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.
Could you possibly clue us in as to what you are talking about? Bipolar, Fet, reflection (negative resistance) oscillator, transmission oscillator, frequency, circuit schematic, phase of the moon?
PCB is not visible. Try to post once again.
If substrate is FR4 (as it seems...) increase to 0.02 the loss tangent (more similar to real value) and see if it oscillates.
Use, instead of ideal passive components, vendor library component models (Q and SRF can be important).
I hope it can help.
Mazz
To brmadhukar:
Thanks for your valuable advice,I will try again tomorrow.and i have a little request,if u make my sch to a pcb,how do u place it?can u send a jpg,i want to get some experience.
To mazz:
i don't konw why the pcb is not visible.i send it again.hope your help **broken link removed**
change "** "to "tt"
You schematic is not making sense to me. What is all that crap to the right
of C6 for? Get rid of it for now.
Is this a reflection or a transmission oscillator? The reason I ask is that is looks a little like a reflection oscillator (you are trying to make a negative resistance at the collector to resonate with the ceramic resonator, but why is there a C1 capacitor?).
To biff44:
The components in the right of C6 is a model of a varator(smv1233),not crap.
and this oscilator is a colpitt sch,it can also be classified as a reflective oscillator.
Colpitts oscillators are transmission type oscillators. You build an amplifier with some gain G and phase shift P. You place a tuned circuit in the feedback path with Loss L and phase shift Q.
IF G > L, AND P + Q = n2Π, it will oscillate.
You might want to break the circuit into pieces and measure the gain and phase shift of the amplifier part, measure the loss and phase shift of the ceramic resonator part, and fix what is not meeting the above criteria.
From layout photo the prototype seems well done.
I'm assuming that the board is double layer and vias are plated through holes.
I can only suggest (once again) to make simulation with real capacitors models and lossy transmission lines.
I hope it can help.
Mazz
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.