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Help needed in senior project! ..... Analog Frequency Divider or Multiplier.......

W

Wicked

Jan 1, 1970
0
Hello:

I need help! We are making an FSK system and I am looking for a
circuit that can divide or multiply a signal coming from the
ossiclator......any books? websites? anything would help!
Thanks
-Shawn
 
W

Wicked

Jan 1, 1970
0
Here is what we are doing in for detail:



I am have a hard time find a multiplier circuit. I was thinking about
using the AD834JN. Are there any better options?

We are building an FSK system. What want to feed the signal from the
oscillator into the "chip" to generate another signal in phase but at
a differnt frequency. I have looked at the data sheet ...but I cant
find a clear circuit that I can use.

Our input is going to be sine wave 5v p-p 30Khz
 
J

John Woodgate

Jan 1, 1970
0
(in <[email protected]>) about 'Help
needed in senior project! ..... Analog Frequency Divider or
Multiplier.......', on Sat, 7 Feb 2004:
feed the signal from the
oscillator into the "chip" to generate another signal in phase but at a
differnt frequency.

That is impossible: the phase angle between two different frequencies is
continuously varying.
 
K

Ken Taylor

Jan 1, 1970
0
Wicked said:
Here is what we are doing in for detail:



I am have a hard time find a multiplier circuit. I was thinking about
using the AD834JN. Are there any better options?

We are building an FSK system. What want to feed the signal from the
oscillator into the "chip" to generate another signal in phase but at
a differnt frequency. I have looked at the data sheet ...but I cant
find a clear circuit that I can use.

Our input is going to be sine wave 5v p-p 30Khz

Maybe I'm misunderstanding you, but I think what you want is a phase-locked
loop. Take a peek at
http://www.lecroy.com/tm/library/LABs/LAB1007/default.asp
and see if that fits, then go a-hunting. The AD834 doesn't do what I think
you want.

Ken
 
J

Jamie

Jan 1, 1970
0
i can think of a simple and dirty way.
use a transformer that will pass the 30khz into
the primary side.
the secondary side will have a center tapped passing to
ground.
the outer taps will pass through a common Full wave detector
using germanium diodes with a slight + current on them from a
center tap pot to give them a little forward current to help
prevent cut off..
the Full wave detector will have double peaks , you connect a
series cap to a shut resistor and you have your doubler
--
the same above can be done with 50 ohm resisters in series
with the diodes with one of them being a trim pot to balance diodes.
the 2 cathodes come to gather into an inductive load so that you can
get your minus side. i like the forward current and series cap my self.
it gets the diodes out of cut off and allows current for reverse
charge of cap.
it may not soiled technical but i try to keep it simple so that idea can
be placed in your head easily..
 
W

Wicked

Jan 1, 1970
0
How about the chip AD539 ? would that work in this application. I
looked at the PPL link (above) but the input to that was a digital
square wave...I am looking the input to me an Analog Sine Wave @ 30Khz
5 Vp-p. My main goal is to have the second wave coming out of the
AD539 (or whatever chip/circuit) to be phase with the orginal sine
wave coming out of the osscilator.

Diagram:


Ossiclattor ----------sine wave 30Khz 5 vp-p---->
(from ossiclator) -----Multiplier ---- = N*30Khz --->
(needs to be
in phase)

I am just concern with gettting that sine wave out of the muliplier to
be in phase. woudl the AD539 or the AD532 work?

Thanks for your help!
 
F

Fred Bloggs

Jan 1, 1970
0
Wicked said:
How about the chip AD539 ? would that work in this application. I
looked at the PPL link (above) but the input to that was a digital
square wave...I am looking the input to me an Analog Sine Wave @ 30Khz
5 Vp-p. My main goal is to have the second wave coming out of the
AD539 (or whatever chip/circuit) to be phase with the orginal sine
wave coming out of the osscilator.

Diagram:


Ossiclattor ----------sine wave 30Khz 5 vp-p---->
(from ossiclator) -----Multiplier ---- = N*30Khz --->
(needs to be
in phase)

I am just concern with gettting that sine wave out of the muliplier to
be in phase. woudl the AD539 or the AD532 work?

Thanks for your help!

You need to see your advisor to discuss how the school has failed you
and negotiate a suitable remedy in lieu of lawsuit.
 
