A pressure transducer having a Wheatstone bridge construction has the properties listed in the table below. The transducer is exited using a constant current source having an adjustable range and temperature coefficient. The zero pressure offset of the transducer must also be cancelled over the operating temperature range.
|
Parameter
|
Min
|
Typ
|
Max
|
Units
|
|
Pressure Range
|
0 1
|
-
|
100
|
kPa
|
|
Bridge Resistance
|
4.5
|
5.0
|
5.5
|
k5
|
|
Temperature Coefficient of Resistance
|
-500
|
-750
|
-1000
|
ppm / 0c
|
|
Bridge Sensitivity
|
900
|
1000
|
1100
|
ppm / kPa
|
|
Temperature Coefficient of Sensitivity
|
200
|
250
|
300
|
ppm
|
|
Zero1Pressure Offset
|
5
|
10
|
15
|
% FS
|
|
Temperature Coefficient of Offset
|
1200
|
1500
|
1800
|
ppm / 0c
|
Estimate an expression for the output voltage that would be acquired from a signal conditioning circuit which incorporates all calibration, cancellation and temperature compensation needed, describing the rationale.
Find out the range of the current variation required to offer a full-scale differential output voltage of 100mV from the transducer and the resulting range of voltage across the bridge of the transducer. Compute the temperature coefficient adjustment necessary in the current source to offer full temperature compensation of the span.
Calculate the range of the cancellation voltage necessary and its related temperature coefficient adjustment required to eliminate the zero-pressure offset over the operating temperature range.