Simulation references
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Contents
- Typical OCEAN variables used in Front-End designing
Keywords:
To be inserted: closed loop gain simulation and loop stability analysis
e.g. (completo, fatto molto bene)
http://lumerink.com/courses/ECE614/Handouts/
http://lumerink.com/courses/ECE614/Handouts/Loop%Analysis.pdf
http://lumerink.com/courses/ECE614/Handouts/Loop%Stability%Analysis.pdf
Introduction
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.
Reference documentation
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
DC operating points
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.
Analyses overview
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”) |
Power consumption evaluation
How to evaluate the power consumption. A detailed Wiki page about this topic has been created, see here.
ADE simulation options
Importante! soprtattutto a livello di numerical evaluation, serve sapere che esistono dei checks su gmin, etc.
ADE L ⇒ Simulation ⇒ Options ⇒ Analog…
Node impedance simulation
How to evaluate the total impedance at a node. A detailed Wiki page about this topic has been created, see here.
PWL voltage and current sources
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.
Noise analyses
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))