Asian Journal of Applied Science and Technology (AJAST) (Open Access Quarterly International Journal) Volume 2, Issue 1, Pages 334-338, 2018 Implementation Function for Audio Amplifier with Its Applications D.Banupriya1, G.Jananni Kalai Vani2, P.Muthu Lekshmi3, R.Kanitha4 1Assistant Professor, Department of Electronics and Communication Engineering, Sasurie Academy of Engineering, Coimbatore, India. 2,3,4Department of Electronics and Communication Engineering, Sasurie Academy of Engineering, Coimbatore, India Article Received: 27 November 2017 Article Accepted: 24 January 2018 Article Published: 30 March 2018 ABSTRACT An audio amplifier is an electronic device that increases the strength (amplitude) of audio signals that pass through it. An audio amplifier amplifies low-power audio signals to a level which is suitable for driving loudspeakers. The input signal of an audio amplifier may only measure a few hundred microwatts, but its output may be tens or even thousands of watts. Design parameters for audio amplifiers include gain, frequency response, distortion and noise. This paper presents a new audio amplifier that imposes voltage on the speakers. The audio amplifier topology is based on two current sources that modulate the desired frequency switches. The operation principle, control circuits, simulation and experiment results are presented. 1. INTRODUCTION An audio power amplifier (or power amp) is an electronic amplifier that reproduces low-power electronic audio signals such as the signal from radio receiver or electric guitar pickup at a level that is strong enough for driving (or powering) loudspeakers or headphones. This includes both amplifiers used in home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers and speaker enclosures. Sound is an energy or wave made by vibrations. When object vibrates, it causes flow in the air particles. These particles collided with each other which make them vibrate. This flow is called sound waves Amplification can be defined as the process of increasing the magnitude of a variable quantity, particularly the magnitude of a voltage and/ or current, without substantially altering any other quality. Audio power amplifiers are classified primarily by the design of the output stage. Classification based during each cycle of signal swing. The main operation classes are [1], [2]. CLASS A operation is where both devices are always on. Class A is the most inefficient of all power amplifier designs averaging around 20%. Because of this, class A amplifiers are large, heavy and run very hot. The positive effect of all this is that class A designs are inherently the most linear, with least amount of distortion. CLASS B is the opposite of class A. Both output devices are never allowed to be on at the same time. The each output devices is on for exactly one half of a complete sinusoidal signal cycle. Due to this operation, class B designs show high efficiency but poor linearity around the crossover region. CLASS AB operation allows both devices to be on at the same time, but just bravely. Only a small amount of current is allowed to flow through both devices unlike the complete load current of class A designs but enough to keep each devices operating so they respond instantly to input voltage demands. CLASS D operation is switching. The output devices are rapidly switched on and off at least for each cycle. This kind of amplifier is great for efficiency. The best application today for class D amplifiers is subwoofers. he power amplifier proposed could be classified as a class D amplifier due to its switching operation and high efficiency. An advantage of this amplifier is that phase shift and distortion are not present when the amplifier operates along frequency band for which it was designed. In the proposed amplifier the output voltage waveform is very close to the reference signal waveform, for all load range and only two frequency switches are employed. 334 | P a g e Online ISSN: 2456-883X Impact Factor: 1.805 Website: www.ajast.net Asian Journal of Applied Science and Technology (AJAST) (Open Access Quarterly International Journal) Volume 2, Issue 1, Pages 334-338, 2018 2. TOPOLOGY 2.1 CIRCIUT DESCRIPTION The proposed circuit consists of two high frequency switches, two coupled pairs of inductors one capacitor in which the voltage is imposed and two fast diodes. Fig: Audio Amplifier 2.2 PRINCIPLE OF OPERATION The following assumptions are made in order to simply the analysis. • The circuit operates in steady state. • All components are considered ideal. • All inductors are equal 2.3 FIRST STAGE During this stage S1 is turned on and S2 is turned off. The current source L1 loads the capacitor C. As the resonant frequency is much lower than the switching frequency. 2.4 SECOND STAGE During this stage S2 is turned on and S1 is turned off. The demagnetizing current of L1, flows through the coupled inductor. 