RE: [IBIS-Users]: Using HSPICE to run IBIS model

Arpad,

I think Doug Burns nailed it - no pullup on an IBIS open-drain output.
The fact that the output is rising at all is interesting, but I agree with
his assessment of leakage currents.

Todd.

________________________

Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@sisoft.com
www.sisoft.com

  _____

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Muranyi, Arpad
Sent: Thursday, October 14, 2010 1:06 AM
To: ibis-users@eda.org
Subject: RE: [IBIS-Users]: Using HSPICE to run IBIS model

Bonnie,

I was working at Intel when the B-element and its variants were

added to HSPICE, and I worked quite a lot with the developer to

help him to get it right. I tested a lot of his work before and

after it was released. The various buffer types were all working

correctly as far as I remember. Your problem description doesn't

give me all the details to be able to pinpoint the problem, but I

wonder how do you expect the signal to move up or down when the

buffer turns off its (only) transistor but your circuit doesn't

seem to have a resistive connection to GND or Vcc?

Arpad

=================================================================

  _____

From: Xuefeng Chen [mailto:Xuefeng.Chen@synopsys.com]
Sent: Wednesday, October 13, 2010 11:48 PM
To: Baker, Bonnie; Muranyi, Arpad; ibis-users@eda.org
Subject: RE: [IBIS-Users]: Using HSPICE to run IBIS model

Hi Bonnie,

  I am sure HSPICE supports all kinds of IBIS buffer types except external
model of VERILOG-AMS or VHDL-A(MS).

  From the mail without the ibis file, it’s hard to figure out the issue.
Would you like contact HSPICE related AC or CAE for help.

Thanks,
Xuefeng

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Baker, Bonnie
Sent: 2010年10月14日 11:53
To: Muranyi, Arpad; ibis-users@eda.org
Subject: [IBIS-Users]: Using HSPICE to run IBIS model

I am using Hspice to run IBIS and comparing it to a Spice simulation. The
Spice simulates the buffer well but the Hspice program is having problems.
My buffer type is I/O_open_drain.

The circuit diagram is:

-------------

I/O / R=0.5 L=2,5e-9

Open- /-----------/\/\/\/\-------|------/\_/\_/\_/\---------|---------O
output

Drain / |
|

Buffer / ---

----
------------                              ---   C=1e-12           ----
C=5e-12
                                             |
|
                                         GND                           GND
The I/O buffer is driven with a rail to rail input signal. The output
signal does to reach the rail as expected. It actually looks like:
---------------------expected-output-high---------------------------------
-----------------
_______
                                                       _______/
                                      _______/
                          _____/
                  ___/
            __/
         _/
        /
       /
      /
__/______________________________________________________
I expect
---------------------expected-and-actual-output-high----------------------
----------------------------
                /
               /
              /
             /
            /
           /
          /
         /
        /
       /
      /
__/______________________________________________________
It appears as if Hspice does not recognize the fact that this buffer is
open drain.
Has anyone else experienced this and is the a work around?
The Hspice netlist is:
*
* HSPICED IBIS I/O open drain BUFFER TEST BENCH
* Temperature
.TEMP 27
* POWER SUPPLIES and SIGNAL VOLTAGES
VVCC         VCC         0 DC=VCC
VGND         GND         0 DC=GND
*PARAMETER DEFINITIONS
.PARAM GND = 0V
.PARAM VCC = VCC_typ
.PARAM VCC_typ = 1.8
* Simulation Options
.OPTIONS ACCT ACCURATE NOPAGE OPTS POST SCALE=1e-6
.OPTIONS METHOD=GEAR
 *=========TRANSIENT ANALYSIS sim========
.TRAN 0.1e-9 13000e-9 START =0.0e-9
*                                     TD
VIN_ibis IN_ibis GND PULSE VCC GND 0ps 0.01ns 0.01ns 149.99ns 300n
*******************AC LOAD**************
B_IO nd_pu nd_pd Out_ibis IN_ibis nd_en SDA_signal nd_pc nd_gc
+ file = 'tsc2014_nokia_3.ibs' model = 'SDA_1'
+ typ = typ power = on
+ buffer = 6
+ ramp_fwf=1 ramp_rwf=1
Rpcb   Out_ibis   n1_pcb          0.50
Lpcb   n1_pcb     OUT_pcb_ibis    2.5e-9
Cpcb   n1_pcb    GND              1e-12
Cpcbload  OUT_pcb_ibis     GND       5e-12
Bonnie
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