Are there any preferred simulation settings for oscillators open-source-silicon.dev #xyce

Are there any preferred simulation settings for os...

CR85

12/30/2021, 8:16 AM

Are there any preferred simulation settings for oscillators (specifically LC oscillator) I am seeing the below issues while trying to run an LC oscillator in sky130 models

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DC operating point failed and "Step size reached minimum step size bound" When specifying an initial condition, I am able to run the simulaton without oscillation when I dont specify IC

It is possible that the negative gm pair is not correctly designed but its hard to decouple unless a baseline circuit works. Attaching the Log file below

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*****
***** Welcome to the Xyce(TM) Parallel Electronic Simulator
*****
***** This is version Xyce DEVELOPMENT-202111250123-(Public_Release-7.4.0-56-g82a079af)-opensource
***** Date: Thu Dec 30 00:13:08 PST 2021


***** Executing netlist LC_run.netlist

***** Reading and parsing netlist...
***** Setting up topology...

Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM2:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM2:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM1:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM1:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM4:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM4:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM3:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM3:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM5:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM5:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning: Voltage Node (XLCCORE:XL1:NET37) does not have a DC path to
 ground
Netlist warning: Voltage Node (XLCCORE:XL1:NET31) does not have a DC path to
 ground
Netlist warning: Voltage Node (OPEN) does not have a DC path to ground
***** Device Count Summary ...
       C level 1 (Capacitor)                   4
       I level 1 (Independent Current Source)  1
       L level 1 (Inductor)                    2
       M level 14 (BSIM4)                      5
       R level 1 (Resistor)                    9
       V level 1 (Independent Voltage Source)  2
       -----------------------------------------
       Total Devices                          23
***** Setting up matrix structure...
***** Number of Unknowns = 36
***** Initializing...

***** Beginning DC Operating Point Calculation...

Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM1:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM1:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM2:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM2:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM3:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM3:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM4:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM4:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM5:MSKY130_FD_PR__NFET_01V8: Source conductance
 reset to 1.0e3 mho
Netlist warning in file
 ../../PDK/open_pdks/sky130/sky130A/libs.tech/ngspice/corners/../../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_01v8__ss.pm3.spice
 at or near line 31
 Device instance XLCCORE:XM5:MSKY130_FD_PR__NFET_01V8: Drain conductance reset
 to 1.0e3 mho
DC Operating Point Failed.  Exiting transient loop

***** Solution Summary *****
	Number Successful Steps Taken:		0
	Number Failed Steps Attempted:		1
	Number Jacobians Evaluated:		4647
	Number Linear Solves:			4647
	Number Failed Linear Solves:		0
	Number Residual Evaluations:		4700
	Number Nonlinear Convergence Failures:	1
	Total Residual Load Time:		0.052192 seconds
	Total Jacobian Load Time:		0.0124643 seconds
	Total Linear Solution Time:		0.0382943 seconds


***** Total Simulation Solvers Run Time: 0.249384 seconds
***** Total Elapsed Run Time:            1.34928 seconds
*****
***** End of Xyce(TM) Simulation
*****

Timing summary of 1 processor
                 Stats                   Count       CPU Time              Wall Time
---------------------------------------- ----- --------------------- ---------------------
Xyce                                         1        1.305 (100.0%)        1.350 (100.0%)
  Analysis                                   1        0.241 (18.48%)        0.249 (18.48%)
    Transient                                1        0.241 (18.48%)        0.249 (18.47%)
      Nonlinear Solve                        1        0.241 (18.47%)        0.249 (18.46%)
        Residual                          4700        0.053 ( 4.06%)        0.054 ( 4.03%)
        Jacobian                          4647        0.014 ( 1.08%)        0.014 ( 1.07%)
        Linear Solve                      4647        0.039 ( 3.00%)        0.041 ( 3.00%)
      Failed DCOP Steps                      1        0.000 (<0.01%)        0.000 (<0.01%)
  Netlist Import                             1        1.048 (80.32%)        1.083 (80.28%)
    Parse Context                            1        0.786 (60.26%)        0.817 (60.57%)
    Distribute Devices                       1        0.253 (19.37%)        0.257 (19.02%)
    Verify Devices                           1        0.000 (<0.01%)        0.000 (<0.01%)
    Instantiate                              1        0.001 ( 0.04%)        0.001 ( 0.04%)
  Late Initialization                        1        0.005 ( 0.36%)        0.005 ( 0.35%)
    Global Indices                           1        0.000 ( 0.01%)        0.000 ( 0.01%)
  Setup Matrix Structure                     1        0.001 ( 0.04%)        0.001 ( 0.04%)

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