AN957 Datasheet, PDF (8/13 Pages) List of Unclassifed Manufacturers – Measuring HEXFETCharacteristics

C_iss, C_oss, and C_rss. Output,
Input and Reverse
Transfer Capacitances
A 1 MHz capacitance bridge
is used for all these tests.The
capacitance to be measured
is connected in series with a
capacitance of known value
to provide dc isolation. If C_u
is the unknown capacitance,
C_k is the known capacitance,
and C_m is the measured
capacitance, then C_u can be
calculated as follows:
Index
AN-957 (v.Int)
CP
OSCILLOSCOPE
100Ω
Figure 16. Test circuit for transconductance
+
50V
-
Cu = ^{CkCm (1)}
Ck - Cm
Figures 17, 18 and 19 show the circuit connections for the three capacitances that characterize power MOSFETs.
HIGH
CB
LOW
2000 pF
G
CK
10 MΩ
S
+
1.0 µF
-
Figure 17. Test circuit for input capacitance
D
HIGH
CB
LOW
2000 pF
G
CK
10 MΩ
S
+
1.0 µF
-
Figure 18. Test circuit for output capacitance
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