Thank you for uploading the schematic.
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I don't know exactly what was the "distortion" you saw.? There are spikes on the waveforms at either end of the resistor.? Those spikes mostly disappear when you plot the differential voltage across the resistor.? By "distortion", did you mean the spikes?
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Those spikes mostly happen because of the capacitance internal to the MOSFETs.? The voltage waveform at each MOSFET's gate is a square-ish wave with fast (1 ns) edges.? That dv/dt (10 V/ns) couples through the gate-to-source or gate-to-drain capacitance to the output pins, nets N004 and N005, that are at either end of the load resistor.? If you zoom-in on just the rising edge of V(N004) (the waveform at the left end of R1), and also plot the gate voltage (V(N006)) at M2, you can see that the fast falling edge at the gate couples to the output pin, making it momentarily fall to -0.9 V.? Then it plateaus at around -0.4 V, for half a microsecond.? That is when M2 is switched OFF but M1 is not switched ON yet.? Neither FET actively drives during that nanosecond so the voltage floats at around -0.4 V because of the capacitance there.
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Half a microsecond later, M1 suddenly switches ON, and V(N004) suddenly rises to +5 V but it overshoots to +5.7 V because of the gate-to-source capacitance in M4.? Then it levels off at +5.0 V.
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I think there is dead time already in your gate drive signals when neither FET is ON, for about half a microsecond.
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The SPICE "PULSE" sources can be slightly challenging to figure out.? Yours are set up for:
- 1ns when the voltage rises from 0V to 10V
- 24.5us when the voltage sits at 10V
- 1ns when the voltage falls from 10V to 0V
- 50u-24.5u-1u-1u = 23.5us when the voltage sits at 0V
So it is not quite a "square" wave because it spends slightly more time at +10V than it does at 0V.? Most first-time SPICE users forget to take into account the rise and fall times.? The "on" time, Ton, is the time when the waveform is at 100%, not the time it is >50%.
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There is no "standard" delay time to use for dead time.? How much you need depends on the MOSFETs and exactly how they are driven.? Use trial-and-error to see what works best.
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In LTspice, it is best to add labels (netnames or nodenames) to every signal you might want to plot.? If you don't label a net, and plot it, and then change something in the circuit, the plotted netname might change to a different point in the circuit, and now it is plotting the wrong signal.? Adding your own labels avoids that.? But also remember that nets should have no more than one netname.
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Andy
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