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Power Amplifiers Class B, AB,C (CMOS 0.35um,0.18um). Imran Khan. Contents. Introduction Class AB,B,C Results Conclusion. Power Amplifiers. Introduction BFL (choke inductor) has a large value in order to provide an approx. constant current. V dd is fixed for every technology - PowerPoint PPT Presentation
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Power AmplifiersClass B, AB,C(CMOS 0.35um,0.18um)
Imran Khan
Contents
Introduction
Class AB,B,C
Results
Conclusion
Power Amplifiers
Introduction BFL (choke inductor) has a large
value in order to provide an approx. constant current.
Vdd is fixed for every technology Vin is the input voltage to be amplified
Linearity Ideal PA is linear but other
PAs are linear in certain limits
Efficiency Normally 30% to 80% Efficiency=Pout/Pin
Power Amplifiers
IntroductionGain (voltage, current, power gain)
magnitude of the output signal (Xo) over the magnitude of the input signal (Xi), G= Xo/Xi
Region of Operation The region of operation of MOSFET is:
Power Amplifiers Amplifier Classes
Class A Efficiency: (10-20)%, theory 50%
Linearity: good, Cond. Cycle: 360º
Class B Efficiency: (35-50)%, theory 78 %
Linearity: <A, Cond. Cycle: 180º
Class AB Efficiency: compromise between A& B
Linearity: between A and B, Cond. Cycle: 181º-359º
Class C Efficiency: (50-60)% max 90% Linearity:
worst, Cond. Cycle:<180
Current FlowingThe red indicates how much of the drain current is flowing through one wave cycle.
Results- Class B (0.18um)
W=375um
Vlow=0.39 V
Results- Class B (0.18um)
Results- Class AB (0.18um)
W=90um
Vlow=0.35um
Results- Class AB (0.18um)
Results- Class C (0.18um)
W=950um
Vlow=0.1V
Results- Class C (0.18um)
Results- Class B (0.35um)
W=1250um
Vlow=0.1V
Results- Class B (0.35um)
W=350um
Vlow=0.6V
Results- Class AB (0.35um)
Results- Class AB (0.35um)
Results- Class C (0.35um)
W=2.5mm
Vlow=0V
Results- Class C (0.35um)
Conclusion
Except class A, all PA can be used in Rf systems
PA is the last element in transmission chain therefore requires most attention.