| 摘要 |
<p>Provided is a heating temperature adjustment circuit in a thermal flow meter capable of adjusting fluctuations of a heating temperature of a heat-generating resistor due to fluctuations of resistances with high accuracy and low cost. The thermal flow meter comprises: a heat-generating resistor that generates heat when a current flows therethrough; a first temperature measuring resistor 1, a second resistor 2, a third resistor 3, and a fourth resistor 4 whose resistance values vary due to temperature; and a fixed resistance 5 having a resistance temperature coefficient lower than that of the first temperature measuring resistor, and measuring a flow rate of a fluid by controlling the heating temperature of the heat-generating resistor. The thermal flow meter includes: a first series circuit in which the fixed resistance 5, the first temperature measuring resistor 1, and the second resistor 2 are connected to one another in series; and a second series circuit in which the third resistor 3 and the fourth resistor 4 are connected to each other in series, and generates a voltage to be added to the second series circuit based on voltages at both ends of the fixed resistance.
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