Analog IC design HowTo's
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Introduction
How to change the default simulation results and saved states directories
By default, all simulation data and results are stored in a ~/simulation
directory automatically created
in your home directory the first time you run a simulation with Cadence IC.
Similarly, Cadence simulation states by default are saved in a ~/.artist_states
hidden directoryautomatically created
in your home directory.
To change these defaults, just use in your home ~/.cdsinit
or ~/.cdsinit_personal
files the following directives:
envSetVal("asimenv.startup" "projectDir" 'string "/path/to/your/custom/simulation/results/directory") envSetVal("asimenv" "saveDir" 'string "/path/to/your/custom/simulation/states/directory")
You can also issue these statements at the CIW command prompt.
See also
http://www.cadence.com/Community/forums/p/17009/1179512.aspx
How to disable the annoying 'beep' sound
Solo pe rla sessione corrente:
CIW ⇒ Options ⇒ User Preferences…
poi nel Command Controls tab c'e' la Beep Volume section
Altrimenti si customizza l'environment editanto il .cdsinit
How to evaluate the power consumption
A detailed Wiki page about this topic has been created, please refer to Power consumption evaluation in Cadence.
How to use SPICE transistor models
How to define the default circuit simulator for ADE
To set the default simulator, e.g. as Spectre, enter the following environment variable in your .cdsenv or .cdsinit file. Syntax to set the default simulator in the .cdsenv
asimenv.startup simulator string "spectre"
Syntax to set the default simualtor in the .cdsinit
envSetVal("asimenv.startup" "simulator" 'string "spectre")
How to set the default models path for Spectre
Syntax to set the default model path in the .cdsenv
spectre.envOpts modelPath string "<pathTo>/myModelFile;section"
Syntax to set the default model path in the .cdsinit
envSetVal("spectre.envOpts" "modelPath" 'string "<pathTo>/myModelFile;section")
Creating a parameterized cell
How to save DC Operating Points’ Parameters of a MOSFET
How to evaluate rise time, delays etc.
riseTime(.....)
delay(......)
Example: Time-over-Threshold
How to make nice looking plots from Cadence
Printing the schematic
How to draw diagonal wires
This is a very useful trick to make your schematics more readable. Diagonal connections are used to draw cross-coupled transistors as in latches and flip-flops.
Press W to begin wiring, then press the F3 key. The Add Wire window will appear.
Change the Draw Mode from the default of “route” to something that allows diagonal or any angle wires.
You can also specify a 45 degree fixed angle with the relative Lock Angle option.
But you can also change between different Draw Modes simply by clicking on the mouse whell or the central mouse button!
See also
http://www.cadence.com/Community/forums/p/16772/1178636.aspx
Performing simulations with HSPICE
Se e' installato
see also here
How to evaluate the total impedance at a node
A detailed Wiki page about this topic has been created, please refer to Node impedance simulation.
How to evaluate the total input/output capacitance of a stage
In ingresso tipicamente e' quella vista sul gate of the input transistor
OP("/M0","cgg")
How to measure the OPAMP slew-rate
Si applica la definizione, mando in ingresso un voltage step e misuro
SR = max{d vout / dt }
ymax(deriv(VT("/out")))
How to choose the proper number of fingers
in potenze di 2, as Manuel dixit?
Create a custom library of ideal building blocks
cd ~/cadence mkdir ideal_blocks cd ideal_blocks mkdir idealLib
poi create a cds.lib with the following directives:
INCLUDE $IC_DIR/tools/dfII/local/cds.lib DEFINE idealLib $HOME/cadence/ideal_blocks/idealLib
poi lanciare virtuoso normalmente