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simple RC circuit

Sali over 11 years ago

Dear all,

Can some one help me to understand why the voltage at time zero drops to a value less than 1 V?

Please check the attached file.

Thanks,

Parents

Sali over 11 years ago

Thanks Marc for your help.
I'm reading now the log file, in the mean while I copied it below:

Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator
Version 7.2.0.109 64bit -- 6 Dec 2009
Copyright (C) 1989-2009 Cadence Design Systems, Inc. All rights reserved worldwide. Cadence, Virtuoso and Spectre are registered trademarks of Cadence Design Systems, Inc. All others are the property of their respective holders.
Protected by U.S. Patents:
        5,610,847; 5,790,436; 5,812,431; 5,859,785; 5,949,992; 5,987,238;
        6,088,523; 6,101,323; 6,151,698; 6,181,754; 6,260,176; 6,278,964;
        6,349,272; 6,374,390; 6,493,849; 6,504,885; 6,618,837; 6,636,839;
        6,778,025; 6,832,358; 6,851,097; 6,928,626; 7,024,652; 7,035,782;
        7,085,700; 7,143,021; 7,493,240; 7,571,401.
Includes RSA BSAFE(R) Cryptographic or Security Protocol Software from RSA Security, Inc.

Simulating `input.scs' on odin.doe.carleton.ca at 12:14:21 PM, Tue Apr 1, 2014 (process id: 24095).
Environment variable:
    SPECTRE_DEFAULTS=-I/CMC/kits/cmosp13.V1.8.0.0DM/IBM_PDK/cmrf8sf/V1.8.0.4DM/Spectre/models -f psfbin
Command line:
     \
        /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/spectre/bin/64bit/spectre \
        input.scs +escchars +log ../psf/spectre.out +inter=mpsc \
        +mpssession=spectre0_23761_1 -format sst2 -raw ../psf \
        -I/CMC/kits/cmosp13.V1.8.0.0DM/IBM_PDK/cmrf8sf/V1.8.0.4DM/Spectre/models \
        +lqtimeout 900 -maxw 5 -maxn 5
spectre pid = 24095
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libinfineon_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libphilips_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libsparam_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libstmodels_sh.so ...
Auto-loading AHDL component.
Finished loading AHDL component in 0 s (elapsed).
Installed AHDL simulation interface.
Circuit inventory:
              nodes 2
          capacitor 1
           resistor 1
            vsource 1
Time for parsing: CPU = 218.965 ms, elapsed = 828.433 ms.
Time accumulated: CPU = 218.965 ms, elapsed = 828.433 ms.
Peak resident memory used = 54.7 Mbytes.
Entering remote command mode using MPSC service (spectre, ipi, v0.0, spectre0_23761_1, ).
*************************************************
Transient Analysis `tran': time = (0 s -> 200 ns)
*************************************************
Notice from spectre during IC analysis, during transient analysis `tran'.
