                          Contents

                   1. Introduction
                   2. Changes made to AIM-Spice
                   3. Student version limitations



1. Introduction

   The AIM-Spice documentation originally appeared in the book
   "Semiconductor Device Modeling for VLSI" by Lee et al., ISBN
   number 0-13-805656-0, Prentice Hall (1993). However,
   AIM-Spice is continously evolving and this file contains all
   updates made to AIM-Spice since the book was published.


2. Changes made to AIM-Spice

   2.1 New Features added in upgrade 3/27/93 of version 1.1

       2.1.1 New Commands in AIM-Postprocessor

             - Preferences in the Format menu
               Lets you change preference values. This command
               displays a dialog box. Your preferences will be
               saved in AIMGPP.INI upon exiting if "Save settings on
               exit" is active. The values are restored the next
               time you load AIM-Postprocessor.

             - Add FFT Plot in the Graph menu
               This command lets you create FFT (Fast Fourier Transform)
               graphs from the graph that is active when you choose
               the command. The command is useful for examining the
               spectrum of the output from non-linear circuits. A dialog
               box is displayed in response to this command. The drop
               down list box contains a list of all traces contained
               in the active graph. One of the traces is selected.
               The other two fields in the dialog box display the
               number of data points in the selected trace and the
               suggested number of samples to use when transforming
               the trace. AIM-Postprocessor transforms each trace
               individually and creates two new graphs for each trace.
               One contains the amplitude of the original trace as a
               function of frequency, and the other contains the phase.
               When AIM-Postprocessor transforms a trace it creates a
               new set of datapoints where the number of points is
               equal to the number of samples you specified in the
               dialog box. The datapoints are equally spaced in the
               time interval. This is done with linear interpolation
               on the original datapoints. The new set of datapoints
               are then transformed. The resolution in frequency is
               the reciprocal of extent in time, and extent in frequency
               is proportional to the number of samples used. So, if
               you want higher resolution in the frequency domain you
               have to run the transient analysis for a longer time in
               AIM-Spice. Run the circuit for many cycles if necessary.
               One final note: AIM-Postprocessor transforms all traces,
               not only those that are functions of time. It is your
               responsibility to create meaningful transforms.


       2.1.2 New and Obsolete Commands in AIM-Spice

             - Preferences in the Options menu (New Command)
               Lets you change preference values. This command displays
               a dialog box. Your preferences will be saved in
               AIMSPICE.INI upon exiting if "Save settings on exit" is
               active. The values are restored the next time you
               load AIM-Spice.

             - Auto Scale in the Format menu in Analysis Mode (New Command)
               By choosing this command, you reset the y-axis limits
               to fit the simulated results. This command can also be
               used during a simulation to enlarge the y-axis if the
               simulated results extend beyond the y-axis interval.
               This command can also be invoked with the Alt+U key
               combination.

             - Analysis Limits (Obsolete Command)
               This command is deleted and this operation is now part
               of the command Select Variables to Plot.


   2.2 New Features added in upgrade 5/25/93 of version 1.1

       2.2.1 Logfiles

             AIM-Spice is now capable of writing logfiles after
             each simulation. This feature can be turned on or off
             with the Preference command in the Options-menu. In
             the preferences dialog box you can specify what to
             include in the log file. The log file will always have
             the same name as the circuit file and the extention
             will be LOG. AIM-Spice will overwrite old logfiles,
             so if you want to save the log file for a simulation
             you should rename the logfile immediately after
             completing the simulation.

      2.2.2 Changes in model parameters

            - Parameter JSDF in MESFET models MESA1 and MESA2 is
              replaced by PHIB and ASTAR:

              Name    Parameter                            Units   Default
              PHIB    Effective Schottky barrier height     eV       0.5
              ASTAR   Effective Richardson constant       A/m^2K^2   4.0


            - Two new model parameters for MOSFET level 7:

              Name    Parameter                            Units   Default
              RDI     Intrinsic drain resistance per       Ohm*um    0.0
                      micron width
              RSI     Intrinsic source resistance per      Ohm*um    0.0
                      micron width

              Level 7 can now be used both as intrinsic and extrinsic model.
              If you specify the original RD and RS you select the
              intrinsic model, and if you specify RSI and RDI you select
              the extrinsic model.

