LTspice, class D power amplifiers.

This page has links for several Class D power amplifiers for operation on LTspice.
If we take the resonant power supply at the end of the SMPS section, and remove the output filter and output rectification we get a class D power amplifier.
The advantage of a class D power amplifier is efficiency, like an SMPS it can be more than 90% efficient, if used at lower frequencies of less than say 5Mhz.
Like a class C amplifier a class D amplifier is non linear however it can still be used for producing FM and AM with high efficiency.
The first circuits operate at fixed frequency, it is only in the later circuits that I have implemented FM and AM modulation.
As always simulation will not show all aspects of the performance of the real circuit.
There will be circuit parasitics which are not included in these simulations.

Reducing switching loss in a class D amplifier

comparson of results for class D power amps.

Class D power amps at fixed frequency with no modulation.

Using Silicon FETs and a 48V supply.

Using Silicon Carbide FETs and a 390V supply.

High V, Class D, silicon carbide FET, 1-84Mhz.

High V, Class D, silicon carbide FET, 7Mhz.

High V, Class D, silicon carbide FET, 14Mhz.

High V, Class D, silicon carbide FET, 28Mhz.

Using GaN FETs and a 390V supply.

A class D power amp, implementing FM modulation.

The frequency modylated RF signal is used to drive the power switches here.

A class D power amp, implementing AM modulation.

To use a class D amplifier to implement AM, the unmodulated RF frequency is used to drive the power switches (FETs), the Audio signal is modulated onto the power supply rail.
To start with we need to modulate the audio onto the power supply.

then we use this power supply to power a class D amplifier.

Class_D_power amp_with_AC_plus_DC_SMPS_for_AM.asc