Using Automated Assistants in Impedance Matching Utility

This section describes the Automated Assistants available in this Utility.

Automated Design and Analysis

The Automated Assistants provide quick design, simulation, yield analysis, and performance display for SmartComponents and enable transformation of lumped elements to transmission line elements. Five Automated Assistants are available in this Utility:

• Matching Assistant is used to generate and update the design contained within a matching or transformer SmartComponent from the given specifications.

• Simulation Assistant is used to analyze the design contained within a SmartComponent.

• Yield Assistant is used to analyze the design sensitivities contained within a SmartComponent.

• Display Assistant is used to easily and quickly display the performance of a SmartComponent.

• Transformation Assistant is used to transform an ideal filter topology to a form that is realizable for high-frequency systems.

Explore each tab page by selecting the associated tab on the control window.

Matching Assistant

The Matching Assistant is used to generate and update the design contained within a matching or transformer SmartComponent from the given specifications. This tool is accessed using the Matching Utility window. From the utility window, full design control is enabled from the Matching Assistant tab. Component design operations can also be accomplished using the utility window menu and toolbar. Any parameter change made from the Matching Assistant tab is reflected on the SmartComponent in the schematic.

To view a SmartComponent, select the SmartComponent from the SmartComponent drop-down list box in the upper right corner of the utility window. The SmartComponent parameters are shown inside the Matching Assistant tab.

Matching Assistant SmartComponents

The Matching Assistant SmartComponents include lumped and distributed element matching networks and transformers.

Matching Networks

Matching networks provide a match between two real or complex impedances over a given frequency range. The response can be lowpass, highpass, or bandpass if allowed by the specified impedance termination.

Transformers

Transformers provide a bandpass match between two unequal but real impedances using a special transform of a lowpass filter network.

Specifications

• ResponseType - frequency response type for transformer networks. Choices consist of Maximally Flat , Chebyshev , Bessel-Thompson , and Gaussian . This menu is used for transformers only.
• Synthesis Technique - Method used to synthesize the matching network - Analytic or Real Frequency . This menu is used for matching networks only.
• Order - The network order. This is approximately the number of reactive components for lowpass and highpass matching networks. For bandpass matching networks or transformers, the number of reactive components is approximately twice the order (exactly twice for transformers). For matching networks, absorption of source and load reactances as well as component transformations can change this number.
• Gain Change - Gain Change in dB over the band for matching networks. During synthesis, this parameter is ignored. However, if optimization is selected, this slope will be applied as part of the optimization goal. This parameter must be positive. The target gain will start at the left passband edge at -(Gain Change) and ramp linearly (in dB) to 0. This field is used for matching networks only.
• Fp1, Fp2 - Lower and upper passband edge frequencies in Hertz. For lowpass and highpass networks, Fp2 is not used and Fp1 is changed to Fp to represent the passband edge frequency. Frequency values are changed by entering new values in the edit box. Units are changed by selecting a new unit identifier from the drop-down menu.
• Line Impedance, Stub Impedance - Characteristic impedance of transmission lines and stubs used in distributed element matching networks.
• Max Reflection Coeff - Maximum reflection coefficient in the passband for certain distributed element matching networks.
• # Sections/Wavelength - Number of transmission line segments per wavelength to use to approximate linear taper with transmission line elements.

Terminations

For transformers, the terminations must be resistive with unequal values. As such, only the R input boxes are available for transformers. For other matching networks, the terminations can be input using lumped components networks, complex impedances, and S-parameter files. Usage for these different types is:

• Lumped Component - Choices include Resistive, Series RL, Series RC, Parallel RL, Parallel RC, Series RLC, Parallel RLC, where R = resistance, L = inductance, and C = capacitance. Component values must be specified by the user. For lowpass networks, choices are limited to Resistive, Series RL, and Parallel RC. For highpass networks, choices are limited to Resistive, Series RC, and Parallel RL.
• Complex Impedance - The impedance is interpreted as frequency independent, expressed in the form 50 + j×10 Ohms. This input approach is useful for narrowband matching. If the true impedance varies significantly with frequency, better accuracy is obtained by specifying the termination using an S-parameter file or manually entering the data using the spreadsheet data entry capability.
• S-Parameter File - Any termination can be represented using a file in Touchstone format representing 1-port parameters ( *.s1p ). The impedance can be specified in S, Z, or Y parameters. For details on data file format, refer to the Circuit Simulation manual under SnP format . The Browse button launches a window to enable selection of the file.
• Manual Data Entry - The complex impedance - specified as an impedance, admittance, or reflection coefficient - can be entered as a function of frequency manually. When the source or load impedance is specified as Manual Entry, the Edit button can be used to open a spreadsheet useful for entering frequency/impedance pairs.
  
