National Instruments PCI-1200 用户手册

© National Instruments Corporation

Figure 3-4 shows how to connect a floating signal source to a PCI-1200 
board configured for DIFF input. Configuration instructions are in the 

 section of Chapter 2, 

Figure 3-4.  Differential Input Connections for Floating Sources

The 100 k

Ω resistors shown in Figure 3-4 create a return path to ground for 

the bias currents of the instrumentation amplifier. If there is no return path, 
the instrumentation amplifier bias currents charge stray capacitances, 

+

+

Floating

Signal

Source

V

m

Measured

Voltage

V

s

+

 I/O Connector

PCI-1200 in DIFF Configuration

1

3

5

7

2

4

6

8

100 k

Ω

Bias

Current
Return 

Paths

ACH0

AGND

11

ACH2

ACH4

ACH6

ACH1

ACH3

ACH5

ACH7

100 k

Ω

–

–

–