RF Electronics Chapter 9: Impedance Matching of Power Amplifiers Page 337
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Figure 9.56 shows the amplifier's frequency response. The large signal S11 is not as good
but the frequency response is flatter than the transformer-matched amplifier shown in
figure 9.51. The gain is very similar. Using a one-line impedance transformation results
in a higher gain at 1 GHz and a lower gain at 800 MHz and 1.2 GHz. At 1 GHz, for typical
substrates, the 90 ° line length is 44 mm long, so that a two-line impedance transformation
can easily be implemented. Figure 9.53 and 9.54 show input capacitors Cin1 to Cin3, and
similarly Cout1 to Cout3, that can be inserted in the hardware to perform some fine-tuning
in case the actual device is slightly different from the model used in the simulation.
Figure 9.57. Stability of the transmission line matched power amplifier, 0.8-1.2 GHz.
Figure 9.57 shows that the amplifier is stable over the entire 600 MHz to 1400 MHz
frequency range, provided the input and output have a VSWR less than 6:1.
Figure 9.58. Stability of the transmission line matched power amplifier, 10 MHz - 2 GHz.
RF Electronics: Design and Simulation
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