Patent Document ID: 5461322
Application ID: 08102835
Patent Flag: 1

Claim One:
1. An autonulling bridge circuit system for measuring resistance changes, comprising: a DC bridge circuit including two current dividing branches with a first branch including a sensor resistance to be measured and a second branch including a voltage controlled resistance means wherein said voltage controlled resistance means is one of a MOSFET and a bipolar junction transistor and wherein each of said first and second branches receives a direct current voltage, said bridge circuit further including a first and second output voltage means each connected to a respective one of said first and second branches; bridge nulling circuit responsive to output of said first and second voltage output means to provide a difference voltage, said bridge nulling circuit also including an integrator means for providing a feedback signal for driving said voltage controlled resistance wherein said feedback signal varies until the difference between said first and said second voltage output is zero at which point said feedback signal remains constant and is proportional to said sensor resistance as a function of the transfer characteristics of said voltage controlled resistance.