Class D

Hello! Have not tried it, but the question is interesting.

Stop trying to divert that you were very anti GaN, and now pro just because it will be "the format" and suit your sales/profit modeling.
One thing you "may" not have factored, is going to be the ones at less than 1/2 the cost of yours, and better advanced from those bigger companies.Now GaN is even making a "big noise" into car poweramps now also.

The primary advantages of GaNFETs (compared to mosfets) are low on resistance and low input capacitance.  The low on resistance allows for higher efficiency, particularly into lower impedance loads. In car audio, available power is pretty limited so it stands to reason that these devices would be making inroads here. 

Saying they are not "faster" is only accurate if you take a very narrow view of "faster". When you look at equivalent RDSon/Vout, you would be hard pressed to find similar speed in silicon.  Big advantage is Qrr is 0, but effectively that is tied to speed as well allowing less dead-time. Lowfi does not know this.

Stop trying to divert that you were very anti GaN, and now pro just because it will be "the format" and suit your sales/profit modeling.

Actually you’re hard pressed to find me being ’anti GaN’; that statement is false. What is true is that I did not believe that they could work without heatsinks and it was your heckling that caused me to take a look.


Its true that for evaluation you don’t need heatsinks and most of our GaNFET prototypes didn’t use them. But in practice, ***they do in fact actually for real do need heatsinks*** which. again, was my original belief. Otherwise, you can expect them to blow right off the circuit board when subjected to low impedance loads at full power! Ask me how I know this :)

The primary advantages of GaNFETs (compared to mosfets) are low on resistance and low input capacitance.

The low input capacitance is a major deal! It makes the driver situation easier to manage. The lack of a body diode is the other issue. Between these two, that’s a good portion of why they are faster. These things interact with the choke in the output filter; GaNFETs won’t switch right if the filter isn’t there to give them a bit of an inductive kick to initiate the switch. Strange but true. We’re talking about something called ’inverse conduction’.


Allowing for less deadtime is of course important. But since both GaNFETs and MOSFETs are operated far below their maximum switching capacities I don’t see this as the big advantage; you can run MOSFETs at the same speeds we’re seeing now with very similar deadtimes. After embarking on this project at this point I think Technics is missing a bet by switching so fast. Deadtime is a constant and does not change with the switching frequency; so the faster you switch, the greater the percentage of the supposed ON time is taken up with deadtime, which increases distortion. Put another way, if Technics simply reduced their switching speed they could get lower distortion.