| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress fluctuation of temperature characteristics by eliminating fluctuation of internal offset voltage in each operational amplifier. SOLUTION: The thermal flowmeter comprises first and second heat-sensitive resistors 11, 12 disposed in an air intake tube, and a control circuit 100 for feedback controlling conduction to the heat-sensitive resistor 11 such that the resistor 11 is held at a specified temperature. The control circuit 100 comprises two operational amplifiers 200, 300 wherein the internal offset voltage VOS3 of one operational amplifier 300 is regulated with reference to the internal offset voltage VOS2 of the other operational amplifier 200 such that the internal offset voltages related to the temperature characteristics of the operational amplifiers 200, 300 are set at '0'.</p> |
