| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a thermal air flow rate detection device high in detection precision at a low cost. <P>SOLUTION: To heighten the voltage level of the air flow signal Vo output from the detection circuit 12 of the air flow rate detection device for heightening the detection sensitivity of the air flow rate can be satisfied by setting the resistance of a feed back resistor R3 high. The output offset voltage of an operational amplifier OP in the air flow rate signal Vo becomes equal to the input offset voltage, therefore the output offset voltage does't vary even the resistance of the feedback resister R3 is set high. Consequently, error in the air flow rate signal Vo does not increase and reduction of detection precision can be prevented even when the detection sensitivity is heightened. The detection precision of the air flow rate can be heighten by decreasing the temperature drift of the differential amplifier Da, because the output level of the differential amplifier Da can follow the fluctuation of the emitter voltage of a transistor Ta for current control, even the offset voltage of the differential amplifier Da is set zero. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
