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# Common-Collector Amplifier - PowerPoint PPT Presentation

Common-Collector Amplifier. Section 13.1-13.4. Topics. Emitter Follower as a power amplifier Push and Pull Output Stage. Design Guideline. Specs: Av, rsp, v_re gm=Av/(1-Av)/rsp Calculate IC from gm. Determine re from IC and V_RE Calculate VBE. Calculate VB. Calculate IB from IC.

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Common-Collector Amplifier

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## Common-Collector Amplifier

Section 13.1-13.4

### Topics

• Emitter Follower as a power amplifier

• Push and Pull Output Stage

### Design Guideline

• Specs: Av, rsp, v_re

• gm=Av/(1-Av)/rsp

• Calculate IC from gm.

• Determine re from IC and V_RE

• Calculate VBE.

• Calculate VB.

• Calculate IB from IC.

• Assume that I1=40 IB

• Calculate R2 from VB.

• Calcualte R1

Vin,pp=2 mV

Vout,pp=1.47 mV

Av(matlab)=0.783

### Large Signal Behavior of Common-Collector Amplifier

The output does not track

the input during the negative swing.

VBE

### Push-Pull Stage

Q1 pushes current into RL.

Q1 and Q2 are off.

Q1 pulls current from RL.

Crossover

Distortion

### Improved Push-Pull Stage

Q1 and Q2 can not be

on at the same time!

V1=Vout+VBE1

V2=Vout-|VBE2|

Keep Q1 and Q2 on

V1-V2=VBE1+|VBE2|=VB

For D1 and D2.

### Output Stage with no DC shift

If I1=I2 and IB1 and IB2,

the input source

does not sink or source

Output voltage.