            - Threshold voltage model is new for MOSFET level 7:

              Name    Parameter                        Units Default
              GAMMAS0 Body effect constant in front    V^1/2   0.0
                      of square root term
              LGAMMAS Sensitivity of GAMMAS on device  V^1/2   0.0
                      length
              WGAMMAS Sensitivity of GAMMAS on device  V^1/2   0.0
                      width
              GAMMAL0 Body effect constant in front of   -     0.0
                      linear term
              LGAMMAL Sensitivity of GAMMAL on device    -     0.0
                      length
              WGAMMAL Sensitivity of GAMMAL on device    -     0.0
                      width
              L0      Gate length of nominal device      m     2um
              W0      Gate width of nominal device       m    20um

              Model parameters GAMMA and DELTA is now obsolete for
              level 7.


   2.3 New Features added in upgrade 6/7/93 of version 1.1

       2.3.1 Changes in model parameters

             - Two new model parameters for MESFET levels 2 & 3 and HFET:
              Name    Parameter                            Units   Default
              RDI     Intrinsic drain resistance           Ohm       0.0
              RSI     Intrinsic source resistance          Ohm       0.0

              The above models can now be used as intrinsic or extrinsic.
              If you specify the original RD and RS you select the
              intrinsic model, and if you specify RSI and RDI you select
              the extrinsic model.

            - New model parameter for MESFET levels 2 & 3:
              Name    Parameter                            Units   Default
              RG      Gete ohmic resistance                Ohm       0.0


       2.3.2 Changes in instance parameters

            - Obsolete instance parameter for MESFET level 2 & 3: TEMP

            - New instance parameters for MESFET level 2 & 3:
              Name    Parameter                            Units   Default
              TD      Drain temperature                   Celcius   TEMP*
              TS      Source temperature                  Celcius   TEMP*

              *TEMP is the circuit temperature specified in the General
              OPtions dialog box.


   2.4 New Features added and bugs fixed in version 1.1e

       2.4.1 Speed search
            In the Select Variables to Plot dialog box you now have the
            possibility to search for specific variables and the. To use
            this feature start entering the name of the variable you want
            to select in the spees search field and the variable is
            automatically scrolled into view.


       2.4.2 Line numbers
            The text editor where you input the circuit description is
            now equipped with line numbers to make it more convenient
            for you to locate errors reported by the kernel.


       2.4.3 Bugs fixed
            Negative Vds gave wrong results for level 7, 8, 9, 10, 11 and
            12 in the previous versions of AIM-Spice. This bug is corrected
            now.

       2.4.4 New model parameters for MESFET model level 2 and 3
            Name    Parameter                            Units   Default
            TETA0   First temperature coefficient          K     Infinite
                    for ETA
            TETA1   Second temperature coefficient         K        0
                    for ETA
            TMU     Temperature coefficient for            K       27
                    mobility
            XTM0    First exponent for temperature         -        0
                    dependence of mobility
            XTM1    Second exponent for temperature        -        0
                    dependence of mobility
            XTM2    Third exponent for temperature         -        0
                    dependence of mobility


   2.5 New Features added in version 1.1f

       2.5.1 New model parameter for MESFET level 2
            Name    Parameter                        Units Default
            RGS     Resistance in series with Cgs     Ohm    0

       2.5.2 New Edit menu in AIM-Postprocessor
            You can now copy an AIM-Postprocessor graph to the clipboard
            by selecting the command Copy Graph from the Edit menu. This
            makes it possible to paste graphs into other Windows
            applications, for example Write.

       2.5.3 New Item in the Format Legend dialog box in AIM-Postprocessor
            It is now possible to change the size of the centered symbols
            used in the graph.


   2.6 New Features added in version 1.1g

       2.6.1 The name of the model parameter RGS for MESFET level 2 has been
             changed to RI (see Section 2.6.2).

       2.6.2 New model parameter for MESFET level 2 and HFET
            Name    Parameter                        Units Default
            RI      Resistance in series with Cgs     Ohm    0
            RF      Resistance in series with Cgd     Ohm    0

       2.6.3 Filesize limit
            The maximum size of a CIR-file to be opened in AIM-Spice has been
            increased to approximately 64K. The limit in number of open files
            has been removed.


   2.7 New Features added in version 1.5

       3.7.1 Online help
            The AIM-Spice docummentation is now available as online help in both
            AIM-Spice itself and AIM-Postprocessor. AIM-Spice also have context
            sensitive help by pressing Shift+F1 while editing a circuit description.
            Depending on the first letter on the current line AIM-Spice will display
            help information about the respective circuit element or the statment.


