| 摘要 |
<p>PURPOSE:To reduce an effect of an internal offset voltage of a differential amplifier circuit which conducts a feedback control on the temperature of a temperature-sensitive resistant body. CONSTITUTION:Temperature-sensitive resistant bodies 7 and 8 are provided in a suction air passage. A power transistor 5 is subjected to a feedback control so that the temperature of the temperature-sensitive resistant body 7 be higher by a prescribed temperature. A voltage VM showing the amount of current supplied to this temperature-sensitive resistant body 7 is amplified as an output voltage and outputted. An operational amplifier 230 and an operational amplifier 360 are located in a feedback control loop and internal offset voltages of the two amplifiers appear as reverse polarities to each other in relation to the output voltage VM. Therefore the internal offset voltages of the operational amplifiers 230 and 360 are offset mutually and the effect on the output voltage VM is reduced.</p> |
