Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

64MHz oscillator, ideas and propositions

Status
Not open for further replies.

neazoi

Advanced Member level 5
Joined
Jan 5, 2008
Messages
4,008
Helped
13
Reputation
26
Reaction score
14
Trophy points
1,318
Location
Greece
Activity points
36,026
Hi, I would like to build this circuit

(Source: hanssummers.com/images/stories/fast/circ.gif)



that uses a 64MHz module as a master oscillator. I would like to replace this with a homebrown oscillator.
Signal quality does not matter too much because it is converted to square wave from the ICs after all.
Searching at the web I found different solutions

1. http://www.circuitsonline.net/forum/view/48065

(look this image in the page

http://www.uploadarchief.net/files/download/butler.png

this is a FET butler oscillator.

2. Another circuit from Elektor mag

**broken link removed**

3. A no name one

http://www.seekic.com/circuit_diagr.../65_~_110MHz_harmonic_crystal_oscillator.html

4. Another noname one

http://www.next.gr/inside-circuits/colpitts-harmonic-oscillator-100mhz-l9117.html

5. An interesting multivibrator that uses a crystal!

http://www.eleccircuit.com/symmetrical-harmonic-oscillator-circuit/

All of these operate on the 3rd harmonic I think. It would be more convenient to find one that operates on the 4th harmonic, since a common 16MHz crystal can be used. I do not know if anyone of these could operate in the 4th harmonic as well.
Which way should I better go for my application? I need something fast and simple.

- - - Updated - - -

An update:
By having a second look, probably a good a simple circuit for my app is the elektor one

**broken link removed**

because the output level will drive nicely the following chips
But it says that:
"When, for example, an 8 MHz crystal is used to obtain an output frequency of 72 MHz (9 × 8 = 72), the frequency determining inductors and capacitors have to be adjusted by a factor of 10/8."

I guess that for 7.1MHz crystal the components must be scaled to 10/7.11 ??
Also what does this scaling mean, I mean how I will calculate the new values?
To verify if I do it right, consider the C2 with a 10/7.11 scaling factor. My calculation shows that it will have a value of 23.463pF, is that correct?
 
Last edited by a moderator:

BradtheRad

Super Moderator
Staff member
Joined
Apr 1, 2011
Messages
14,579
Helped
2,855
Reputation
5,720
Reaction score
2,853
Trophy points
1,393
Location
Minneapolis, Minnesota, USA
Activity points
108,883
Scaling is most reliable with the 3rd harmonic. The harmonics at 2x or 4x won't work.

Your original (slow) frequency is the instigator for your output (fast) frequency. The input waveform transitions are what drives the 3x resonant action.

Every transition of the input waveform, must serve to reinforce your output waveform's transition. It needs to be in the same direction. This is only possible at odd harmonics.
 

chuckey

Advanced Member level 5
Joined
Dec 26, 2010
Messages
4,854
Helped
1,309
Reputation
2,624
Reaction score
1,281
Trophy points
1,393
Location
Southampton and holiday cottage in Wensleydale (UK
Activity points
31,695
Sorry , I have not read all your references but as I understand your problem is doing a X4 multiplication. How about a tuned circuit input with a centre tapped secondary and two diodes feeding the output, like a power supply rectifier circuit. A bit of amplification (4XXX cmos buffer?) then another doubler circuit.
Frank
 

Warpspeed

Advanced Member level 5
Joined
May 23, 2015
Messages
2,326
Helped
768
Reputation
1,538
Reaction score
774
Trophy points
1,393
Location
Melbourne, Australia
Activity points
19,944
That 64Mhz oscillator just gets divided straight down to 32Mhz.

Why not use a standard 32Mhz crystal oscillator module that is more or less a standard readily available part.

**broken link removed**
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top