Changes
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<td> [[Image:Diff0.png|thumb|left|640px|A generic macromodel with input and output stages.]] </td>
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<td> [[Image:Diff1.png|thumb|540pxleft|640px|An ideal differentiator using a capacitor.]] </td>
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<td> [[Image:Diff2.png|thumb|540pxleft|640px|An ideal differentiator using an inductor.]] </td>
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[[Image:Diff3.png|thumb|left|550px640px|A practical voltage differentiator circuit using an Op Amp.]]
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<td> [[Image:Diff4.png|thumb|700pxleft|720px|RF.Spice's "Analog Differentiator" block circuit.]] </td>
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<td> [[Image:Integ2.png|thumb|700pxleft|720px|RF.Spice's "Analog Integrator" block circuit.]] </td>
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<td> [[Image:Integ3.png|thumb|700pxleft|720px|The block diagram of a generalized analog filter with a rational s-domain transfer function.]] </td>
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<td> [[Image:Integ4.png|thumb|left|560px|The property dialog of the generalized analog filter block.]] </td>
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<td> [[Image:Integ5.png|thumb|700pxleft|720px|RF.Spice's "Digital Integrator" block circuit.]] </td>
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<td> [[Image:Integ6.png|thumb|700pxleft|720px|The block diagram of a generalized IIR digital filter with a rational z-domain transfer function.]] </td>
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<td> [[Image:Integ7.png|thumb|left|560px|The property dialog of the generalized digital filter block.]] </td>
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<td> [[Image:Integ8.png|thumb|700pxleft|720px|The block diagram of a generalized FIR digital filter.]] </td>
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== A Note on SPICE Simulation of Virtual Blocks ==
Most of the virtual blocks can be used in both transient and AC analysis tests. Obviously, nonlinear operations must be performed in the time domain. For example, you can see the performance of voltage controlled oscillators (VCO) only in a transient test, and using them in conjunction with AC frequency sweep analysis is meaningless. The same is true for frequency conversion blocks such as frequency multipliers. In addition, certain blocks such frequency conversion blocks may require harmonic wave input signals and may not work properly with arbitrary waveforms.
When your circuit involves several interconnected virtual blocks, the SPICE simulation of your circuit is likely to encounter convergence problems. This is more frequent when you a transient analysis of such circuits. In those case, we recommend that you change the SPICE integration method. You can do this by opening the '''SPICE Simulation Options''' dialog from the Simulate Menu. There are two options available: trapezoidal or gear. The default option is "trap". Changing the integration method to "gear" can improve the convergence of the transient analysis.
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[[Image:Integ9.png|thumb|left|640px|Setting the integration method in the SPICE Simulation Options dialog.]]
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<p> </p>
