800W Power Amplifier MOSFET

Amplifier

    In this blog we talk about audio amplifiers and I would like to get more detail information about them. An audio power amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain. 

     If we talk about the history of amplifiers, we can say, the audio amplifier was invented in 1909 by Lee De Forest when he invented the triode vacuum tube. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio. Early audio power amplifiers were based on vacuum tubes (also known as valves), and some of these achieved notably high quality (e.g., theWilliamson amplifier of 1947-9). Most modern audio amplifiers are based on solid state devices (transistors such as BJTs, FETs andMOSFETs), but there are still some who prefer tube-based amplifiers, and the valve sound. Audio power amplifiers based on transistors became practical with the wide availability of inexpensive transistors in the late 1960s.

    So, an electronic amplifier, or shortened amp is an electronic device that increases the power of a signal. So if you have a sound from a device and want the sound to be amplified, the amplifier is the device that can help you do this. Numerous types of electronic amplifiers are specialized to various applications. An amplifier can refer to anything from an electrical circuit that uses a single active component, to a complete system such as a packaged audio hi-fi amplifier. 

    Amplifier that any device is characterized by different specifications which actually should be taken when it is designed in consideration of them, and here are some highlights:

Noise

andwidth, 

Gain, 

Efficiency, 

Linearity, 

Output dynamic range, 

Rise time, settling time, ringing and over shoot that characterize the step response

Generic Amplifier

100W Bipolar Power Amplfier

Circuit Description:

This is a plain 100 watt power amplifier designed to subsist (relatively) tranquil to build next to a reasonable fee. It has a better performance (read: musical quality) than the standard STK module amps with the intention of are used in the sphere of almost all throng advertise stereo receiver manufactured at the moment. at what time I originally built this contraption, it was since I considered necessary a 100 WPC amp and resolve not fancy slightly money. The design is essentially a standard format, and I’m positively present are business entities with the purpose of are alike. To my knowlwdge, it is not an exact emulate of a commercial entity, nor am I aware of one patents on topology. on behalf of practiced builders: I am aware to many improvements and adjustments can come to pass made, but the theory was to keep it straightforward and have to achieve-able by anybody who is a circuit, and has not the patience to do a sloppy mission.

If alone crave Bipolar Transistor power amplifier circuit. , clothed in fashion HIFI OCL 100W RMS. I think this track ought to ensue an remarkable array, this circuit is the get through of the fundamental transistor BD317 and BD318 save transistor digit BD139, BD140, BC556 too comfortable in that case try to procure after the 35V power source with simply then build is not complex on behalf of other details in the same way as the answer of a only some appreciate Circuit. Input stage is a BC556 transistor, which largely of the sincere ring benefit, and on the placid DC voltage stabilizes. This feeds a level remove stage wherever the voltage swing to (-) track references. The Transconductance stage is a Darlington, recover frerqency high-level linearity. The BD317, 318 on a instead great radio dish-heart volume is dependent on voltage. The BD319 presents this low-z and has a C (ob) of merely a hardly any of PF, which is effectively swamped by the pole-splitting 220pF cap. The commotion is supplied by BC546 in force load (current), which is approximately 20 mA. The current, until the BC556 is inadequate to approximately 70 mA taking part in the most awful belongings.

Circuit Diagram:

Analog circuit

Analog circuit is a electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two different levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that represents the signal. The word analogue is derived from the Greek word ανάλογος (analogos) meaning "proportional".

Electronic circuit

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another. Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as silicon or gallium arsenide. Article: ww.wikipedia.org

Circuit

Type of electrical engineering circuit

• Electronic circuit, active electronic components connected in a circuit
• Analog circuit 
• Mixed-signal integrated circuit
• Digital circuit
• Synchronous circuit
• Printed circuit board (PCB)
• Series and parallel circuits
• Telecommunication circuit
• Circuit diagram
• Balanced circuit
• Integrated circuit
• Asynchronous circuit 
• LC circuit

...

10W Class D power amplifier

The TDA7480 is a class D audio amplifier assembled in Power DIP (PDIP20) package, specially designed for high efficiency applications, capable of 10W output power at a load of 8w/4w and a total harmonic distorsion of 10%. Requires a split-supply (max. ±20V).

The main selling point of this amplifier is the very low dissipated power compared to normal class AB amplifiers. Only a small "on board" copper area heatsink is required for normal operation. The IC has built-in stand-by and mute feature, overvoltage protection, short circuit protection and thermal overload protection.


The output of the amplifier is a high frequency square wave (~100Khz), rail to rail, with variable duty cycle. To obtain the audio signal, the output must be low pass filtered. The preamplifier provides the voltage gain of the overall amplifier. The second stage is the class D power stage, with a gain 1.5. The class D amplifier stage is done with a multivibrator. With no signal it generates a 50% duty cycle square wave, with signal applied, it changes the duty cycle. The switching frequency is set by the voltage on pin 9.

The most important filter capacitor is C5 between the pins 16 and 17. The value of the parasitic inductance between this capacitance and the IC pins is related to the amplitude of the spikes on the power supply pins at every commutations of the output. For any commutation, there is an abrupt variation of the current in the parasitic inductances in series to the supply. This abrupt variation increases as the output current increases and can be typically of a few amperes on 10ns. With this slew rate of the current, an inductance of a few nH (i.e. the lead inductance of the pin) generates voltage spikes in order of volts. These spikes can cause distortion / offset increase due to the non linear coupling on the internal elementary devices in the signal circuit, overvoltage on the IC, strong noise on the logic signals inside the chip causing incertain logic levels, dangerous for the IC. To avoid these spikes, it is mandatory to put a quality bypass capacitor at a distance lower than 5mm from the pins.

The capacitor C8 on pin 9 must be a low inductance type and should be placed close to the IC. The voltage on this pin sets the switching frequency. The purpose of C8 is to filter the high frequency noise from entering the IC as it could generate distortion/offset.

C4 on pin 8 sets the bandwidth of the class D amplifier. It is important that the reference ground of this capacitor is as near as possible to the IC signal ground.

C3 on pin 11 filters the high frequency noise that can enter in the input and that can cause intermodulation aliasing noise at the output. No signal at frequency greater than half of the switching frequency can enter in the IC without generating aliasing noise.

The electrolitic capacitors must have a good ESR, ESL at switching frequency (around 100Khz) and a sufficient maximum operating voltage.

The low pass filter placed after the switching stage is dimensioned to eliminate the high frequency PWM waves and to feed the audio signal to the loudspeaker. The losses in the filter capacitor C14 due to the ESR will be neglegible if multilayer film capacitors are used.Multilayer Mylar, Polypropilen or Policarbonate film capacitors are recomended, avoid using ceramic capacitors.

The losses in the inductor L1 at low frequencies are mainly due to the coil winding series resistance. At higher frequencies, where the Skin Effect becomes of importance, a multiwire winding could be effective to obtain the maximum in terms of efficiency. However, for most of the applications the use of a single wire winding with adequate cross section is enough. The inductor used for the filter must sustain a DC current greater than the specified current limitation value without saturation and the coil material must show very low hysteresis losses.