Typical Multiplexer Switching Schemes; Single-Ended Switching - Keithley 7021 Instruction Manual

Figure 2-5 shows how each bank of the Model 7021 is con-
nected to the backplane. Notice that since the Model 7021 is
a two-pole card, there is no connection made to the GUARD
terminal of the backplane. The Model 7021 is shipped from
the factory with the backplane jumpers installed.
7021
Bank
(1 of 2)
H
L
H = High Backplane
L = Low
Jumpers
G = Guard
Figure 2-5
Bank connections to backplane
Removing (cutting) the backplane jumpers isolates the card
from the backplane, and subsequently, any card installed in
an adjacent slot. For information on removing the jumpers,
refer to Section 4.
HI
LO
Source or
Measure
Figure 2-6
Single-ended switching example
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7001/7002
Analog
Backplane
H
L
G
Bank A
Bank B
H
Out
L
7021
NOTE
The Model 7001/7002 does not provide an
analog backplane for the non-701X/702X/
703X series cards. As a result, any of these
cards installed in one slot in the main-
frame is electrically isolated from any card
installed in the other slot. The only way to
connect a Model 7021 to one of these
cards is to wire them together.

Typical multiplexer switching schemes

The following paragraphs describe some basic switching
schemes that are possible with a two-pole switching multi-
plexer. These switching schemes include some various
shielding configurations to help minimize noise pickup in
sensitive measurement applications. These shields are shown
connected to chassis ground. For some test configurations,
shielding may prove to be more effective connected to circuit
common. Chassis ground is accessible at the rear panel of the
Model 7001/7002 mainframe.

Single-ended switching

In the single-ended switching configuration, the source or
measure instrument is connected to the DUT through a sin-
gle pathway as shown in Figure 2-6. The instrument is con-
nected to the output of one of the banks, and the DUT is
shown connected to one of the inputs for that bank.
In
Multiplexer Configuration
Optional
Shield
DUT
2-3