common-base amplifier. response of cb stage to small input change
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Common-Base Amplifier
Common-Base Amplifier
Response of CB Stage to small Input Change
Input Impedance
Application of CB Stages
Response to a Source of Finite Source Resistance
Output Impedance
Input Impedance
General CB
(VA=infinity, RB>0)
Base resistance (RB) decreases voltage gain.
CB Stage with Biasing
Design Goal
Goal: i2>>i1
Bypass Capacitor
(Base resistance decreases gain!)
Design Guideline
• Given: Rin, AV• Select RE>>(1/gm). – gm →IC.– RE=10Rin
• Av=gmRC →RC
• Vb=IERE+VBE• Let I(R1)=40IB →(R1+R2) • R2 is known from Vb and R1.• 1/(C1ω)=(1/gm)/20• 1/(beta+1)/(C1 ω)=(1/gm)/20
Common Base Amplifier
ADS SimulationADS Analysi
s
Vs,pp(mV) 4 4
Vin,pp(mV) 2 1.90
Vout,pp(mV) 17 N/A
Vout,pp/Vin,pp 8.5 11
Vout,pp/Vs,pp 4.25
5.23
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