• Interpret as Input/Output Impedance - These options are available for three cases of source and load impedance; complex load, S-parameter file, and Manual entry. Use the Interpret as Input Impedance option to specify that the value you have entered is of impedance looking into the device (S-parameters of the measured device, for instance). Use the Interpret as Output Impedance option to specify that the value you have entered is of impedance looking out from the device (impedance you want to see). For more information, see Designing with an S2P File.

Design

The design is accomplished using one of the these methods.

• Click Design on the Matching Assistant tab.
• Click Design on the utility window toolbar.
• Choose Tools > Auto-Design from the utility window menu.
  After completion of the synthesis, a dialog box appears.

Optimization range

All networks can be viewed using the spin box. Each network can be viewed in two places:

• Dialog Box - shows a text based description of the current network.
• Schematic Window - shows the actual drawing of the current network.

For each network, the maximum error in the passband response in dB (taken with respect to the ideal flat or sloped response) appears in the dialog box. The response over the specified passband is also shown in an interactive graph. The scale on this graph can be changed manually using the spin box immediately below the graph. Checking the Autoscale box will automatically choose the scale to fit the response within the graph area.

The response of the matching network can be optimized from this dialog by clicking the Optimize button. The vertical lines on the graph, which by default lie at the edges of the band, are markers used for specification of the optimization frequencies. These markers can be moved by clicking and dragging them with the mouse, with the marker frequency being displayed in the corresponding text box to the right of the plot (the markers and labels for the text boxes are color coordinated). If the radio box for Frequency Range is selected, the optimization will be performed to minimize the Maximum Error over the range of frequencies between the two markers. If the radio box for Discrete Frequencies is selected, initially only a single marker is present. Up to three additional markers can be added by clicking the appropriate Activate button. Each added marker can also be removed by clicking the corresponding Deactivate button. Under this option, the optimization will be performed to minimize the Maximum Error at the frequencies indicated by the markers. Clicking the Optimize All button sequentially optimizes all networks found using the optimization parameters displayed. This optimization process can be canceled from the progress indicator that appears after the optimizer is launched. After the optimization is complete, the updated network appears in the dialog box and on the schematic.

Discrete optimization points

Synthesis Technique

Two different techniques are available for lumped element matching network synthesis: Analytic and Real Frequency .

• Analytic - For this method, a Chebyshev filter is chosen that can completely or partially absorb the source and load reactances, as outlined in [1], [2]. If the specified network order generates reactance topologies at the ends of the network that cannot absorb the specified terminations, the Utility informs the user that the network order is increased by one. This synthesis procedure is very robust, particularly for terminations that are modeled as lumped components. For terminations specified as a complex impedance, the Utility computes the simplest lumped component topology that produces this impedance at the band edge or center frequency. For terminations specified using an S-parameter file or manual entry, the Utility generates a lumped component model for the specified impedance variation with frequency.
• Real Frequency - This method uses the basic Chebyshev matching capability of the Analytic approach. However, application of the technique is modified by breaking the frequency band into small pieces, performing the match over this small band by finding a lumped component fit to the impedance given, and retaining the networks with the lowest insertion loss. Typically, optimization is required to obtain a good match over the entire passband. This approach is useful for loads that are not well modeled using the simple lumped component network choices given. For lowpass or highpass networks with N = 2 or bandpass networks with N = 1, this method synthesizes narrowband 2 component matching networks (L networks), retaining those that provide the best match over the band.
• Transformers - Lumped element transformers provide a pseudo-bandpass response to match two real and unequal resistances over a specified frequency band. The approach uses a transformation of a lowpass filter network to achieve the match [1], [3]. The quality of the match in terms of passband error depends upon the frequency bandwidth chosen as well as the ratio of the terminating impedances. Distributed element transformers create a true bandpass response over the band.
• Narrow Band Matching Networks - The lumped two element (Ell) matching network as well as the single stub matching network provide exact matching at a single frequency.

