Here is a very simple MOSFET amplifier. I don't have the name for it. The output is similar to JLH output stage, but it can actually work in class B with MOSFET. Achieve good performance with relatively small number of parts. It also has the capability of almost rail to rail voltage swing, which is the weak point of most other MOSFET designs.
[EDIT] Added constant current source for the bias. Thus, the power rail fluctuation will not affect the bias.
[EDIT] Added constant current source for the bias. Thus, the power rail fluctuation will not affect the bias.
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Nice to see the bootstrap to get the voltage swing for the MOSFETs. How about idle current stability with temperature, have you simulated?
Here the bias Vgs is proportional to the supply voltage. If the power supply is not regulated, the bias should be stable.
In the case of regulated power supply, I suggest to add an extra pair of 0.22 sensing resistors to the source of mosfet.
In general, mosfet internal resistance rises along with the temperature. You can get away without source resistors.
That is at 10KHz. You can get near -80dB with 1KHz. It is about the same performance as the Blameless with EF2.
I would disagree, quite strongly. Below please see my take on the Blameless with EF2 an 2 pairs of output devices. THD vs, frequency at 150W/4ohm. It is not a toy, and it is the real thing measurement.
The results are important. The whole thing is simulated, but I do care about simulation as about a first essential step only. You guys need to build real amplifiers. Simulation is not everything.
https://pmacura.cz/DIY_250W_4ohm_amplifier.html
My final version.
Loop gain. As the output stage is included in the Miller compensation loop, don't worry about astronomical unit loop gain bandwidth. As you can see, even though, it is stable.
Loop gain. As the output stage is included in the Miller compensation loop, don't worry about astronomical unit loop gain bandwidth. As you can see, even though, it is stable.
Eisenport 1
I always find these simple structures very appealing.
A great idea jxdking - and it reminds me of the iron port design, which was completely experimental.
I always find these simple structures very appealing.
A great idea jxdking - and it reminds me of the iron port design, which was completely experimental.
Nice. Now it would be good to build a sample. That’s why we do it. Excuse me, I am a 70 years old old school guy, and the goal of this hobby for us was to build the amplifiers. Simulators do not make the speakers to sound, yet 😉. Yes they are an effective tool, but just the first step.
The distortion coming from the average MOSFET is hilarious high. Even bias it into class A, the THD number doesn't even budge -3dB. For class A, the JLH style BJT output stage might be better.
It might be the problem with my simulation software. However, the simulation of the Blameless topology is pretty accurate.
Maybe I should try the new Lateral type MOSFET.
It might be the problem with my simulation software. However, the simulation of the Blameless topology is pretty accurate.
Maybe I should try the new Lateral type MOSFET.
It is good to use error correction to reduce distortion of MOSFETs with high Vgs.
Is there a way to try to cancel this out, e.g. to drive it with something of the inverse distortion?
I see this sometimes mentioned in tube amps, perhaps there are a few methods to 'linearise' a device without using feedback?