AWR eBooks

RF Electronics Chapter4: Transmission Line Transformers and Hybrids Page 69 2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0. parameters of the Rogers RO4003 substrate can be obtained by using the Libraries *AWR Web Site Rogers RO RO4003 and select 32 mil, 1 oz. and place that as a component in a circuit. Until recently Rogers only specified an Er= 3.38 for the RO4003 laminate. The latest data sheet from Rogers for RO4003C [5] indicates Er (Process specification) = 3.38 and Er (Design specification) = 3.55. Suggesting that for simulation the value of Er=3.55 gives better results. Those values are used here. The values indicated in MSUB for RO4003 on the CADENCE AWR Web site are ErNom=3.48 and Er=3.55. The value of ErNom is ignored by CADENCE AWR DE and Er=3.55 is used in the simulation. Note some of the earlier designs in this book using the RO4003 substrate still use the 3.38 value. Determining the required track width and length, as shown in figures 2.21 to 2.23, results in a track width of 1.788 mm for the 50 lines and 0.9519 mm for the 70.71 lines. The layout must allow the isolation resistor to be soldered to the PCB. This requires that a resistor, with a PCB footprint is used. Firstly, determine the size of the surface mount resistor to be used. In our layout, an AVX 1206 resistor was used. AVX resistors are no longer included in the CADENCE AWR web site libraries in CADENCE AWR DE V10 or later, but Panasonic resistors are. Selecting Libraries *AWR web site Parts by type Lumped element Resistor Panasonic Resistor For General Equipment S parameter, allows different size footprint resistors to be selected (0603, 1005, 1608 mm). Simply place the resistor with the required size footprint in the schematic, this will then automatically include the footprint in the layout. If another size footprint, say 1206 is required, then the footprint can be imported by simply placing a suitable size component like a capacitor or inductor. For our circuit, a Coilcraft inductor is used to provide the 1206 footprint. Select Libraries *AWR web site Parts by type Lumped element Inductor Coilcraft RF Inductors Data 1206CS series. Then place any inductor in list in the circuit. Right clicking and selecting the inductor's properties, then selecting Layout, shows all the available Coilcraft Footprints, as shown in figure 4.8. The layout properties of the isolation resistor in the Wilkinson Hybrid can now be selected. The library name will be blank. Selecting the Coilcraft Library and the 1206 imperial, (3216 metric) footprint will then link that footprint to the resistor. The inductor can then be removed from the circuit, as the footprint will remain linked to the resistor. With a Modelithics EXEMPLAR Library installed, resistor footprints and their associated simulation files can also be placed. Available footprints are 0402, 0603 and 0805 imperial, which are suitable sizes for microwave layouts. Figure 4.8. Selecting a footprint for resistor R1. RF Electronics: Design and Simulation 69 www.cadence.com/go/awr

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