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Modeling and Analysis of PSRR in Analog PWM Class D Amplifiers
Tong Ge; Chang, J.S.; Wei Shu;Circuits and Systems, 2006. ISCAS 2006. Proceedings. 2006 IEEE International Symposium on 0-0 0 Page(s):4 pp.Digital Object Identifier 10.1109/ISCAS.2006.1692853
指導教授：易昶霈學 生：杜彥諴學 號： 98662006
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OUTLINE INTRODUCTION MODELING OF PWM CDAS INVESTIGATION INTO THE PARMETERS
AFFECTING PSRR RESULTS CONCLUSIONS
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INTRODUCTION Power Efficiency CDA modulation method PSRR
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INTRODUCTION Power Efficiency
note : CDA’s MOS operate in triode and cut-off regions that have low quiescent power.
Type Performance
Class A <25%
Class B <78.5%
Class AB 25%~78.5%
Class D >80%
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INTRODUCTION CDA modulation method
1. Pulse Width Modulation
2. Sigma-Delta Modulation
3. Bang-Bang Control Moudlation
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INTRODUCTION CDA modulation method
1. Pulse Width Modulation
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INTRODUCTION CDA modulation method
2. Sigma-Delta Modulation(Pulse-Density-Modulated-like)
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INTRODUCTION CDA modulation method
3. Bang-Bang Control Modulation(Pulse-Density-Modulated-like)
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INTRODUCTION CDA modulation method
4. Digital CDA modulation method
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INTRODUCTION PSRR(Power Supply Rejection Ratio)
嚴格來說就是電源 IC 對輸入電壓所挾帶來的雜訊 (Vin Ripple) 清除的能力
電源斥拒比 (PSRR) 影響輸出訊號的因素除了電路本身之外還有電源級 . PSRR 是一個用來描述輸出訊號受電源影響的量 . PSRR 越大輸出訊號越不受電源影響 .
Critical parameter
1. Gain of integrator
2. Gain of PWM
3. Gain of feedback factor
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MODELING OF PWM CDAs Modeling an open-loop PWM CDA Modeling a close-loop PWM CDA
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MODELING OF PWM CDAs Modeling an open-loop PWM CDA
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MODELING OF PWM CDAs Modeling an open-loop PWM CDAGpwm = gain of PWM stage
N = noise in supply rail
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MODELING OF PWM CDAs Modeling a close-loop PWM CDA
積分器
Feedback network(R1 and Rfb)
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MODELING OF PWM CDAs Modeling a close-loop PWM CDA
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MODELING OF PWM CDAs Modeling a close-loop PWM CDAG1=amp input to inverting input of integrator
H1= feedback factor
Aop = op-amp open –loop gain
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MODELING OF PWM CDAs Modeling a close-loop PWM CDA
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INVESTIGATION INTO THE PARMETERS AFFECTING PSRR
The gain of integrator The gain of PWM stage The feedback factor
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INVESTIGATION INTO THE PARMETERS AFFECTING PSRR
The gain of integratorEq10 中 Gint可以大幅的增加 PSRR,所以 Aop越大越好 .會在 fig6再一次
看到
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INVESTIGATION INTO THE PARMETERS AFFECTING PSRR
The gain of PWM stage
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INVESTIGATION INTO THE PARMETERS AFFECTING PSRR
The feedback factor
Increasing H1 results in two major shortcomings
1. reduced dynamic range of the amplifier
2. reduced amplifier gain
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RESULTS
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CONCLUSIONS
這篇 PAPER 表現了 , 一個分析 CDA 中 PSRR 的方法探討了影響 PSRR 的三個因素
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Thanks for pay attention.
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