voltage control oscillator

[javvad]

i want do design voltage control oscillator which have carrier
frequency 137MHZ and frequency deviation 40MHZ means want to design fm
modulator have these .thanks

 

[Joel Koltner]

i want do design voltage control oscillator which have carrier
frequency 137MHZ and frequency deviation 40MHZ means want to design fm
modulator have these .thanks

Plastonek's "RF Oscillator Circuit Analysis and Design with Breadboard
Experiments" has something very similar to this, but it's probably impossible
to get ahold of anymore. Wes Hayward's "Introduction to Radio Frequency
Design" has enough information to get you going as well...

A 40MHz deviation on a 137MHz carrier is huge, though -- do you really need
it? I don't think there's any reasonably simple way to get such a huge
deciation using "simple" VCOs... you'd be much better off getting 40MHz
deviation at, e.g., 800MHz and then mixing the result down to a center of
137MHz.

 

[Jan Panteltje]

i want do design voltage control oscillator which have carrier
frequency 137MHZ and frequency deviation 40MHZ means want to design fm
modulator have these .thanks

varicap LC have transistor connect ;-)

 

[Fred Bloggs]

i want do design voltage control oscillator which have carrier
frequency 137MHZ and frequency deviation 40MHZ means want to design fm
modulator have these .thanks

Okay, good luck with your endeavor.

 

[[email protected]]

i want do design voltage control oscillator which have carrier
frequency 137MHZ and frequency deviation 40MHZ means want to design fm
modulator have these .thanks

As Joel Koltner says, this is a large frequency deviation for a 137MHz
varactor tuned oscillator.

It would probably be a lot easier - if rather more expensive - to buy
one of the faster Analog Devices direct digital synthesis (DDS) chips,
such as the AD9911

http://www.analog.com/UploadedFiles/Data_Sheets/AD9911.pdf

and an analog to digital converter, then digitise your voltage and use
the digital output to set the output frequency.

This won't work if this is a homework problem or a design for high
volume production, but for a lot of real life applications it offers
the quickest and most reliable route to the frequency range you are
asking for.

Analog Devices have a lot of DDS chips aimed at a variety of
application - the AD9911 was just the cheapest one on the list that
could get up to 174MHz.

 

[Baron]

ok but 800mhz is near to microwave range there are orter problems at
microwave range 1st how i will see these 2nd help me what you advice
me what are the techiniques to control deviation thanks

800Mhz is no where near microwave! Its UHF. 3Ghz is microwave.
http://en.wikipedia.org/wiki/Ultra_high_frequency

 

[John O'Flaherty]

800Mhz is no where near microwave! Its UHF. 3Ghz is microwave.
http://en.wikipedia.org/wiki/Ultra_high_frequency

American Heritage dictionary defines microwave as 1 mm to 1 m in
length. 800 MHz is .375 m, so it would qualify.
Merriam-Webster also says "between about one millimeter and one
meter".
The Wikipedia article "microwave" agrees - 300 MHz to 300 GHz.
http://en.wikipedia.org/wiki/Microwave

I think the article you cited intends to include UHF in microwaves.
The sentence is a little unclear:
"Radio waves whose frequency is above the UHF band fall into the SHF
(Super high frequency) and EHF (Extremely high frequency) bands; all
of which fall into the Microwave frequency range."

However, there are other dictionaries show different limits...
Encarta dictionary says "1 mm to 30 cm"
Compact Oxford English Dictionary says "0.001-0.3 m".
That would be a lower limit of 1 GHz, which would put 800 MHz pretty
close.

 

[Winfield]

Joel Koltner wrote:

ok but 800mhz is near to microwave range there are orter problems at
microwave range 1st how i will see these 2nd help me what you advice
me what are the techiniques to control deviation thanks

Minicircuits has a nice selection of inexpensive
VCO modules, as well as RF mixers, you can use to
solve your problem, http://www.minicircuits.com/

 

[Baron]

American Heritage dictionary defines microwave as 1 mm to 1 m in
length. 800 MHz is .375 m, so it would qualify.
Merriam-Webster also says "between about one millimeter and one
meter".
The Wikipedia article "microwave" agrees - 300 MHz to 300 GHz.
http://en.wikipedia.org/wiki/Microwave

I think the article you cited intends to include UHF in microwaves.
The sentence is a little unclear:
"Radio waves whose frequency is above the UHF band fall into the SHF
(Super high frequency) and EHF (Extremely high frequency) bands; all
of which fall into the Microwave frequency range."

The definition implies sub definitions of microwaves.

However, there are other dictionaries show different limits...
Encarta dictionary says "1 mm to 30 cm"
Compact Oxford English Dictionary says "0.001-0.3 m".
That would be a lower limit of 1 GHz, which would put 800 MHz pretty
close.

Mmmm. My ARRL Handbook sites UHF from 300 to 3000 Mhz and VHF 30 to 300
Mhz Page 4:14 Without stating microwaves.

But I do agree that it isn't very clear, and I haven't found anything
more definitive.

I suspect that like you, I have taken ( U micro ) to mean 1000th part
of, and in that context we must agree.

As a ham... 3Ghz plus is microwaves. 10 & 24 Ghz is plumbing. ;-)

 

[John Fields]

I suspect that like you, I have taken ( U micro ) to mean 1000th part
of, and in that context we must agree.

 

[Baron]

Ooo Hangs head in shame. ;-) Thanks for the correction.

