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4.4 Setting the Test Signal Level
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4.4.4 Setting the Constant Voltage (CV) Level
Test signal level
setting screen
The digit keys (If held down continuously, the corresponding digit increments
or decrements continuously.) (If the limit for the corresponding digit is reached,
these keys change to non-reversed video and become inactive.)
Monitor display
Test frequency
Set value for
constant voltage
Voltage between test
samples
Limit value for the
current
Current flowing
through the test
sample
Test frequency (Hz)
42.0 - 1.000 M
1.001 M - 5.000 M
Constant voltage
0.010 V- 5.000 V
0.010 V - 1.000 V
NOTE
NOTE
1.
Press this key to set constant voltage (CV), and the monitor display will
change immediately.
2.
Change the set constant voltage value using the digit keys.
The definable constant voltage depends on the frequency.
The accuracy of the constant voltage is
10% 10 mV for 42.0 Hz to 1.000
MHz, and
20% 10 mV for 1.001 MHz to 5.000 MHz.
When the test frequency is higher than 1 MHz at an open-circuit voltage of
more than 1 V, the voltage is automatically set to 1 V.
3.
When the setting has been established, press the
key to return to the
Initial screen.
Testing some types of sample is not possible using constant voltage. In this
case, the following symbol appears on the display:
In such a case, constant voltage testing is not performed. Change the constant
voltage level to a value not more than the value being shown as Vmoni.
Reference
When a 1
μ
F capacitance is measured at 10 kHz, the CV operation range
can be obtained as follows. Sample impedance Zm becomes as follows:
Zm = Rm + jXm = 0
Ω
- j15.9
Ω
Xm=-1/(2
π
fC)
The impedance Zm' observed from the generator is as follows:
Zm' = Ro + Zm = 50
Ω
- j15.9
Ω
Ro: Output resistance (50
Ω
)
Accordingly, the voltage Vm across both leads of the sample is as follows:
Vm = |Zm|
x
Vo/|Zm'| Vo: generator output
= 15.9
Ω
x
Vo/52.5
Ω
Because the generator output voltage range is 10 mV to 5 V for 10 kHz, the CV
operation range per the above expression is Vm = 3.03 mV to 1.51 V.
