[ibis-macro] Re: Replacing BIRD 122 with "Reserved_Model" keyword in [External Model]
- From: Scott McMorrow <scott@xxxxxxxxxxxxx>
- To: James Zhou <james.zhou@xxxxxxxxxx>
- Date: Tue, 17 Jan 2012 21:16:26 -0500
James
if the driver output impedance is constant it is therefore "static", which
is a synonym. It is a non-real fictional entity. It is a zero order
model for output impedance. By definition a driver is not LTI. It is not
part of the interconnect. A driver is used to drive an interconnect, not be
part of the interconnect. If you want to perform LTI linearization, I
contend that it be done after the driver is used to "ping" the
interconnect. Otherwise, how will the real condition of differing rising
and falling output impedance of drivers be handled, along with other
non-ideal driver characteristics? IBIS driver models do a better job of
this than a simple output impedance.The model that Walter proposes is an
over-simplification.
Scott
On Tue, Jan 17, 2012 at 9:01 PM, James Zhou <james.zhou@xxxxxxxxxx> wrote:
> Hi Scott, ****
>
> ** **
>
> Not quite sure what is "static driver output impedance". Walter's original
> statement "the impedance is constant over the operating range of the
> device" is just another way to say that the Tx driver is LTI. ****
>
> ** **
>
> Thanks,****
>
> James Zhou****
>
> ** **
>
> ** **
>
> *From:* Scott McMorrow [mailto:scott@xxxxxxxxxxxxx]
> *Sent:* Tuesday, January 17, 2012 4:51 PM
> *To:* James Zhou
> *Cc:* IBIS-ATM; Arpad_Muranyi@xxxxxxxxxx
> *Subject:* Re: [ibis-macro] Re: Replacing BIRD 122 with "Reserved_Model"
> keyword in [External Model]****
>
> ** **
>
> Consistent, but not complete. Small signal linearization does not
> require a static driver output impedance.****
>
> On Jan 17, 2012 7:43 PM, "James Zhou" <james.zhou@xxxxxxxxxx> wrote:****
>
> Arpad,****
>
> ****
>
> This interpretation of "small signal" is consistent with and equivalent to
> the assumption of LTI. ****
>
> ****
>
> Thanks for the clarification,****
>
> James ****
>
> ****
>
> ****
>
> *From:* ibis-macro-bounce@xxxxxxxxxxxxx [mailto:
> ibis-macro-bounce@xxxxxxxxxxxxx] *On Behalf Of *Muranyi, Arpad
> *Sent:* Tuesday, January 17, 2012 4:27 PM
> *To:* IBIS-ATM
> *Subject:* [ibis-macro] Re: Replacing BIRD 122 with "Reserved_Model"
> keyword in [External Model]****
>
> ****
>
> James,****
>
> ****
>
> I think by “small signal” Walter means what is described****
>
> in this article:****
>
> ****
>
> http://en.wikipedia.org/wiki/Small-signal_model****
>
> ****
>
> Thanks,****
>
> ****
>
> Arpad****
>
> ===========================================================****
>
> ****
>
> *From:* ibis-macro-bounce@xxxxxxxxxxxxx [mailto:
> ibis-macro-bounce@xxxxxxxxxxxxx] *On Behalf Of *James Zhou
> *Sent:* Tuesday, January 17, 2012 5:25 PM
> *To:* wkatz@xxxxxxxxxx; IBIS-ATM
> *Subject:* [ibis-macro] Re: Replacing BIRD 122 with "Reserved_Model"
> keyword in [External Model]****
>
> ****
>
> Hi Walter, ****
>
> ****
>
> Please see my comments and questions below: ****
>
> ****
>
> (1) "This implies that AMI modeling assumes a small signal interface to
