Cadence Mixed-Signal Circuit Design Environment User Guide
Obtaining an Initial Solution
October 2003
183
Product Version 5.0
Initialization Method
For the initialization (or reset) method, create the mixed-signal stimuli as shown in the
following figure.
The stimuli should initialize both analog and digital circuitry and drive the design into the
starting solution at time
t_reset
and to the final solution at time
t_final
.
The stimuli is divided into two parts: time
t_zeroplus
(t_0+) to
t_reset
is the reset
stimuli, and time
t_reset
to
t_final
is the transient test stimuli.
The initialization method lets you run many simulations using the same reset stimuli but
different transient test stimuli.
The reset stimuli should drive the design into the reset state so that the simulation result
obtained from the transient test stimuli is not dependent on random initial conditions. Applying
transient stimuli after initializing the design with random or ambiguous states (X-states), can
cause logic cycles--oscillations in a loop of logic circuits.
To use the initialization method
1. Set
VMX_DC_INTERVAL
to 0 and
VMX_MAX_DC_ITER
to 0.
This prevents the circuit simulator and the logic simulator from performing a DC
relaxation loop.
t_0+
t_reset
t_final
Time
Stimuli
application
Design
Solution
Reset stimuli
Transient test stimuli
Initial
solution
Reset
solution
Final transient
solution
Summary :
Cadence Mixed-Signal Circuit Design Environment User Guide Obtaining an Initial Solution October 2003 183 Product Version 5.0 Initialization Method For the initialization (or reset) method, create the mixed-signal stimuli as shown in the following figure. t_0+ t_reset t_final Time Stimuli application Design Solution Reset stimuli Transient test stimuli Initial solution Reset solution Final transient solution
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solution,reset,transient,time,design,initialization,test,method,treset,tfinal,logic,initial,into