$Revision:   1.3  $
$Author:   pwt  $
$Date:   15 Oct 1991 15:45:36  $

"Parts" on-line help file
Release 4.04, July 1990
(C) Copyright 1986-1990 MicroSim Corporation
DMOD 1
Diode - Forward Current

Device curve:

        Vfwd    forward voltage across junction for Ifwd
        Ifwd    forward current @ Vfwd

Model parameters:

        IS      saturation current
        N       emission coefficient
        RS      series resistance
        IKF     high-injection "knee" current
        XTI     IS temperature coefficient
        EG      activation energy

This screen estimates the parameters IS and RS from three voltage and current
values.  Try to include data from low current values (where the increase in
current is exponential), moderate current values, and high current value (where
the increase in current is clearly resistive).

The last two model parameters, XTI and EG, may be changed.  We have set them to
be normal values for silicon diodes.  For Schottky-barrier diodes these may be
changed to XTI = 2 and EG = 0.69, which will give better modeling over
temperature.

Also, it is sometimes helpful to set up traces for a few values of temperature
(use Trace command) for adjusting XTI.
DMOD 2
Diode - Junction Capacitance

Device curve:

        Vrev    reverse voltage across diode (junction) for Cj
        Cj      junction capacitance @ Vrev

Model parameters:

        CJO     zero-bias junction capacitance
        VJ      junction potential
        M       junction grading coefficient
        FC      coefficient for onset of forward-bias depletion capacitance

This screen estimates the parameters CJO and M from a capacitance values given
at non-zero reverse biases (a zero value for a Vj data point is OK).

The value for FC has been set to be normal for silicon diodes, but is
relatively unimportant, as forward capacitance is dominated by diffusion
capacitance (and modeled by transit time).

The data sheets for most switching and power diodes have little detail about
reverse bias capacitance, because it is not too important.  Varicap diodes
usually have better, more complete information.  Be aware that the diode
package adds some fixed amount of capacitance that is not included in the
device model, but may be included by the user with a small capacitor across the
diode.  Having determined the package capacitance, subtract that from the total
capacitance to model the diode junction.
DMOD 3
Diode - Reverse Leakage

Device curve:

        Vrev    reverse voltage for Irev
        Irev    reverse (leakage) current @ Vrev

Model parameters:

        ISR     recombination current saturation value
        NR      recombination current emission coefficient

This screen derives the generation-recombination current values for the device
which, with the capacitance modeling (previous screen), provides the primary
leakage mechanism of the diode junction.

Reverse current leakage is increased by imperfections in manufacturing which
are not modeled.  Breakdown also increases reverse current, but this is modeled
in the next screen.
DMOD 4
Diode - Reverse Breakdown

Device data:

        Vz      nominal Zener voltage @ Iz
        Iz      nominal Zener current for Vz
        Zz      Zener impedance (resistance) @ Vz,Iz

Model parameters:

        BV      reverse breakdown voltage (a positive value)
        IBV     reverse breakdown current (a positive value)

This screen estimates the parameters BV and IBV for reverse breakdown
operation, which is how voltage regulator (Zener or avalanche) diodes work. 
Enter the values for Vz, Iz, and Zz.

BV and IBV will nearly equal Vz and Iz.  As the breakdown effect is modeled by
an exponential function, the value of BV and IBV will adjust so that device
impedance, Zz (ratio of the change in voltage to the change in current) is
correct at Vz,Iz.
DMOD 5
Diode - Reverse Recovery

Device data:

        Trr     reverse recovery time
        Ifwd    forward current (before switching)
        Irev    initial reverse current
        Rl      load resistance (total load of test fixture)

Model parameters:

        TT      transit time

This screen estimates the parameter TT from switching time.  Enter values for
the upper list.  Be sure to include the test fixture resistance and pulse
generator resistance in Rl.

