However injection locking also works when the frequencies ratios
involved are rational numbers.
For 22MHz and 10MHz, the corresponding ratio is 11/5 a rational number.
For 42MHz and 10MHz, the frequency ratio is 21/5 a rational number
Bruce
Bruce Griffiths wrote:
To generate either 6MHz or 7MHz from 10MHz one can always use
something akin to a conjugate regenerative divider.
For 7Mhz this requires a mixer a 7MHz bandpass filter, a 3MHz bandpass
filter, a couple of power splitter/combiners, and a couple of amplifiers.
For 6Mhz this requires a mixer a 6MHz bandpass filter, a 4MHz bandpass
filter, a couple of power splitter/combiners, and a couple of amplifiers.
Bruce
francesco messineo wrote:
Hi Murray and all,
Yes, indeed injection locking looks very interesting, and I started
reading around. Seems relatively easy for 22 MHz, but not as easy for
42 MHz (good values should be 6 or 7 MHz, right?).
So far the practical circuit I've seen are few, and this would make me
lean in favour of
direct synthesys which indeed looks easy but forces me to abandon the
old oscillator
circuits.
In the next days I'll try simulating a few ideas with spice and then
decide.
First wild idea: how about making two CMOS gate xtal oscillators with
injection locking as you describe? I'd need 2 MHz (10 divided by five)
for the 22 MHz, but how practical would be obtaining the 6 or 7 MHz
from 10 MHz? It would need another oscillator locked....
Thanks
Frank IZ8DWF
On 2/2/10, Murray Greenman<[email protected]> wrote:
-----Original Message-----
From: Murray Greenman
Sent: Wednesday, 3 February 2010 9:00 a.m.
To: '[email protected]'
Subject: Injection locking
Frank,
Bruce's collection would be a good place to start. Thanks Bruce.
Most of
the examples relate to microwave applications, where often there
is no
alternative, but the approach works well on HF and VHF as well,
and more
importantly, can be achieved with existing oscillators with little
modification. The IL technique works with ratios from 20:1 to 1:20 or
more, and works well with the GPSDO as a reference.
My experience is mostly with locking HF crystal oscillators. It works
with overtone as well as fundamental oscillators. With an overtone
oscillator you can couple into the mode suppression choke. With a
tuned
tank Pierce oscillator you can couple into the output tank. With a
Colpitts, inject into the emitter, collector, or bottom of the
crystal.
I have made an excellent 10MHz CMOS gate oscillator with 2MHz
injection
into a varicap acting as one of the crystal load caps (output side).
Kit VK2LL and others have used 10MHz injection to lock the 20MHz
reference in common Icom HF transceivers.
Arguably the father of the Injection Locking technique would be Vasil
Uzunoglu, and I have some references for articles by him. The most
readable article is "Synchronous Oscillator outperforms the PLL"
(from
EDN 1999) http://www.edn.com/contents/images/46326.pdf. It shows
how to
emitter-lock a conventional Colpitts oscillator. The secret here
is to
get the bias correct. The test and measurement techniques he uses
are a
good way to assess performance. Robert Adler (inventor of the TV
remote!) also explored the IL technique.
See:
http://www.edn.com/contents/images/46326.pdf
US Patent 4,355,404 "Carrier Recovery Network for QPSK Modems
employing
Synchronized Oscillators", Uzunoglu 1982
US Patent 6,580,330 "Injection Locked Oscillator Automatic Frequency
Centering method and Apparatus", Katznelson& Petrovic 2003 (has a
good
list of background papers to read)
"A study of locking oscillators..." Proc IEEE R Adler 1973
http://ieeexplore.ieee.org/iel5/5/31361/31173/01451222.pdf
http://en.wikipedia.org/wiki/Injection_locking
http://www.amalgamate2000.com/radio-hobbies/radio/synchronous_oscillator
.htm
http://potol.eecs.berkeley.edu/~jr/research/PDFs/2009-01-ASPDAC-Bhansali
-Roychowdhury-GenAdler.pdf
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.130.2535&rep=re
p1&type=pdf
That should keep you busy for a while!
73,
Murray ZL1BPU
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