三极管β值对电压放大倍数的影响新探

Discussion about Effect of β of Transistors on Voltage Gain

一般电子技术教材认为,在单级共发射极放大电路中,改变三极管的β值对电压放大倍数的影响不明显。即当增大(或减小)β值时,在静态发射极电流IE不变的情况下,电压放大倍数不会明显增大(或减小)。然而IE能否保持不变?与哪些因素有关?若IE发生了改变结果又会怎样?这些问题一般教材均未给予讨论。这些问题不讨论清楚,很容易在分析电路时出现错误。对以上问题进行了分析讨论并运用实验方法加以验证,最终得出明确结论。

Most of the electronics textbooks think that the change of transistor parameter current amplification factor β can cause little change of voltage gain in one - stage common emitter configuration amplifiers. That is to say under the condition of constant static emitter current when the β is increased （or decreased）,the voltage gain will not be increased （or decreascd） clearly. However,can IE be kept constantly？ Which factors do it related to？ If Ie can＇t keep constant,what the result will be？ All of these questions aren＇t discussed in common textbooks. If we don＇t know the answers of the questions,it＇s easy to make mistakes while analyzing the amplification circuits. The above mentioned questions will be analyzed and discussed thoroughly and the conclusions will be reached clearly in this paper. Yet,experiments are used to prove the conclusions.