V10.4 beta (Latest build: 7310) of the Ampsa Amplifier Design Wizard has been released. The impedance-matching capabilities were extended in this version. This includes a new error function for harmonic control and more options when fixed components are added to the terminations before a matching problem is solved.
With the release of V10.0 the software was restructured comprehensively to eliminate most of the temporary files used previously. Temporary storage is now mostly in memory. Multiple documents are handled better (C++ classes were created for the graphics, schematics and artwork too, and very little data and very few routines are shared by the different document types). Dynamic arrays were also used to handle large and small circuits better.
Several features were implemented in the V10 Impedance-Matching Module to simplify synthesis of matching networks based on load-pull data. In addition to point-matches, circular areas of allowable input or output reflection coefficients on the Smith Chart can now be defined and the circumferences of these circles, or the areas inside or outside the circles, can be set as targets for the input or output impedance of the matching networks to be synthesized. This is useful when the matching networks for high efficiency mode amplifiers are synthesized with the ADW. This feature can also be used to map the constant gain circles (inherent stability required) and constant gain circles of linear amplifiers to equivalent IMW terminations. This is, however, not required in the ADW because this transformation has been automated in the regular design flow (Class A, AB and B).
Series lines could previously be added to the terminations of a matching problem to be solved. This capability has been extended to allow stubs and an additional series line to be added too before the matching problem is solved. The stubs can be used for biasing purposes or to force open or short terminations at the source or load termination for harmonic control.
Control over the 2nd and 3rd harmonic reactances are also provided when the bandwidth is less than an octave. A range of target reactance values can be set at each harmonic frequency. The resistance at the harmonic frequencies should ideally be zero, but this can only be realized at resonant frequencies. Instead, harmonic power is minimized by targeting high Q (X/R), or low or high input/output impedances for the matching network at the harmonic frequencies. More information is provided under Public Downloads (IMWV10_PowerMatchExample.pdf).
Many interface improvements were also made. These include unlimited undo's in the ADW text editor, extension of the unicode features to ADW circuit files (.ani; now stored as unicode files), displaying constant output power contours for the (modified) transistor in the Device-Modification Module, reorganization of the Power Optimization Page in the Optimization Wizard, improvements in the graphics views, improvements in editing tabular data and many small changes like dimming of the Save button when a document is up to date and square windows for the graphs displayed.The option (View | Copy View command) is now also provided to copy the data in any of the ADW tables to the clipboard for pasting in programs such as Microsoft Excel (TM) and the option to hide some of the traces on a graph. The program and installer executables are now also digitally signed.
The performance of harmonic control matching networks can now be optimized in the Analysis Module. Optimization will be required when extra components (bias networks, etc.) are added to the network or when lumped capacitors and inductors are replaced with distributed elements. The optimization features can also be used to restore the performance after modifications to the network aimed at reducing the microstrip discontinuity effects (tapering the widths of steps and open-ended stubs, changing line widths, etc.).
The optimization features can also be used to optimize the matching network to fit the S-parameters associated with an EM simulation of the network. Find the most significant changes required and then apply these changes in reverse to the original network and do an EM simulation again. Alternatively, the extended microstrip step command (MSTP) and the new T-junction commands (MJIS, MJOS, MJSS) can also be used to define the associated discontinuities explicitly. The parameters of these models can then be optimized to provide a better fit to the EM simulation after which the line lengths in the circuit can be optimized to restore the performance targeted. (The relevant discontinuity model parameters can be set for optimization in the Artwork View.)
Note that the discontinuities are defined implicitly when SLINE, OSTUB and SSTUB commands are used. The parameters of the implicit models used are fixed.
A list of recent changes is provided below:
- A correction was made to the constant mismatch circles displayed in the Impedance-Matching Module. When no harmonic control is used and the results are displayed the reference planes are at input and output of the actual matching networks synthesized. When the harmonics are controlled, the reference planes are at the input and output of the complete network (matching network plus any connecting networks specified by using the File | Terminations | Add Lines command).
- Main-line lengths of 180 degrees at any of the frequencies specified in the Impedance-Matching Module (harmonic frequencies included) should be avoided. The matching module uses lumped-element PI-sections or T-sections to model transmission lines during the synthesis process and the model is undefined at these lengths. This condition will be now be trapped and a warning will be issued.
- An issue with updating some of the tables in the Impedance-Matching Module was corrected.
- Only the line widths in the artwork were previously clipped to the artwork resolution. The line lengths are now also clipped to the resolution. This simplifies exporting the artwork with different resolutions in Sonnet Software(R) format to allow for limitations in the memory allowed for the electromagnetic simulation.
- The option to reverse update the changes to made when a circuit is fitted to a set of two-port parameters is now provided. This is useful when the artwork is adjusted to provide a better fit to the electrical (schematic) performance targeted. (EM optimization.)