Designing with an S2P File

Use these steps for designing with an S2P file:

1. For input match, start with a resistive source of 50 Ohms, load pointing to S11 of the S2P file. Design optimize "input match." You need to optimize repeatedly to improve the performance, until you see not much change.
2. For output match, start with S22 of the S2P file as source, load set to 50 Ohms. Design and optimize.

   Note You do not have to set the interpret as input/output, so DO NOT choose those buttons at all while designing with S2P files. This button essentially toggles whether the program takes the conjugate of the data you enter or not. Sometimes you collect impedance data for the device you have, or sometimes it is for the impedance you want. So, effectively, it changes the perspective of whether you are looking into the DUT or looking into the matching circuit. This is used mostly while using the Manual entry mode for Impedances.

3. You can try using analytical or higher order to see whether you can improve the performance further.

Simulation Assistant

The Simulation Assistant is used to analyze the design contained within a SmartComponent. The Assistant creates a simulation circuit around the SmartComponent, then automatically performs the appropriate simulation. If set, the Assistant automatically displays the simulation results.

The Simulation Assistant is accessed using the Matching Utility window, where full simulation control is enabled from the Simulation Assistant tab. Basic simulation can also be accomplished using the utility window menu and toolbar.

For all simulation operations, the selected SmartComponent is designed if necessary, a simulation schematic is created, the simulation is performed, and the results are displayed. The simulation frequency sweep must be specified on the Simulation Assistant tab in the utility window as described in detail below.

Simulation Frequency Sweep

The simulation frequency sweep is specified on the Matching Utility window. While performing the simulation from the utility window, select the Simulation Assistant tab and specify the sweep by entering the start frequency, stop frequency, and either frequency step size or number of points. The values entered are stored in the selected SmartComponent (as displayed in the SmartComponent drop-down list box) and are recalled each time this SmartComponent is selected.

Displaying Results Automatically

If you click the Automatically Display Results button on the utility window Simulation Assistant tab, the simulation results are displayed automatically after completion of the analysis.

Starting the Simulation

The simulation can accomplished using one of these methods.

• Click the Simulate button on the Simulation Assistant tab.
• Click the Simulate button on the utility window toolbar.
• Choose Tools > Auto-Simulate from the utility window menu.

Simulation Templates

In some cases, you can simulate the SmartComponent manually.
To generate a simulation schematic around the selected SmartComponent:

1. Click the Create Template button on the utility window Simulation Assistant tab.
2. You can examine or modify the simulation schematic, then manually start the simulation by choosing Simulate > Simulate from the Schematic window.
3. When you are finished, click the Update from Template button on the Simulation Assistant tab to transfer any changes you have made to the SmartComponent on the simulation schematic to the original SmartComponent and redesign if necessary.
4. Close the simulation schematic by choosing File > Close Design from the Schematic window menu, although this results in loss of any changes you have made to the SmartComponent.

Yield Assistant

The Yield Assistant is used to analyze the design sensitivities contained within a SmartComponent. The Assistant creates a yield analysis circuit containing the SmartComponent, then performs a simulation. By sweeping the component values for a selected set of components in the network, this analysis generates a probability density function of the performance given statistical variations of the component values. The probability that the performance remains within the specified bounds is the yield of the network.

The Yield Assistant is accessed using the Matching Utility window, where full control is enabled from the Yield Assistant tab. Basic yield analysis can also be accomplished using the utility window menu and toolbar.

The selected SmartComponent must be designed before yield analysis can be performed. The analysis proceeds by statistically sweeping the value of each selected component and analyzing the impact of this component value variation on the frequency response of the network.

Simulation Frequency Sweep

The simulation frequency sweep is specified on the Yield Assistant tab of the Matching Utility window. From this tab, specify the sweep by entering the start frequency, stop frequency, and either frequency step size or number of points. The values entered are stored in the selected SmartComponent (as displayed in the SmartComponent drop-down list box) and are recalled each time this SmartComponent is selected.

Statistical Components

The Statistical Components list-box displays all components that are statistically varied during simulation. Clicking Update opens the dialog box (shown below) to simplify the process of selecting components.

The matching network is shown in the schematic with the currently selected component highlighted. If you want this component value to be swept statistically during the analysis, select Enabled in the Statistics Status box. You can then specify the parameters of the statistical sweep. After you have specified all parameters for a component, clicking Next takes you to the next component in the network. The analysis allows for a maximum of 4 components to be selected at one time. After you have finished specification, you can click Done from the dialog box to return to the Yield Assistant tab. Clicking View under the Statistical Components box opens a dialog box from which you can view a summary of the statistical parameters for each selected component. There are also buttons to take you directly to the Modify Component Parameters dialog from this summary dialog to facilitate editing of the statistical sweep parameters.

