[SI-LIST] Re: How to do crystal simulation

  • From: "Haixiao Weng" <haixiao.weng@xxxxxxxxx>
  • To: Lurker <lurker_li@xxxxxxxxx>
  • Date: Thu, 19 Jun 2008 09:45:42 -0500

I never use the E element to simulate the crystal. Your problem may come
from the phase. Here, the crystal_in and crystal_out has the same phase
(controlled by the VCVS). I believe they should be 180 degree different.

You may also need to consider the DC feedback. Usually, a resonator has a
feedback resistor such as 500Kohm but a crystal doesn't have. Suppose you
use a CMOS inverter as the amplifier, you need a feedback resistor.

Regards,
Haixiao

On 6/19/08, Lurker <lurker_li@xxxxxxxxx> wrote:
>
> Hi Beal,
>
> I'm li. Please check the script. It doesn't work.
>
> *Crystal sim
>
> .option acct post list
>
> .param cu=2
> E1 a1 0 a4 0 max=+3.3 min=0 cu
>
> L1 a1 a2 0.08h
> C1 a2 a3 8pf
> R1 a3 a4 600
> c2 a1 a4 8pf
> c3 a1 0 22pf IC=0.5
> c4 a4 0 22pf IC=0.5
> R2 a1 a4 1m
>
>
> .temp 50
> .tran 10ps 100ns start=0ns
>
> .print PAR('v(a1)')
>
> .end
>
>
> Best Regards,
>
> Lurker Li
>
> Tel: 86-21-58966996-1021
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On
> Behalf Of Beal, Weston
> Sent: Wednesday, June 18, 2008 10:45 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: How to do crystal simulation
>
> =20
> Based on your description of you circuit, I would not expect it to =
> oscillate. An oscillator needs some amplification element and all of you =
> circuit is passive elements. You should find a reference on basic =
> oscillator design.
> http://en.wikipedia.org/wiki/Pierce_oscillator
>
> It sounds like you got your circuit from an IC design guide that =
> suggested a circuit for the input to a clock generator. The part you =
> missed is that the IC itself provides the amplifier that you are missing =
> in your circuit.
>
> Regards,
> Weston
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
> On Behalf Of ? ?
> Sent: Wednesday, June 18, 2008 6:40 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: How to do crystal simulation
>
> Hi David and Haixiao
> =20
> Thank you!=20
> I just got the crystal internal circuit.  It's  L. C. R in serial and =
> parallel with a C.
> I will have a try in Hspice with a initialized capacitor or inductor.=20
> The outside circuit is two capacitor( both of them is about 22ps) =
> connected crystal's output and input with a R(1Mohm) in parallel.
>   I don't have ADS tool. So I can't use it. If necessory I will release =
> the Hspice simulation script tomorrow night. Then you can see the =
> electrical circuit clearly.
> I'm not sure whether it can run or not.=20
> =20
> =20
> =20
>
> "Pommerenke, David" <davidjp@xxxxxxx> =D0=B4=B5=C0=A3=BA
>    Li,
>
> Your attached file was not delivered, but normally I just set initial =
> conditions on the capacitor or the inductor that is part of the XTAL =
> model.
>
>
> Dr. David Pommerenke
> Missouri University of Science and Technology (MST), former name: UMR
> 118 EECH, 301 W. 16th Street, Rolla, MO 65409-0040
> 573 341 4531, cell: 573 308 2019
>
>
> =20
> Did you add stimulus to start the spice simulation? For example, a 1ns =
> pulse.
> ADS has more choice on crystal simulation. Check the ADS help on =
> oscillators.
>
> Regards,
> Haixiao
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
> On Behalf Of ? ?
> Sent: Tuesday, June 17, 2008 8:35 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] How to do crystal simulation
>
> Hi all,
>
> I have a problem with crystal simulation. Please check the attached. I =
> can't get the crystal start to "shake". The frequency I want to get is =
> 25MHz. I didn't get the internal circuit for crystal. The Pspice model =
> seems didn't work. What shall I do?
>
>
>
>
>
>
>
>      =20
> ---------------------------------
> =
> =D1=C5=BB=A2=D3=CA=CF=E4=A3=AC=C4=FA=B5=C4=D6=D5=C9=FA=D3=CA=CF=E4=A3=A1
>
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