RF Electronics Chapter 7: RF Filters Page 214
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Chebyshev filters are poor and these filters should not be used for data communications
or applications where the group delay is important.
Figure 7.7. Cauer-Chebyshev Lowpass Filter.
Figure 7.8. Cauer-Chebyshev Lowpass Filter Frequency Response.
Figure 7.9 shows the passband response of the four different filter types. The 0.1 dB
passband ripple of the Cauer-Chebyshev and Chebyshev filters can clearly be seen. The
Bessel filter has a significant attenuation for frequencies above 100 MHz.
Both the Chebyshev and Cauer-Chebyshev filters have poles on an ellipse and are
elliptical filters. As a result, it is better not to specify a filter as an elliptic filter since it
does not fully specify the filter type.
From filter tables, which include losses due to the finite Q values of the filter elements, it
can be determined that for a given Q value for the components, the Chebyshev filter has
a higher passband insertion loss than a Butterworth filter and a Bessel filter has a lower
insertion loss than a Butterworth filter. The same applies for Bandpass filters, so that for
the same unloaded Q of the resonators used in coupled resonator RF filters, the Bessel
filter will have the lowest insertion loss and the Chebyshev filter will have the highest
insertion loss.
CAP
ID=C1
C=7.153 pF
CAP
ID=C7
C=2.776 pF
CAP
ID=C6
C=3.835 pF
CAP
ID=C5
C=0.7878 pF
CAP
ID=C4
C=5.627 pF
CAP
ID=C3
C=9.595 pF
CAP
ID=C2
C=10.67 pF
PORT
P=2
Z=50 Ohm
PORT
P=1
Z=50 Ohm
IND
ID=L3
L=16.46 nH
IND
ID=L2
L=16.23 nH
IND
ID=L1
L=21.39 nH
RF Electronics: Design and Simulation
214 www.cadence.com/go/awr
