AN4368

Conditioning the signal

DocID025334 Rev 1

11/18

6

Conditioning the signal

Figure 8 shows the output voltage of the first important signal generated by the PIR sensor.

Once the application is supplied, the signal is almost constant. The common mode voltage

is 1.1 V but, this voltage may vary from one sensor to another. Based on this figure, it is

clear that the sensor has not detected any motion. However, thanks to signal conditioning,

the signal can be amplified and peaks, representing motion, can be detected.

Figure 8: Output voltage of the PIR sensor