Simulation references

Contents

In this page we give a detailed description of a few common simulation tasks (e.g. power consumption evaluation in Cadence) which can be encountered during the analog design activity.

Spectre ssimulator official documentation! Si impara praticamente tutto!

Attenzione pero' che e' sotto MMSIM (Multi-Mode Simulation) package!

Spectre User Guide and Spectre Reference Guide

/usr/cadence/MMSIM_10.11/doc/spectreuser/spectreuser.pdf

/usr/cadence/MMSIM_10.11/doc/spectreref/spectreref.pdf

MOS transistor parameters evaluated from the transistor model, typically some version of the BSIM4 model.

ADE L ⇒ Results ⇒ Print ⇒ DC Operating Points

Quali DOP vengono elencati dipende poi dal modello! I DC op. poiints piu' importanti sono:

Parameter Description
betaeff
gds
gm
id
ids
region
ron
vds
vdsat
vgs
vth


betaeff


gmoverid

etc.

breve rassegna di cosa vuol dire simualre

DC, TRAN, AC etc.

Calculator Description OCEAN syntax example
vt wire transient voltage VT(“/out”)
it node transient current IT(“/M1/D”)
vf wire AC sweep voltage VF(“/Vin”)
if node AC sweep current IF(“/C0/MINUS”)
vdc wire DC voltage VDC(“/vdd_disc”)
idc node DC current IDC(“/V0/PLUS”)
vs wire DC sweep voltage VS(“/net012”)
is node DC sweep current IS(“/R1/PLUS”)
op instance DC operating point OP(“M0”,“gm”)
opt instance transient DC operating point OPT(“M0”,“vth”)
var design variable VAR(“Ibias”)
mp instance model parameter MP(“M0”,“vtho”)

How to evaluate the power consumption. A detailed Wiki page about this topic has been created, see here.

Importante! soprtattutto a livello di numerical evaluation, serve sapere che esistono dei checks su gmin, etc.

ADE L ⇒ Simulation ⇒ Options ⇒ Analog…

How to evaluate the total impedance at a node. A detailed Wiki page about this topic has been created, see here.

piecewise linear (PWL)

Vpwl (piece-wise linear) to be used in transient simulations.

Values can be also specified into a plain text file and then using a Vpwlf voltage source, which takes file values and convert them to a standard Vpwl source.

analogLib ⇒ Sources ⇒ Independent ⇒ Vpwlf

The syntax is a column of time values and a column of voltage or current values,

t0   vo
t1   v1
t2   v2
...  ...

Specify the full path to the file or copy it in the same directory of the netlist

cd ~/scratch/<tech_dir>/data
mkdir vpwlf

Notare che posso anche passare il nome del file ad ADE come variabile, usare

pPar("filename")

nel CDF parameter dell'istanza.

http://www.cadence.com/Community/forums/t/23078.aspx

Both standard AC noise analysis and transient noise analysis. Click

here.

Typical OCEAN variables used in Front-End designing


Delta-like input current spike

Use an ipulse current source with a trapezoidal shape Let w be rise time, pulse width and fall time of the current pulse (e.g. 1ns), then set i2 to

Qin*1.6e-19/(2*w)

with Qin expressed as the number of electrons.


Equivalent Noise Charge (ENC)


Time over threshold (ToT)

Define a ToT output variable in ADE L with the usage of the cross() OCEAN function,

(cross(VT("/Vout_comp") 0.3 1 "falling" nil nil) - cross(VT("/Vout_comp") 0.3 1 "rising" nil nil))



Last update: Luca Pacher - Sep 25, 2013

  • vlsi/workbook/analog/simref.txt
  • Ultima modifica: 25/03/2014 21:26
  • da pacher