[Amps] worthwhile patents on RF amplifiers?

[Steve Thompson]

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