Implementation Function for Audio Amplifier with Its Applications
D.Banupriya1, G.Jananni Kalai Vani2, P.Muthu Lekshmi3, R.Kanitha4
1
Assistant 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
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.
A B S T R A C T
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
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
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. However the results reveal the need of a soft commutation
cell in order to avoid the energy dissipation due to the coupled inductors when the main switches are opened. On the
other hand the amplification of radio frequency signals requires a higher cutoff frequency and this can be achieved
the redefining the components L and C.
REFERENCES
[1] Proposal of audio amplifier- Demercil Souza Oliveira-Conference papers 2000 Comparative study of audio
amplifier-Jan Feb 2017
[2] J. Pakarinen and D. T. Yeh, “A review of digital techniques for modeling vacuum-tube guitar amplifiers,”
[3] T. H´elie, “Volterra series and state transformation for realtime simulations of audio circuits including saturations: application to the Moog ladder filter,” IEEE Transactions on Audio, Speech and Language
Processing, vol. 18, no. 4, pp. 747– 759, 2010.
[4] D. T. Yeh, J. S. Abel, A. Vladimirescu, and J. O. Smith, “Numerical methods for simulation of guitar distortion circuits,” Computer Music Journal, vol. 32, no. 2, pp. 23–42, 2008.
[5] M. N. Gallo, “Method and apparatus for distortion of audio signals and emulation of vacuum tube amplifiers,” US patent Application 2008/0218259 A1. Filed on March 2007, published on September
2008.
[6] J. Macak and J. Schimmel, “Nonlinear circuit simulation using time-variant filter,” in Proceedings of the
International Conference on Digital Audio Effects, Como, Italy, September 2009.
[7] D. T. Yeh, Digital implementation of musical distortion circuits by analysis and simulation, Ph.D. thesis,
Stanford University, Palo Alto, Calif, USA, 2009, https://ccrma.stanford.edu/
∼dtyeh/papers/DavidYehThesissinglesided.pdf.
[8] D. T. Yeh, J. S. Abel, and J. O. Smith, “Automated physical modeling of nonlinear audio circuits for
real-time audio effects - part I: theoretical development,” IEEE Transactions on
[9] Audio, Speech and Language Processing, vol. 18, no. 4, pp. 728– 737, 2010.
[10] M. Karjalainen and J. Pakarinen, “Wave digital simulation of a vacuum-tube amplifier,” in Proceedings of
IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP ’06), vol. 5, pp. 153–
156, Toulouse, France, 2006.
[11] G. De Sanctis and A. Sarti, “Virtual analog modeling in the wave-digital domain,” IEEE Transactions on
Audio, Speech and Language Processing, vol. 18, no. 4, pp. 715–727, 2010.
[12] J. Pakarinen, M. Tikander, and M. Karjalainen, “Wave digital modeling of the output chain of a
vacuum-tube amplifier,” in Proceedings of the 12th International Conference on Digital Audio Effects (DAFx ’09), Como, Italy, September 2009.
[13] J. Pakarinen and M. Karjalainen, “Enhanced wave digitaltriode model for real-time tube amplifier emulation,” IEEE Transactions on Audio, Speech and Language Processing, vol. 18, no. 4, pp. 738–746,