作者fairwarning (一輪明月與藍夜!!)
看板Grad-ProbAsk
標題[理工] [電子]-電流鏡
時間Wed Sep 16 12:45:17 2009
[電路圖]
http://www.wretch.cc/album/show.php?i=fairwarning&b=4&f=1893012287&p=0
[題目]
For the current mirror,the two BJTs are idential expect that the emitter area
of Q2 is three times of that of Q1.
Assume that Q2 is active , Vbe=0.6V , and the Early voltage is infinite;
(1)if β=∞ ,IL=?
(2)if β=10 ,IL=?
[解答]
(1) IL=0.6mA (2) IL=0.428mA
為了增加題目文完整度...順便打(1)打出..
請問大家(2)要怎麼解呢?
謝謝大家的幫忙~~ 謝謝!
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◆ From: 140.127.150.126
1F：推 eageoneal:列兩端BASE電流 右邊為左邊3倍 再利用IC=BIB 列方程式 09/16 13:42
2F：→ eageoneal:設左邊IB為X 右邊IB為3倍X 中間為3+1=4X 左邊IC為 10X 09/16 13:44
3F：→ eageoneal:{5-(-4.4)}/47=14X X=0.0142mA 鎖球極為右邊IC=30X= 09/16 13:46
4F：→ eageoneal:=0.42857...mA 09/16 13:46
5F：→ fairwarning:謝謝喔..我自己試試看!! 09/16 16:32