Spectre Command-Line Options

The spectre command takes the following syntax at the command line:

spectre options inputfile

If no options are specified, the Spectre® circuit simulator saves the .print file in the current working directory, and saves the .measure and .mt0 files in the .raw subdirectory of the netlist directory.

The Spectre circuit simulator reads default values for all the command line arguments marked with a dagger (†) from the UNIX environment variable %S_DEFAULTS.

Command option	Description
`-help`	Lists the Spectre command options and their descriptions. In addition, lists the available components, analyses, and design checks. You can use `-h` as an abbreviation of `-help`.
`-help` name	Displays help information for the specified component or analysis name. If name is `all`, the help information for all components and analyses is displayed. You can use `-h` as an abbreviation of -`help`.
`-helpsort` name	Displays the help information for the specified component or analysis name and sorts all the parameters alphabetically. You can use `-hs` as an abbreviation of `-helpsort`.
`-helpfull` name	Displays detailed information for the specified component or analysis name, including parameter types and range limits. You can use `-hf` as an abbreviation of `-helpfull`.
`-helpsortfull` name	Displays detailed information for the specified component or analysis name, including parameter types and range limits. In addition, it sorts all parameters by name. You can use `-hsf` as an abbreviation of `-helpsortfull`.
`-param`	Ignores the file containing the suggested parameter range limits. You can use `-p` as an abbreviation of `-param`.
`+param` file	Reads the specified file for suggested parameter range limits. You can use `+p` as an abbreviation of `+param`.
`+paramdefault` file	Reads the default values of the parameters from the specified file and applies them. However, if same parameters are specified in the netlist, their values override the default values in the specified file. This option can be set multiple times. Each line in the parameter file should contain three entries: primitive name, parameter name, and value. For example: tran start 2e-3 The primitive name is limited to analyses primitives, which includes the options analysis. The value should be a constant. Expressions are not allowed.
`=paramdefault` file	Reads the specified file and ignores all previously specified files. Refer to `+paramedefault` for details.
`-paramdefault`	Disables the reading of any parameter defaults that have been specified.
`-log`	Displays the log information on the standard output (shell) only and does not copy it to a log file. You can use `-l` as an abbreviation of `-log`.
`+log` file	Displays the log information on the standard output (shell) and copies it to the specified log file. You can use `+l` as an abbreviation of `+log`.
`=log` file	Sends the log informaion to the specified file only and does not display it on the standard output (shell). You can use `=l` as an abbreviation of `=log`.
`-raw` raw	Saves the simulation results in the specified file or directory named raw. In raw, `%C`, which is specified in the directory or file name is replaced by a circuit name. You can use `-r` as an abbreviation of `-raw`.
`-format` fmt	Generates raw data in the format fmt. You can use `-f` as an abbreviation of `-format`. Possible values for fmt are `nutbin`, `nutascii`, `psfbin`, `psfascii`, `psfbinf`, `psfxl`, `sst2`, `fsdb`, `fsdb5`, `wdf`, `uwi`, and `tr0ascii`.
`+rtsf`	Enables the fast waveform viewing mode for psf output. You can use this option only if you have specified the -`f psfbin,` `-f psfbinf` or `-f psfxl` format options.
`-outdir` path	Changes the default location of Spectre output files. It does not change the location of raw directory if explicitly specified with the `-raw` option, and of files that contain slashes in the name.
`-uwifmt` name	Specifies a user defined output format. To specify multiple formats use `:` as a delimiter. This option is valid only when waveform format is defined as `uwi` using the `-format` option.
`-uwilib` lib	Absolute path to the user-defined output format library. This option is used together with `-uwifmt`. Use `:` to specify more than one library.
`+checkpoint`	Turns on the checkpoint capability. You can use `+cp` as an abbreviation of `+checkpoint`.
`-checkpoint`	Turns off the checkpoint capability. You can use `-cp` as an abbreviation of `-checkpoint`.
`+savestate`	Turns on the savestate capability. You may use `+ss` as an abbreviation of `+savestate`.
`-savestate`	Turns off the savestate capability. You may use `-ss` as an abbreviation of `-savestate`.
`-recover`	Does not restart the simulation, even if a checkpoint file exists. You can use `-rec` as an abbreviation of `-recover`.
`+recover[=`filename`]`	Restarts the simulation from a checkpoint or savestate file. Savestate file will be used if both files exist. You can use `+rec[=`filename`]` as an abbreviation of `+recover[=`filename`]`.
`-cols` N	Sets screen width (in characters) to N. This is needed only if the simulator cannot determine screen width automatically, and if default value of 80 is not acceptable. Spectre cannot determine screen width if output is redirected to a file or a pipe. You can use `-c` as an abbreviation of `-cols`. Spectre cannot determine the screen width if the output is redirected to a file or a pipe.
`-colslog` N	Sets the log-file width based on the number of characters specified. The default is 80 characters.
`-%`X	In quoted strings within the netlist, replaces `%`X with nothing where X is any uppercase or lowercase letter.
