eldo_user

Examples
Example 24—Cell Characterization: Setup Time Extraction
* OVERSHOOT NOM: 6.9442E+00
*| Absolute Relative Parameter Parameter Parameter
*| Sensitivity Sensitivity (%/%) Nominal Value Variation Name
*| 1.7559E+06 2.5286E+00 1.00000e-05 1.000e+00% X_OPAMP1.W4
*| -9.2694E+05 -1.3348E+00 1.00000e-05 1.000e+00% X_OPAMP1.W5
*| 9.0192E+04 2.5976E-01 2.00000e-05 1.000e+00% X_OPAMP1.W1
*| -9.1152E+04 -1.5752E-01 1.20000e-05 1.000e+00% X_OPAMP1.W7
*| 3.6566E+04 1.3164E-01 2.50000e-05 1.000e+00% X_OPAMP1.W2
Example 24—Cell Characterization: Setup
Time Extraction
Netlist file: extract_setup_time_passfail.cir
This example shows how to extract the setup time of a D-type flip-flop, using the pass-fail
method of the built-in optimizer in Eldo. This example contains lots of comments to explain the
simulation commands.
Summary of Eldo commands used in this example:
• .OPTIMIZE—Optimize circuit parameters.
• .PARAMOPT—Specifies the optimizer design variables.
• .EXTRACT—Extract characteristics from the simulator results.
Netlist Explanation
xdff out nout in ck nr vss vdd dspc_ff
The above line defines the circuit, a simple flip-flop.
.param tck=20n
.param trf=0.1n
vnr nr 0 pwl 0 ps 1n 0 2n 0 3n ps
vin in 0 pwl 0 0 'tck-ts' 0 'tck-ts+trf' ps
vck ck 0 pwl 0 ps 'tck' ps 'tck+trf' 0
The above lines specify the parameterized input signals, specifically the IN input and the CK
input.
.tran 1n 100n
The above specifies a transient analysis is to be performed lasting 100ns with a plotting
increment of 1ns.
.option eps=2e-8
The above line specifies a tightened accuracy to measure delays in picoseconds. Note that this
value for EPS triggers a (normal) warning 382, stating that the value is unusually small.
1334
Eldo® User's Manual, 15.3