The screen does a transient simulation of the diode switching.  Some of the
parameters from earlier screens that have dynamic effects, for example, CJO,
are included in the simulation.  You may need to adjust the X-axis to see the
entire waveform.
QMOD 1
Bipolar Transistor - Junction Voltage

Device data:

        Vbe     base-emitter voltage @ Ib (device in saturation)
        Vce     collector-emitter voltage (device in saturation)
        Ib      base current for Vbe and Vce
        %Ib     fraction of Ib (not a data sheet value)

Model parameters:

        IS      saturation current
        XTI     temperature coefficient for IS
        EG      activation energy

This screen estimates the parameter IS from the saturation characteristics of
the transistor.  IS is a semiconductor junction parameter and should not be
confused with the collector current in saturation.  The data sheet will have
values or curves for Vbe and Vce in a "forced beta" (where the ratio Ic/Ib is
much lower than the normal current gain) or "saturated" condition.  Enter
values of Vbe and Vce for the same Ib.

The value of %Ib is a "fudge" value and is not critical.  It factors how much
of the base current will be shunted through the ideal diode of the Gummel-Poon
transistor model.  We have set it to a "normal" amount.

Obtaining an accurate value for IS is not critical, since other parameters will
be set relative to IS, and only the ratio between values will be important.  It
is necessary, though, to not have a wildly inaccurate value.  The last two
model parameters, XTI and EG, may be changed.  We have set them to be normal
values for silicon transistors.

The display graphs for this screen are not too useful.  However, they do let
you know something is happening.
QMOD 2
Bipolar Transistor - Output Admittance

Device curve:

        Ic      collector current for hoe
        hoe     small-signal open-circuit output admittance @Ic (and @Vce)

Conditions:

        Vce     collector-emitter voltage for the device curve

Model parameters:

        VAF     forward Early voltage

This screen estimates the parameter VAF, which sets the output conductance of
the transistor in a common emitter configuration.

The parameter VAF controls one aspect of basewidth modulation in the
Gummel-Poon transistor model.  This manifests itself as output conductance. 
Typical values are 50-to-100 volts for normal transistors and 1-to-10 volts for
super-beta transistors.
QMOD 3
Bipolar Transistor - Forward DC Beta

Device curve:

        Ic      collector current for hFE (@ Vce)
        hFE     forward DC beta @ Ic

Conditions:

        Vce     collector-emitter voltage for the device curve

Model parameters:

        BF      ideal maximum forward beta
        ISE     non-ideal base-emitter diode saturation current
        NE      non-ideal base-emitter diode emission coefficient
        IKF     forward beta roll-off "knee" current
        NK      forward beta roll-off slope exponent
        XTB     forward beta temperature coefficient

This screen estimates parameters for the celebrated Gummel-Poon bipolar
transistor model.  Try to include data from low current values (beta rising),
moderate current values, and high current value (beta falling).  The value Vce
adjusts the beta data for basewidth modulation effects.

Transistor data sheets usually show minimum beta values and have a maximum
value for only one collector current value.  One way to obtain an average value
is to use the current level that specifies both minimum and maximum beta, using
a value somewhat below the average of the minimum and maximum.  Then ratio the
other minimum values by the same amount.  Or just use the curves (if available)
from the data sheet.

The value for XTB has been set to be normal for bipolar transistors but may be
changed.  It is sometimes helpful to set up traces for a few values of
temperature (use Trace command) for adjusting XTB.
QMOD 4
Bipolar Transistor - Vce(sat) Voltage

Device curve:

        Ic      collector current for Vce (@ Ib/Ic)
        Vce     collector-emitter voltage @ Ic

Conditions:

        Ic/Ib   "forced beta" ratio for device curve

Model parameters:

        BR      ideal maximum reverse beta
        ISC     non-ideal base-collector diode saturation current
        NC      non-ideal base-collector diode emission coefficient
        IKR     reverse beta roll-off "knee" current
        RC      series collector resistance

This screen estimates more parameters for the Gummel-Poon transistor model. 
Try to include data from low current values (Vce falling), moderate current
values, and high current value (Vce rising).  Also, be sure to check/enter the
value for the "forced beta" ratio of collector to base current.

The reverse Gummel-Poon parameters correspond to the forward parameters, except
they are for reverse operation (that is, emitter swapped with the collector). 
It would be more accurate to obtain these the same way as the forward
parameters, but reverse operation is rarely published data.  Fortunately, it
does not affect operation when the transistor is saturated, that is, when the
base-collector junction is forward biased.
QMOD 5
Bipolar Transistor - C-B Capacitance

Device curve:

        Vcb     reverse voltage collector-base junction for Cobo
        Cobo    open circuit output capacitance @ Vcb

Model parameters:

        CJC     0-bias collector-base junction capacitance
        VJC     collector-base junction potential
        MJC     collector-base junction grading coefficient
        FC      coefficient for onset of forward-bias depletion capacitance

This screen estimates the parameters CJC and MJC from capacitance values given
at non-zero reverse biases (a zero value for Vcb is OK).