`+%`Xstring	In quoted strings within the netlist, replaces `%`X with string, where X is an uppercase or lowercase letter. You can modify the string by using the `:x` operators. Example: `+%KmyFile.txt`, if the netlist contains `file=../models/%K`, the file path is expanded to `../models/myFile.txt`.
`+error`	Prints error messages.
`-error`	Does not print error messages.
`+varedefnerror`	Prints error messages if Verilog-A modules are redefined.
`+warn`	Prints warning messages on the screen.
`-warn`	Does not print warning messages on the screen.
`-maxwarns` N	Maximum number of times a particular type of warning message will be issued per analysis. You may use `-maxw` as an abbreviation of `-maxwarns`.
`-maxnotes` N	Maximum number of times a particular type of notice message will be issued per analysis. You can use `-maxn` as an abbreviation of `-maxnotes`.
`-maxwarnstolog` N	Maximum number of times a particular type of warning message will be printed to log file per analysis. You can use `-maxwtl` as an abbreviation of `-maxwarnstolog`.
`-maxnotestolog` N	Maximum number of times a particular type of notice message will be printed to log file per analysis. You may use `-maxntl` as an abbreviation of `-maxnotestolog`.
`+note`	Prints notices on the screen.
`-note`	Does not print notices on screen.
`+info`	Prints informational messages.
`-info`	Does not print informational messages.
`-debug`	Does not print debugging messages.
`+debug`	Prints debugging messages.
-timer	Turn off all timers.
+timer	Turn on all timers.
`+diagnose`	Enables diagnostic mode that provides debugging information to help you resolve simulation issues related to performance or convergence.
`+diagnose_minstep=1e-12`	Prints debugging information if the step size is less than the specified value, while running transient analysis in diagnostic mode.
`+transteps`	Prints all transient steps in diagnostic mode.
`+diagnose_top=`N	Prints top N (N>=2) signals that limit step size or cause convergence failures in diagnostic mode.
`+diagnose_fpe`	Identify devices that cause floating point exceptions and print the bias voltages of the devices during dc and transient analyses in diagnostic mode. This option enforces single thread simulation.
`+detect_negcap`	Identify negative capacitance when convergence difficulty happens during transient analysis in diagnostic mode.
`+fix_bad_pivot`	Reorder matrix when a bad pivot is detected during matrix factorization in transient analysis.
`-slave <`cmd`>`	Starts the attached simulator using the command cmd.
`-slvhost <`hostname`>`	Runs the attached simulator on machine hostname. Defaults to local machine.
`-V`	Prints version information.
`-W`	Prints subversion information.
`-cmiversion`	Prints CMI version information.
`-cmiconfig` file	Reads the specified file for information to modify the existing CMI configuration.
`-alias <`name`>`	Gives name to the license manager as the name of the simulator invoked.
`-E`	Runs the C preprocessor on an input file. In SPICE mode, the first line in the file must be a comment.
`-D<`x`>`	Defines string x and runs the C preprocessor.
`-D<`x`=`y`>`	Defines string x to be y and runs the C preprocessor.
`-U<`x`>`	Clears string x and runs the C preprocessor.
`-I<`dir`>`	Runs the C preprocessor and searches the directory dir for include files.
`+sensdata <`file`>`	Sends the sensitivity analyses data to file.
`+multithread`	Enables the multithreading capability. Spectre automatically detects the number of processors and selects the proper number of threads to use. (See note on the `options` help page about using multithreading). `+mt` can be used as an abbreviation of `+multithread`.
`+multithread`=N	Enables the multithreading capability. N is the specified number of threads. A maximum of 64 threads are allowed. `+mt` can be used as an abbreviation of `+multithread`.
`-multithread`	Disables the multithreading capability. By default, multithreading is disabled for Spectre. However, it is enabled for Spectre APS. `-mt` can be used as an abbreviation of `-multithread`.
`+mtmode` <value>	Selects the multithreading mode. Possible values are `passive` and `active`.
`-processor`	Sets the CPU affinity of a process similar to Linux `taskset` command. It specifies a numerical list of processors that may contain multiple items, separated by comma, for example, `-processor 0-3,5,7`. Specification of numerical value out of range for current system results in the process termination with Invalid argument error message. You can use `-proc` as an abbreviation of `-processor`.
`-interactive`	Runs Spectre in the non-interactive mode, that is, process the input file and then return. You can use `-inter` as an abbreviation of `-interactive`.
`+interactive`	Runs Spectre in the interactive mode based on the type specified. You can use `+inter` as an abbreviation of `+interactive`.
`+interactive=`type	Runs in the interactive mode of the type specified. You can use `+inter` as an abbreviation of `+interactive`. Possible values for type are `skill` or `mpsc.`
`+mpssession=`sessionName	Specifies the sessionName for running an interactive session using multiprocess SKILL (MPS). This option must be specified when using the `+interactive=mpsc` setting.
`+mpshost=`sessionHost	Specifies the name of the sessionHost that will be used for an interactive session using MPS.
`-64`	Runs the 64-bit Spectre binary.
`-32`	Runs the 32-bit Spectre binary.
`-mdlcontrol`	Ignores the MDL control file. You can use `-mdl` as an abbreviation of `-mdlcontrol`.
`+mdlcontrol`	Runs Spectre with the default MDL control file. You can use `+mdl` as an abbreviation of `+mdlcontrol`.
`+mdlcontrole`	Runs Spectre with the default MDL control file. You can use `+mdle` as an abbreviation of `+mdlcontrole`.
`=mdlcontrol` file	Specifies the location of the MDL control file. You can use `=mdl` as an abbreviation of `=mdlcontrol`.
