TERMS EXPLAINED IN CLASS D AMPLIFIERS

Class D amplifiers are one most used and popular amplifier due to efficiency, theoretically class d amplifiers are 100 percent efficient. But this cannot be achieved practically as no device is 100 percent efficient. Though class d amplifiers reach more than 90% of efficiency if designed very carefully.

Understanding class d amplifiers are very much simple if you are familiar with the Switch mode power supply or commonly called SMPS or switching supply.

Input for the class d amplifier is first modulated either using Pulse Width Modulation ie PWM or sigma Delta modulates. Order of modulation starts generally from two and can reach as higher as 5 or even higher.

Class d amplifier can either be half bridged which requires dual power supply or full bridge and can be powers with single power supply. The problem with full bridge is that it requires more hardware or switching MOSFET which decrease its efficiency.

Another thing that make the class d amplifiers better is bridge tied load configuration or bridging multiple amplifiers so that its output power can be doubled. In bridge tied load configuration two half bridge amplifiers as bridged so that its output is doubled and the power for this configuration should be dual Power supply.

What is happening in class d amp is the modulated PWM is turning on and off the MOSFET bridge. during this MOSFETs ate switched on alternately. But if two of the MOSFETs on high side is turned on a pop sound can be created which may be very annoying. Also if there is delay between the next switching sequence the there might be dead sound between the sound.

CLASS D AMPLIFIER BASED ON SG3524 PWM IC #11

SG3524 is a PWM controller IC. This IC is normally used in power management , in buck or boost converters. Since class D audio amplifier is can be understood with the analogy of SMPS power supply, we can use the SG3524 as the PWM generator for the class D audio amplifier. The voltage level of the audio input to the circuit determines the instantaneous duty cycle of the output waveform whose frequency can be determined by the use of timing resistor and capacitor RT and CT. Then the low pass filter at out desired frequency cut off the high switching frequency typically 400 KHz .
Here's the link for its datasheet from Texas Instruments (http://www.ti.com.cn/cn/lit/ds/symlink/sg3524.pdf).

Mosfet can be driven by using the MOSFET driver using the dedicated IC driver like International Rectifier's IR2101 with both high side and low side drivers.
Here's the link on basic of class D amplifier(http://shortedwire.blogspot.com/2014/08/introduction-to-class-d-amplifier-4.html).
The dead generator is used in the circuit in order to avoid the turning on of the mosfet on  high side and low side at the same time of the same side of the bridge.
Sorry for the low q schematic.

Here some terms explained in the class d amplifier
http://shortedwire.blogspot.com/2015/07/terms-explained-in-class-d-amplifiers.html

CLASS D AMPLIFIER DESIGN BASED ON IR4301 #7

IR4301 is powerful IC with inbuilt power MOSFETS for the class D amplfliers.Many reference designs are available from International Rectifier also using various supplies and also with single supply and also with the dual power supply with both configuration of stereo mode and mono mode. IR4301 is a bit difficult to solder in home with home made PCB but a little effort will make is sound with whole lots of WATTS.

The filter is desingned for about cutoff frequency at around 30KHz and with the ouptut speaker of 4 watts..
With 18-0-18 transformer with 3 amps of current . We can get about 46 volts of output. This circuit can give output to 18*18/4 Watts of power with some lossed in circuit and also in mosfets.

Here's the IR4301 class d amp with single rail power supply .

With some shielded cable as signal source as input and output. This circuit works fine.

Check out the link is you are confused with the terms in class d amplier. 

http://shortedwire.blogspot.com/2015/07/terms-explained-in-class-d-amplifiers.html

INTRODUCTION TO #CLASS D AMPLIFIER #4

Class D amplifiers have theoretically 100 PERCENT of efficiency. Class D amplifiers are different than other types or class of amplifiers. They are different and we can compare the analogy of class d amplfiers with smps. Class D amplifiers can also be built using the smps controllers like UC3842 or SG3524 smps controllers and PWM generators..
Class D amplifiers first modulated the signal into the PWM and most of them uses sigma delta modulation techniques.
Most of the dedicated class d amplifiers like International Rectifiers' IRS2092 have their dedicated PWM modulator. They also have inbuilt High side And Low Side drivers for Mosfets.
Generally second order LC low pass filter is used for for filtering out the high frequency carrier frequency.
IR4301 is IC >100 watts and have inbuilt mosftest and only outside low pass frequency are required.
Similarly NXP TDA8950 of 340 watts of BTL (Bridge Tied Load)  configuration .

I will be posting circuit using SG3524 and IR4301 and TDA8950.