1. Common-Collector Amplifier
Section

2. Topics Emitter Follower as a power amplifier
Push and Pull Output Stage

3. 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

4. Common-Collector Amplifier

5. Vin, m=1 mV
Vin,pp=2 mV
Vout,pp=1.47 mV
Av(ADS)=0.735
Av(matlab)=0.783

6. Large Signal Behavior of Common-Collector Amplifier
The output does not track
the input during the negative swing.

7. Vin, m=1.71 V
VBE

8. Push-Pull Stage Q1 pushes current into RL. Q1 and Q2 are off.
Q1 pulls current from RL.

9. Vout versus Vin

10. DC Sweep

11. Vout Versus Vin

12. Transient Simulation

13. Vout Versus Vin
Crossover
Distortion

14. Improved Push-Pull Stage
Q1 and Q2 can not be
on at the same time!
Keep Q1 and Q2 on
V1=Vout+VBE1
V2=Vout-|VBE2|
V1-V2=VBE1+|VBE2|=VB

15. Example 13.5

16. Implementation of VB
Add I1 to provide current
For D1 and D2.

17. Current flowing through the Source

18. Output Stage with no DC shift
If I1=I2 and IB1 and IB2,
the input source
does not sink or source
Output voltage.