| 摘要 |
PURPOSE:To obtain the reference voltage that has no dependence on temperatures down to a comparatively low level of voltage, by using the 1st and 2nd transistors (Q), the 1st and 2nd resistances (R) and an absolute temperature proportional constant current source. CONSTITUTION:When the B-E voltage of the 1st transistor Q21 is set at VBE1, the current flowing the 1st resistance R21 is set as I22=VBE1/R21. When the constant current value supplied from a constant current source I21 is set at I21, the current flowing to the 2nd resistance R22 is set as I23=I21+I22. When the potential difference between both terminals of R22 is set at Vr2, Vr2=R22.I23. Then VBE1=VgO-alphaT, where band gap voltage is VgO, the temperature coefficient is alpha and the absolute temperature is T, respectively. While I21=betaT is obtained when the temperature coefficient is referred to as beta. Therefore the reference voltage Vr2=[betaR22-alpha(R22/R21)]T+VgO(R22/R21) is obtained. Thus the temperature coefficient of Vr2 is set at O if the value of resistance is decided so that the coefficient of the temperature T of the 1st term is set at O. As a result, it is possible to obtain the reference voltage that has no dependence on the temperature down to a comparatively low level of voltage with a small number of elements. |