> the analog channel." ****
>
> Can you please clarify the meaning of "a small signal interface"? The only
> necessary assumption when representing a channel using impulse response is
> that the channel must be LTI. ****
>
> ****
>
> (2) "This also implies that the differential impedance of a Tx or Rx is
> constant over the operating range of the device."****
>
> There are several possible cases of "impedance of a Tx or Rx". It could be
> the input or, the output or, the load impedance of Tx analog block. Please
> clarify which one is referred to by this statement. Same questions exist
> for Rx. ****
>
> ****
>
> Thanks,****
>
> James Zhou****
>
> QLogic Corp.****
>
> ****
>
> ****
>
> ****
>
> ****
>
> ****
>
> *From:* ibis-macro-bounce@xxxxxxxxxxxxx
> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] *On Behalf Of *Walter Katz
> *Sent:* Tuesday, January 17, 2012 1:16 PM
> *To:* IBIS-ATM
> *Subject:* [ibis-macro] Replacing BIRD 122 with "Reserved_Model" keyword
> in [External Model]****
>
> ****
>
> All,****
>
> ****
>
> I would like to extend BIRD 116 to allow the following for AMI [Model]s***
> *
>
> ****
>
> [External Model]****
>
> Language ISS****
>
> Reserved_ModelAMI_Tstonefile_Tx|AMI_Tstonefile_Rx|AMI_Thevenin_Tx|AMI_Thevenin_Rx
> ****
>
> [End External Model]****
>
> ****
>
> AMI modeling assumes that a channel can be represented by an Impulse
> Response. This implies that AMI modeling assumes a small signal interface
> to the analog channel. This also implies that the differential impedance of
> a Tx or Rx is constant over the operating range of the device. Note that
> any legacy IBIS model (IV, Vt curves, Series Pin), that when used in the
> real operating range of a SerDes channel (where AMI modeling is applicable)
> can be accurately represented by the following Thevenin Tx and Rx models.
> ****
>
> ****
>
> ****
>
> *Reserved_Model AMI_Tstonefile_Tx*****
>
> [External Model] ****
>
> Language ISS ****
>
> Reserved_Model AMI_Tstonefile_Tx****
>
> [End External Model]****
>
> ****
>
> Is equivalent to:****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Corner Typ AMI_Tstonefile_Tx.cir AMI_Tstonefile_Tx****
>
> Parameters Tstonefile = AMIfile(Tstonefile) | Tstonefile must be an AMI
> Model_Specific parameter****
>
> Converter_Parameters Vhi = AMIfile(Voh) | Voh must be an AMI
> Model_Specific parameter****
>
> Converter_Parameters Vlo = AMIfile(Vol) | Vol is 0 if it is not an AMI
> Model_Specific parameter ****
>
> Converter_Parameters Trf = 1.0ps ****
>
> Ports my_driveP my_driveN A_signal_pos A_signal_neg****
>
> D_to_A D_drive my_driveP 0 Vlo Vhi Trf Trf Typ Non-Inverting ****
>
> D_to_A D_drive my_driveN 0 Vlo Vhi Trf Trf Typ Inverting ****
>
> [End External Model]****
>
> ****
>
> AMI_Tstonefile_Tx.cir.****
>
> ****
>
> .SUBCKT AMI_Tstonefile_Tx my_driveP my_driveN A_signal_pos A_signal_neg **
> **
>
> + Tstonefile=“NA.s4p” ****
>
> Sdriver my_driveP my_driveN A_signal_pos A_signal_neg 0 MNAME=Smodel_name*
> ***
>
> .MODEL Smodel_name S N=4 TSTONEFILE=Tstonefile****
>
> .ends****
>
> ****
>
> ****
>
