[ibis-macro] [Model] and [external Model] Voltage Levels
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "IBIS-ATM" <ibis-macro@xxxxxxxxxxxxx>
- Date: Sat, 27 Apr 2013 14:23:23 -0400 (EDT)
All,
IBIS 5.1 says (p 95):
The rules for pad connections with [External Model] are identical to those
for [Model]. The [Pin Mapping] keyword may be used with [External Model]s
but is not required. If used, the [External Model] specific voltage
supply ports-A_puref, A_pdref, A_gcref, A_pcref, and A_extref-are
connected as defined under the [Pin Mapping] keyword. In all cases, the
voltage levels connected on the reserved supply ports are defined by the
[Power Clamp Reference], [GND Clamp Reference], [Pullup Reference],
[Pulldown Reference], and/or [Voltage Range] keywords, as in the case of
[Model].
Does this mean that the subckt generate A_puref, or the EDA tool must
supply a DC voltage source with value [Voltage Range] ([Pullup
Reference]). In a power aware simulation in only makes sense that the EDA
Tool supply a signal to A_puref with a value ~[Voltage Range]. Arpad
claims that the [External Model] subckt can either consume A_puref or
generate A_puref.
On page 45 it says:
Keyword: [Voltage Range]
Required: Yes, if [Pullup Reference], [Pulldown Reference], [POWER
Clamp Reference], and [GND Clamp Reference] are not present
Description: Defines the power supply voltage tolerance over which the
model is intended to operate. It also specifies the default voltage rail
to which the [Pullup] and [POWER Clamp] I-V data is referenced.
This implies that the EDA tool supplies the Pullup Voltage in the range of
typ min max. But of course this says than a Max (Fast) simulation cannot
supply more than max, and a Min simulation cannot supply less than min,
but this make no sense if there is fluctuations of the reference voltage.
So we clearly cannot use [External Model] to do power simulations since
the PuRef must be fixed.
Arpad's statement in the Interconnect meeting that an External Model can
either consume or generate the PuRef without an indication to the EDA tool
of what it is going to do. The HSPICE B element has a switch to do it
either way. External Model does not define such a switch.
Walter
Walter Katz
wkatz@xxxxxxxxxx
Phone 303.449-2308
Mobile 303.335-6156
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