RF Electronics Chapter 7: RF Filters Page 230
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
inductors over capacitors is a serious problem, then a filter with two coupling capacitors
and one inductor can easily be obtained using these equations. The group delay of such a
filter can still be made sufficiently flat over the passband using optimisation.
Figure 7.34. Filter with both capacitive and inductive coupling.
Figure 7.35. Frequency response of the filter of figure 7.34.
The input and output impedances of the filter can be changed to 50 Ω, by replacing C1
and C7 with capacitive transformers as shown in figure 7.36. The equations for the value
of C1 is calculated by the equation for C1s (C1shunt) and C3 is calculated as C1t (C1top).
The impedance transformation for the output is done in a similar manner. This will
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