    C0: Initial condition computed for node net04 is in error by 909.091 mV.
        Decrease `rforce' to reduce error in computed initial conditions. However, setting rforce too small may result in convergence difficulties or in the matrix becoming singular.
Important parameter values:
    start = 0 s
    outputstart = 0 s
    stop = 200 ns
    step = 200 ps
    maxstep = 4 ns
    ic = all
    skipdc = no
    reltol = 1e-03
    abstol(I) = 1 pA
    abstol(V) = 1 uV
    temp = 27 C
    tnom = 25 C
    tempeffects = all
    errpreset = moderate
    method = traponly
    lteratio = 3.5
    relref = sigglobal
    cmin = 0 F
    gmin = 1 pS
    tran: time = 8.095 ns    (4.05 %), step = 4 ns            (2 %)
    tran: time = 16.1 ns     (8.05 %), step = 4 ns            (2 %)
    tran: time = 28.1 ns       (14 %), step = 4 ns            (2 %)
    tran: time = 36.1 ns       (18 %), step = 4 ns            (2 %)
    tran: time = 48.1 ns       (24 %), step = 4 ns            (2 %)
    tran: time = 56.1 ns       (28 %), step = 4 ns            (2 %)
    tran: time = 68.1 ns       (34 %), step = 4 ns            (2 %)
    tran: time = 76.1 ns       (38 %), step = 4 ns            (2 %)
    tran: time = 88.09 ns      (44 %), step = 4 ns            (2 %)
    tran: time = 96.09 ns      (48 %), step = 4 ns            (2 %)
    tran: time = 108.1 ns      (54 %), step = 4 ns            (2 %)
    tran: time = 116.1 ns      (58 %), step = 4 ns            (2 %)
    tran: time = 128.1 ns      (64 %), step = 4 ns            (2 %)
    tran: time = 136.1 ns      (68 %), step = 4 ns            (2 %)
    tran: time = 148.1 ns      (74 %), step = 4 ns            (2 %)
    tran: time = 156.1 ns      (78 %), step = 4 ns            (2 %)
    tran: time = 168.1 ns      (84 %), step = 4 ns            (2 %)
    tran: time = 176.1 ns      (88 %), step = 4 ns            (2 %)
    tran: time = 188.1 ns      (94 %), step = 4 ns            (2 %)
    tran: time = 196.1 ns      (98 %), step = 4 ns            (2 %)
Number of accepted tran steps =             61
Initial condition solution time: CPU = 1 ms, elapsed = 256.062 us.
Intrinsic tran analysis time:    CPU = 2 ms, elapsed = 3.15404 ms.
Total time required for tran analysis `tran': CPU = 4 ms, elapsed = 8.13818 ms.
Time accumulated: CPU = 224.965 ms, elapsed = 1.01592 s.
Peak resident memory used = 59.1 Mbytes.
finalTimeOP: writing operating point information to rawfile.
modelParameter: writing model parameter values to rawfile.
element: writing instance parameter values to rawfile.
outputParameter: writing output parameter values to rawfile.
designParamVals: writing netlist parameters to rawfile.
primitives: writing primitives to rawfile.
subckts: writing subcircuits to rawfile.
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Reply

