Combination magnetic and capacitive sensor
Described is an invention that adds capacitive sensing ability with a single magnetic field sensor location or distributed within an array of surfaces of the sensor. The capacitive sensing can be achieved by modifying a classic Hall effect sensor or putting separate capacitive sensor plates in close proximity to the hall effect sensor.
1. A capacitive sensor device comprising:
two Hall sensor plates;
a differential amplifier used as a single ended amplifier with an analog to digital converter;
a voltage source providing a reference threshold voltage;
additional switching transistors that can change a state between a high and low impedance; and
conducting electrodes adjacent to the Hall plates, wherein if the electrodes are connected with a conducting closed loop, then a resulting shorted turn will tend to reject alternating current magnetic fields but will not affect a static magnetic field if applied long enough and the shorted turn has sufficient loss.
2. The device of claim 1 wherein the switching transistors may be a field effect transistor or other bipolar device.
3. The device of claim 1 , wherein a source and a receptor electrode are operated far apart from each other for multi-factor detection where the device is within a physical unclonable function.
4. A magnetic and capacitive sensor device comprising:
time interval where Hall plate electrodes are connected to make a Hall effect magnetic sensor;
a time interval where the Hall plate electrodes are connected to make a capacitive sensor; and
a switch control that enables the change of switched connections.
5. The device of claim 4 , where the switch control connects multiple Hall plates together forming a larger conducting area.
6. The device of claim 4 , where the switch control connects Hall plates creating a driving point capacitive sensor.
7. The device of claim 4 , where the switch control connects multiple Hall plate channels to measure both magnetic and capacitive modes simultaneously.
8. The device of claim 4 , where the switch control connects Hall plates sequentially between magnetic and capacitive modes.
9. The device of claim 4 , where the switch control connects X-direction or Y-direction facing Hall plate channels to measure both magnetic and capacitive modes.
10. The device of claim 4 , where the switch control connects Z-direction facing Hall plate channels to measure both magnetic and capacitive modes.