Patent ID: 7023215

Claim:
An apparatus for powering and reading data from a plurality of field effect sensors over two wires, comprising: a power supply; a first field effect sensor having a first power terminal coupled to a first terminal of said power supply and a second power terminal coupled to a second terminal of said power supply; a first load resistor having a first terminal coupled to an output terminal of said first field effect sensor and a second terminal coupled to said second terminal of said power supply, said first load resistor having a first value of resistance; a second field effect sensor having a first power terminal coupled to a first terminal of said power supply and a second power terminal coupled to a second terminal of said power supply; a second load resistor having a first terminal coupled to an output terminal of said second field effect sensor and a second terminal coupled to said second terminal of said power supply, said second load resistor having a second value of resistance, said second value of resistance being substantially different from said first value of resistance; and a detection circuit coupled to said first field effect sensor and said second field effect sensor.