The value for FC has been set to be normal for silicon transistors but may be
changed.  The value of FC is relatively unimportant, as forward capacitance is
dominated by diffusion capacitance (and modeled by transit time).

Be aware that the transistor package adds some fixed amount of capacitance that
is not included in the device model, but may be included by the user with a
small capacitor across the junction.  Having determined the package
capacitance, subtract that from the total capacitance to model the junction.
QMOD 6
Bipolar Transistor - E-B Capacitance

Device curve:

        Veb     reverse voltage emitter-base junction for Cibo
        Cibo    open circuit input capacitance @ Veb

Model parameters:

        CJE     zero-bias emitter-base junction capacitance
        VJE     emitter-base junction potential
        MJE     emitter-base junction grading coefficient

This screen estimates the parameters CJE and MJE from capacitance values given
at non-zero reverse biases (a zero value for Veb1 is OK).

The value of FC from the previous screen is used and is still relatively
unimportant, as forward capacitance is dominated by diffusion capacitance.

Be aware that the transistor package adds some fixed amount of capacitance that
is not included in the device model, but may be included by the user with a
small capacitor across the junction.  Having determined the package
capacitance, subtract that from the total capacitance to model the junction.
QMOD 7
Bipolar Transistor - Storage Time

Device curve:

        Ic      collector current for ts (@ Ic/Ib)
        ts      storage time (not "shelf life") @ Ic

Conditions:

        Ic/Ib   "forced beta" ratio for device curve

Model parameters:

        TR      reverse transit time

This screen estimates the parameter TR, which controls the delay until the
transistor leaves saturation when switching off.  Be sure to check/enter a
value for the "forced beta" ratio when the transistor was on and saturated.

The storage time curve is controlled by the forward and reverse beta
characteristics of the transistor.  The parameter TR acts like a multiplying
factor without changing the character of the curve.  Use the storage time for
the collector current range you are interested in.
QMOD 8
Bipolar Transistor - Gain Bandwidth

Device curve:

        Ic      collector current for fT (@ Vce)
        fT              frequency at which small-signal forward current
                        transfer ratio extrapolates to unity @ Ic

Conditions:

        Vce     collector-emitter voltage for device curve

Model parameters:

        TF      forward transit time
        ITF     current for TF dependency on Ic
        XTF     coefficient for TF dependency on Vce
        VTF     voltage for TF dependency on Vce

This screen estimates the parameter TF, which, along with collector-base
capacitance, limits high-frequency gain.  The value of TF also controls
rise/fall times in switching circuits, which is another way to measure
transistor speed, though we haven't thought of a rule-of-thumb conversion
between rise/fall time and high-frequency cutoff.

Also, it is sometimes helpful to set up traces for a few values of Vce (use
Trace command) for adjusting VTF.
JMOD 1
JFET - Transconductance

Device curve:

        Id      drain current for gFS
        gFS     forward transconductance @ Id

Model parameters:

        BETA    transconductance coefficient
        RD      drain resistance
        RS      source resistance
        BETATCE temperature coefficient for BETA

This screen estimates the parameter BETA, which sets the change in drain
current vs. gate-source voltage.  BETATCE is set manually, using traces at
other temperatures to judge the effect (the default setting is a nominal value
chosen from inspecting many data sheets).

Also, it is sometimes helpful to set up traces for a few values of temperature
(use Trace command) for adjusting BETATCE.
JMOD 2
JFET - Output Conductance

Device curve:

        Id      drain current for gOS
        gOS     output conductance @ Id

Model parameters:

        LAMBDA  channel-length modulation

This screen estimates the parameter LAMBDA, which sets the slope of the drain
current vs. drain-source voltage in saturation.
JMOD 3
JFET - Transfer Curve

Device curve:

        Vgs     gate-source voltage for Id (@ Vds)
        Id      drain current @ Vgs

Conditions:

        Vds     drain-source voltage for device curve

Model parameters:

        VTO     threshold voltage
        VTOTC   temperature coefficient for VTO

This screen estimates the parameter VTO, which is the threshold ("pinchoff")
voltage.  VTOTC is set manually, using traces at other temperatures to judge
the effect (the default setting is a nominal value chosen from inspecting many
data sheets).