   2.8 New Features added in version 1.5a

       2.8.1 New diode model parameters for both level 1 and 2
            Name    Parameter                        Units Default
            IKF     Corner for high injection          A   infinite
            ISR     Recombination satuartion current   A      0
            NR      Recombination emission coefficient -      2


   2.9 New Features added in version 1.5b

       2.9.1 The BSIM3 model is now implemented as MOSFET level 14

       2.9.2 Changes in model parameters for MESFET level 2
            The parameter ALPHAT has been renamed to TVTO.

       2.9.3 New model parameters for MESFET level 2
            Name    Parameter                             Units   Default
            ALPHA   Bulk charge parameter                  1/V       0
            THETA   Mobility enhancement coefficient     m^2/V^2s    0
            ZETA    Transconductance compensation           -        1
                    factor
            RTC1    First order temperature coefficient    1/C      0
                    for parasitic resistances
            RTC2    Second order temperature coefficient   1/C^2    0
                    for parasitic resistances

       2.9.4 New charge storage model for MOSFET level 7
            A new charge conserving charge storage model has been
            implemented for the MOSFET level 7 model. See the online
            reference for details.

       2.9.5 New model parameters for MOSFET level 7
            Name    Parameter                             Units   Default
            THETA   Mobility degradation coefficient     m^3/V^2s    0
            DELTA   Transition width parameter              -        5
            CV      Charge storage model selector           -        1
            CVE     Meyer-like capacitor model selector     -        1
            FPE     Charge partitioning scheme selector     -        1
            XQC     Charge partitioning factor              -       0.6
            MCV     Transistion width parameter used by
                    the charge partitioning scheme          -        10
            ALPHA   Parameter accounting for the threshold
                    dependence on the channel potential     -       1.05
            VFB     Flat band voltage                       V     Calculated

       2.9.6 Bug fix to the HBT model
            The saturation effect in BETA has been removed. Instead, we have
            introduced a limitation of the intrinsic collector current.  See
            the on-line SPICE reference.

       2.9.7 Changes in model parameters for MESFET level 3
            The parameter VBI has been removed.


   2.10 New Features added in version 1.6

       2.10.1 P-channel HFET is now available


   2.11 New Features added in version 1.6a

        2.11.1 New model parameters for HFETA
            Name    Parameter                             Units   Default
            CDS     Drain-source capacitance                F        0
            P       Charge partitioning parameter           -        1
            KAPPA   Relative increase in gds at high        -        0
                    frequencies
            DELF    Gds transistion width                   Hz       0
            FGDS    Transistion frequency for Gds           Hz       0
            TF      Characteristic temperature for          C      TEMP
                    the frequency dependence of Gds

        2.11.2 Obsolete model parameter for HFETA
            The parameter ALPHAG has been removed

        2.11.3 Improved Export command in AIM-Postprocessor
            The Export command in AIM-Postprocessor has been extended. It is
            now possible to export data from the plots in the active graph
            window.


   2.12 New Features added in version 1.7

        2.12.1 New MOSFET model level 15
            A new amorphous silicon TFT model (ASIA2) is now available. See the
            online reference for details.

        2.12.2 New MOSFET model level 16
            A new poly-silicon TFT model (PSIA2) is now available. See the online
            reference for details.

        2.12.3 32-bit version for Windows-95 and Windows-NT is now available.


   2.13 New Features added in version 1.7a

        2.13.1 BSIM3 version 2 has been replaced by version 3


   2.14 New Features added in version 1.7b

        2.14.1 New model parameters added in the ASIA1 model (level 11)
            Three new model parameters have been added to the ASIA1 model: EPS,
            EPSI and MC.  See the online reference manual for details.

        2.14.2 New a-Si TFT model
            A new model for a-Si TFTs has been added. The name is ASIA2 and it
            can be referenced by specifying level=15 on the model line. See the
            online reference manual for details.

        2.14.3 Line thickness in AIM-Postrpocessor
            The line thickness of any line graph in AIM-Postprocessor can now be
            varied.

        2.14.4 Loading AIM-Spice output files in AIM-Postprocessor
            AIM-Posprocessor can now read AIM-Spice output files generated by both
            the 16-bit and 32-bit versions of AIM-Spice.


   2.15 New Features added in version 2.0

        2.15.1 Toolbars
            Both AIM-Spive and AIM-Postprocessor are now equipped with toolbars.
            See the online help for details.

        2.15.2 Analysis speed buttons in AIM-Spice
            Press one of the new Analysis speed buttons and AIM-Spice will simulate
            your circuit directlty using the current settings.

