# CLASS D Amplifier Circuit Question

Joined May 12, 2016
4
Hello everyone

Ive been searching about class D amplifies.

What I know so far is that a class d amplifier is a switching amplifier.

There are three steps in creating a classe d amplifier.

1 - create PWM from signal.

2 - amplify output from PWM with switching transistors

3 - use a low pass filter.

The problem is that in step two, I have 2 transistors from Vcc to ground.
It seems that I need a delay circuit to prevent my circuit from having a short circuit from Vcc to ground(when both transistors would be conducting at the same time).
But i can't find a circuit like that to help me

This is the block diagram

#### wayneh

Joined Sep 9, 2010
17,152
Do you want to build one or just get one? You can buy them very inexpensively - cheaper than you can make one.

Have you searched for schematics for Class D amplifiers? You'll find hundreds. And yes, they all have to solve the "shoot through" problem.

Joined May 12, 2016
4
Do you want to build one or just get one? You can buy them very inexpensively - cheaper than you can make one.

Have you searched for schematics for Class D amplifiers? You'll find hundreds. And yes, they all have to solve the "shoot through" problem.
i want to build one on ltspice

#### #12

Joined Nov 30, 2010
18,219
i want to build one on ltspice
A little correction, please. You can't "build" anything with a simulator program. The best you can do is simulate a circuit.
Please don't say, "build" when you have no parts and no intention of connecting them together.
Say, "simulate". This will avoid misunderstanding.

#### ronv

Joined Nov 12, 2008
3,770
Hello everyone

Ive been searching about class D amplifies.

What I know so far is that a class d amplifier is a switching amplifier.

There are three steps in creating a classe d amplifier.

1 - create PWM from signal.

2 - amplify output from PWM with switching transistors

3 - use a low pass filter.

The problem is that in step two, I have 2 transistors from Vcc to ground.
It seems that I need a delay circuit to prevent my circuit from having a short circuit from Vcc to ground(when both transistors would be conducting at the same time).
But i can't find a circuit like that to help me

This is the block diagram
IR makes several with built in dead time. I have models for some of them.
http://www.irf.com/product-info/datasheets/data/ir2184.pdf

#### dannyf

Joined Sep 13, 2015
2,197
There are three steps in creating a classe d amplifier.
That's simply one of many ways to do a class D amp.

Simply put, you can view a class D amp as a power comparator + a low-pass filter.