Note: The SPICE "standard" is for VTO to be a negative value for a depletion
transistor, regardless of device type (NJF or PJF).
JMOD 4
JFET - Reverse Transfer Capacitance

Device curve:

        Vgs     gate-source voltage for Crss (@ Vds)
        Crss    reverse transfer capacitance @ Vgs

Conditions:

        Vds     drain-source voltage for device curve

Model parameters:

        CGD     zero-bias gate-drain capacitance
        M       junction grading factor
        PB      built-in potential
        FC      forward-bias coefficient

This screen estimates the parameters CGD and M.  The reverse transfer, or
"Miller", capacitance is modeled.

The parameter FC applies to forward-biased junctions and is included for
completeness.
JMOD 5
JFET - Input Capacitance

Device curve:

        Vgs     gate-source voltage for Ciss (@ Vds)
        Ciss    input capacitance @ Vgs

Conditions:

        Vds     drain-source voltage for device curve

Model parameters:

        CGS     zero-bias gate-source capacitance

This screen estimates the parameter CGS, which is derived from Ciss - Crss.  As
a check, since most JFETs are designed to be symmetrical, the value found for
CGS should be close to that found for CGD (previous screen).
JMOD 6
JFET - Passive Gate Leakage

Device curve:

        Vdg     drain-gate voltage for Igss
        Igss    gate leakage current @ Vdg

Model parameters:

        ISR     recombination current saturation value
        NR      recombination current emission coefficient
        IS      junction saturation current
        N       junction emission coefficient
        XTI     IS temperature coefficient

This screen derives the generation-recombination current values for the device
which, with the capacitance modeling (previous screens), provides the primary
leakage mechanism of the device's junction.

Passive reverse current leakage is increased by imperfections in manufacturing
and breakdown, which are not modeled.

Also, it is sometimes helpful to set up traces for a few values of temperature
(use Trace command) for adjusting XTI.
JMOD 7
JFET - Active Gate Leakage

Device curve:

        Vdg     drain-gate voltage for Ig (@ Id)
        Ig      gate leakage current @ Vdg

Conditions:

        Id      drain current for device curve

Model parameters:

        ALPHA   impact ionization coefficient
        VK      ionization "knee" voltage

This screen estimates active gate current when the JFET is on, which may be
much larger than when the JFET is cut off.

Impact ionization by drain-current carriers generate carriers in the gate
space-charge region, which get swept out through the gate.  This causes gate
current which is an exponential function of drain voltage and proportional to
drain current.

Note that the lowest values of active leakage current are generally less than
the passive leakage values (previous screen); this is because the passive
values are measured with source and drain shorted together, which usually
doubles the junction area and, thus, the current.  Active leakage current
occurs in the drain-gate junction only, so the lowest levels represent passive
leakage for that junction.
JMOD 8
JFET - Noise Voltage

Device curve:

        Freq    frequency for en (@ Ids)
        en      equivalent input noise voltage (in volts/root-hertz) @ Freq

Conditions:

        Ids     drain current for device curve

Model parameters:

        KF      flicker noise coefficient
        AF      flicker noise exponent

This screen estimates the parameter KF, to set the correct amount of flicker
noise.  AF may be set manually but is normally close to 1.  The broadband noise
of a JFET is "shot" noise and is set by the conductance of the channel.
PWRMOS 1
Power MOSFET - Transconductance

Device curve:

        Id      drain current for gFS
        gFS     forward transconductance @ Id

Model parameters:

        KP      transconductance
        W       channel width
        L       channel length
        RS      source ohmic resistance

This screen estimates the basic geometry of the power MOSFET, its conductance
parameter, and high-current effects of series resistance in the device.

Many general assumptions are made about the device structure (such as oxide
thickness), but the model will remain accurate in spite of these assumptions. 
The transconductance would ideally increase proportional to the square-root of
the drain current, but is limited by the effects of RS.
PWRMOS 2
Power MOSFET - Transfer Curve

Device curve:

        Vgs     gate-source voltage for Id
        Id      drain current @ Vgs

Model parameters:

        VTO     zero-bias threshold voltage

This screen estimates the device threshold voltage.