J

John Fields

Jan 1, 1970
0
Here is what we are doing in for detail:



I am have a hard time find a multiplier circuit. I was thinking about
using the AD834JN. Are there any better options?

We are building an FSK system. What want to feed the signal from the
oscillator into the "chip" to generate another signal in phase but at
a differnt frequency. I have looked at the data sheet ...but I cant
find a clear circuit that I can use.

Our input is going to be sine wave 5v p-p 30Khz

---
That's not enough detail.

What, specifically, are you trying to do, and what do you think that FSK
means?

What do you want your output frequencies to be?

What do you mean by "in phase"?
 
B

Ben Bradley

Jan 1, 1970
0
In said:
How about the chip AD539 ? would that work in this application. I
looked at the PPL link (above)

No, that's not a "PPL"...
but the input to that was a digital
square wave...I am looking the input to me an Analog Sine Wave @ 30Khz
5 Vp-p.

Do you know that it's fairly easy to convert a sine wave to a
square wave?
My main goal is to have the second wave coming out of the
AD539 (or whatever chip/circuit) to be phase with the orginal sine
wave coming out of the osscilator.

Diagram:


Ossiclattor ----------sine wave 30Khz 5 vp-p---->
(from ossiclator) -----Multiplier ---- = N*30Khz --->
(needs to be
in phase)

This looks like an old-fashioned "multiplier" to get higher
frequency reference from a lower frequency crystal oscillator. In
such a case, the "multiplier" will just be an non-linear (Class B or
Class C) amplifier stage with a "tank circuit" on the output tuned to
the output frequency. If you don't need to pass any AM or (much) FM
through to the output, this is as good a method as any.
I am just concern with gettting that sine wave out of the muliplier to
be in phase. woudl the AD539 or the AD532 work?

By "in phase" I presume you mean you can trigger an oscilloscope on
the 30kHz input, and the 60kHz (or N*30kHz) will appear steady. Yes,
this do it.
Thanks for your help!

Maybe Fred Bloggs' advice is good. And learn the English spelling
of oscillator.
 
G

gwhite

Jan 1, 1970
0
Wicked said:
Hello:

I need help! We are making an FSK system and I am looking for a
circuit that can divide or multiply a signal coming from the
ossiclator......any books? websites? anything would help!

Regarding a frequency reference coming from an oscillator:

No one uses analog frequency dividers any more, they can have trouble "starting"
for one thing. Even in the old days tube divide-by-2 was available w/
"relaxation" circuits, so there had to be a compelling reason for an analog
divider. Those days are long gone.

_Everyone_ uses digital frequency dividers nowadays since they are easily
integrated into IC's. Analog frequency multipliers are still used. PLL's are
most the most common method today of div and mult, and they are mixed signal
devices.



Wolaver: an excellent book despite the bad review from the idiot EE student
http://www.amazon.com/exec/obidos/t...f=sr_1_2/102-5140977-4485701?v=glance&s=books

Egan: complements the above quite well
http://www.amazon.com/exec/obidos/t...f=sr_1_1/102-5140977-4485701?v=glance&s=books
I don't have his other one:
http://www.amazon.com/exec/obidos/t..._books_5/102-5140977-4485701?v=glance&s=books

Gardner is one of the "old classics," but I prefer the first two
http://www.amazon.com/exec/obidos/t..._books_4/102-5140977-4485701?v=glance&s=books


PLL's are not really that easy if you really want to understand them at a deep
level. That's why there are so many thick and heavy books on the subject.
 
T

Tim Shoppa

Jan 1, 1970
0
How about the chip AD539 ? would that work in this application. I
looked at the PPL link (above) but the input to that was a digital
square wave...I am looking the input to me an Analog Sine Wave @ 30Khz
5 Vp-p. My main goal is to have the second wave coming out of the
AD539 (or whatever chip/circuit) to be phase with the orginal sine
wave coming out of the osscilator.

Diagram:


Ossiclattor ----------sine wave 30Khz 5 vp-p---->
(from ossiclator) -----Multiplier ---- = N*30Khz --->
(needs to be
in phase)

I am just concern with gettting that sine wave out of the muliplier to
be in phase. woudl the AD539 or the AD532 work?

