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RF Electronics Chapter 9: Impedance Matching of Power Amplifiers Page 325 2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0. Table 9.1. Small signal S parameter data for the MRFE6VS25N LDMOSFET [4]. ! Copyright - Freescale Semiconductor, Inc., 2012 ! 06/05/2012 ! Rev. 0 ! MRFE6VS25NR1 S-Paraneters ! Vdd = 50 Vdc, Idq = 150 mA # hz S ma R 6.8 ! ! freq magS11 angS11 magS21 angS21 magS12 angS12 magS22 angS22 2.000E+08 0.9588 -24.15 3.9246 148.64 0.0050 64.44 0.9219 -20.86 2.050E+08 0.9589 -24.74 3.9198 148.14 0.0051 63.54 0.9212 -21.64 2.100E+08 0.9574 -25.36 3.9118 147.68 0.0052 63.28 0.9204 -22.38 2.150E+08 0.9577 -25.94 3.9024 147.12 0.0054 63.06 0.9200 -23.15 2.200E+08 0.9586 -26.54 3.9027 146.67 0.0055 62.06 0.9214 -23.84 2.250E+08 0.9588 -27.04 3.8941 146.08 0.0056 62.31 0.9223 -24.59 2.300E+08 0.9593 -27.52 3.8839 145.59 0.0056 60.79 0.9230 -25.15 2.350E+08 0.9606 -28.03 3.8837 145.11 0.0057 60.66 0.9245 -25.85 2.400E+08 0.9602 -28.55 3.8761 144.57 0.0059 60.43 0.9247 -26.36 2.450E+08 0.9601 -29.03 3.8684 143.98 0.0060 59.64 0.9254 -26.88 + Many more lines, with the last lines: 1.090E+09 0.8987 -129.90 2.4501 44.61 0.0034 86.22 0.8218 -124.10 1.095E+09 0.8985 -130.50 2.4388 44.04 0.0035 88.73 0.8214 -124.67 1.100E+09 0.8986 -131.09 2.4267 43.49 0.0036 88.85 0.8210 -125.26 The frequency steps are 5 MHz, from 200 MHz to 1.1 GHz, except for a gap from 500 to 650 MHz. This can now be used as a sub-circuit in Cadence AWR DE. For this example, an amplifier with a bandwidth of 300MHz to 400MHz is required. An input matching network will consist of a coupling capacitor followed by a Pi section and a lowpass T section. Having the lowpass T section at the input of the MOSFET provides a lower Q match for the input capacitance of the MOSFET than a Pi network. At the output, a lowpass T section is used to provide a high amplifier efficiency, by having an inductor in series with the output and minimising the RF harmonic currents flowing through the FET. This is followed by a Pi section in order to obtain good harmonic filtering. To determine the components of the matching networks the input and output impedances of the MOSFET is required. The centre of the 300 MHz to 400 MHz frequency band is 350 MHz, for which the S parameter data are given. From equation 8.4, for an amplifier with a perfect output match, 11 S in and from equation 8.5, for an amplifier with a perfect input match, 22 S out , so that from equation 8.1: 11 11 0 1 1 S S Z Z in Eqn. 9.23 22 22 0 1 1 S S Z Z out Eqn. 9.24 However, the S parameter data in table 9.1 is for a reference impedance of 6.8 Ω. The reference impedance of the S parameter data will thus first need to be changed. The easiest way to do this is to use the S parameter file MRFE6VS25R1 of figure 9.1 as a sub-circuit as shown in figure 9.33, by creating a new Graph Tabular, and then using that to display Z(11), Z(22) and if needed the S parameters with a 50 Ohm reference. Those values can then be exported by selecting the tabular graph and then selecting Graph Export Trace Data. Then save the tabular graph to a file. RF Electronics: Design and Simulation 325 www.cadence.com/go/awr