The actual value of VTO is not as important as obtaining a good value of drain
current vs. Vgs as the device will be used.  For library use, use a drain
current close to the maximum continuous rating.
PWRMOS 3
Power MOSFET - Rds(on) Resistance

Device curve:

        Id      drain current for Rds
        Rds     static drain-source on-state resistance @ Id

Conditions:

        Vgs     gate-source voltage for device curve

Model parameters:

        RD      ohmic drain resistance

This screen estimates the "on-resistance" of the device.

The MOS model has three contributions to the "on-resistance": the channel
resistance of the device, and an ohmic resistance in series with each the
source and the drain.  This screen adjusts RD so the total resistance is
correct.  However, RD cannot become negative.
PWRMOS 4
Power MOSFET - Zero-bias Leakage

Device curve:

        Vds     drain-source voltage for Idss
        Idss    zero gate voltage drain current @ Vds

Model parameters:

        RDS     drain-source shunt resistance (PSpice extension MOS model)

This screen estimates the drain-source leakage of the device.  This leakage is
due primarily to surface effects and is modeled by a shunt drain-source
resistance.  Enter the values for the upper list.

PWRMOS 5
Power MOSFET - Output Capacitance

Device data:

        Ciss    input capacitance @ Vds
        Coss    output capacitance @ Vds
        Crss    reverse transfer capacitance @ Vds
        Vds     drain-source voltage for Ciss, Coss, and Crss

Model parameters:

        CBD     zero-bias bulk-drain junction capacitance
        PB      bulk junction potential
        MJ      bulk junction grading coefficient
        FC      bulk junction forward-bias capacitance coefficient

This screen estimates the output capacitance of the device.

The output capacitance is usually not critical, being small enough when
compared with the load currents that are controlled by the device.
PWRMOS 6
Power MOSFET - Turn-on Charge

Device data:

        Qg      total gate charge to switch load, Id, using supply, Vdd
        Qgs             gate-source charge to start switching
        Vdd     supply voltage for Qg
        Id      load (drain) current

Model parameters:

        CGSO    gate-source overlap capacitance
        CGDO    gate-drain overlap capacitance

This screen estimates the device's stray capacitances associated with the gate.
These capacitances, along with the channel capacitance, make up the amounts of
charge required to switch the device.

The value Qgs is the amount of charge required to raise the gate-source voltage
from zero to that required to support the load current.  Qg is the total charge
to complete the switching of the load current.  The difference of these charges
is due to "Miller", or gate-drain, capacitance.

Note that the values of CGSO and CGDO are multiplied by the channel width to
yield the actual value of the capacitance.
PWRMOS 7
Power MOSFET - Switching Time

Device data:

        tf      fall time for switching load, Id, using supply, Vdd
        Id      load (drain) current for tf
        Vdd     supply voltage for tf
        Zo      input generator impedance

Model parameters:

        RG      gate ohmic resistance

This screen estimates the value of series gate resistance from switching time.

Most power MOSFET devices use a self-aligned process with polysilicon gate
material.  The polysilicon impedes the gate current, reducing the charging rate
of the gate, which increases the turn-on time.  While there are many switching
times specified (turn-on delay, rise time, etc.), they are all related by the
parasitic capacitances, which have already been determined in the "gate charge"
screen.  Only the series resistance needs to be determined, which can be done
reliably with the fall time characteristic.

Note that "fall time" means the period in which the drain current is "falling"
in value, not the output voltage.
PWRMOS 8
Power MOSFET - Reverse Drain Current

Device curve:

        Vsd     diode (source-drain) forward voltage for Idr
        Idr     reverse drain current @ Vsd

Model parameters:

        IS      bulk junction saturation current
        N       bulk junction emission coefficient
        RB      bulk series resistance

This screen estimates the forward voltage drop of the "body" diode.

