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

  • From: "Lurker" <lurker_li@xxxxxxxxx>
  • To: "'Haixiao Weng'" <haixiao.weng@xxxxxxxxx>
  • Date: Fri, 20 Jun 2008 10:43:47 +0800

Hi Haixiao,

What element are you used for simulating crystal? 
Node a1 is the output of the crystal and the input of related IC.
Node a4 is the input of the crystal and the output of related IC.
I haven't got IC's internal circuit yet. So I use E element instead. 
Would you please give me some suggestion to oscillate it?


Best Regards,

Lurker Li



-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Haixiao Weng
Sent: Thursday, June 19, 2008 10:46 PM
To: Lurker
Cc: Beal, Weston; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: How to do crystal simulation

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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