Continue to Site

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.

Register Log in

32.768k crystal oscillator de-Q freq shift

Status
Not open for further replies.
T

tommydidi

Member level 1
Joined
Sep 5, 2007
Messages
36
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,494
Hi Guys,

I de-Q'd the crystal oscillator by adjusting the values of Cx and Lx to give the right w0, my transient simulation is dramatically faster but why the f0 is shifted a bit to ~33.5KHz? Thanks.


tommydidi
 

What do you mean by de-Q'd? How much is the Q in the Xtal model. Low Q are always faster but will give slightly different Center frequencies. Generally in my simulation I assume Q of abt 50K. But this frequency shift doesnt matter unless u are trying to do some jitter sims.
 

Thanks yuvan.

What I meant was divide Lx by 100 while times Cx by 100, so the center freq is still kept the same but the new Q (de-Q) will be smaller due to the bigger Cx.

Also, how do I calculate the steady state current for the Gm stage? Thanks.
 

I assume you're -ve resistance is done by some common source stage...So, you can refer Vittoz (I forgot ) for optimial sizing of the gm stage..and thus the current required.
 

Is it asking too much if we want see a circuit schematic?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top