> *Reserved_Model AMI_Tstonefile_Rx*****
>
> ****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Reserved_Model AMI_Tstonefile_Rx****
>
> [End External Model]****
>
> ****
>
> Is equivalent to:****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Corner Typ AMI_Tstonefile_Rx.cir AMI_Tstonefile_Rx****
>
> Parameters Tstonefile = AMIfile(Tstonefile) ****
>
> Ports A_signal_pos A_signal_neg A_int_pos A_int_neg****
>
> A_to_D D_receive A_int_pos A_int_neg -.02 .02 Typ****
>
> [End External Model]****
>
> ****
>
> AMI_Tstonefile_Rx.cir.****
>
> ****
>
> .SUBCKT AMI_Tstonefile_Rx A_signal_pos A_signal_neg A_int_pos A_int_neg **
> **
>
> + Tstonefile=“NA.s4p” ****
>
> Sdriver A_signal_pos A_signal_neg A_int_pos A_int_neg 0 MNAME=Smodel_name
> ** **
>
> .MODEL Smodel_name S N=4 TSTONEFILE=Tstonefile****
>
> .ends****
>
> ****
>
> ****
>
> *Reserved_Model AMI_Thevenin_Tx*****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Reserved_Model AMI_Thevenin_Tx****
>
> [End External Model]****
>
> ****
>
> Is equivalent to:****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Corner Typ AMI_*Thevenin*_Tx.cir AMI* Thevenin*_Tx****
>
> Parameters Rt = AMIfile(Rt) ****
>
> Parameters Rs = AMIfile(Rs) ****
>
> Parameters Cc = AMIfile(Cc) ****
>
> Parameters Vt = AMIfile(Vt) ****
>
> Parameters Cac = AMIfile(Cac) ****
>
> Parameters Rac = AMIfile(Rac) ****
>
> Parameters Rd = AMIfile(Rd) ****
>
> Parameters Cd = AMIfile(Cd)****
>
> Parameters Trf = AMIfile(Trf)****
>
> | Only AMI Model_Specific parameters Rt Rs Cc Vt Cac Rac Rd Cd defined in
> the ****
>
> | .ami file shall be passed as parameters to the subckt AMI* Thevenin*_Tx
> instance****
>
> Converter_Parameters Vhi = AMIfile(Voh) | Voh must be an AMI
> Model_Specific parameter****
>
> Converter_Parameters Vlo = AMIfile(Vol) | Vol is 0 if it is not an AMI
> Model_Specific parameter ****
>
> Converter_Parameters Trf = AMIfile(Trf) | Trf is 1p if it is not an AMI
> Model_Specific parameter ****
>
> Ports my_driveP my_driveN A_signal_pos A_signal_neg****
>
> D_to_A D_drive my_driveP 0 Vlo Vhi Trf Trf Typ Non-Inverting ****
>
> D_to_A D_drive my_driveN 0 Vlo Vhi Trf Trf Typ Inverting ****
>
> [End External Model]****
>
> ****
>
> AMI_*Thevenin*_Tx.cir****
>
> ****
>
> .SUBCKT AMI_*Thevenin*_Tx my_driveP my_driveN A_signal_pos A_signal_neg **
> **
>
> + Rt=1Meg Rs=1Meg Cc=0. Vt=0. Cac=0. Rac=1Meg Rd=1Meg Cd=0.****
>
> E_H E_my_driveP 0 VCVS my_driveP 0 1.****
>
> E_L E_my_driveN 0 VCVS my_driveN 0 1.****
>
> R_Rs_H E_my_driveP A_signal_pos R=’Rs’****
>
> R_Rs_L E_my_driveN A_signal_neg R=’Rs’****
>
> R_Rd A_signal_pos A_signal_neg R=’Rd’****
>
> C_Rd A_signal_pos A_signal_neg C=’Cd’****
>
> R_Rt_H A_signal_pos Vt R=’Rt’****
>
> R_Rt_H A_signal_neg Vt R=’Rt’****
>
> V_Vt Vt 0 DC=’Vt’****
>
> C_Cc_H A_signal_pos 0 C=’Cc’****
>
> C_CC_L A_signal_neg 0 C=’Cc’****
>
> R_ac A_signal_pos Nac R=’Rac’****
>
> C_ac A_signal_neg Nac C=’Cac’****
>
> .ends ****
>
> ****
>
> ****
>
> ****
>
> *Reserved_Model AMI_Thevenin_Rx*****
>
> ****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Reserved_Model AMI_Thevenin_Rx****