`=mdlcontrole` file	Specifies the location of the MDL control file. You can use `=mdle` as an abbreviation of `=mdlcontrole`.
`-checklimitfile` file	Writes assert violations to file. In file, %C is replaced by the circuit name. You can use `-cl` as an abbreviation of `-checklimitfile`.
`-dochecklimit`	Disables the checklimit capability. You can use `-docl` as an abbreviation of `-dochecklimit`.
`+dochecklimit`	Enables the checklimit capability. You can use `+docl` as an abbreviation of `+dochecklimit`.
`-dynchecks`	Disables the dynchecks capability.
`+lqtimeout` value	Specifies the duration (in seconds) for which Spectre should wait to retrieve a license. When set to `0`, Spectre waits until license is available. You can use `+lqt` as an abbreviation of `+lqtimeout`.
`+lqsleep` value	Specifies the wait duration between two attempts made by Spectre to check out a license when queuing. Setting the value to a positive number overrides the default wait duration of 30 seconds. You can use `+lqs` as an abbreviation of `+lqsleep`.
`+lqmmtoken`	Enables queuing for the token license capability. When specified, Spectre registers the token request with the license server and waits for authorization. In addition, Spectre ignores all non-token licenses during the wait time since only token licenses are queued.
`+lsuspend`	Enables the license suspend/resume capability. When Spectre receives `SIGTSTP` it checks in all the licenses before it gets suspended. The licenses are checked out again when `SIGCONT` is received. You may use `+lsusp` as an abbreviation of `+lsuspend`.
`+lmode` value	Checks out the licenses according to the specified value during initialization phase. Possible values are `<`num`>` and `RF`. <num> is a numeric value greater than 1, which specifies the number of token licenses to be checked out together. For example, to run Spectre APS with the multi-core option, specify `+lmode 4`. `RF` checks out the required licenses for the RF functionality. This value is case insensitive. If a simulation requires more licenses than the value specified using `+lmode`, the additional licenses are checked out after the initialization phase.
`+lorder` value	Specifies the license check out order. Values are case insensitive. Possible values are: `PRODUCT:` Spectre attempts to check out the product+options combination licenses only. `MMSIM`: Spectre attempts to check out Virtuoso_Multi_Mode_Simulation (Spectre MMSIM) tokens only. `PRODUCT:MMSIM`: Spectre attempts to check out the product licenses first and then Spectre MMSIM tokens. `MMSIM`:`PRODUCT`: Spectre attempts to check out the Spectre MMSIM tokens first and then product licenses. Default is `PRODUCT:MMSIM`.
`-ahdlcom` value	Starting with MMSIM15.1, support for the `-ahdlcom` option has been removed.
`-va,define MACRO[=`value`]`	Defines a macro with higher priority than the one defined in Verilog-A files.
`-rf_ahdl_functionality`	Specifies the value for AHDL functionality in RF analysis. Possible values are `141` and `151`. Default value is `151`.
`-ahdllint[=value]`	Enables Verilog-A linter check. Possible values are `no`, `warn`, `static`, `error`, and `force`. The default value is `warn`. This option is not available in Spectre base. It is availabe only in Spectre APS and Spectre XPS.
`-ahdllint_maxwarn[=value]`	Specifies the maximum number of Verilog-A linter warning messages to be reported by the simulator for each message ID. The default value is 5.
`-ahdllint_summary_maxentries[=value]`
	Specifies the maximum number of messages to display in dynamic linter summary. The default value is 25.
`-ahdllint_warn_id=`value	Specifies a message ID and applies the `-ahdllint_maxwarn` option only to the specified ID. This option should always be used with the `ahdllint_maxwarn` option and should be directly specified after it at the command line, otherwise, the option will be ignored.
`-ahdllint_log` <file>	Specifies the file name to which the Verilog-A linter messages need to be written. By default, the Verilog-A linter messages are written to the output log file.
`-ahdllibdir path`	Redirects the library files generated by AHDL to the specified path. If both `-ahdllibddir` and `-outdir` options are specified, the library files generated by AHDL are stored under the path specified by the `-ahdllibdir` option and other output files are stored in the path specified by the `-outdir` option.
`-ahdlsourceramp`	Disables source ramping for Verilog-A models. Source ramping of Verilog-A models is enabled by default because it helps with convergence for most designs. However, in certain corner cases, the default behavior could lead to convergence difficulties, which can be avoided by using this option.
`-ahdlshipdbdir=`sharing_path
	Specifies the sharing directory for Verilog-A library compilation. If this option is specified, the simulator will search for reusable library in the sharing_path. If library is found, reuse it, otherwise, compile a new library in the local directory.
`-ahdlshipdbmode=read_only or create_or_update`
	Indicates whether to create or update the library under sharing_path specified by `-ahdlshipdbdir`. Possible values are `read_only` and `create_or_update`. `read_only` is the default behavior for `-ahdlshipdbdir` appearing alone. `create_or_update` will copy the newly-built library in local directory to sharing_path if no any library already or if the library is outdated.
`+errpreset`=value	Selects a predetermined collection of parameter settings. Possible values are `liberal`, `moderate`, and `conservative`.
`+aps`	Enables Spectre APS mode.
`+aps`=value	Enables Spectre APS mode and overrides the errpreset value in all transient analyses to apply the specified value. Possible values are `liberal`, `moderate`, or `conservative`.
