eldo_user

Eldo Control Language
Testbenches
Testbenches
A testbench is a sequence of parameterized simulator commands or circuit element descriptions,
which can be viewed as the encapsulation of a set of commands or element descriptions that are
necessary within a specific context. For example, to perform a slew-rate characterization, it may
be necessary to instantiate the loading capacitor with a certain capacitance value, to define the
slope of a PWL input signal as a specific value, and to run a transient simulation of a certain
duration. These sets of commands can be reused in multiple simulations, and each time the
parameterized parts can receive different values. A complete simulation is defined by
assembling one or more testbenches, typically with the base netlist. This assembly process is
explicit.
This section contains:
Testbench Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 809
Testbench Instantiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811
Rules for Testbench Location Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813
Testbench Definition
A testbench definition starts with the .define_testbench keyword, and finishes with a
.end_define_testbench command. A testbench accepts input arguments. The number of
arguments is not limited; a testbench may have no arguments at all.
Tip
See “.DEFINE_TESTBENCH” in the Eldo Reference Manual.
A testbench is a set of simulator commands or circuit element descriptions that can be
parametrized using the arguments of the testbench.
A testbench can be considered as a user-defined macro. When instantiated, the testbench call is
simply replaced with its content, where all occurrences to testbench arguments are replaced
with their instantiation value.
A testbench may be instantiated in either of the following ways:
• In the netlist (or in another testbench) using a . command,
which then appears as an additional Eldo command in a regular Eldo netlist.
• From the simulation function used in a task (in which case the calling syntax uses
parenthesis and comma-separated arguments—similar to classical programming) to
request to instantiate the testbench into the netlist that will be simulated (see “Defining
and Running Simulations” on page 841).
A testbench may call another testbench defined in the same netlist/file as itself, or in another
netlist/file (as long as it is included in the main netlist with a .INCLUDE or a .LIB command).
Eldo® User's Manual, 15.3 809