement window.
9. Set up the measurement of the capacitance as described, e.g. in "Measuring a
capacitor" on page 65.
10. To activate the voltage bias, press the [Bias Enable] key.
The lighting [Bias Enable] key indicates that bias is active.
6.3.3 Current bias
Option: R&S LCX-K108
When measuring inductances, it is often necessary to superimpose a current bias on
the test signal. You can set an internal current bias from 0 mA to 200 mA (DC), with a
resolution of 1 mA. An external current bias is not supported.
Discharging a current bias before power off
1.
NOTICE! Risk of instrument damage caused by overvoltage. When you power off
the instrument with the mains power switch, make sure that the bias current is fully
discharged.
When activated, deactivate the bias by pressing [Bias Enable] key.
A progress bar indicates that the discharging process is running.
2. Wait until the process has finished.
Setting a current bias
To bias an inductive component sample:
1. To select the inductance measurement (DUT component type), press the [L] key.
2. Configure the test signal.
3. To select the parameters for measurement results display:
Configuring BIAS