The actual value of IS is not so important as obtaining a good value of voltage
drop vs. current as the device will be used.
OPAMP 1
Operational Amplifier - Large Signal Swing

Device data:

        +Vpwr   positive power supply
        -Vpwr   negative power supply
        +Vout   maximum positive output swing
        -Vout   maximum negative output swing
        +SR     positive-going slew-rate limit
        -SR     negative-going slew-rate limit
        Pd      quiescent power dissipation

Macromodel internal parameters:

        VC      output limiter offset (to Vcc)
        VE      output limiter offset (to Vee)

This screen sets the value of output voltage limiters but also gathers
information that will be useful in later screens.  The graph shows the largest
amplitude output a sinewave signal can be for a given frequency to have no
distortion.  This is limited by the amplifier's output swing and slew-rate.

Power supply values: These are the data sheet values used in conjunction with
the maximum output values and are not the power supply values for the circuit
simulation (which may be different).  The opamp model limits the output swing
by an amount relative to the power supply, so the output swing limit will track
the power supply in the simulation.

Slew-rates: Since Parts uses primary units (e.g., volts, amps, farads, etc.),
the variety of ways of specifying slew-rate needs to be converted to
volts/second, for example, 5V/uS is 5,000,000 V/S.
OPAMP_B 2
Operational Amplifier - Open Loop Gain

Device data:

        Cc      compensation capacitor
        Ib      input bias current
        Av-dc   open-loop gain (DC)
        f-0db   unity gain frequency
        CMRR    common-mode rejection ratio

Macromodel internal parameters:

        BF      input transistor beta
        C2      compensation capacitor
        CEE     slew-rate limiting capacitor
        GA      interstage transconductance
        GCM     common-mode transconductance
        IEE     input stage current
        RC      input stage load resistance
        RE      input stage emitter resistance
        REE     input stage current source output resistance
        RP      power dissipation

This screen completes the input stage and inner stage.  The compensation
capacitor value (Cc) is sometimes available on the data sheet in the circuit
diagram of the opamp.  If not, 20-to-30pF is a fair value.  For opamps with
external compensation, use one of the values on the data sheet for the external
capacitor.  Then be sure to use that value for the other input data.

About open-loop gain: this is a ratio of input/output signal, i.e.,
small-signal amplification.  Being a pure number, it has no units.  If the gain
is specified as 20V/mV, the gain is 20,000; if the gain is spec'd as 90db, put
in 90db (Parts converts xdb to 10x/20).

Unity gain frequency: This frequency is the intersection of a straight-line
extension of the of the mid-band, open-loop, gain roll-off to unity gain (zero
decibel).  The graph will show gain with only the low-frequency pole included. 
The high-frequency pole is calculated from open-loop phase margin.

CMRR has no frequency dependence.
OPAMP_J 2
Operational Amplifier - Open Loop Gain

Device data:

        Cc      compensation capacitor
        Ib      input bias current
        Av-dc   open-loop gain (DC)
        f-0db   unity gain frequency
        CMRR    common-mode rejection ratio

Macromodel internal parameters:

        BETA    input transistor transconductance
        C2      compensation capacitor
        CSS     slew-rate limiting capacitor
        GA      interstage transconductance
        GCM     common-mode transconductance
        IS      input leakage current
        ISS     input stage current
        RD      input stage load resistance
        RP      power dissipation
        RSS     input stage current source output resistance

This screen completes the input stage and inner stage.  The compensation
capacitor value (Cc) is sometimes available on the data sheet in the circuit
diagram of the opamp.  If not, 10-to-20pF is a fair value.  For opamps with
external compensation, use one of the values on the data sheet for the external
capacitor.  Then be sure to use that value for the other input data.

Open-loop gain: This is a ratio of input/output signal, i.e., small-signal
amplification.  Being a pure number, it has no units.  If the gain is spec'd as
20V/mV, the gain is 20,000; if the gain is specified as 90db, put in 90db
(Parts converts xdb to 10x/20).

Unity gain frequency: This frequency is the intersection of a straight-line
extension of the of the mid-band, open-loop, gain roll-off to unity gain (zero
decibel).  The graph will show gain with only the low-frequency pole included. 
The high-frequency pole is calculated from open-loop phase margin.

