RF Electronics Chapter 7: RF Filters Page 229
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
of the resonators are simply the resonant capacitance (371 pF in the design example) and
the inductance of the resonator is adjusted to account for the coupling inductors. For this,
the equations for the coupling capacitors in figure 7.29 are replaced with the equations
shown in figure 7.32, which also shows the circuit of the filter. Figure 7.33 shows the
frequency response of the filter. The group delay for inductive coupling has an opposite
slope to the one for capacitive coupling.
Figure 7.32. Inductively coupled LC resonator filter.
Figure 7.33. Frequency response of the filter of figure 7.32.
By using a combination of capacitive and inductive coupling, as shown in figure 7.34, a
flatter group delay is obtained, as shown in figure 7.35. The equations from the Global
Definitions folder of the Cadence AWR DE project for figures 7.34 and 7.35 are shown
in figure 7.34. If a filter with a flat group delay is to be designed and the extra cost of
RF Electronics: Design and Simulation
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