My Summer Project A Class D amp YAY! >_>

Thread Starter


Joined Nov 9, 2018
I will preface this as I'm a college ECE senior trying to design a class D power amp. last semester we built a full bridge power inverter and I noticed the topology of the circuits was near identical. I'm going to build a tube pre-amp and turn this puppy in to a 50W hybrid amp for my guitar (Eventually a 100W one for Bass). But right now I want to get the power section down.

I have a question about my efficiency. You'll see from my simulated wave forms that if I look at the AVG power out / AVG power in I have an efficiency of ~98%.
Normally, I'd be super excited about this, but from experience and knowing how dumb I am, realistically the efficiency should be at around 70-80%, like with my power inverter from last semester. Also all of those spikes past a kW make me suspicious. I was wondering if there were any professional engineers on the forum that could tell me a better way on how to measure this efficiency using LtSPICE.
Any Help will be greatly appreciated.