Chapter 4
Signal Connections
PCI-MIO E Series User Manual
4-12
©
National Instruments Corporation
Figure 4-2. PCI-MIO E Series PGIA
The PGIA applies gain and common-mode voltage rejection and
presents high input impedance to the analog input signals connected to
your PCI-MIO E Series board. Signals are routed to the positive and
negative inputs of the PGIA through input multiplexers on the board.
The PGIA converts two input signals to a signal that is the difference
between the two input signals multiplied by the gain setting of the
amplifier. The amplifier output voltage is referenced to the ground for
the board. Your PCI-MIO E Series board A/D converter (ADC)
measures this output voltage when it performs A/D conversions.
You must reference all signals to ground either at the source device or
at the board. If you have a floating source, you should reference the
signal to ground by using the RSE input mode or the DIFF input
configuration with bias resistors (see the Differential Connections for
Nonreferenced or Floating Signal Sources section later in this chapter).
If you have a grounded source, you should not reference the signal to
AIGND. You can avoid this reference by using DIFF or NRSE input
configurations.
-
Instrumentation
Amplifier
-
Measured
Voltage
V
m
+
+
PGIA
V
in+
V
in-
V
m
= [V
in+
- V
in-
]* Gain
