RF Electronics Chapter 7: RF Filters Page 218
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
The design of the low reflection filter above has been based on a diplexer design.
Microwaves101 [8] and Mini-Circuits [5] use a reflectionless filter design technique
based on even and odd mode impedances [7]. This includes some cross-coupling between
the output and the input. Figure 7.14 shows the circuit diagram similar to that used by [5]
and figure 7.15 shows the frequency response and return loss after optimisation. The
return loss of figure 7.15 is much better that that shown in [8] and shows the advantages
of being able to optimise circuits using Cadence AWRDE. Figure 7.15 shows that the
return loss is ideal (<-300 dB), but the stopband attenuation is poorer than that of figure
7.13.
Figure 7.14. Even & Odd mode, impedance reflectionless filter circuit.
Figure 7.15. Even & Odd mode, impedance reflectionless filter frequency response.
RF Electronics: Design and Simulation
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