Patent ID: 6518773
Filing Date: 2003-02-11
Classification: G01D

Abstract:
An apparatus for adjusting a sensitivity of a sensor, comprising:a sensor that is activated when supplied with a predetermined drive current, the sensor including a sensor input terminal receiving the drive current and a sensor output terminal emitting a sensor current, wherein the sensor has a variable sensitivity dependent on a value of the drive current; first and second fixed resistors connected in series between a high potential power source and a low potential power source, wherein a node voltage at a first node between the first and second resistors defines a reference voltage; a single operational amplifier having a first input terminal connected to the first node, a second input terminal, and an output terminal connected to the sensor input terminal for supplying the drive current; a variable resistor connected between the sensor output and the low potential power source; and a second node directly coupling the sensor output terminal to the second input terminal and the variable resistor, wherein a node voltage at the second node defines a sensor voltage, the variable resistor varying the sensor current to maintain the sensor voltage at a value approximately equal to the reference voltage.