[Amps] worthwhile patents on RF amplifiers?

[Steve]

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