The # Simulations parameter specifies the number of Monte Carlo simulations that are used to estimate the statistical behavior of the network. Increasing the number of simulations increases the statistical sample size and therefore provide a better estimate of the performance at the expense of increased computational time.

Yield Optimization

The network component values can also be optimized so that the performance is less sensitive to component value variations. This can be accomplished by selecting the Yield Optimization check box. In this case, the optimization requires that a set of performance goals be specified for the network. The yield is defined as the probability that the network frequency response satisfies these performance specifications given the statistical properties of the individual components. Each component has a default set of goals depending on the type of response (lowpass, bandpass, etc.). Each goal specifies the insertion loss performance of the network in dB and can represent a specification that the value stay above or below the stated level. The specification can be at a single point, or over a given frequency band.
To modify default goals:

1. Press Set Yield Spec/Goals button on the Yield Assistant tab to open the dialog.
2. Add or delete goals:
   
   • Use the Add Goal button to add new goals.
   • Use the Del button to the right of the goal to delete individual goals
   • Use the Delete All Goals button to delete all goals. The goals can be reset to their default values using the Default button.
   • A goal is used in the analysis only if the Active box at the left of the goal line is checked.
     The # Iterations parameter available for Yield Optimization specifies the maximum number of optimization iterations that the simulation performs to try to find the appropriate network component values.

Displaying Results Automatically

If the Automatically Display Results box on the utility window Yield Assistant tab is selected, the simulation results is displayed automatically after completion of the analysis.

Starting the Simulation

The yield analysis can accomplished using one of these methods.

• Click the Simulate button on the Yield Assistant tab.
• Click the Simulate Yield button on the utility window toolbar.
• Choose Tools > Auto-Simulate Yield from the utility window menu.

Yield Results

For each component (up to a maximum of 4) chosen for yield analysis, a yield sensitivity histogram is displayed. The yield definition can be changed on the first page of the display by setting passband frequencies Fp_1 and Fp_2 as well as the maximum insertion loss at these frequencies, and stopband frequencies Fs_1 and Fs_2 as well as the minimum insertion loss at these frequencies. Other pages in the display show the overall statistics of the yield as well as the frequency response for each of the Monte Carlo simulations.

Yield Templates

In some cases, you can simulate the SmartComponent manually.
To generate a simulation schematic around the selected SmartComponent:

1. Click the Create Template button on the utility window Yield Assistant tab.
2. After examining or modifying the simulation schematic, manually start the simulation by choosing Simulate > Simulate from the Schematic window.
3. When you are finished, click the Close Template button on the Yield Assistant tab to return to the original design. You can also manually close the simulation schematic by choosing File > Close Design from the Schematic window menu.

Display Assistant

The Display Assistant is used to easily and quickly display the performance of a SmartComponent. The display templates are preconfigured display files that provide a comprehensive look at the performance of the component. You can create your own displays or modify the included display templates using the built in features of Advanced Design System, but in most situations, the included display templates provides all the information you need.
The Display Assistant is accessed using the Matching Utility window, where full display control is enabled from the Display Assistant tab. Basic display selection can also be accomplished using the utility window menu and toolbar

Before using the Display Assistant, a valid dataset from a simulation of the selected SmartComponent must exist in the current project data directory. This simulation can be conveniently accomplished using the Simulation Assistant. Refer to Simulation Assistant for details on this step.

Opening a Display

To display results from a SmartComponent simulation using the utility window, select the SmartComponent from the SmartComponent drop-down list box in the upper right corner of the utility window. The display is then launched using one of the these methods.

• Click Display on the Display Assistant tab.
• Click Automatically Display Simulation Results on the utility window toolbar.
• Choose Tools > Auto-Display from the utility window menu.
  If no valid dataset exists for the selected SmartComponent, the Display button on the Display Assistant tab is de-activated. If the toolbar or menu are used to try to display the results, a message appears indicating that no dataset exists.

Display Template Features

The display templates opened by the Display Assistant have common features that are discussed here. For features unique to the display templates of some SmartComponents, refer to the chapter SmartComponent Reference.

