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help me please in my voltage controlled oscillator design

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bere

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i want to design a vco to produce 60MHZ with a reference crystal.i want to do it using a phase locked loop with frequency dividers until it locks at 60mhz.is it possible to do it all on a bread board and how do i show the output?could you please help me with vco circuit diagrams.my e-mail is manyere_allen@yahoo.co.uk
 
Re: help me please in my voltage controlled oscillator desig

bere said:
i want to design a vco to produce 60MHZ with a reference crystal.i want to do it using a phase locked loop with frequency dividers until it locks at 60mhz.is it possible to do it all on a bread board and how do i show the output?could you please help me with vco circuit diagrams.my e-mail is manyere_allen@yahoo.co.uk

You don't want to be trying to build RF designs on breadboard, certainly not at 60MHz!. For a VCO you simply add a varactor diode to your 60MHz LC oscillator.
 
Here is a block diagram of what you need to do to lock the 60 Mhz oscillator to a crystal. Check my website for more PLL info.
 

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reply on the vco design

thaks a lot for the block diagram.but i still want to know where i get the output from?i have a 10MHZ crystal,how do i use it to force the vco to oscillate at 60MHZ?does it mean that i have to add certain components and how do i show the output from the vco to prove that for sure its producing 60mhz?do i have to use specific components ie,the resistors capacitors?looking forward to your reply.
 
Re: reply on the vco design

bere said:
thaks a lot for the block diagram.but i still want to know where i get the output from?i have a 10MHZ crystal,how do i use it to force the vco to oscillate at 60MHZ?does it mean that i have to add certain components and how do i show the output from the vco to prove that for sure its producing 60mhz?do i have to use specific components ie,the resistors capacitors?looking forward to your reply.

The output from the VCO is the line with the arrow pointing OUTWARDS, the one that goes to the divider.

As you specify a 10MHz crystal, you would use a divide by 6 divider (rather than divide by 60).
 
help on the vco

thank you so much.so i get the output from the vco,is it possible to show it on an oscilloscope?and how do i go about it?this circuit can now be connected on a breadboard?you said all i need is a varactor?do you have an example of a vco circuit with a varactor connected?i want to see the layout?
 
Re: help on the vco

bere said:
thank you so much.so i get the output from the vco,is it possible to show it on an oscilloscope?and how do i go about it?this circuit can now be connected on a breadboard?you said all i need is a varactor?do you have an example of a vco circuit with a varactor connected?i want to see the layout?
I don't want to discourage you from eventually building this phaselocked loop, but this is not a project for a beginner. You need to learn how to walk before you can run.
 
help on vco

thanks a lot for the help,i have a vco circuit that i have?what i wanted to ask is how do i calculate the values of the capacitors and resistors as well as the inductance?are there any formulas which are applied?lookng forward to your reply?
 
Re: help on vco

bere said:
thanks a lot for the help,i have a vco circuit that i have?what i wanted to ask is how do i calculate the values of the capacitors and resistors as well as the inductance?are there any formulas which are applied?lookng forward to your reply?
You would be more likely to get an answer if you posted a schematic.
 
reply to vco design

thank you for the formulas.if u go to this website,www.uoguelph.ca/~antoon/gadgets/pll/pll.html theres a topic on phase locked loops tutorial by tony van roon.there is a 'BASIC VCO CIRCUIT' down the page but with no values of capacitance,resistance and inductance,thats what i'm trying to work around that circuit.could you help on how i go about to get the values to make it oscillate around 60mhz.
 
This circuit simulates well. I didn't build it.
 

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reply to vco design

thanx a lot for the circuit.i would want to know which formulas or way you used to get to those values.Input is where the Vctrl control is?maybe a little explanation of the circuit will help me a lot?what is D2 and D3 doing?but i do understand that the tank circuit is R2,C5,D1 and R4.what are the effects of C6,C4 etc
 
Re: reply to vco design

bere said:
thanx a lot for the circuit.i would want to know which formulas or way you used to get to those values.Input is where the Vctrl control is?maybe a little explanation of the circuit will help me a lot?what is D2 and D3 doing?but i do understand that the tank circuit is R2,C5,D1 and R4.what are the effects of C6,C4 etc

The current through R3, D2 and D3 forward biases D2 and D3 such that the base is at about 1 volt. The Vbe drop puts the emitter at about 0.4v. R1 provides an emitter current of about 800uA.
The tank equivalent circuit is shown below. The resonant frequency Fr is

Fr=1/(2*pi*√(L*C))

Where C is the combination of all the capacitors in the schematic below.

Parallel caps add; series caps are calculated as follows:

1/Cseries = 1/C1 + 1/C2 +1/C3 + .... 1/Cn.

C4 is for DC blocking. C1, C5 and C7 are for RF bypassing.
 

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reply to vco design

input from the filter will go to Vctrl isnt'?thank you so much,will tell you about the results when i'm through with connecting it on the breadboard.i also want to ask that how do i know that its 60MHZ on the oscilloscope?i think connecting on the bread board wont' give me an problem.
 
reply to vco design

thanx a lot for the detail.connecting to the breadboard wont give any problems,i hope.and hope that its not too large a circuit for the board i have,will tell you about the results.how do i show the output on an oscilloscope now?i just want to see if it produces oscillations,and that its sinusoidal?
 
reply to vco design

thanx a lot for the detail.connecting to the breadboard wont give any problems,i hope.and hope that its not too large a circuit for the board i have,will tell you about the results.how do i show the output on an oscilloscope now?i just want to see if it produces oscillations,and that its sinusoidal?
 
You shouldn't attempt to build RF circuits on breadboard, it's the worst possible method you could try to use. It's very likely the breadboard will prevent the circuit working, particularly at 60MHz.

The output of the oscillator WILL be a sinewave, the ringing action of the tuned circuit guarantees it - massively overdriving it 'might' possibly manage a squarewave?, but it's unlikely.
 
Back in the days before Protoboards (which I think are what you are referring to as breadboards), I used to "breadboard" high frequency circuits on single-sided copper clad. I laid out the circuit on 0.1" grid vellum, drilled all necessary holes, then cut pads with an annular cutter called a Roto-Bor. Later I used Vector pad cutters, which you could (and probably still can) buy with or without a handle. The one without the handle worked well in a drill press if you had one that would run at low speed. It had a tendency to occasionally pull the pad off the board. I see that they are now charging over $60 US for them. What a ripoff!
I have bought (at Fry's) double-sided material with plated-through holes on a 0.1" grid, with ground plane on one side. A couple years ago it was about $120 for about 1 sq ft, but you can cut it up and make a lot of little circuits, so I think it's worth it.
 
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