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Common-Collector Amplifier. Section 5.3. Topics. Emitter Follower Core Effect of Transistor Output Resistance Emitter Follower with Biasing. Voltage Gain of Emitter Follower. Use a current source to implement RE. R E =infinity imples that A V =1.
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Common-Collector Amplifier Section 5.3
Topics • Emitter Follower Core • Effect of Transistor Output Resistance • Emitter Follower with Biasing
Use a current source to implement RE RE=infinity imples that AV=1
Output Resistance RS is transformed to a smaller output resistance.
Application of Common Collector Stage Av=-(RC||Rsp)/(1/gm) RSP=8 Ohms << RC AV=-RSP/(1/gm)
Interpose a Emitter Follower between the CE Stage and the speaker CE stage: -(RC||Rin1)/(1/gm)
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(ADS)=0.735 Av(matlab)=0.783
Vin, m=1.71 V Need to adjust V_RE.