Not really, Jim...unless you mean something special by "nonlinear
multipliers" like diodes/varactors which I suspect fall under your comment.
In the two-way radios of the 60's & early 80's before synthesizers, I
designed many a single stage multiplier of 2x or 3x, which were preferred
and sometimes 4x. They worked very well...using cap input coupling, to keep
the base Z low at the harmonics and keeping the conduction angle optimized
for output level. Also, the adjacent harmonics are easier to filter than
higher orders of multiplication (when that is a factor. Only a single
resonant circuit was required between stages.
The bottom line depends upon the spurious requirements. Then there are
always preferences for what we may have used in the past - and what the
application actually is.
Starting with a spectral comb(like a square wave or other pulse-type
waveform) and picking off the desired harmonic can also be very effective,
but again, it depends upon the specific application.
I did a synthesizer mixer with no tuned circuits to get from 40 MHz
crystal oscillator to 220MHz to mix down a VCO to an IF for the programmable
divider. Was really sweet! Did the same for what I believe was the very
first synthesized 2M hand held in 1973. A Motorola HT220. Even had the
Transmit VCO _ON_ yes _ON_ the TX frequency. Total current drain was 7ma.
Tx spurious (-70dBc) better than the original (-35-40dB) Still have it.

--
Steve N, K,9;d, c. i My email has no u's.

"Jim Thompson" wrote in message
...
On Mon, 16 Feb 2004 00:18:49 GMT, "W3JDR" wrote:

I think it boils down to something very practical:
...It becomes a matter of how close and how large the
undesired spectral components are compared to the desired spectral
components. ...
As an example, a x4 multiplier stage will have a desired output at Fin x
4,
and close-in undesired products at Fin x 3 and Fin x 5. ...
Joe, W3JDR

[snip]

I would think a "W3JDR" would know that even harmonics are *much*
harder to obtain in nonlinear multipliers.

...Jim Thompson

Not really, Jim...unless you mean something special by "nonlinear
multipliers" like diodes/varactors which I suspect fall under your comment.
In the two-way radios of the 60's & early 80's before synthesizers, I
designed many a single stage multiplier of 2x or 3x, which were preferred
and sometimes 4x. They worked very well...using cap input coupling, to keep
the base Z low at the harmonics and keeping the conduction angle optimized
for output level. Also, the adjacent harmonics are easier to filter than
higher orders of multiplication (when that is a factor. Only a single
resonant circuit was required between stages.
The bottom line depends upon the spurious requirements. Then there are
always preferences for what we may have used in the past - and what the
application actually is.
Starting with a spectral comb(like a square wave or other pulse-type
waveform) and picking off the desired harmonic can also be very effective,
but again, it depends upon the specific application.
I did a synthesizer mixer with no tuned circuits to get from 40 MHz
crystal oscillator to 220MHz to mix down a VCO to an IF for the programmable
divider. Was really sweet! Did the same for what I believe was the very
first synthesized 2M hand held in 1973. A Motorola HT220. Even had the
Transmit VCO _ON_ yes _ON_ the TX frequency. Total current drain was 7ma.
Tx spurious (-70dBc) better than the original (-35-40dB) Still have it.

--
Steve N, K,9;d, c. i My email has no u's.

"Jim Thompson" wrote in message
...
On Mon, 16 Feb 2004 00:18:49 GMT, "W3JDR" wrote:

I think it boils down to something very practical:
...It becomes a matter of how close and how large the
undesired spectral components are compared to the desired spectral
components. ...
As an example, a x4 multiplier stage will have a desired output at Fin x
4,
and close-in undesired products at Fin x 3 and Fin x 5. ...
Joe, W3JDR

[snip]

I would think a "W3JDR" would know that even harmonics are *much*
harder to obtain in nonlinear multipliers.

...Jim Thompson

On Mon, 16 Feb 2004 00:18:49 GMT, "W3JDR" wrote:

I think it boils down to something very practical:

If you want good spectral purity, then you need to bandpass filter the
output of the multiplier. It becomes a matter of how close and how large the
undesired spectral components are compared to the desired spectral
components. After that, you can consult your filter design charts to
determine how complex a filter will be required and whether it's physically
realizable.

As an example, a x4 multiplier stage will have a desired output at Fin x 4,
and close-in undesired products at Fin x 3 and Fin x 5. This means the
output bandpass filter has to be able to attenuate signals at +/-25% of the
center frequency sufficiently to meet the desired spectral purity. In
practice with simple single-ended multiplier designs, a x4 multiplier is
approaching the threshold of realizability for high purity applications
(40-60 dB purity). It is possible to make push-pull and push-push
multipliers that have better output purity, but these techniques are seldom
used.

Joe
W3JDR


[snip]

I would think a "W3JDR" would know that even harmonics are *much*
harder to obtain in nonlinear multipliers.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

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?
--

The BBC: Licensed at public expense to spread lies.

See my previous post. What is your application? That would help get better
advise.

--
Steve N, K,9;d, c. i My email has no u's.

"Paul Burridge" wrote in message
...
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?
--

The BBC: Licensed at public expense to spread lies.

See my previous post. What is your application? That would help get better
advise.

--
Steve N, K,9;d, c. i My email has no u's.

"Paul Burridge" wrote in message
...
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?
--

The BBC: Licensed at public expense to spread lies.

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

On Wed, 18 Feb 2004 10:05:58 GMT, Active8
,invalid wrote:


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.

Fourier? I wouldn't trust it. Sounds French. :-

--

The BBC: Licensed at public expense to spread lies.

On Wed, 18 Feb 2004 11:51:42 +0000,
said...
On Wed, 18 Feb 2004 10:05:58 GMT, Active8
,invalid wrote:


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.

Fourier? I wouldn't trust it. Sounds French. :-


Then do a wavelet.
--
Best Regards,
Mike

On Wed, 18 Feb 2004 11:51:42 +0000,
said...
On Wed, 18 Feb 2004 10:05:58 GMT, Active8
,invalid wrote:


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.

Fourier? I wouldn't trust it. Sounds French. :-


Then do a wavelet.
--
Best Regards,
Mike