MM0704, Lesson 2
By using resonant
circuits, it is possible
to achieve combinations
of the outputs
previously discussed (figure 2-12). The single, cutoff frequency of the low-pass and high-pass filters overlap and
provide the designer with two cutoff frequencies. The pass band between f1 and f2 can be varied to a very narrow
Figure 2-12. Transmission Characteristics of Band-Pass Filters.
Band-rejection filters may be used to remove a specific band of objectionable frequencies, such as static interference,
from a transmitter that is interfering with television reception.
L-section. The parallel-tuned circuit (L1-C1) and the series-tuned circuit (L2-C2) are tuned to the band frequencies to
be rejected (figure 2-13). The
Figure 2-13. L-Section Band-Rejection Filter