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I am doing a sound amplifier using LTspice and I would like to know if someone know why my gate driver output has spikes only when it is connected to the half-bridge circuit.

enter image description here

The INP terminal is receiving a sine PWM signal from a comparator on the high-side driver and an inverted one on the low-side driver.

High-side driver output (without connecting it to a half-bridge):

High-side driver output (with a half bridge connected to it): enter image description here

Those spikes are also happening on the low-side driver. Btw, it is not affecting the entire circuit, but I would like to know how to make those spikes disappear. Any suggestions?

Hiei1
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  • Those are usually signs of cross-conduction. Without showing the rest of the schematic, it's impossible to tell. Check your sources, plot only the waveforms they generate and see that the `tr` and `tf` do not interfere with each other. – a concerned citizen Mar 05 '21 at 16:34
  • If you're asking why the spikes appear in the simulation, it is because it is modelling the parasitics of the MOSFETs. If you build the circuit, it should look similar. – rdtsc Mar 05 '21 at 17:09
  • I just added the right-hand part circuit. The gate driver inputs are coming from a comparator, which compares a sinusoidal signal to a triangle signal, making a sine PWM signal – Hiei1 Mar 05 '21 at 17:47
  • @rdtsc Do you have an idea on how to block those spikes? – Hiei1 Mar 05 '21 at 17:54
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    @Hiei1 Do you have any sort of dead-time? Try adding series resistors to the gates, 10 Ohms or so. Also, add some labels to the nodes (press `F4`), nobody can tell where those `N00x` nodes are. – a concerned citizen Mar 05 '21 at 17:55
  • @aconcernedcitizen not yet. Just added a resistor and the spikes have decreased a little but not everything. Do you know how can I add dead-time without changing the sources? – Hiei1 Mar 05 '21 at 18:01
  • @Hiei1 Try something [similar](https://electronics.stackexchange.com/q/372155/95619). But if you intend to build this amplifier, you will need more than simply placing those ICs and hoping it will work *well*. Unless you have very large (relative) dead-time, you will get some sort of cross-conduction, you will need [proper gate drivers](https://www.ti.com/seclit/ml/slup306/slup306.pdf), snubbers, protections, and those LC values are too high (don't forget the speakers will also attenuate since they'll be woofers, it seems). You may need to know a bit more, it's not quite as simple. – a concerned citizen Mar 05 '21 at 18:25
  • @aconcernedcitizen Cheers mate. Already doing research, thank you very much for the guidance. – Hiei1 Mar 05 '21 at 18:46

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