3. CONTROL CIRCUIT Two different control straggles were implemented. The first one is the simply hysteresis control, the inverter operates only in two states, which means that the switches operate in a complementary manner. 335 | P a g e Online ISSN: 2456-883X Impact Factor: 1.805 Website: www.ajast.net Asian Journal of Applied Science and Technology (AJAST) (Open Access Quarterly International Journal) Volume 2, Issue 1, Pages 334-338, 2018 4. SIMULATION RESULTS 4.1 MAIN WAVEFORM In order to comprise the correct operation of the proposed circuit a simulation of the proposed converter was performed with the following parameters. Where RC is the load characteristics resistance. C 10µF L1=L2=Ld1=Ld2 1mH Vd1=Vd2 50V R c 8Ώ The reference signal expression is: X (t) =0.3sin (2π20t) +0.3sin (2π100t) +0.3sin (2π200t) 4.2 EXPERIMENTAL RESULTS In order to confirm the correct operations of the converter a prototype was implemented according to the following parameters, L1=L2=Ld1=Ld2=1mH C=5µF Initially the converter was used to amplify a sinusoidal reference signal with a resistive load. The structure measured efficiency for 650W was around 80%. For a better understanding of the converter behavior. Bode plots were drawn from experimental raw data. For the experiment, a reference sinusoidal signal of 2V amplitude was provided by the signal generator described above. A dc input voltage of 40V was supplied by the symmetrical sources, for a voltage gain of approximately 10. In this experiment the convertor operated with no load. From the Bode plot it is observed that the curve falls in a rate of approximately of 60dB/decade, characterizing a 3rd order system response. In order to verify the application as an audio amplifier a 4 Ohms system with three speakers was employed. The reference signal generated by a CD player and the waveform imposed to the speakers. Using the software Wave star version 1.2,2 from Tektronix the spectrum of the reference signal and the output waveform were generated. These figures illustrate only the harmonic content associated with the fundamental wave which presents a frequency of 1180Hz calculated by the software. It can be easily noticed that the frequency of the reference signal is smaller, calculated in 283 Hz. The harmonic distortion calculated for the input and output waveform is approximately 10%. For the waveform the THD was less than 1%. The difference between these values is easily explained by the Bode plot. 5. AUDIO AMPLIFIES IN FUTURE ELECTRONICS Future Electronics has a full selection of programmable audio amplifier chips from several manufacturers that can be used to design a home audio amplifier, mini audio amplifier, audio amplifier IC (integrated circuit), car audio 336 | P a g e Online ISSN: 2456-883X Impact Factor: 1.805 Website: www.ajast.net Asian Journal of Applied Science and Technology (AJAST) (Open Access Quarterly International Journal) Volume 2, Issue 1, Pages 334-338, 2018 amplifier, digital audio amplifier, inline audio amplifier, low power audio amplifier, PC audio amplifier, TV audio amplifier or stereo audio amplifier. Simply choose from the audio amplifier technical attributes below and your search results will quickly be narrowed to match your specific audio amplifier application needs. If you have a preferred brand, we deal with several manufacturers such as New Japan Radio, NXP, ON Semiconductor, STMicroelectronics or Wolfson Microelectronics, among other manufacturers. You can easily refine your audio amplifier product search results by clicking your preferred audio amplifier brand below from our list of manufacturers. 6. APPLICATIONS FOR AUDIO AMPLIFIERS 1. Applications for audio amplifiers include home audio systems, concert and theatrical sound reinforcement and public address systems. 2. The sound card in a personal computer, every stereo system and every home theatre system contains one or several audio amplifiers. 3. Other applications include instrument amplifiers such as guitar amplifiers, professional and amateur mobile radio and portable consumer products such as games and children’s toys. 4. Power amplifiers are available in standalone units, which are used by hi-fi audio enthusiasts and designers of public address systems (PA systems) and sound reinforcement systems. 5. Important applications include public address systems, theatrical and concert sound reinforcement systems, and domestic systems such as a stereo. Instrument amplifiers including guitar amplifiers and electric keyboard amplifiers also use audio power amplifiers. 7. CONCLUSIONS A new amplifier is presented which presents only two switches operating high frequency, two fast diodes and two pairs of coupled inductors. Two different control techniques were proposed and the double hysteresis control presented better performance because the circulating reactive power was reduced, contributing for the significant increase of efficiency, specially in higher power applications. Simulations and experimental results were presented which confirm the good performance of the invertors.