6. BJT small signal

6. BJT small signal - Sem I 0809/rosdiyana Chapter 5: BJT...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Sem I 0809/rosdiyana Chapter 5: BJT Small-Signal Analysis Contents Common-Emitter fixed-bias configuration Voltage divider bias CE Emitter bias Emitter-follower configuration Common-base configuration Collector-feedback configuration Hybrid equivalent circuit and model r e transistor model employs a diode and controlled current source to duplicate the behavior of a transistor in the region of interest. The r e and hybrid models will be used to analyze small- signal AC analysis of standard transistor network configurations. Ex: Common-base, common-emitter and common-collector configurations. The network analyzed represent the majority of those appearing in practice today. BJT Small Signal Analysis AC equivalent of a network is obtained by: 1. Setting all DC sources to zero 2. Replacing all capacitors by s/c equiv. 3. Redraw the network in more convenient and logical form Common-Emitter (CE) Fixed-Bias Configuration The input (Vi) is applied to the base and the output (Vo) is from the collector. The Common-Emitter is characterized as having high input impedance and low output impedance with a high voltage and current gain. Removing DC effects of VCC and Capacitors Common-Emitter (CE) Fixed-Bias Configuration re Model Determine , re, and ro: and ro: look in the specification sheet for the transistor or test the transistor using a curve tracer. r e : calculate r e using dc analysis: E e I 26mV r = Common-Emitter (CE) Fixed-Bias Configuration Impedance Calculations Input Impedance: Output Impedance: e B i r || R Z = e B e i r 10 R r Z 2245 O r || R Z C o = c o 10 ro Z R R c 2245 Common-Emitter (CE) Fixed-Bias Configuration Gain Calculations Voltage Gain (Av): Current Gain (Ai): Current Gain from Voltage Gain: e o C i o v r ) r || (R V V A- = = C o e C v 10R r r R A - = ) r )(R R (r r R I I A e B C o o B i o i + + = = e B C o i r 10 R , 10R r A 2245 C i v i R Z A A- = Common-Emitter (CE) Fixed-Bias Configuration Voltage Gain e C v C o e o C e b o C b v e b i o C b O i O v r R A 10R or r if r ) r || (R r I ) r || (R I A r I V ) r || (R I V V V A = = =- = =- = = Common-Emitter (CE) Fixed-Bias Configuration Current gain ( 29 ( 29 ( 29 ( 29 C i v i B o B o i o i e B C o e B C o B o i o i e B B C o o i b b o i o i e B B i b e B i B b C o o b o C o b o o R Z A A oo equation t this use can or we R r R r I I A , r 10 R and 10R r if r R R r R r I I A r R R R r r I I I I I I A r R R I I and r R I R I R r r I I and R r I r I circuits output and input the to rule divider - current the applying by determined is gain current The- = = 2245 = + + = =...
View Full Document

Page1 / 56

6. BJT small signal - Sem I 0809/rosdiyana Chapter 5: BJT...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online