- The options to force displaying the gain in rectangular plots to dB and to use a logarithmic frequency axis were added to the Preferences Dialog (Modify | Preferences menu command).
- The option to slope the gain (in dB) linearly or logarithmically with frequency was added to the Analysis Module and Modification Network Optimization Wizards. This is useful when equalizers are designed by using the Double-Section Modification Wizard.
- The option to slope the gain (in dB) linearly or logarithmically with frequency was added to the Impedance-Matching Module.
- Impedance-matching data files (.mmi) can now be merged by using the File | Import menu command. Different frequencies should be used in the two files (Use a slight offset in the actual frequencies if necessary). This feature is useful when matching networks for Doherty amplifiers are designed (the same matching network is then required to solve two different matching problems at the same time).
- Negative lengths can now be assigned to the connecting lines specified for shunt capacitors or shunt inductors in the Impedance-Matching Module. This allows the lumped components to be moved closer to the main-line (less parasitic effects).
- Issues related to coarser settings of the artwork resolution (Artwork | Artwork Options and Parameters menu command) were resolved.
- A correction was made in the optimization section of the Analysis Module. Better results will now be obtained when a slope in the gain required is specified.
- A passband issue when a circuit is optimized to fit a set of S-parameters was fixed.
- A resolution issue associated with the explicit T-junction commands (MJIS, MJOS, MJSS) was fixed.
- Negative lengths can now be specified for the connecting lines added on the input or output side of the matching network to be synthesized (Specifications | Terminations | Add Lines command). This is useful for de-embedding lines added to measure the impedances of interest.
- An optimization issue and a graphics issue in the results section of the Impedance-Matching Module (active optimization of non-commensurate solutions) were fixed.
- The fixed elements allowed (source and load connecting networks cascaded with the matching network) were extended to allow a shunt capacitor and series inductor on the source side, and a series inductor and shunt capacitor on the load side. A shunt capacitor and/or shunt inductor is now also allowed in parallel with the stubs previously allowed. The fixed components allowed can be used to model the output circuit of a transistor in simple cases after which the intrinsic load line can be controlled.
- The error function used when the harmonic terminations are controlled in the Impedance-Matching Module has been modified. Additional error factors (MRDf , MRD2ndH , MRD3rdH) are also now listed when a solution is displayed. These error factors provide numeric measures of how well the fundamental, second harmonic and third harmonic parts of the matching problem were solved (right-click the view for help). The option to revert to the previous error function is provided on the specifications dialog for the 2nd harmonic reactances (Specifications | Terminations | X2nd Harmonic command).
- When the option to slope the gain of an impedance-matching problem is used the option is now provided to scale the gain values in place with the values calculated. This provides an easy way of relaxing the gain-bandwidth constraints on a matching problem in a frequency-selective way.
- When the passband is less than one octave, options to control the intrinsic load-lines associated with the 2nd and/or 3rd harmonics are now also provided (CIL Wizard | Select to control the intrinsic load line). High or low harmonic impedances can be targeted. The magnitude of the fundamental frequency impedance (MAG[ZLi_fund(f0)] and the ZF factor is used to decide the magnitude of the harmonic impedance to be targeted. When the impedance required is low, the value targeted is MAG[ZLi_fund(f0)] / ZF and when it is high ZF * MAG[ZLi_fund(f0)] is targeted. Different ZF factors can be specified for the 2nd harmonics and the 3rd harmonics. Low 2nd harmonic impedances are typically required for class B and class F operation. High 3rd harmonic impedances are required for class F operation.
- Point matches or circle matches are now allowed when the power is controlled in the CIL wizard. When a point match is required, the optimum point on each power contour should be selected manually if the default is not acceptable. This can be done by left-clicking the mouse on the angle of interest in the table. This should be done for each passband frequency. Note that the weights of the error function used to select the default optimum points can be adjusted on the page where the contours of interest are selected. Each power contour is semi-elliptic and to allow for a circle match two potential circles are fitted to each contour. The first circle (Option A) encloses the optimum power point (maximum power), while the position of the second circle (Option B) is adjusted to be closer to the center of the power contour. The options to transform (match) the load termination of the matching network to points on the circumference of each circle of interest or to any point inside each circle of interest are provided. Note that the intrinsic or the external load terminations on each contour can be listed.
- When the intrinsic load line is controlled in the CIL wizard, the harmonic terminations required at the insertion point of the matching network for low or high intrinsic load impedances at the 2nd and 3rd harmonic frequencies can now be established automatically (only the fundamental frequency termination was considered previously). Amplifier classes currently considered are class-A, Class-B, Class-F and continuous class-F. In the continuous class-F case, a specific 2nd harmonic reactance (intrinsic) is required at each frequency (not necessarily, low or high). These reactance values are also calculated. The harmonic-control file required in the matching section is set up automatically when this feature is used. A range of target reactances is defined at each frequency.