>
> [End External Model]****
>
> ****
>
> Is equivalent to:****
>
> ****
>
> ****
>
> [External Model] ****
>
> Language ISS ****
>
> Corner Typ *AMI_Thevenin_Rx*.cir *AMI_Thevenin_Rx*****
>
> Parameters Rt = AMIfile(Rt) ****
>
> Parameters Cc = AMIfile(Cc) ****
>
> Parameters Vt = AMIfile(Vt) ****
>
> Parameters Cac = AMIfile(Cac) ****
>
> Parameters Rac = AMIfile(Rac) ****
>
> Parameters Rd = AMIfile(Rd) ****
>
> Parameters Cd = AMIfile(Cd)****
>
> |Only AMI Model_Specific parameters Rt Cc Vt Cac Rac Rd Cd defined in the
> ****
>
> |.ami file shall be passed as parameters to the subckt AMI* Thevenin*_Tx
> instance****
>
> Ports A_signal_pos A_signal_neg A_int_pos A_int_neg****
>
> A_to_D D_receive A_int_pos A_int_neg -.02 .02 Typ****
>
> [End External Model]****
>
> [External Model] ****
>
> ****
>
> ****
>
> *AMI_Thevenin_Rx*.cir.****
>
> ****
>
> .subckt *AMI_Thevenin_Rx* A_signal_pos A_signal_neg A_int_pos A_int_neg **
> **
>
> + Rt=1Meg Cc=0. Vt=0. Cac=0. Rac=1Meg Rd=1Meg Cd=0.****
>
> E_H A_int_pos 0 VCVS A_signal_pos 0 1.****
>
> E_L A_int_neg 0 VCVS A_signal_neg 0 1.****
>
> R_Rd A_signal_pos A_signal_neg R=’Rd’****
>
> C_Rd A_signal_pos A_signal_neg C=’Cd’****
>
> R_Rt_H A_signal_pos Vt R=’Rt’****
>
> R_Rt_H A_signal_neg Vt R=’Rt’****
>
> V_Vt Vt 0 DC=’Vt’****
>
> C_Cc_H A_signal_pos 0 C=’Cc’****
>
> C_CC_L A_signal_neg 0 C=’Cc’****
>
> R_ac A_signal_pos Nac R=’Rac’****
>
> C_ac A_signal_neg Nac C=’Cac’****
>
> .ends ****
>
> ****
>
> Walter Katz****
>
> wkatz@xxxxxxxxxx****
>
> Phone 303.449-2308****
>
> Mobile 720.333-1107****
>
> ****
>
> ****
> ------------------------------
>
> This message and any attached documents contain information from QLogic
> Corporation or its wholly-owned subsidiaries that may be confidential. If
> you are not the intended recipient, you may not read, copy, distribute, or
> use this information. If you have received this transmission in error,
> please notify the sender immediately by reply e-mail and then delete this
> message.****
>
> ** **
> ------------------------------
>
> This message and any attached documents contain information from QLogic
> Corporation or its wholly-owned subsidiaries that may be confidential. If
> you are not the intended recipient, you may not read, copy, distribute, or
> use this information. If you have received this transmission in error,
> please notify the sender immediately by reply e-mail and then delete this
> message.****
>
> ------------------------------
> This message and any attached documents contain information from QLogic
> Corporation or its wholly-owned subsidiaries that may be confidential. If
> you are not the intended recipient, you may not read, copy, distribute, or
> use this information. If you have received this transmission in error,
> please notify the sender immediately by reply e-mail and then delete this
> message.
>
--
Scott McMorrow
Teraspeed Consulting Group LLC
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Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
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