RadioBanter - View Single Post

February 18th 04, 11:05 AM

On Mon, 16 Feb 2004 11:53:11 +0000,
said...
On Sun, 15 Feb 2004 16:46:32 -0700, Jim Thompson
wrote:

On Sun, 15 Feb 2004 23:48:47 +0000, Paul Burridge
wrote:

What's the maximum multiplication factor it's practical and sensible
to attempt to achieve in one single stage of multiplication? (Say from
a 7Mhz square wave source with 5nS rise/fall times.)

You ought to be able to answer that yourself... what's the spectral
roll-off of a square wave ??

I suppose it boils down to how much signal is left in the mush as the
harmonics get higher and higher. Knew I shoulda held on to that
spectrum analyser I used to have. :-(
I suppose that's the proper answer though: get the rise/fall times as
small and possible, measure the specral output and pick a suitable
harmonic with enough energy in it to set it 'comfortably' above the
noise floor?

Gee. I could have sworn Jim was hinting at the math approach.
Wouldn'tcha just love to predict that roll-off on paper and *then*
see it in real life? Starts with an "F", looks like a number,
sounds like a frog.

--
Best Regards,
Mike