JLH Class-A in a with MOSFET's

tschrama · 10th February 2002, 12:46 PM

JLH Class-A in a with MOSFET's

why?

It's weekend, just playing with my spice program, not build, no intention to build it, no MOSFET fan, no nothing, just maybe somebody gets inspired :-).

greetings,
Thijs

sonnya · 10th February 2002, 02:12 PM

How was the spice simulation on this circuit?

How is the DC and AC-response?

Sonny

tschrama · 10th February 2002, 03:05 PM

AC:
Low roll off
is set by the output cap at 20Hz

High roll off
at 800KHz nice gentle roll off, no peaks or instability .. but in real live this thing is propably not easly to get stable, that's why the second MOSFET isa set to draw 28mA, this help the cicuit to stay stable and gives it a high slew rate...a simple compensation cap also does the trick, but compromises HF responce

second harmonic at -86dB (0dB set at 1Watt output),higher harmonics are even lower...

Iq is set at 1.2A... so it is also a 35 Watt heating system

not bad he.....

tschrama · 10th February 2002, 03:23 PM

I just like playing with the computer so here another one.. a MOSFET 'MJamp'

all remarks above also apply to this one, simulated not build, not measured! But simulates even better! hopefuly somebody gets inspired and designs a pratical version or even builds one ...

these are no original designs.. all is based on designs found on the web, just tries to make them more simple, with simple components...

happy weeknend,
greetings,
thijs

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10th February 2002, 02:12 PM	#2
sonnya diyAudio Member Join Date: Oct 2001 Location: Denmark	How was the spice simulation on this circuit? How is the DC and AC-response? Sonny

10th February 2002, 03:05 PM	#3
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	AC: Low roll off is set by the output cap at 20Hz High roll off at 800KHz nice gentle roll off, no peaks or instability .. but in real live this thing is propably not easly to get stable, that's why the second MOSFET isa set to draw 28mA, this help the cicuit to stay stable and gives it a high slew rate...a simple compensation cap also does the trick, but compromises HF responce second harmonic at -86dB (0dB set at 1Watt output),higher harmonics are even lower... Iq is set at 1.2A... so it is also a 35 Watt heating system not bad he.....