| 摘要 |
PURPOSE:To enable the switching operation at a frequency higher than a conventional frequency by using an element capable of turning off at a high speed as only a transistor TR in the driving stage and making the turn-off time shorter in a smaller current area. CONSTITUTION:An element capable of turning off at a speed higher than that of a TR 2 in the output stage is used as a TR 1 in the driving stage. A diode 3 is provided to improve the turn-off time. Since only the TR 1 in the driving stage is turned off at a high speed, the reduction of the current amplification factor accompanied with the increase of turning-off speed is limited to only the driving stage, and a higher current amplification factor is secured in comparison with the increase of turning off speed of the whole of a Darlington TR. Not only the extension of the turn-off time in a small current area as the essential purpose is improved but the collector current-turn-off time characteristic is improved as shown by a dotted line B. |
