However annoying patents are, these things are always patented, and
have to be. These guys filed in 2009. Without patents it wouldn't
make sense to do all that work--make all that investment--only
to have it ripped off the nanosecond you ship.
The front end is a capacitive charge pump that charges many capacitors
and switches in series, then flips another set of switches to
discharge the caps in parallel, creating a raw output. A
synchronous buck efficiently regulates the rough voltage
thus created down to the desired output.
It runs the switches and caps at HV in series, so only low
voltage switches are needed. Ditto for the finishing regulator.
http://patft.uspto.gov/netacgi/nph-...50&s1=8212541.PN.&OS=PN/8212541&RS=PN/8212541
The main inventive notion here seems to have been getting the operations
within the range of fast, low-voltage elements.
I haven't looked at it in depth yet..time for Christmas!
Okay, I looked at it a little deeper.
I missed on a couple points.
First, the switched capacitor switches aren't low voltage. There
are only a few of them, so that doesn't fly. Also, when S1 of
Fig. 6 is open, one of the switches S2 has to stand off the entire
input voltage. Let's hope S2 never pops!
Second, I figured out the "energy recirculation" -- it's kind
of elegant. The charge pump efficiency is improved by charging
the series capacitor string *through the synchronous buck*.
That way, the series capacitor strings' peak charge current is
controlled, avoiding inrush charging losses. That's clever.
In effect, the buck runs off the switched-cap converter's ripple
voltage when the cap string is in series, and off the charge
pump caps in parallel during the paralleled time.
It also means you don't need nearly as many switched-cap stages
to get to the roughed output used to feed the sync. buck.
The VHF aspect is confined to the synch. buck finishing regulator.
Its low input voltage allows the use of fast, small geometry
devices.
There, I think that's the gist of it.
No galvanic isolation, which might be changed by substitution of
a suitable isolated "buck."
Cheers,
James Arthur