jszair
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Hi, I'm simulating a ota with capacitance feedback and run into convergence problem in transient analysis. DC analysis is fine. The following are simulation reports, any suggestion?
Report part 1 --------------------------------------------------------------------------------
Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator Version 6.2.1.170 -- 10 Feb 2008 Copyright (C) 1989-2007 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.
Includes RSA BSAFE(R) Cryptographic or Security Protocol Software from RSA Security, Inc.
Simulating `input.scs' on princess.ece.utexas.edu at 12:43:23 PM, Wed Jul 7, 2010. Command line: \ /usr/local/packages/cadence_2007/mmsim/tools.lnx86/spectre/bin/32bit/spectre \ input.scs +escchars +log ../psf/spectre.out +inter=mpsc \ +mpssession=spectre0_22309_8 -format sst2 -raw ../psf \ +lqtimeout 900 -maxw 5 -maxn 5 spectre pid = 23836
Loading /usr/local/packages/cadence_2007/mmsim/tools.lnx86/cmi/lib/5.0/libinfineon_sh.so ... Loading /usr/local/packages/cadence_2007/mmsim/tools.lnx86/cmi/lib/5.0/libnortel_sh.so ... Loading /usr/local/packages/cadence_2007/mmsim/tools.lnx86/cmi/lib/5.0/libphilips_sh.so ... Loading /usr/local/packages/cadence_2007/mmsim/tools.lnx86/cmi/lib/5.0/libsparam_sh.so ... Loading /usr/local/packages/cadence_2007/mmsim/tools.lnx86/cmi/lib/5.0/libstmodels_sh.so ... Using new Spectre Parser.
Warning from spectre during initial setup. WARNING (CMI-2426): I0.I3.M4: `Pdiblc2' = -10e-06 is negative. WARNING (CMI-2426): I0.I3.M5: `Pdiblc2' = -10e-06 is negative. WARNING (CMI-2426): I0.I3.M6: `Pdiblc2' = -10e-06 is negative. WARNING (CMI-2426): I0.I3.M7: `Pdiblc2' = -10e-06 is negative. WARNING (CMI-2426): I0.I2.M7: `Pdiblc2' = -10e-06 is negative. Further occurrences of this warning will be suppressed. Notice from spectre during topology check. Only one connection to the following 2 nodes: net051 net058 No DC path from node `net051' to ground, Gmin installed to provide path.
Circuit inventory: nodes 84 equations 104 bsim3v3 82 capacitor 6 isource 1 resistor 10 transformer 4 vcvs 9 vsource 7
Warning from spectre. WARNING (SPECTRE-6006): 71 warnings suppressed.
Entering remote command mode using MPSC service (spectre, ipi, v0.0, spectre0_22309_8, ).
************************************************ Transient Analysis `tran': time = (0 s -> 10 us) ************************************************ Trying `homotopy = gmin' for initial conditions. Trying `homotopy = source' for initial conditions. Trying `homotopy = dptran' for initial conditions. Important parameter values: start = 0 s outputstart = 0 s stop = 10 us step = 10 ns maxstep = 200 ns ic = all skipdc = no reltol = 1e-03 abstol(V) = 1 uV abstol(I) = 1 pA temp = 27 C tnom = 27 C tempeffects = all errpreset = moderate method = traponly lteratio = 3.5 relref = sigglobal cmin = 0 F gmin = 1 pS maxrsd = 0 Ohm mos_method = s mos_vres = 50 mV
Error found by spectre at time = 9.75307 ns during transient analysis `tran'. ERROR (SPECTRE-16192): No convergence achieved with the minimum time step specified. Last acceptable solution computed at 9.75307 ns.
The values for those nodes that did not converge on the last Newton iteration are given below. The manner in which the convergence criteria were not satisfied is also given. Failed test: | Value | > RelTol*Ref + AbsTol
I(V0:p) = 20.6083 A, previously 5.98046 A. update too large: | -14.989 A | > 20.6083 mA + 1 pA I(V2:p) = 2.14192 A, previously 621.687 mA. update too large: | -1.55777 A | > 2.14192 mA + 1 pA I(I0.I1.I4.E2:p) = -46.5438 A, previously -13.5091 A. update too large: | 33.8504 A | > 46.5438 mA + 1 pA I(I0.I2.I2.E2:p) = 27.7649 A, previously 8.06592 A. update too large: | -20.1853 A | > 27.7649 mA + 1 pA I(I0.I3.I2.E2:p) = -620.767 A, previously -180.165 A. update too large: | 451.48 A | > 620.767 mA + 1 pA I(I0.V0:p) = -13.1749 A, previously -3.83602 A. update too large: | 9.56953 A | > 13.1749 mA + 1 pA I(I2.K0:t1) = -6.22303 A, previously -1.80596 A. update too large: | 4.52613 A | > 6.22303 mA + 1 pA I(I2.K1:t1) = 4.08111 A, previously 1.18427 A. update too large: | -2.96836 A | > 4.08111 mA + 1 pA
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