Class D Amplifier design notes

I’m having trouble trying to design a Class D Amplifier. Does anyone have any tips on where I can start?

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I’m aiming to design a 4 NMOS H-Bridge switching configuration. I understand that I am going to need:

  • two half bridge gate drivers to driver the mosfets
  • a comparator stage to compare the audible and high frequency signal
  • low pass filter stage to filter the high frequencies.

A few design constraints of this amp includes:

  • 5W output
  • 42kHz switching frequency
  • 2kHz audible signal

amplifierfilterh-bridgemosfet-drivergate-drivingShareCiteEditFollowFlagasked 21 hours agoTurei1122 bronze badges New contributor

  • 2You seem to be on the right track. Question seems too broad. Please search the net or this SE to see similar circuits others have designed already. Please edit into the question, the sub-circuits you have already found the schematics and design for. Please visit the tour page if you have not already done so. – AJN 21 hours ago 
  • 1Try searching for UcD — “universal class D” (or nCore, but UcD is good enough for you to start with). Best put aside the classical theory when it comes to practise. – a concerned citizen 17 hours ago
  • 1You might want to look into sigma-delta self oscillating class D designs which I’ve found to be much “simpler” then the triangle wave + comparator method. – Unimportant 17 hours ago

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1 Answer


I would recommend to start with the following two tutorials.

The first tutorial is to understand the big picture, the classification of amplifiers. The second tutorial is to understand the principles, components required, and how to build the real thing.

(1) Amplifier Classes – Electronics Tutorials

(2) How to Build a Class-D Power Amp – Cezar Chirila, All About Circuits, 2018apr29

ShareCiteEditDeleteFlaganswered 21 hours agotlfong012,33111 gold badge77 silver badges1515 bronze badges

  • 1Thank you for those tutorials. I feel like my understanding on the Class D amplifier has grown more from them. – Turei 56 mins ago
  • @Turei, (1) I glad that you like those tutorials from ET and AAC. Actually I have carefully chosen them from many others not so educational to newbies. (2) Possible errata: the very last line of your question on constraints says “2kHz” audio frequency. I guess you mean “20kHz”. (3) The AAC tutorial uses N-channel power MOSFET IRF540N, which is OK but a bit too old. You might like to consider using its newer, logical level trigger replacement IRL540N. Have a great project. Cheers. – tlfong01 just now   Edit   

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