        2.15.3 New model parameters added in the HFET model
            The following model parameters have been added to the HFET model: VT1,
            VT2, ETA1, ETA2, D1, D2. See the online reference manual for details.

        2.15.4 New model parameters added in the PSIA2 model (MOSFET level 16)
            The following model parameters have been added to the PSIA2 model: EB,
            I00, DD, DG, AT, BT. Some of the other parameters have been renamed.
            See the online reference manual for details.


   2.16 New Features added in version 2.0a

        2.16.1 New model parameters added in the PSIA2 model (MOSFET level 16)
            The following model parameters have been added to the PSIA2 model:
            ETAC0, ETAC00, and MC. See the online reference manual for details.

        2.16.2 Improved C-V model for the PSIA2 model (MOSFET level 16)
            An improved C-V model has been implemented in the PSIA2 model which
            includes the effect of frequency dispersion, traps and high field
            effects.


   2.17 New Features added in version 2.0b

        2.17.1 Fixed a bug in the capacitance model of MOSFET level 11.


   2.18 New Features added and bug fixes in version 2.0c

        2.18.1 Temperature effects included for MOSFET level 16.

        2.18.2 Capacitance model for MOSFET level 15 corrected.
            The above threshold gate-to-channel capacitance (Cgc) at zero
            frequency has been modified not to include the effects of trapped
            charge. Cgc is now proportional to Cox above threshold.

        2.18.3 The value of the density of states changed for MOSFET level 15
            The value for density of states has been changed from 1.0E26 to
            3.0E25

        2.18.4 Locking of built in editor under Windows 95
            Some users have reported strange behavior of the built in editor when
            running under Windows 95. The user could not enter any text. This
            bug has now been fixed.


   2.19 New Features added in version 2.0d

       2.19.1  HFET model temperature dependence
            Temperature dependence of key model parameters such as, for
            example, threshold voltage and mobility has been included.

       2.19.1  HFET level 2 model included
            A second level HFET model has been included to increase the speed in
            simulation of digital HFET circuits. See the online reference
            manual for details.


   2.20 New Features added in version 2.1a

       2.20.1  BSIM3 version 3.0 has been replaced by version 3.1

       2.20.2  The Fonts command
            A new Fonts command in the Format menu lets the user specify which
            font to use in the text editor.

       2.20.3  New toolbar buttons in AIM-Spice
            See the online help for details.

       2.20.4  Shortcut menus in AIM-Spice
            Right-clicking inside a circuit or graph window will bring up a
            shortcut menu.

       2.20.5  Detecting multiple traces in AIM-Postprocessor
            To be able to plot traces with both increasing and decreasing x-
            values, the option "Detect Multiple Traces" in the preference dialog
            box has been added. To correctly plot such traces this option has to
            be turned off.

       2.20.6  Arrow key functionality in AIM-Postprocessor
            The arrow keys can now be used to move the cursors in increments of
            one pixel.


   2.21 New Features added in version 2.1b

       2.21.1  Registry
            The 32-bit versions of AIM-Spice and AIM-Postrpcessor now use the
            registry instead of ini-files.

       2.21.2  Context menus
            Context menus have been added for both AIM-Spice and AIM-
            Postprocessor.


   2.22 New Features added in version 2.1c

       2.22.1  Viewing device parameters
            After a DC operating point analysis is completed, the user can now
            look at device parameters (including small signal parameters) by
            using the command Device Parameters in the View menu.  The active
            window must be the table that displays the operating point information.
            Alternatively, double clicking the table window will also display the
            device parameters of the corresponding circuit.
            Currently supported only for the BJT and BSIM3 models.

       2.22.2  Toggling the status bar
            The status bar can now be shown/hiden by choosing the Status Bar
            command in the View menu.


   2.23 New Features added in version 2.2

       2.23.1  Obsolete model parameter
            The model parameter ALPHA in the MOSFET level 15 model has been
            removed.

       2.23.2  New model parameters in MOSFET level 15
            Name    Parameter                             Units   Default
            KASAT   Temperature coefficient of ALPHASAT     -      0.006

       2.23.3  New model parameters in MOSFET level 16
            Name    Parameter                             Units   Default
            DVT     The difference between VON and the      V        0
                    threshold voltage
            VON     On-voltage                              V        0



3. Student Version Limitation

   The student version of AIM-Spice is limited in two ways:
     - Maximum number of nodes in a circuit is 50
     - Maximum number of transistors in a circuit is 20
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