Hi,

I'm looking for a sine-wave generator with a variable frequency at least in the interval (9.1MHz-10.1 MHz).

The output power is not important because it will be connected an LM4132 Voltage Follower which amplifies the signal.

Can you suggest me how to create this variable signal?

I have to realize a PCB, thus, if you know an IC which makes these oscillations should be exactly what I'm looking for.

Thank you.

 

Colpitss Oscillator https://www.electronics-tutorials.ws/oscillator/colpitts.html
or this could be of interest
https://www.electroschematics.com/10-to-1000-mhz-oscillator/

 

Of course, you can tune each sinewave oscillator - however, in many cases it is necessary to vary TWO componenet values at the same time (parallel tuning). Single-element tuning capabilities require somewhat more complex circuitry (two opamps for example). What are your requirements?

 

If you want digital control of freq a DDS quite simple to use.

https://www.analog.com/en/analog-dialogue/articles/all-about-direct-digital-synthesis.html

Questions -

1) How do you want to control freq.
2) Resolution of freq changes needed ?
3) Accuracy of freq generated ?
4) Amplitude of sinewave
5) Linearity of control versus freq out


Regards, Dana.

 

Of course, you can tune each sinewave oscillator - however, in many cases it is necessary to vary TWO componenet values at the same time (parallel tuning). Single-element tuning capabilities require somewhat more complex circuitry (two opamps for example). What are your requirements?

In terms of frequency step, f_step=1kHz should be sufficient. Concerning the stability, 30ppm in the temperature range is fine. Do you know if there are some IC that perform this task? Or it is necessary to create with discrete components?

 

If you want digital control of freq a DDS quite simple to use.

https://www.analog.com/en/analog-dialogue/articles/all-about-direct-digital-synthesis.html


Regards, Dana.

Thank you, but the circuit must be analogue.

 

Some 10 Mhz capable here -

https://www.everythingrf.com/search/vcxo/filters?page=1&country=global&soutput_waveform=;Sinewave;


Regards, Dana.

 

If you want digital control of freq a DDS quite simple to use.

https://www.analog.com/en/analog-dialogue/articles/all-about-direct-digital-synthesis.html

Questions -

1) How do you want to control freq.
2) Resolution of freq changes needed ?
3) Accuracy of freq generated ?
4) Amplitude of sinewave
5) Linearity of control versus freq out


Regards, Dana.

1) How do you want to control freq.
I would like to control the frequency through a potentiometer or something like that.
2) Resolution of freq changes needed ?
f_step=1kHz is sufficient.
3) Accuracy of freq generated ?
I think that 30ppm is sufficient
4) Amplitude of sinewave
It is not very important because I'm going to connect this generator in series with a votage follower LM6321.
5) Linearity of control versus freq out
As linear as possible but I have not particular requirements.

Thank you.

 

If you wanted a pot controlled change you could take sparky1's circuit and replace
C4 with a Varicap.

Google "colpitts varicap", a number of circuits/images of circuits.

Some report using a 1N4001 as a substitute for a Varicap and get good results.

http://www.hanssummers.com/varicap.html



Regards, Dana.

 

Old component but still available: SN74S124N
Also SN74LS624 - SN74LS629

 

Oldies but goldies!

 

Search carefully in the Silicon Labs site - I recall the SI510 or 511 but they are factory programmable. Others, loved by radio amateurs, you can program them on the fly, IIRC.

While writing, I am now in doubt if they have sine output.

Otherwise try the family including the AD9833 (has sweeping capability). I am sure that my Siglent generator is built based on it.

 

Search carefully in the Silicon Labs site - I recall the SI510 or 511 but they are factory programmable. Others, loved by radio amateurs, you can program them on the fly, IIRC.

While writing, I am now in doubt if they have sine output.

Otherwise try the family including the AD9833 (has sweeping capability). I am sure that my Siglent generator is built based on it.

TS wants analog approach per prior comment.

Regards, Dana.

 

Yes Dana, that's why:

While writing, I am now in doubt if they have sine output.

 

The VCO I have referenced all give square wave output.
Since the TS is only interested in a narrow band around 10MHz this can be easily fixed.

 

Just curious, why does the circuitry need to be analog?

 

Thank you, but the circuit must be analogue.

Why? Is there some reason?

No analog RC or LC oscillator is going to give you 30 ppm accuracy or stability, no matter how clever you are; if you're extremely lucky, you might be able to achieve 1000 ppm (0.1%). A temperature-compensated crystal oscillator (TCXO) will achieve 30 ppm or even better, but even the voltage-controlled TCXOs aren't tunable beyond ± a few ppm.

If you really want tunability from 9.1 to 10.1 MHz combined with 30 ppm stability and accuracy the only practical solution I'm aware of is to use a DDS chip, as mentioned above, driven by a stable TCXO.

The attached app note details one use of Analog Devices' AD9850 DDS chip, as a Local Oscillator (LO) for amateur radio.

 

Hello,

You could have a look at the old "huff and puff" design for oscillator stabilisation.
Here is a library with a lot of articles on the subject:
http://www.hanssummers.com/huffpuff/library.html

Bertus

 

LM4132

LM4132/LM4132-Q1 SOT-23 Precision Low Dropout Voltage Reference

 

You could put an analog sine wave oscillator inside a phase locked loop. That would give you stability as good as your timing reference. If you want ±30 PPM over the commercial temperature range, you should count on keeping your reference oscillator in an oven.

It can be done, but you would have to go to some trouble and expense to do it.