 

[Don Bowey]

Minicircuits has a nice selection of inexpensive
VCO modules, as well as RF mixers, you can use to
solve your problem, http://www.minicircuits.com/

Does anyone have a clue about what the OP is building?

40 MHz. Bandwidth at 137 MHz. seems a bit out of scale. Around 137 MHz is,
if I recall correctly, where some of the satellite weather maps are
transmitted, and a 40 kHz bandwidth would be approriate.

 

[MooseFET]

Does anyone have a clue about what the OP is building?

40 MHz. Bandwidth at 137 MHz. seems a bit out of scale. Around 137 MHz is,
if I recall correctly, where some of the satellite weather maps are
transmitted, and a 40 kHz bandwidth would be approriate.

40MHz is only out of scale if he is building a radio. Lots of other
things require frequencies as high as radios but are doing very
different things with them. For all we know he may be making a new
version of the "Russian woodpecker".

 

[neon]

This is like I WANTOBE and i don't think he will.

 

[javvad]

Plastonek's "RF Oscillator Circuit Analysis and Design with Breadboard
Experiments" has something very similar to this, but it's probably impossible
to get ahold of anymore.  Wes Hayward's "Introduction to Radio Frequency
Design" has enough information to get you going as well...

A 40MHz deviation on a 137MHz carrier is huge, though -- do you really need
it?  I don't think there's any reasonably simple way to get such a huge
deciation using "simple" VCOs... you'd be much better off getting 40MHz
deviation at, e.g., 800MHz and then mixing the result down to a center of
137MHz.

can u see this data sheet for me
http://www.minicircuits.com/pdfs/JTOS-300P.pdf
and give the advice can i do this with this device
thanks

 

[Winfield]

can u see this data sheet for me
http://www.minicircuits.com/pdfs/JTOS-300P.pdf
and give the advice can i do this with this device

First, you said you wanted 117 to 157MHz, right? This
part with its 148 to 174MHz range, misses on having the
right frequency, and with only 26MHz of span, or 15% of
Fmax, it misses on that account as well - you asked for
25% span. Also, did you notice its tuning sensitivity
changing from 16 to 11 MHz/V across the span? That's
tuning nonlinearity.

This MiniCircuits VCO is pretty representative of what's
feasible in VCO design, and shows why Joel suggested that
you mix the outputs of two high-frequency oscillators,
like 800MHz. First, you can get enough deviation, and
second, you can select a high enough frequency so that
you can use say the bottom 30 to 40% of the tuning range
and thereby get better linearity. Go look at those high
frequency MiniCircuits VCOs.

 

[javvad]

 First, you said you wanted 117 to 157MHz, right?  This
 part with its 148 to 174MHz range, misses on having the
 right frequency, and with only 26MHz of span, or 15% of
 Fmax, it misses on that account as well - you asked for
 25% span.  Also, did you notice its tuning sensitivity
 changing from 16 to 11 MHz/V across the span?  That's
 tuning nonlinearity.

 This MiniCircuits VCO is pretty representative of what's
 feasible in VCO design, and shows why Joel suggested that
 you mix the outputs of two high-frequency oscillators,
 like 800MHz.  First, you can get enough deviation, and
 second, you can select a high enough frequency so that
 you can use say the bottom 30 to 40% of the tuning range
 and thereby get better linearity.  Go look at those high
 frequency MiniCircuits VCOs.- Hide quoted text -

- Show quoted text -

what is the theory of vco well if i apply the message signal at input
like ramp and initial frequency is let suppose 125MHZ and final
frequency is 200MHZ weather it will change the frequency of VCO or
not from 125MHZ to 200MHZ
2nd does frequency of message signal can be greater then carrier
frequency? thanks

 

[javvad]

 First, you said you wanted 117 to 157MHz, right?  This
 part with its 148 to 174MHz range, misses on having the
 right frequency, and with only 26MHz of span, or 15% of
 Fmax, it misses on that account as well - you asked for
 25% span.  Also, did you notice its tuning sensitivity
 changing from 16 to 11 MHz/V across the span?  That's
 tuning nonlinearity.

 This MiniCircuits VCO is pretty representative of what's
 feasible in VCO design, and shows why Joel suggested that
 you mix the outputs of two high-frequency oscillators,
 like 800MHz.  First, you can get enough deviation, and
 second, you can select a high enough frequency so that
 you can use say the bottom 30 to 40% of the tuning range
 and thereby get better linearity.  Go look at those high
 frequency MiniCircuits VCOs.- Hide quoted text -

- Show quoted text -

can u see this for me
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=744-1057-ND
or this
http://www.crystek.com/microwave/admin/webapps/welcome/files/vco/CVCO33CL-0125-0200.pdf
or advise me for direction

 

[Winfield]

can u see this for me
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=744-...
or this
http://www.crystek.com/microwave/admin/webapps/welcome/files/vco/CVCO...
or advise me for direction

I think it's time you told us what you're trying to do.

 

[javvad]

 I think it's time you told us what you're trying to do.

i m designing frequency jammer and i have to generate band 137MHZ to
177MHZ
for this porpuse i see the BP.lathi book page 230 there a method given
for wide band fm but my circuitry is too large with this then i think
to make vco for this to vary the input signal and output sig frequency
very with this and i can cover whole band i want to know that weather
i m going right way or can u guid me in this whole work