Part2 - AP NG TAN SO CAO CUA MACH KHUECH AI GHEP RC Chng 2...

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8 Chöông 2 : ÑAÙP ÖÙNG TAÀN SOÁ CAO CUÛA MAÏCH KHUEÁCH ÑAÏI GHEÙP RC I. Boä khueách ñaïi transistor ôû taàn soá cao : 1. Maïch töông ñöông hình Π : bb' be ' be ' bc ' h ib' fe 1/hoe C C r A r B Taàn soá caét 3db: e b e b c b c b e b C r C C r f ' ' ' ' ' 2 1 ) ( 2 1 Π + Π = β (3)(C b’c <<C b’e ) Taàn soá giôùi haïn cuûa transistor ( taïi ñoù h fe =1) fe T h f f . = (4) g m = EQ ib e b fe I h r h 40 1 ' = = (5) 2. Boä khueách ñaïi cöïc phaùt chung ôû taàn soá cao-Ñieän dung Miller : ->o L o ->oo i i Cc2 R Ce Vcc Cc1 i r R2 R1 Re Rc ' ' M m ' ' Vbe i i RL Rc gVbe C Cbe Rbe Haøm truyeàn toång quaùt : A i = A im H j ω + 1 1 (4) A im =-g m R b'e (5) ( coi R c >>R L ) r bb' 10 ÷ 50 Ω (1) h ie = r bb' + r b'e = r bb + h fe EQ I 3 10 25 - (2) i i ' =i i i bb b b i r R R + ' (1) coi r bb' 0 ; L c b R C >> ' 1 m c b g C << ' ta coù : R b'e =r b'e //R b (2)(khoâng coù r i ) R b'e =r i //r b'e //R b (2') (coù r i ) C M =C b'c (1+g m L c L c R R R R + ) (3)
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9 A im =-g m R b'e L c c R R R + (5'0 ( khi coù R c ~R L ) ) ( 1 ' ' M e b e b H C C R + = ω (6) ) ' // ( 1 b E E L R R C = (7) II.
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Part2 - AP NG TAN SO CAO CUA MACH KHUECH AI GHEP RC Chng 2...

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