ThevEmCir

# ThevEmCir - Thvenin Emitter Circuit The Thvenin equivalent...

This preview shows pages 1–2. Sign up to view the full content.

Thévenin Emitter Circuit The Thévenin equivalent circuit seen looking into the emitter is useful in calculating the response of common-collector stages. It consists of a voltage source v e ( oc ) in series with a resistor r ie from the emitter node to signal ground. Fig. 1(a) shows the BJT symbol with a Thévenin source connected to the base. The resistor R tc represents the external load resistance in series with the collector. With the emitter open circuited, we denote the emitter voltage by v e ( oc ) . The voltage source in the Thévenin emitter circuit has this value. To solve for it, we use the simpli f ed T model in Fig. 1(b). Figure 1: (a) BJT with Thévenin source connected to the base. (b) Simpli f ed T model circuit for calculating v e ( oc ) . The current i 0 e can be solved for by superposition of the sources v tb and αi 0 e .I ti sg iv en by i 0 e = v tb r 0 e + r 0 + R tc + αi 0 e R tc r 0 e + r 0 + R tc (1) This can be solved for i 0 e to obtain i 0 e = v tb r 0 e + r 0 +(1 α ) R tc = v tb r 0 e + r 0 + R tc / (1 + β ) (2) Theopen-c ircu item ittervo ltageisg ivenby v e ( oc ) =

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 05/26/2011 for the course ECE 3050 taught by Professor Hollis during the Summer '08 term at Georgia Tech.

### Page1 / 2

ThevEmCir - Thvenin Emitter Circuit The Thvenin equivalent...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online