`++aps`	Enables ++aps mode. Unlike the `+aps` mode, the ++aps mode uses a different time-step control algorithm as compared to Spectre. This results in improved performance, while satisfying error tolerances and constraints.
`++aps`=value	Enables the ++aps mode and overrides the errpreset value in all transient analyses to apply the specified value. Possible values are `liberal`, `moderate`, or `conservative`.
`+preset=`value	Enables Spectre X. The most accurate mode is `cx`, and the highest performing mode is `vx`. Possible values are `cx`, `ax`, `mx`, `lx`, `vx`.
`+postlpreset=`value	Defines parasitic optimization in Spectre X. If not set, Spectre X enables parasitic optimization if post-layout content is detected. If set, parasitic optimization is enforced. The most accurate parasitic optimization is `cx`, and the highest performing parasitic optimization is `vx`. Parasitic optimization can be disabled with `off`. Possible values are `off, cx, ax, mx, lx, vx`.
`-preset_override`	Spectre X by default ignores solver options defined in the netlist. The option `-preset_override` forces Spectre X to honor solver options defined in the netlist. The option can also be used to honor individual solver options: `-preset_override=reltol,method`.
`+xdp=`value	Enables Spectre X distributed, multi-processing simulation. Supports RSH/SSH in manual mode: `+xdp=rsh\|ssh +hosts="host1:1 host2:3"`. In farm mode, `+xdp` needs to be set and the job distribution system controls the host/core usage.
`+hosts` “<hostname>: number of processes”	Defines the machine specifications that will be used for distributed processing. This option must be used when you specify the rsh or ssh values with the `+xdp` option. The format of the machine specification is the same for both rsh and ssh. Each machine specification, which can be separated by the space delimiter contains the name of the machine and number of cores to be used on the machine in the following format: "`host_name:number_of_processes`". For example: `+hosts "hostA:4 hostB:4"`. This setting specifies that four processes will be used on both hostA and hostB for performing the simulation.
`+ms`	Enables Spectre MS mode.
`+xps`	Enables the Spectre XPS mode.
`+xps=s[`value`]`	Enables Spectre XPS SPICE accuracy mode. The optional value is the speed setting.
`+speed=`value	The simulation group speed setting. The lower number means conservative setting.
`+query`=value	Queries the recommended number of threads or licenses required to run simulation on the current computer or on another computer with similar configuration. Possible values are: "mtinfo: prints the number of threads required to run the simulation "meminfo: prints an estimate of the memory that will be required to run the simulation "all: prints the recommended number of threads, the memory usage estimate, and all possible license combinations for the design used in simulation "alllic: prints all possible license combinations for the design used for simulation "tokenlic: prints the number of MMSIM tokens required. This is the default value.
`+liclog`	Writes the license check-in and check-out information in the log file.
`+disk_check [=`value`]`	Suspend the simulation when available disk storage is less than `N` bytes. Here, `N` is the value specified using the optional [=value] of `+disk_check` or netlist option `disk_check_thresh`. For example, `+disk_check=1e10`.
`-clearcache`	Clears the Spectre cache directory `/home/<`username`>/.cadence/mmsim`. You can use `-cc` as an abbreviation for -`clearcache`.
`-disableCPP`	Disable CPP preprocesses in situations where Spectre implicitly calls CPP, such as `-I` and `-D`. However, if `-E` is specified, `-disableCPP` has no effect.
`+dcopt[=value]`	Speeds up the simulation in Spectre and Spectre APS for post-layout circuits that consist of a large number of parasitic resistors and capacitors, which require significant time in DC simulation. This option can also be used to solve the non-convergence issues in DC simulations of any other circuit. In some cases, the DC solution obtained using the `dcopt` may not be as accurate as the true DC solution.
`+lite`	Enables a lightweight simulation session where most or all of the computationally intensive features (device check asserts, info analysis, current probing, power probing, instance preservation, and so on) are disabled. By default, `++aps` is used as the simulation engine. This can be a useful tool in isolating the computational time used by simulation engine during a simulation performance debugging.
`+config` <file>	Enables the user to append all Spectre commands defined in file to the netlist. file may contain one or more Spectre netlist lines. Multiple `+config` on the same Spectre command line are supported. They are incrementally processed.
`=config` <file>	Enables the user to append all Spectre commands defined in file to the netlist. All `+config` statements on the same Spectre command line are ignored.
`-config`	Disable all `+config` statements on the same Spectre command line. Disables all preceding `=config` statements on the same Spectre command line.
`+pre_config` <file>	Enables the user to prepend all Spectre commands defined in <file> to the netlist. <file> may contain one or more Spectre netlist lines. Multiple +pre_config on the same Spectre command line are supported. They are incrementally processed.
`+top <`value`>`	When specified with a subcircuit name, all elements, models, and so on will be exposed to the top level and the subcircuit will not exist anymore. As a result, instantiation from this subcircuit will be illegal. Instances inside the subcircuit will automatically connect to the instance at the top level if they connect to the same node.
`-hpc`	Disables the hpc option.