CMRR has no frequency dependence.
OPAMP 3
Operational Amplifier - Open Loop Phase

Device data:

        Phi     phase margin (in degrees) @ unity gain frequency

Macromodel internal parameter:

        C1      phase control capacitor

This screen adjusts the open-loop unity-gain phase margin, which models the
high-frequency pole.  Sometimes this value is not available in a table but can
be found from a graph.  This value is not critical for lower-frequency circuits
or lower-Q filters: just use the value we provided, which is typical for normal
opamps.
OPAMP 4
Operational Amplifier - Maximum Output Swing

Device data:

        Ro-dc   DC output resistance
        Ro-ac   AC output resistance
        Ios     short-circuit output current limit

Macromodel internal parameters:

        RO1     output resistor #1
        RO2     output resistor #2
        GB      output stage transconductance

This screen adjusts the output drive.  The graph shows the maximum output level
for a resistive load.  The data sheet usually lists an output resistance Ro =
Ro-dc + Ro-ac.  Split this value so that Ro-dc is about 2 x Ro-ac.
VCOMP 1
Voltage Comparator - Transfer Function

Device data:

        +Vpwr   positive power supply
        -Vpwr   negative power supply
        +Vicr   positive common-mode range
        -Vicr   negative common-mode range
        Ib      input bias current
        Avd     DC gain
        Rl      output load resistance
        Pd      power dissipation

Macromodel internal parameters:

        BF1     input stage gain
        BF5     output stage gain
        RP      power dissipation resistance
        VI      input offset

This screen sets gain values and an input offset (to model comparators whose
common-mode input includes ground).  The screen shows the transfer function,
usually un-informative, except to let you know something is happening.

About power supply values: these are the data sheet values used in conjunction
with the maximum output values, and are not the power supply values for the
circuit simulation (which may be different).
VCOMP 2
Voltage Comparator - Falling Delay

Device data:

        Vst     input voltage step size
        Vod     input voltage step overdrive
        td      delay time

Macromodel internal parameter:

        TR3     input stage reverse transit time

This screen sets reaction time to input signals.  The data sheet usually gives
"falling delay" which includes some of the transition in the output waveform
(from 100% to 90%).  Usually the transition is much faster than the delay and
can be ignored (or subtracted from the value).  The precise value is not
critical given the unit-to-unit variation.
VCOMP 3
Voltage Comparator - Transition Time

Device data:

        Vst     input voltage step size
        Vod     input voltage step overdrive
        ttr     transition time

Macromodel internal parameter:

        TF5     output transistor forward transit time

This screen sets the "slew-rate" of the output.  The data sheet usually gives a
value going from 90% to 10%, which will be within 25% of the full swing time. 
The precise value is not critical given the unit-to-unit variation.
VCOMP 4
Voltage Comparator - Rising Delay

Device data:

        Vst     input voltage step size
        Vod     input voltage step overdrive
        td      delay time

Macromodel internal parameter:

        TR5     output transistor reverse transit time

This screen sets the reaction to input signals, but in the opposite direction. 
The data sheet usually gives "rising delay", which includes some of the
transition in the output waveform (from 0% to 10%).  Usually the transition is
much faster than the delay and can be ignored (or subtracted from the value). 
The precise value is not critical given the unit-to-unit variation.
KMOD 1
Nonlinear Magnetic Cores - Hysteresis Curve

Device curve:

        H       magnetic influence (in Oersteds)
        B       magnetic flux (in Gauss)

Conditions:

        æi      initial permeability

Model parameters:

        Ms      magnetization saturation
        A       thermal energy parameter
        C       domain flexing parameter
        K       domain anisotropy parameter

This screen estimates the bulk material parameters from the envelope of the
B-H curve and the value for the initial permeability of the material.  The
"initial" B-H curve, starting from the origin, is also shown but is
characterized only by the value for initial permeability.

Unlike most screens in Parts, in this screen the extent of the X-axis plays a
role in extracting the model parameters.  Owing to the hysteresis (memory)
effects in magnetic materials, how the material behaves depends on, virtually,
its entire history.  This means the B-H curve will depend on how strong a field
it has been subjected to.  To accommodate this behavior, Parts simulates a
range of fields with magnitudes up to the maximum extent displayed by the
X-axis.  For example, if you set the X-axis for a range of -5 to +5, Parts will
use fields in that range when extracting the model parameters; the same range
of fields will also be used if you set the X-axis for a range of 0 to +5. 
After you have fitted the parameters, you may change the X-axis to see the
material's behavior under a different range of external fields.

Warning: numerous evaluations are made when extracting these model parameters. 
Even the fastest computers will appear to stall, momentarily, while performing
the extraction.
