Keithley 7022, Instruction Manual

Page: 64 / 107

Operation
5-10
The thick film is tested by applying a voltage across the resis-
tor network and measuring the voltage across each resistor
element and/or across combined elements. In Figure 5-7,
crosspoints 3 and 19 are closed to apply voltage across the
network, and crosspoints 11 and 17 are closed to measure the
voltage drop across R3.
Transistor testing
A matrix system for testing DC parameters of transistors is
shown in Figure 5-8. This system uses two Source Measure
Units (SMU). There are three SMUs available from Kei-
thley; the Model 236 Source Measure Unit, Model 237 High
Voltage Source Measure Unit and Model 238 High Current
Source Measure Unit. Keep in mind that if using the Models
237 (high voltage capability) or 238 (high current capabil-
ity), do not exceed the maximum signal levels of the card.
Maximum allowable DC signals are 110V and 1A, 30W with
resistive load.
This system tests two transistors but can be expanded to test
more by simply using additional Model 7022 cards. The
Model 7001 will accommodate two cards. Daisy-chaining
six Model 7001s expands the system to 12 cards allowing 24
or more transistors to be tested. Daisy-chaining six Model
7002s expands the system to 60 cards allowing 120 or more
transistors to be tested. The limits on the number of cards in
the Model 7001/7002 switch system are due to triggering.
NOTE
The Model 7022 is a general purpose card
and cannot be used to check FETs or tran-
sistors that have high gain or low power.
To test these devices, a card with low off-
set current and high isolation characteris-
tics must be used.
Output HI
Sense HI
Sense LO
Output LO
SMU #1
Output HI
Sense HI
Sense LO
Output LO
SMU #2
L H L H L
7022
Rows
A
B
C
1 2 3
H L H L H L
4 5 6
H
L
H
L
H
L
H
L
Columns
H
D
E
H
L
Figure 5-8
Transistor testing
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