Device for operating passive infrared sensors

A system for measuring a sensor, the sensor including a first sensor terminal and a second sensor terminal, comprising:

• a first transistor including a third terminal, a fourth terminal and a fifth terminal, the third terminal being a first transistor control terminal and connected to the first sensor terminal;
• a second transistor including a sixth terminal, a seventh terminal and a eighth terminal, the sixth terminal being a second transistor control terminal and connected to the second sensor terminal;
• a current divider including a reference current input, a control input, a first current divider output and a second current divider output, wherein the first current divider output is connected to the fourth terminal of the first transistor and the second current divider output is connected to the seventh terminal of the second transistor;
• a reference current source connected to the reference current input;
• a first load circuit connected to the fifth terminal of the first transistor at a first differential output node;
• a second load circuit connected to the eighth terminal of the second transistor at a second differential output node;
• a first integrating circuit connected to the first differential output node, and configured to integrate a first differential output signal;
• a second integrating circuit connected to the second differential output node, and configured to integrate a second differential output signal;
• a comparator including a first comparator input, a second comparator input and a comparator output, wherein the first comparator input is connected to the first differential output node and the second comparator input is connected to the second differential output node;
• and
• a digital integrator having a digital integrator input and a digital integrator output, wherein the digital integrator input is driven by the comparator output;
• wherein:
• a value of a current divider control signal driving the current divider control input depends from the digital integrator output.