Sali over 11 years ago

Thanks Marc for your help.
I'm reading now the log file, in the mean while I copied it below:

Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator
Version 7.2.0.109 64bit -- 6 Dec 2009
Copyright (C) 1989-2009 Cadence Design Systems, Inc. All rights reserved worldwide. Cadence, Virtuoso and Spectre are registered trademarks of Cadence Design Systems, Inc. All others are the property of their respective holders.
Protected by U.S. Patents:
        5,610,847; 5,790,436; 5,812,431; 5,859,785; 5,949,992; 5,987,238;
        6,088,523; 6,101,323; 6,151,698; 6,181,754; 6,260,176; 6,278,964;
        6,349,272; 6,374,390; 6,493,849; 6,504,885; 6,618,837; 6,636,839;
        6,778,025; 6,832,358; 6,851,097; 6,928,626; 7,024,652; 7,035,782;
        7,085,700; 7,143,021; 7,493,240; 7,571,401.
Includes RSA BSAFE(R) Cryptographic or Security Protocol Software from RSA Security, Inc.

Simulating `input.scs' on odin.doe.carleton.ca at 12:14:21 PM, Tue Apr 1, 2014 (process id: 24095).
Environment variable:
    SPECTRE_DEFAULTS=-I/CMC/kits/cmosp13.V1.8.0.0DM/IBM_PDK/cmrf8sf/V1.8.0.4DM/Spectre/models -f psfbin
Command line:
     \
        /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/spectre/bin/64bit/spectre \
        input.scs +escchars +log ../psf/spectre.out +inter=mpsc \
        +mpssession=spectre0_23761_1 -format sst2 -raw ../psf \
        -I/CMC/kits/cmosp13.V1.8.0.0DM/IBM_PDK/cmrf8sf/V1.8.0.4DM/Spectre/models \
        +lqtimeout 900 -maxw 5 -maxn 5
spectre pid = 24095
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libinfineon_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libphilips_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libsparam_sh.so ...
Loading /CMC/tools/cadence/MMSIM_07.20.109_lnx86/tools.lnx86/cmi/lib/64bit/5.0/libstmodels_sh.so ...
Auto-loading AHDL component.
Finished loading AHDL component in 0 s (elapsed).
Installed AHDL simulation interface.
Circuit inventory:
              nodes 2
          capacitor 1
           resistor 1
            vsource 1
Time for parsing: CPU = 218.965 ms, elapsed = 828.433 ms.
Time accumulated: CPU = 218.965 ms, elapsed = 828.433 ms.
Peak resident memory used = 54.7 Mbytes.
Entering remote command mode using MPSC service (spectre, ipi, v0.0, spectre0_23761_1, ).
*************************************************
Transient Analysis `tran': time = (0 s -> 200 ns)
*************************************************
Notice from spectre during IC analysis, during transient analysis `tran'.
    C0: Initial condition computed for node net04 is in error by 909.091 mV.
        Decrease `rforce' to reduce error in computed initial conditions. However, setting rforce too small may result in convergence difficulties or in the matrix becoming singular.
Important parameter values:
    start = 0 s
    outputstart = 0 s
    stop = 200 ns
    step = 200 ps
    maxstep = 4 ns
    ic = all
    skipdc = no
    reltol = 1e-03
    abstol(I) = 1 pA
    abstol(V) = 1 uV
    temp = 27 C
    tnom = 25 C
    tempeffects = all
    errpreset = moderate
    method = traponly
    lteratio = 3.5
    relref = sigglobal
    cmin = 0 F
    gmin = 1 pS
    tran: time = 8.095 ns    (4.05 %), step = 4 ns            (2 %)
    tran: time = 16.1 ns     (8.05 %), step = 4 ns            (2 %)
    tran: time = 28.1 ns       (14 %), step = 4 ns            (2 %)
    tran: time = 36.1 ns       (18 %), step = 4 ns            (2 %)
    tran: time = 48.1 ns       (24 %), step = 4 ns            (2 %)
    tran: time = 56.1 ns       (28 %), step = 4 ns            (2 %)
    tran: time = 68.1 ns       (34 %), step = 4 ns            (2 %)
    tran: time = 76.1 ns       (38 %), step = 4 ns            (2 %)
    tran: time = 88.09 ns      (44 %), step = 4 ns            (2 %)
    tran: time = 96.09 ns      (48 %), step = 4 ns            (2 %)
    tran: time = 108.1 ns      (54 %), step = 4 ns            (2 %)
    tran: time = 116.1 ns      (58 %), step = 4 ns            (2 %)
    tran: time = 128.1 ns      (64 %), step = 4 ns            (2 %)
    tran: time = 136.1 ns      (68 %), step = 4 ns            (2 %)
    tran: time = 148.1 ns      (74 %), step = 4 ns            (2 %)
    tran: time = 156.1 ns      (78 %), step = 4 ns            (2 %)
    tran: time = 168.1 ns      (84 %), step = 4 ns            (2 %)
    tran: time = 176.1 ns      (88 %), step = 4 ns            (2 %)
    tran: time = 188.1 ns      (94 %), step = 4 ns            (2 %)
    tran: time = 196.1 ns      (98 %), step = 4 ns            (2 %)
Number of accepted tran steps =             61
Initial condition solution time: CPU = 1 ms, elapsed = 256.062 us.
Intrinsic tran analysis time:    CPU = 2 ms, elapsed = 3.15404 ms.
Total time required for tran analysis `tran': CPU = 4 ms, elapsed = 8.13818 ms.
Time accumulated: CPU = 224.965 ms, elapsed = 1.01592 s.
Peak resident memory used = 59.1 Mbytes.
finalTimeOP: writing operating point information to rawfile.
modelParameter: writing model parameter values to rawfile.
element: writing instance parameter values to rawfile.
outputParameter: writing output parameter values to rawfile.
designParamVals: writing netlist parameters to rawfile.
primitives: writing primitives to rawfile.
subckts: writing subcircuits to rawfile.
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