The first patent number didn't bring anything up for me, so I searched
for Mr Dishop, who appears to be president of Dishtronix who, I think,
own TenTec and Emtron. Several amplifier patents come up, including
8130039 which describes amplifiers along the lines of what you mention.
The only vaguely unusual feature I notice is that the amplifier
subcircuits operate at something other than 50ohms in and/or out which
can simplify the combining. It's hardly novel.
I yet haven't gathered the enthusiam to wade through the flimflam on the
second one.
Steve
I was looking through some recent solid state RF amplifier patents,
and 2 stood out for comment here. You may be able to view these or at
least the cover sheet and abstracts with online free patent viewers
now that you have these numbers:
US0285168 was awarded by the USPO around Dec. of 2007, invented by
Steven Dishop of Bellefontaine, OH. The address is given Pearce and
Gordon LLP in Cleveland. In it claims are made for a solid state
module that has push pull MOSFETs operating at least 200 watts and 50
volts. An input and output transformer or balun is used to convert
single ended to balanced for the transistors and match (1:4 on
output). Then there is a claim for a four FET similar amplifier where
a pair of FETs are operated in push pull, with drains tied together,
and these are then operated push pull with another similar par,
driven out of phase with the first. This one is 400 watts. I don't
understand what is unique about any of this, and have seen similar
amplifier constructions for decades. How can this patent hold valid?
The second one, US5187580, assigned to Advanced Energy Industries in
Ft Collins (a real RF company, BTW) was awarded in Feb. of 1993. In
this one the inventors suggest making a single ended MOSFET class E
amplifier that works better without a shunt capacitor across D to S
of the output device. They claim that the varactor capacitance of the
Cds alone is sufficient, even better, and that the larger devices can
be made to work at higher power and frequencies this way.
Multi-kilowatts and 65 MHz. Normally in class E the voltage at the
device is forced to zero before it switches, in this one it switches
with substantial voltage across it, even suggests this is better. I
don't see mention of improved efficiency with this technique, just
very high power availability. Something bothersome is the claim that
it must operate in a different class than A, B, AB, C, D, E, F...but
no real math or proof of anything other than a suboptimal class E.
Its the first RF amplifier patent I have seen where the invention is
of a strange performance without sufficient explanation. Maybe I am
being stupid and should just take these at face value? One has to
wonder if their wattmeters were tricked, or harmonics were excessive,
or whatever. None of this is described.
Solid state RF amplifier experts, chime in!
73 John
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