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3.11 Linear Simplification Techniques 397
The setting of the SortingMethod option is relevant only if you specify more than one sampling
point. In general, SortingMethod −> LeastMeanInfluence is the preferred setting for multiple
sampling points.
StripIndependentBlocks
With StripIndependentBlocks −> True, clusters of equations which are decoupled from the variable
of interest, are searched for and discarded after approximation. This option is effective only in
conjunction with the setting CompressEquations −> True.
UseExternals
The setting UseExternals −> True causes the MathLink application MSBG.exe to be used for matrix
approximation. This is the recommended setting for all platforms for which native Analog Insydes
versions exist. You can set UseExternals −> False to run Analog Insydes on other platforms or
for debugging purposes in conjunction with the option Protocol. Alternatively, you can also load
and unload the module manually as described in Section 3.13.3. For more information refer to
UseExternals (Section 3.14.7).
Examples
In the following we approximate the system of nodal equations representing the small-signal
equivalent circuit of the common-emitter amplifier with respect to the output variable V$5. To
obtain an approximation of the amplifier’s passband voltage gain, we select a sampling frequency
of kHz. At the sampling point we allow the magnitude of the solution of the approximated
equations to deviate from the original design-point value by .
Load Analog Insydes.
Define an AC model for
BJTs.
In[1]:= AC,
Scope −> Global,
Ports −> {B, C, E},
Parameters −> {Rbe, Cbc, Cbe, beta, Ro,
RBE, CBC, CBE, BETA, RO},
Definition −> Netlist[
{CBE, {B, E}, Symbolic −> Cbe, Value −> CBE},
{RBE, {X, E}, Symbolic −> Rbe, Value −> RBE},
{CBC, {B, C}, Symbolic −> Cbc, Value −> CBC},
{CC, {B, X, C, E},
Symbolic −> beta, Value −> BETA},
{RO, {C, E}, Symbolic −> Ro, Value −> RO}
]
]
] // ExpandSubcircuits;