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 Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage Voltage Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage

Voltage Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage Functional Block I Voltage Controlled Oscillator ► Wien Bridge Sine Oscillator ► ► Compensated Triangle Oscillator Using LM6365 ► ► Triangle Oscillator with double Detector Circuit ► ► Crystal Oscillator Simplified Triangle Oscillator with single voltage detector (Final VCO based on this circuit)

Functional Block I Voltage Controlled Oscillator Final VCO design

Voltage Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage Functional Block II Level Detector ► Wien Bridge Sine Oscillator ► ► Compensated Triangle Oscillator Using LM6365 ► ► Triangle Oscillator with double Detector Circuit ► ► Crystal Oscillator Simplified Triangle Oscillator with single voltage detector Final Selection

Voltage Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage Functional Block III Sine Shaping ► ► Overdriven CA3080 ► ► Breakpoint Sine Shaper ► ► BJT non-linear amplifier

Voltage Controlled Oscillator Level Detector Sine Shaping Circuit Amplifier Stage Functional Block IV Amplifier ► ► Variable Inverting Amplifier with Offset Adjustment

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:  % at 500 kHz, 50% D.C.  % at 10 kHz, 50% D.C.  % at 1.0 MHz, 50% D.C.

Sine Shaper Frequency Response (Standalone)

Sine Shaper Frequency Response (Integrated)

Output Waveforms

Output Waveforms (Frequency Modulated)

► Practical Issues  Cost of components alone is $ not including power source  Practical frequencies of the function generator are limited to above 30 kHz for the sine wave and below 500 kHz for the triangle wave due to the discharge control MOSFET which is too slow to turn off  Output amplifier induces overshooting on square wave at higher frequencies ► Advantages  Produces all the basic requirements of a function generator  Good frequency range  Good amplitude range  Simple to design and build  Expandable for modulation  Minimal Circuit footprint Conclusion

References ► Adel S. Sedra and Kenneth C. Smith, Microelectronics Circuits. New York: Oxford University Press, ► Bernie Hutchins, Electronotes. “Contrasting sinewave generation in the analog and digital cases”, ► National Semiconductor, Appl. Note 271, pp. 9. ► John W. Fattaruso and Robert G. Meyer, “Triangle-to-Sine Wave Conversion with MOS Technology,” ► 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 ► ► 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 ►,” 2005, ► eCircuit Centre, “Opamp Triangle-Wave Generator,” 2005, ► ► 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 ► National Semiconductor, ► National Semiconductor, LM6165/LM6265/LM6365 High Speed Operational Amplifier, pp. 9, May ► ► Analog Applications Journal, Design of op amp sine wave oscillators, Texas Instruments Incorporated, August ► ► National Semiconductor, “Precise Tri-Wave Generation,” Linear Brief 23, March ► ► MX.COM Inc, Appl. Note

Thank You