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Section
1II
3-5.
THEORY OF OPERATION
The basic operating theory of the 4085M is described in paragraphs 3-7 through ,
3-6.
3-18. A thorough understanding of the information presented in t�ese paragraphs is
i mportant for effective use of the 4085M.
The function of the 4085M is to connect the "m easurement ports" to the
3-7.
"m easurement pins." The 4085A can be thought of as an 8 x 48 matrix,
3-5. Each crossing point is connected to or disconnected from a port by relays
properly controlling the relays, virtually any connection between the m easurement , ports
and m easurem ent pins is possible.
3-8.
M easurement Ports
3-9.
The measurement ports are connected to the S M U, Vm, and Vs terminals of the
4145A. Table 3-1 gives a brief description of each port. Only SM U Port 1 can be used for
low current m easurem ents. Generally, S M U l is connected to this port, but other S M Us
can be connected to this port.
3-10. M easurement Pins
3-1 1 . The 4085A can be equipped with up to 48 sets of m easurement pins. Each set
.
consists of a SENSE pin, FORCE pin, and GUARD pi,:" and
concentric circles at the center of the 4085A, as shown in Figure 3-6. Each pin ' is
spring-loaded to ensure good electrical contact with the contact pads oC a test fixture or
a personality board, which attaches to the probe card of a wafer prober. Only the FORCE
and GUARD pins are used for 4085M applications. The SENSE pin is not used, because it
is intended for m easurem ents requiring
4145A. When connected to PORT 2, 3, or 4, the SE NSE and FORCE pins are identical
(they're tied to each other inside the 1 6078A Adapter). 'When PORT I is used,- however,
the SE N SE pin is
4145A
r
:
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I
4084A
I
I
L
_
_
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_
3-6
open.
r - - - - - - - - - - - - - - - - - - - - - - - - �l
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16078A
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Vm
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Vs
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PORT
_ _
Control
Relay
_
_
_ _ _
_
_
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Figure 3-5 . Switching Matrix
all
a
Kelvin connection, which is not possible with the
- .
Measuremant
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4085A
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4085�1
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as
shown'in Figure
•.
are arranged to form three
Pins
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Model 4085M
.
.
. . ...
By
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