If you do not specify an input file, the Spectre simulator reads from standard input. When +/- pairs of spectre command options are available, the default is the first value given in the previous list. For further information about the percent code options, +% and -%, see Chapter 15, “Managing Files”, in the Spectre Classic Simulator, Spectre APS, Spectre X, and Spectre XPS User Guide.

Default Values

The Spectre simulator reads default values for all the command line arguments marked with a dagger (†) from the UNIX environment variable %S_DEFAULTS. The name of the simulator as called replaces %S. Typically, this name is spectre, and the Spectre simulator looks for spectre_DEFAULTS. However, the name can be different if you move the executable to a file with a different name or if you call the Spectre simulator through a symbolic or hard link with a different name. This feature lets you set different default values for each name you use to call the Spectre simulator.

If the variable %S_DEFAULTS does not exist, SPECTRE_DEFAULTS is used instead. The command line arguments always override any specifications from the options statement in the circuit file. The options statement specifications, in turn, override any specifications in the environment variable.

Default Parameter Values

Many Spectre parameters have default values, and sometimes you will need to know them so you can determine whether they are acceptable for your simulation. You can find the default values for component, analysis, and control statement parameters by consulting the documentation for the statement in Spectre online help (spectre -h). Values given for parameters in the online help are the default values.

The following examples show some defaults for different types of parameters from the Spectre online help:

Parameter	Description
`nf=1.0`	Forward emission coefficient.
`etchc`	Narrowing due to etching for capacitances.
`homotopy=all`	Method used when no convergence occurs on initial attempt of DC analysis. You can specify methods and their orders by specifying a vector setting such as `homotopy=[source ptran gmin]`. Possible values are `none`, `gmin`, `source`, `dptran`, `ptran`, and `all`.

Spectre Circuit Simulator Reference
Product Version 23.1, September 2023