User`s guide

4-4 Agilent 4155C/4156C User’s Guide Vol.2, Edition 6
Quasi-static C-V Measurements
Measurement Functions
Operation
In the QSCV measurement, the 4155C/4156C executes the capacitance
measurement at the sweep steps except for the sweep start voltage and stop voltage.
At each sweep step, the capacitance measurement is executed over the voltage
range: output voltage ± cvoltage/2 (V). where cvoltage is the capacitance
measurement voltage. See Figure 4-1.
The operation of the quasi-static CV measurements are explained below. This is the
case of start < stop.
a. Measurement trigger enables the sweep source output. The sweep source forces
start V.
b. The sweep source changes the output voltage to the first step output voltage -Vq
V, and waits for hold time. where Vq = cvoltage/2 V.
c. Repeats d. and e. for the Nth sweep step. where N is integer, 1 to NO. OF STEP
(NO. OF STEP = |start - stop| / |step| - 1).
d. The sweep source changes the output voltage to the Nth step output voltage -Vq
V, and waits for delay time.
e. The measurement unit measures the following items:
V
0
Voltage at the Nth step voltage - Vq V
IL
0
Leakage current at the Nth step voltage - Vq V
I Current at the voltage transition to the Nth step voltage + Vq V
V Voltage at the Nth step voltage + Vq V
IL Leakage current at the Nth step voltage + Vq V
f. After the sweep measurement, the sweep source changes output voltage to 0 V.
Measurement data at the Nth sweep step is the Nth step voltage (center value of
the voltage range for the Nth measurement) and the capacitance measurement
data at the Nth sweep step.
NOTE When |step voltage| = capacitance measurement voltage (cvoltage), V
0
and IL
0
are
not measured for the second step and later. The capacitance calculation uses the V
and IL values at the previous step, instead.