EE42/100 Fall 2005 Prof. Fearing 1

Week 14b/ Lecture 25 Dec. 1, 2005

Example Applications1. Class D Audio Amplifier• (phasors, opamp, MOSFET)

2. Atomic Force Microscope

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www.irf.com/product-info/audio/classdtutorial.pdf

Traditional Linear Amplifier

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Example: Vcc = 25V, load = 1 ohms, IXYS 24N50

current

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http://www.extron.com/technology/archive.asp?id=ts122001

How Pulse Width Modulation Works

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vo

http://users.ece.gatech.edu/~mleach/ece4435/f01/ClassD2.pdf

How a Triangle Output Oscillator Works (relaxation oscillator)

V1

-V1

vT

vo

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Output Stage

|H()|

-50V

+50V

VLVin

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Whole Class D amplifier

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feedback

Integrator and Input Circuitry

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Quantize and Gate Drive

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Output Section

Gate Driver

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Class D Amplifier Summary- Review Concepts

push-pull output (load line) (compare to CMOS output)diode limiterop amp integrator1 bit quantizer (comparator)protection logicpush-pull output (load line) (compare to CMOS output)low pass filter

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2. Example Micromechatronic System: Atomic Force Microscope

http://stm2.nrl.navy.mil/how-afm/how-afm.html

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http://stm2.nrl.navy.mil/how-afm/how-afm.html

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Target density: 1 terabit/sq. in.

Example Application: Atomic Force Microscopy/Data Storage

http://www.zurich.ibm.com/st/storage/millipede.html

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Example Application: Atomic Force Microscopy/Data Storage

Target density: 1 terabit/sq. in.

http://www.zurich.ibm.com/st/storage/millipede.html

thermal actuation/readout