CAS signal conditioning circuits with operational amplifier
A signal conditioning circuit allows adapting the input levels of a signal to other levels of voltages, so that these signals can be acquired in the next stage of the circuit that is designed:
The best way to explain is with an example:
It is desired that an input of a sensor Lm335 (10mv / ° C) sensor range -10 to 100 ° C
Work from 0 ° C to 50 ° C
That is 0 ° C output 0 Volts
And at 50 ° C output 5 Volts
The sensor delivers to:
0 ° C --------> a voltage of 2.73v
50 ° C --------> a voltage of 3.23v
Step 1. Draw a graph where the desired output is observed.
We can observe two pairs of points in the graph
Table 1. Points of the graph
|
Entry (X)
|
Output (Y)
|
Initial Point
|
2.73
|
0
|
final point
|
3.23
|
5
|
Step 2. How do you want a linear output? This means that the previous graph is the graph of a line. Therefore we can find the slope (m) with the equation (1), where the output is (Y) and the input (X)
Now replacing in equation (1) the data of table 1.
Step 3. We use equation (1) to find the equation of the line.
Now we replace the initial values in equation (2) and the value of the slope
This means Y is the output of the operational and X the sensor input
Step 4. We use Operational Amplifier in adder configuration
