(1)多子通过EB(发射结注入B区 返回 经EB结 EB结正偏匡区多子(电子) 注入B区→in 扩散 B区多子(空穴)→注入匡区→iP 注意:(n)注入B区的电子是B区的非平衡少数载流子 E注入匡区的空穴是E区的非平衡少数载流子 所以 E en Ep sven 因为 NTP i>i) C b 88 b C EP e B LE
所以 i E = ie n +i EP≈ien (因为 N+ P ie n >>iEP) (1) 多子通过EB(发射)结注入B区 EB 结正偏 E 区多子（电子） 注入 B 区→ien B 区多子（空穴）→注入 E 区→iE P 经 EB 结 扩散 注意：（ie n）注入 B 区的电子是 B 区的非平衡少数载流子 (iE P )注入 E 区的空穴是 E 区的非平衡少数载流子 EB EC RC b Rb c e iEP ib1 icn1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ien iE 返回
(2)由浓度差引起基区非平衡少数载流子的扩散与复合。 返回 B区非平衡少子i 浓度差 向cB结扩散 复合 扩散 与B区多子复合→in(很少) R C b 8888 b B e
B 区非平衡少子 ien 向 CB 结扩散 与 B 区多子复合→i b1 (很少 ) 复合 浓度差 扩散 (2) 由浓度差引起基区非平衡少数载流子的扩散与复合。 EB EC RC b Rb c e ib1 icn1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ien 返回
(3集电极对载流子的收集 返回 cB结反偏 漂移 3区到达cB结的非平衡少子 经GB结 c区 3区少子(电子) 漂移c区→in CB0cn2cp c区少子(空穴)B区→i 注意:IoBn:反向饱合电流不受vεE控制 T↑→I CBO 所以i=iam+lcB B LBELBItLB2-ICB0. LB2-LEP 888 hL b E C EP en B e
CB 结反偏 B 区到达 CB 结的非平衡少子 C 区→icn1 B 区少子（电子） C 区→icn2 C 区少子（空穴） B 区→icp 注意：ICB0：反向饱合电流 不受 VBE控制 T↑ → ICB0↑ 所以 ic=icn1+ICB0 iB=iB1+iB2-ICB0, iB2=iEP 经 CB 结 ICB0=icn2+icp 漂移 漂移 漂移 (3)集电极对载流子的收集 EB EC RC b Rb c e ● ● ● ● iEP ib1 icn1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ien iC iE iB iC iB icn2 icp 返回
载流子的传输过程小结: 123457 将 NPN BJT接成共射极型:以射极为输入和输出回路的公共端 即:VB>>V,发射结正偏→易于E区多子扩散 返回 vg>0,集中结反偏→易于B区少子漂移 b Rb E B b12 E i=i+ C P E +lEp E B e‖i E CBO i+ 2 iclcBo +icnI iB=ibl +iEP-IcBO
E EC B EB EC RC b Rb c e ● ● ● ● 载流子的传输过程小结： 将NPN BJT接成共射极型：以射极为输入和输出回路的公共端 即： VBE>>VT , 发射结正偏→ 易于E区多子扩散 VCB＞0 ， 集中结反偏→ 易于B区少子漂移 b c e iE iB iC iEP ib1 i cn1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ien iC iE iB ien= icn1 + ib1 iE = ien + iEP ≈ ien ICBO= icn2 + icp iE iE iC iC iB iB iC= ICBO + icn1 ; iB= ib1 + iEP -ICBO icn2 icp 1 2 3 4 5 7 返回
2.共基电流分配关系: 123457 CB电流放大倍数:定义a=n/i(一般性的定义) 返回 CB直流电流放大倍数:a=(c-lc/~I/g(忽略IcBo CB输出端交流短路电流增益:α dn|"C数 C≈c=0.99< 所以i=ai+lCBo (反映运对i的控制作用) R C B b E LEP en E E
2. 共基电流分配关系： CB 电流放大倍数：定义 α=icn1 / iE （一般性的定义） CB 直流电流放大倍数: =(IC-ICBO) / IE≈IC / IE（忽略 ICBO） CB 输出端交流短路电流增益： E c d i d i = vCB=常 数 ≈ ＝0.99<1 所以 ic= iE+ICB0 (反映 iE对 ic的控制作用) EB EC RC b Rb c e ● ● ● ● iEP ib1 icn1 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ien iC iE iB iC iB icn2 icp 1 2 3 4 5 7 返回