Basic Layout

Basic Layout of Display Templates shows the basic layout of the display templates. Area one of the display template contains a graph of the most important parameters of the SmartComponent. Area two contains several graphs that give a comprehensive look at the component's performance. Area three contains a table listing the basic specifications and performance of the component.

Basic Layout of Display Templates

Typical Area One Graph

The following figure shows a typical graph from area one of a display template.

Basic Layout

Basic Layout of Display Templates shows the basic layout of the display templates. Area one of the display template contains a graph of the most important parameters of the SmartComponent. Area two contains several graphs that give a comprehensive look at the component's performance. Area three contains a table listing the basic specifications and performance of the component.

Basic Layout of Display Templates

The frequency range of the graph is determined by the Simulation Assistant. As you change the frequency range in the Simulation Assistant, this graph updates automatically. The markers A and B are used to define the frequency range of the graphs in area two. This feature is used to zero in on the region of interest and obtain a comprehensive look at the component's performance. The marker M1 can be moved by dragging the marker with the mouse. The performance at the frequency given by M1 is shown in the table in area three.

Typical Area Two Graphs

Typical Graphs from Area Two shows typical graphs from area 2 of a display template.

Typical Graphs from Area Two

These graphs provide a quick, comprehensive look at the component's performance. Their frequency range is determined by the location of the "A" and "B" markers found in the main graph. Any markers such as M2 shown here can be moved by dragging them with the mouse. Performance criteria at the marker frequency displays in the table in area three.

Typical Area Three Templates

Typical Table from Area Three shows a typical table from area three of a display template.

Typical Table from Area Three

The white rows show the specifications and important performance criteria for the component. The gray rows show the performance criteria at the user defined marker frequencies. The box below the table provides explanatory information for the table.

Using Display Templates in Other Applications

In some cases, you can use one of the display templates provided with the Impedance Matching Utility for other applications.
To gain access to one of the templates:

1. Select the template from the Available Templates field and click the Open Display Template button on the utility window Display Assistant tab.
2. Insert a dataset of your choice using the dataset pull-down list box in the upper left corner of the display. If some parameters in the display template are not defined in the selected dataset, you can make appropriate modifications to the display. These changes can be saved using the commands in the display File menu.

Transformation Assistant
After a Matching Utility SmartComponent has been designed, the lumped inductors and capacitors can be transformed into equivalent distributed element counterparts using the Transformation Assistant . This feature enables you to quickly and easily transform an ideal filter topology to a form that is realizable for high-frequency systems.

Opening the Transformation Assistant

The Transformation Assistant dialog box is accessed from the Matching Utility window, either by selecting Tools > Distributed Element Transformations from the Tools menu or from the Toolbar.

When the Transformation Assistant is opened, the SmartComponent subnetwork appears in the schematic window and a dialog box is opened. The transformations are accomplished using the controls on the dialog.

Selecting a Transformation Type

The type of transformation to be applied is selected from three options:

• LC to TLine - Transforms lumped inductors and capacitors to ideal transmission line elements. Eight different inductor/capacitor combinations can be transformed to different series lines, series stubs, or shunt stubs.
• TLine to TLine (Kuroda) - Apply Kuroda's identities in order to transform series short circuited stubs to shunt stubs that are realizable in microstrip and other printed transmission line technologies.
• LC, TLine to Microstrip - Transforms lumped inductors and capacitors as well as ideal transmission line structures to microstrip equivalent components. Application of this transformation requires a valid license for the Passive Circuit DesignGuide.
  After a transform has been selected, the graphical area displays the components that can be transformed using the current selection. Black components represent elements included in the original circuit available for transformation, while gray components represent elements not included in the original circuit. From this graphical area, use the left mouse button to select one of the available component types. The graphical area changes to reveal the different distributed element equivalents available for substitution. Transformations Available for Series Inductor Circuit shows the transformations available when a series inductor circuit has been selected.

Transformations Available for Series Inductor Circuit

From this point, the type of equivalent network can be selected using the left mouse button from the available structures at the right of the graphics area. A box highlights the currently selected structure. Text at the bottom of the window changes as different selections are made, providing some help concerning the particular transform selected.

