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The simulator does a transient response by knowing the voltages and currents at one time and estimating what they would be at a time in the future. There are two important things to determine how close the time in the future is.
The first is how rapidly are drive sources changing. The other is an accuracy thing. You are linearily extrapolating the present voltages and currents interacting with the inductors and capacitors to get the future values.
Usually in a SPICE type simulator you set the maximum time step and the program will go in finer increments if the voltages and currents change rapidly.
When do we define minimum time step as there are maximum and minimum time step to input in the transient analysis in ADS ?
What is the rule of thumb for maximum time step, let say we are going to simulate a circuit at 1Ghz ( =1ns) ,thus we choose the maximum time step to be 0.01ns and simulate for 2ns to get two full cycle.
Any comment ?
such as pspice:
it have a auto default step time,but this default time maybe too small in implement,if it is small,implementation will occur too much CPU time,and very difficult to get simulate result,so you can adjust it by youself!
like they say before it`s depend on the simulator.
however in pspice or hspice you can stablish this parameter how you like it for the tipy of analisis your making, so you can determinate the characteristics of your circuit.
a good seleccionof this time can be the diference between a good or wrong analisis.
when it depends on the simulator you're using, the general form for a transient analisys step size is as follow
.tran time_step final_time initial_time max_step_size
(this form is formo pspice hspice)
(and you also can define to use de initial conditions if there)
In Spectre, if u didn't define "step" and "max. step", simulator define these parameters from "stop".
U can get wrong results even for conservative accuracy, if "step" or "max.step" are too big.
So, better to define "step" reference to ur fastest signal change.
Defining small "max.step" is not so good, because sometimes it caose long simulation time.
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