| 摘要 |
PURPOSE:To increase the degree of integration of an IC by adding a transistor element to a conventional constant current circuit to increase apparently the value of a start resistance up to an hFE-fold level as much as a relevant transistor and therefore attaining the starting purpose with small start resistance value. CONSTITUTION:A transistor TRQ7 is newly provided with its base and collector connected to the base of a TRQ6 and an earth terminal (c) respectively. While a start resistance R2 is connected between an input terminal (a) and the emitter of the TRQ7. The base current of the TRQ6 which is needed in a start mode of a constant current circuit is supplied from the base of the TRQ7. When the input voltage is varied by DELTAV after the constant current circuit is started, the variance amount DELTAIB7 of the base current of the TRQ7 flowing to the collector of a TRQ4 is calculated as DELTAIB7=DELTAV/(R2XhFEQ7), where the emitter earth current amplification factor of the TRQ7 is shown by hFEQ7. Thus the value of the R2 is apparently equal to an hFE-fold level as much as the TRQ7. Thus the constant current circuit can be started with the start resistance of a low level. |
