ELG 4135 Electronics III Course Project Low Cost

ELG 4135 Electronics III Course Project Low Cost, Low Power Function Generator By Md Amirul Bhuiya Norman Escobar December 1, 2006

Introduction ► What are Function Generators? ► Why a Function Generator? ► Project Objectives § Function Generators can produce Square, Triangular and Sinusoidal waveforms over a wide range of frequencies and amplitudes as well as modulated waveforms (AM, FSK) and signal noise. § Essential tool in Electrical Engineering § Can be implemented with basic inexpensive components § Most circuits needed have a direct relevance to the course § 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 Amplifier Stage Sine Shaping Circuit

Functional Block I 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 LM 6365 ► 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 LM 6365 ► Triangle Oscillator with double Detector Circuit ► Crystal Oscillator Amplifier Stage

Functional Block III Sine Shaping Voltage Controlled Oscillator ► Level Detector Overdriven CA 3080 ► 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 k. Hz § Square: 4 Hz to 1. 3 MHz & up § Sine: 30 k. Hz to 1. 3 MHz & up (independent) § Sine: 30 k. Hz to 500 k. Hz (dependent)

Performance & Results ► Duty Cycle Adjustment: 1% - 80% ► Amplitude Control: 0 V – 26 V p-p ► DC Offset Control: 0 V - +/- 5 V ► THD of Sinewave: § 0. 768 % at 500 k. Hz, 50% D. C. § 0. 878 % at 10 k. Hz, 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. 30 ofnot §§ Produces all the basicalone requirements a includinggenerator power source function § Good Practical frequencies frequency rangeof the function generator are limited to above 30 k. Hz for the sine wave § Good amplitude range and below 500 k. Hz 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/sine 1. 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. e. Circuit Centre, “Opamp Triangle-Wave Generator, ” 2005, http: //www. ecircuitcenter. com/Circuits/op_tri_gen. htm National Semiconductor, Appl. Note 263, (Sine Wave Generation. Techniques).

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, LM 6165/LM 6265/LM 6365 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.

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