Transcript Document 7294677

ELG4135 Electronics III Course Project
Low Cost, Low Power
Function Generator
By
Md Amirul Bhuiya
Norman Escobar
December 1, 2006
Introduction
►
What are Function Generators?
 Function Generators can produce Square, Triangular and Sinusoidal
waveforms over a wide range of frequencies and amplitudes as well as
modulated waveforms (AM, FM, FSK) and signal noise.
►
Why a Function Generator?
 Essential tool in Electrical Engineering
 Can be implemented with basic inexpensive components
 Most circuits needed have a direct relevance to the course
►
Project Objectives
 To build a low-cost Function Generator capable of:
►
►
►
►
Producing Square, Triangular and Sine waveforms with amplitude control
adjusting the waveform frequencies up to 1 MHz or higher
Producing a Sine wave with minimal THD (ideally under 1%).
The function generator should be low cost
Agenda
► In
this Presentation we will talk about:
 The Design
 Performance & Results
 Advantages & Disadvantages (Conclusion)
Design
► Block

Diagram
Voltage Controlled
Oscillator (VCO)

Level Detector

Sine Shaping Circuit

Output stage (Variable
Power Amplifier)
Voltage
Voltage
Controlled
Controlled
Oscillator
Oscillator
Level
Level
Detector
Detector
Amplifier
Amplifier
Stage
Stage
Sine Shaping
Sine Shaping
Circuit
Circuit
Functional Block I
Voltage Controlled Oscillator
Voltage
Controlled
Oscillator
Level
Detector
Sine Shaping
Circuit
Simplified Triangle Oscillator with single voltage detector
(Final VCO based on this circuit)
►
Wien Bridge Sine
Oscillator
►
Compensated Triangle
Oscillator Using LM6365
►
Triangle Oscillator with
double Detector Circuit
►
Crystal Oscillator
Amplifier
Stage
Functional Block I
Voltage Controlled Oscillator
Final VCO design
Functional Block II
Level Detector
Voltage
Controlled
Oscillator
Level
Detector
Sine Shaping
Circuit
Simplified Triangle Oscillator with single voltage detector
Final Selection
►
Wien Bridge Sine
Oscillator
►
Compensated Triangle
Oscillator Using LM6365
►
Triangle Oscillator with
double Detector Circuit
►
Crystal Oscillator
Amplifier
Stage
Functional Block III
Sine Shaping
Voltage
Controlled
Oscillator
►
Level
Detector
Overdriven CA3080
►
Breakpoint Sine Shaper
►
BJT non-linear amplifier
Amplifier
Stage
Sine Shaping
Circuit
Functional Block IV
Amplifier
Voltage
Controlled
Oscillator
►
Variable Inverting
Amplifier with Offset
Adjustment
Level
Detector
Amplifier
Stage
Sine Shaping
Circuit
Overall Circuit
Performance & Results
► Waveforms
Produced
 Triangular, Square and Sinusoidal
► Overall
Frequency Range: 4 Hz – 1.3 MHz
► Practical Frequency Range:




Triangle: 4 Hz to 500 kHz
Square: 4 Hz to 1.3 MHz & up
Sine: 30 kHz to 1.3 MHz & up (independent)
Sine: 30 kHz to 500 kHz (dependent)
Performance & Results
► Duty
Cycle Adjustment: 1% - 80%
► Amplitude Control: 0 V – 26 V p-p
► DC Offset Control: 0V - +/- 5 V
► THD of Sinewave:
 0.768 % at 500 kHz, 50% D.C.
 0.878 % at 10 kHz, 50% D.C.
 1.155 % at 1.0 MHz, 50% D.C.
Sine Shaper Frequency Response
(Standalone)
Sine Shaper Frequency Response
(Integrated)
Output Waveforms
Output Waveforms
(Frequency Modulated)
Conclusion
Practical Issues
► Advantages
Cost of components
is $106.30ofnot
 Produces
all the basicalone
requirements
a
includinggenerator
power source
function
Practical
frequencies
 Good
frequency
rangeof the function generator
are limited
to above
30 kHz for the sine wave
 Good
amplitude
range
and
below
500
kHz
for
the
triangle
wave
due
to
 Simple to design and build
the discharge control MOSFET which is too slow
 Expandable
to turn off for modulation
 Minimal
Circuit footprint
Output amplifier
induces overshooting on
square wave at higher frequencies
References
►
►
►
►
►
►
►
Adel S. Sedra and Kenneth C. Smith, Microelectronics Circuits. New York: Oxford
University Press, 2004.
Bernie Hutchins, Electronotes. “Contrasting sinewave generation in the analog
and digital cases”, http://www.synthtech.com/tutor/sine1.pdf.
National Semiconductor, Appl. Note 271, pp. 9.
John W. Fattaruso and Robert G. Meyer, “Triangle-to-Sine Wave Conversion with
MOS Technology,” IEEE Journal of Solid-State Circuits, vol. Sc-20, No. 2, April
1985.
Kim B. Östman, Sami T. Sipilä, Ivan S. Uzunov, and Nikolay T. Tchamov, “Novel
VCO Architecture Using Series Above-IC FBAR and Parallel LC Resonance,” IEEE
Journal of Solid-State Circuits, vol. 41, no. 10, October 2006.
eCircuit Centre, “Opamp Triangle-Wave Generator,” 2005,
http://www.ecircuitcenter.com/Circuits/op_tri_gen/op_tri_gen.htm
National Semiconductor, Appl. Note 263, (Sine Wave GenerationTechniques).
References
►
►
►
►
►
“Triangle to Sine Conversion (Nonlinear Function Fitting),” class notes by M. H.
Miller for ECE 414, College of Engineering and Computer Science, University of
Michigan-Dearborn, May 2004.
National Semiconductor, LM6165/LM6265/LM6365 High Speed Operational
Amplifier, pp. 9, May 1999.
Analog Applications Journal, Design of op amp sine wave oscillators, Texas
Instruments Incorporated, August 2000.
National Semiconductor, “Precise Tri-Wave Generation,” Linear Brief 23, March
1986.
MX.COM Inc, Appl. Note 20830065.001.
Thank You