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IBIS Models Support in Eldo
Buffers
Buffers
IBIS is a modeling technique that provides a simple table-based buffer model for semiconductor
devices. IBIS models can be used to characterize I/V output curves, rising/falling transition
waveforms, and package parasitic information of the device. There are four types of buffer in
IBIS:
• “Single-Ended Buffers” on page 735
• “Pseudo-Differential Buffers” on page 739
• “True Differential Buffers” on page 741
• “Series Buffers” on page 742
IBIS also defines a global list of port names with fixed functionality that can be applied to all
types of buffers. Eldo uses the same port naming and definition for the buffer equivalent
subcircuit. Table 17-1 lists the port names and their descriptions. Port names starting with “A”
are used to define analog ports while those starting with “D” are used to define digital ports.
Table 17-1. List of Predefined Port Names and their Descriptions
Port Name Description
A_signal I/O signal port for a model unit
A_signal_pos Non-inverting port of a differential model
A_signal_neg Inverting port of a differential model
A_pos
Non-inverting port for series or series switch models
A_neg
Inverting port for series or series switch models
A_puref Voltage reference port for pull-up structure
A_pcref Voltage reference port for power clamp structure
A_pdref Voltage reference port for pull-down structure
A_gcref Voltage reference port for ground clamp structure
A_gnd
Global reference voltage port
D_drive Digital input to a model unit
D_enable Digital enable for a model unit
D_receive Digital receive port of a model unit, based on data on A_signal (and/
or A_signal_pos and A_signal_neg)
D_switch Digital input for control of a series switch model
Table 17-2 lists all the available buffer types, assigns a number for each type, lists nodes used
by buffer type, and provides the min/max number needed for each buffer type. “[ ]” is used to
Eldo® User's Manual, 15.3 733