The AD539 is a "voltage multiplier", not a "frequency multiplier".
In other words you are chasing a red herring.

A phase-locked loop frequency multiplier is by definition locked
in phase with the input signal. Different phase comparator block choices
will give you different phase shifts between the input and output. Start
with the MC4046 data sheet if you are interested and your textbooks
don't talk about phase comparators. Most VCO's don't make good sine
waves (there are exceptions, but most applications don't care enough
to go to the trouble so I'm very dubious that you'd go to the same
trouble.)

This is all of dubious value, because you do not need nor want a
PLL for simple FSK modulation. Once you add in phase shift keying
then product modulators (aka voltage multipliers) like the AD539 become
useful for demodulation, but you're asking all the wrong questions if
that's what you are chasing after.

Tim.
 
K

Ken Taylor

Jan 1, 1970
0
Wicked said:
How about the chip AD539 ? would that work in this application. I
looked at the PPL link (above) but the input to that was a digital
square wave...I am looking the input to me an Analog Sine Wave @ 30Khz
5 Vp-p. My main goal is to have the second wave coming out of the
AD539 (or whatever chip/circuit) to be phase with the orginal sine
wave coming out of the osscilator.

Diagram:


Ossiclattor ----------sine wave 30Khz 5 vp-p---->
(from ossiclator) -----Multiplier ---- = N*30Khz --->
(needs to be
in phase)

I am just concern with gettting that sine wave out of the muliplier to
be in phase. woudl the AD539 or the AD532 work?

Thanks for your help!

As others have said, you need to clarify for yourself what FSK is. For a
chip solutions hunt about for something like the XR2201 -
http://www.klm-tech.com/technicothica/xr.html
or
http://www.klm-tech.com/technicothica/spec.html

Ken
 
G

gwhite

Jan 1, 1970
0
Tim said:
The AD539 is a "voltage multiplier", not a "frequency multiplier".
In other words you are chasing a red herring.

A phase-locked loop frequency multiplier is by definition locked
in phase with the input signal. Different phase comparator block choices
will give you different phase shifts between the input and output. Start
with the MC4046 data sheet if you are interested and your textbooks
don't talk about phase comparators. Most VCO's don't make good sine
waves (there are exceptions, but most applications don't care enough
to go to the trouble so I'm very dubious that you'd go to the same
trouble.)

This is all of dubious value, because you do not need nor want a
PLL for simple FSK modulation. Once you add in phase shift keying
then product modulators (aka voltage multipliers) like the AD539 become
useful for demodulation, but you're asking all the wrong questions if
that's what you are chasing after.


"Voltage multipliers" can be used to produce FSK transmissions. But I've only
seen it done (been there, done that) where higher orders of modulation (such as
QAM) are also required to be available for system design. So I agree that the
OP "doesn't want it" -- something simpler is likely in order.


Sin(ws·t) /¯¯¯\
O-------+--->( X )----------------+
| \___/ |
|¯¯¯| | |
| H | | |
| I | cos(wc·t) |+
±1 | L | |¯¯¯|
O-----| B | |sum|---O FSK
| E | |___|
| R | sin(wc·t) |+
| T | | |
|___| | |
| /¯¯¯\ |
+--->( X )----------------+
\___/


The FSK is produced by changing the polarity on the Hilbert transform.
Obviously the schematic is conceptual and implemention may be different. The
amount of frequency deviation is determined by ws (freq of shift). Nothing is
stated here about the symbol rate.
 
W

Wicked

Jan 1, 1970
0
I cant find the Data sheet to MC4046. Can you please send me a link.
Yeah, the other chip wont work b/c it is a stright multipier not a
freq multiplier. What are some other good PLL chips?

Thanks!
 
B

Bill Sloman

Jan 1, 1970
0
I cant find the Data sheet to MC4046. Can you please send me a link.
Yeah, the other chip wont work b/c it is a stright multipier not a
freq multiplier. What are some other good PLL chips?

Have a look at

http://www.semiconductors.philips.com/acrobat/datasheets/74HCT9046A_5.pdf

The 9046 is the Philips refinement of the 4046. The applications note
part of the data sheet (page 6 onwards)lists a couple of the problems
with the original 4046, and is well worth reading.
 
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