Component Selection

After the type of circuit component to be transformed is selected, the actual circuit elements to apply the transform to can be selected using the Component Selection tools. As the left and right arrows within this area are clicked, valid components within the original circuit are highlighted, and their instance names (i.e., L1, C4) appears in the text box on the Transformation Assistant dialog. The three buttons are used to select which specific components should be subject to the current transformation:

• Add - Add the currently selected component(s) to the transformation list.
• Add All - Add all circuit components of the appropriate type to the transformation list.
• Cut - Remove the currently selected (highlighted) item in the transformation list from the list.

Transformation Buttons

The buttons across the bottom of the dialog box are used to accomplish the transformation on the selected components.

• Transform - Apply the selected transform to the component in the transformation list.
• Undo - Undo the last performed transform. This button can be used repeatedly to undo all previous transformations.
• OK - Accept the current transformed circuit and close the dialog box. After the transformed circuit has been accepted, transformations cannot be undone.
• Cancel - Close the dialog box and revert to the original, untransformed circuit.

Changing Component Type

After all transformations have been made on a specific component type (such as series inductor), use the left mouse button to click the red return arrow in the upper left hand corner of the graphic area (or use the right mouse button to click anywhere on the graphic area) to return to the main component selection page. Then you can select another component type and repeat the transformation steps for this new selection.

Transmission Line Types

Five basic transmission line elements can be produced using the Transformation Assistant are:

Additional Transformation Functions

Unit Element

For certain transformations, either the electrical length or characteristic impedance of the resulting transmission line must be specified by the user. If the Unit Element box is checked, the resulting transmission line has an electrical length of 45 degrees and the characteristic impedance is computed appropriately. If the Unit Element box is unchecked, then the Characteristic Impedance (Z0) box becomes active and the computation uses this characteristic impedance to compute the appropriate length.

Characteristic Impedance

The Characteristic Impedance (Z0) box is used to specify the transmission line characteristic impedance for certain transformations. In cases where either the electrical length or the characteristic impedance can be specified, this box works in conjunction with the Unit Element box as discussed above. In certain other cases, this Characteristic Impedance (Z0) box is used alone. For example, when adding lines to the front or end of a network as part of Kuroda's identities, the characteristic impedance of the transformation can be specified using this box.

Adding Transmission Lines

As part of the TLine to TLine transformation, unit element (45 degree electrical length) transmission lines can be added to the front or end of the network. The characteristic impedance of these lines is specified using the Characteristic Impedance (Z0) box. Such lines can be added as needed during the transformation process. Addition of these lines changes the phase response and, if the characteristic impedance is not equal to the network terminal impedance, the magnitude response of the network.

Microstrip Substrate

When performing LC, TLine to MLine transformations, the microstrip substrate thickness (h) and relative permittivity (Er) must be specified. All microstrip elements within a design must share the same substrate parameters. The substrate parameters used in the final design are the values that appear in the boxes after the final transformation step.

TLine to TLine Transforms (Kuroda Identities)

The TLine to TLine transforms are typically used to transform series short circuited stubs to parallel open circuited stubs in preparation for implementation in planar transmission line technologies. However, these operations only work on Unit Element lines with electrical lengths of 45 degrees. Therefore, when performing lumped to ideal distributed transformations, you must perform substitutions that conform to this Unit Element specification. Preferred stubs (highlighted in blue on the graphical area) as well as series transmission lines (transformed with the Unit Element box checked) can be transformed in this way. When adding transmission line elements before or after the network, the electrical length is 45 degrees and only the characteristic impedance must be specified.

Microstrip Transforms

The LC, TLine to MLine transformations form a somewhat unique class of operations. This set of transformations takes lumped inductor/capacitor combinations as well as ideal series transmission lines and shunt transmission line stubs (obtained from the LC to TLine transformations), and converts them to microstrip. Note that series stubs cannot be used in this transformation since these cannot be realized in microstrip.

Note This set of transforms is only available if a valid license for the Passive Circuit DesignGuide exists.

In addition to the standard transmission line topologies, certain lumped elements can be replaced with SmartComponents from the Passive Circuit DesignGuide. The available SmartComponents are:

When making such substitutions, the design capabilities of the Passive Circuit DesignGuide are used to realize the topologies. In this case, however, the design procedure is approximate, and some tuning of the elements is required before the substituted device offers the correct performance. In such cases, after completion of the transformation, push into the SmartComponent on the schematic window and open the Passive Circuit DesignGuide control window. The Simulation and Optimization Assistants in the Passive Circuit DesignGuide SmartComponent can then be used to quickly and efficiently tune the performance of each individual element.