[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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