LCX_UserManual_en_08_1.pdf - 第65页

Performing measurements R&S ® LCX Series 65 User Manual 1 179.2260.02 ─ 08 7 Performing measurements Using the R&S LCX and the corresponding test fixture, you can measure various com- ponent types. The following …

Measurement setups

R&S

LCX Series

64User Manual 1179.2260.02 ─ 08

a) Select the measurement pair softkey in the upper left corner, to open the selec-

tion editor.

b) Select the parameters "Lp-Rp" (parallel inductance, parallel resistance).

c) Confirm your selection.

d) Repeat the steps to select the second parameters, e.g. select "Lp-Q" (parallel

inductance, quality factor).

4. To set the current bias value:

a) Press the [Bias Level] key.

b) Enter a current value using the keypad on the screen.

Confirm with

6. Set up the measurement of the inductance as described, e.g. in "Measuring an

inductor" on page 66.

7. To activate the current 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.

The R&S LCX starts the discharging process, as described in "Discharging a cur-

rent bias before power off" on page 63.

2. Wait for the inductor or coil to discharge before disconnecting.

3. Remove the component sample.

Configuring BIAS

Performing measurements

R&S

LCX Series

65User Manual 1179.2260.02 ─ 08

7 Performing measurements

Using the R&S LCX and the corresponding test fixture, you can measure various com-

ponent types. The following description explains how to proceed for measuring the typ-

ical components and what to consider.

Considerations on grounded DUTs

The R&S LCX operates on earth ground as reference. Therefore, it is not possible to

measure grounded DUTs.

Prerequisite of each measurement is the correction of the measurement setup to com-

pensate stray capacities, residual inductances and residual resistances of test fixtures,

leads and terminals. Therefore, the first steps are the open and short circuit correction,

to minimize the measurement errors.

We assume that you have set up your measurement and aligned the instrument as

described, e.g. in "Basic measurement steps" on page 34, including the example for

measuring a resistor.

If there are specific steps to consider for measurements of certain components, we

explicitly point them out in the corresponding descriptions.

Measuring a capacitor

This example refers to a measurement of a capacitor of 1000 µF, by using the Kelvin

clip lead (R&S LCX-Z2), see Section 6.1.2, "Kelvin clip lead", on page 54. To measure

this component sample, a DC voltage bias is necessary.

1. To select the capacitance measurement (DUT component type), press the [C] key.

2. Set the measurement frequency of the test signal, e.g., 1 kHz.

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) Repeat the steps to select the second parameters, e.g. select "Cp-Rp" (parallel

capacitance, parallel resistance).

4. Set the bias voltage according to the measurement requirements, see Section 6.3,

"Configuring BIAS", on page 61.

5. Connect the sample capacitor to the terminals of the test fixture:

a) Connect the black terminal to the negative (-) terminal of the capacitor.

b) Accordingly, connect the positive (+) terminal.

The measurement starts and you can see the readings on the screen.

As the preselected frequency of 1 kHz does not match to the intended working

point of the capacitor, the measurement result shows approximately only "Cp ≈

900 µF".

Performing measurements

R&S

LCX Series

66User Manual 1179.2260.02 ─ 08

6. To achieve the expected result, set the frequency to 50 Hz.

The expected value is approximately 1000 µF ± tolerance. The dissipation factor

"D" is low, even close to 0, and the phase angle is ≈ -87°.

Decreasing the frequency reduces the loss angle, and thus the real components

come closer to the ideal value.

Measuring an inductor

This example refers to a measurement of an inductor of 280 µH on a printed circuit

board, by using the miniature SMD tweezers (R&S LCX-Z4), see Section 6.1.4, "Test

tweezers for SMD components", on page 56.

1. To select the inductance measurement (DUT component type), press the [L] key.

2. Set the measurement frequency of the test signal, e.g., 500 kHz.

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 "Ls-Q" (serial inductance, quality factor).

c) Repeat the steps to select the second parameters, e.g. select "Z-Θ" (impe-

dance, phase angle).

4. Carefully contact the miniature tweezers of the test fixture to the sample inductor

on the circuit board.

5. Hold the tweezers closed during measurement.

The measurement starts and you can see the readings on the screen.

The expected result is approximately "Ls ≈ 280 µH" ± tolerance. The phase angle

"Z-Θ"≈ +70°.

Measuring the primary or secondary inductance of a transformer

This example refers to a measurement of a transformer with the test fixture (R&S LCX-

Z5), see Section 6.1.5, "Test fixture with cables for transformer components",

on page 57.

A transformer measurement often leads to varying measurement results due to iron

core losses and to the unknown state of the premagnetized core. The sample compo-

nent depends on both, the frequency and the measurement voltage. Varying the fre-

quency causes changes in magnetization and iron core losses, which impact the phase

angle, and an increasing measurement voltage leads to higher impedance.

This measurement on the transformer, also considered as "open" measurement, corre-

sponds to the measurement of a single coil.

To measure the primary or secondary inductance:

1. For inductance measurements, press the [L] key.

2. Set the measurement frequency, e.g. the mains frequency for a mains transformer.

3. Select the parameters for measurement results display as described under "Mea-

suring an inductor" on page 66.