| 摘要 |
PURPOSE:To generate a constant current having no temperature characteristic whose characteristic is constant independently of temperature change by operating a fluctuated current component of a constant current in response to the temperature characteristic of a constant current circuit and adding a temperature characteristic canceling circuit canceling the fluctuated current component. CONSTITUTION:A current multiplied by M times the temperature sensing current flowing to a transistor (Tr)38 flows to a Tr40 and the said current is added to a constant current I0 to form an output current IOUT. In applying differential differentiation to the current IOUT by a temperature T, the relation of sigmaIOUT/sigmaT =(VT/R0).[(1/T)-gamma]1nN+M.(M/R1).[(sigmaVF/sigmaT)-gammaVF] is obtained, where VF is a forward voltage drop of a diode 16 and =(1/R0)sigmaR0/'T. Thus, in setting the emitter area ratio M of the Trs 40, 38 and resistance values R0, R1 of the resistors 18, 42 to satisfy sigmaIOUT/sigmaT=0, the fluctuated current component of the current IOUT due to temperature change is canceled by an output current MI1 of a temperature characteristic cancellation circuit 34 to obtain the output current IOUT without temperature characteristic. |
