Stats

  • Locked Locked
  • Replies 10
  • Subscribers 125
  • Views 19845
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Transient and DC operating point are different

BaaB

Hi,

I just run DC and transient analyses to find the operating point. However, the result is different. 

Transient analysis will perform DC analysis first, so should they be equal?

I tried the two separately and the results are different. 

Here is the netlist (if necessary).

// Generated for: spectre
// Generated on: Apr 9 00:29:19 2016
// Design library name: Huan
// Design cell name: Differential_Amp
// Design view name: schematic
simulator lang=spectre
global 0 vdd!
include "/root/Desktop/SaveOpPoint.scs"
parameters x=1
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=dio3
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=dio_dnw
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=dio
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfres_sa
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfmvar
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfind
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rtmom
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_bbmvar
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfesd
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_mim
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfrtmom
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfres_hri
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfres_rpo
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_3vna
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_m
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfmos
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfmim
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfjvar
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_3m
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_res
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_bip3
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_bip
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_3v
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfmos33
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_na
include "/root/TSMC018/tsmc18rf/../models/spectre/rf018.scs" section=tt_rfsbd
include "/root/Desktop/SaveOpPoint.scs"

// Library name: Huan
// Cell name: Differential_Amp
// View name: schematic
R4 (vdd! VP) resistor r=1K
R3 (vdd! VN) resistor r=1K
V3 (net08 net07) vsource dc=600.0m type=dc
V2 (net016 0) vsource dc=x type=dc
V0 (vdd! 0) vsource dc=1.8 type=dc
V6 (Vin2 net016) vsource mag=1 type=sine ampl=1m sinephase=180 freq=1M
V5 (Vin net016) vsource mag=1 type=sine ampl=1m sinephase=0 freq=1M
I11 (VS 0) isource dc=1.6m type=dc
M3 (net015 net08 net07 net07) nch l=180n w=2u m=50 ad=5.4e-13 as=5.568e-13 \
pd=2.54u ps=2.6368u nrd=0.135 nrs=0.135
M1 (VP Vin2 VS VS) nch l=180n w=2u m=50 ad=5.4e-13 as=5.568e-13 pd=2.54u \
ps=2.6368u nrd=0.135 nrs=0.135
M0 (VN Vin VS VS) nch l=180n w=2u m=50 ad=5.4e-13 as=5.568e-13 pd=2.54u \
ps=2.6368u nrd=0.135 nrs=0.135
simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=27 \
tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" \
checklimitdest=psf
dcOp dc write="spectre.dc" maxiters=150 maxsteps=10000 annotate=status
dcOpInfo info what=oppoint where=rawfile
dc dc param=x start=0 stop=1.8 lin=200 oppoint=rawfile maxiters=150 \
maxsteps=10000 annotate=status
tran tran stop=300u write="spectre.ic" writefinal="spectre.fc" \
annotate=status infotimes=[0] maxiters=5 infoname=tran_Info
finalTimeOP info what=oppoint where=rawfile
tran_Info info what=oppoint where=rawfile
modelParameter info what=models where=rawfile
element info what=inst where=rawfile
outputParameter info what=output where=rawfile
designParamVals info what=parameters where=rawfile
primitives info what=primitives where=rawfile
subckts info what=subckts where=rawfile
saveOptions options save=allpub

Parents

  • Thank you.

    As you said last time I also checked the DC sources value and time-zero value and they are equal.

    I've just checked operating points from two files as you said. However, in my case, these files don't have current info. 

    What I see the difference is currents through M0 and M1 in two cases.

    DC analysis: iM0 = iM1 = 800.026uA

    Tran analysis: iM0=800.002uA and iM1=799.999uA

    I got this by running each analysis separately and then from ADE print operating points.

Reply

  • Thank you.

    As you said last time I also checked the DC sources value and time-zero value and they are equal.

    I've just checked operating points from two files as you said. However, in my case, these files don't have current info. 

    What I see the difference is currents through M0 and M1 in two cases.

    DC analysis: iM0 = iM1 = 800.026uA

    Tran analysis: iM0=800.002uA and iM1=799.999uA

    I got this by running each analysis separately and then from ADE print operating points.

Children
No Data

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.