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Unformatted text preview: 0.2 8e7 8.5e7 9e7 9.5e7 1e8
acfrequency 1.1e8 1.15e8 1.2e8 Note that the frequency response looks slightly asymmetric in this plot. When the frequency range is
expanded (shown below, in blue) we see that this ﬁlter’s response is actually pretty ugly, and “falls apart”
at low frequencies. For comparison, the red plot shows the response of a “pure” series LC ﬁlter.
0 2e7 4e7 6e7 8e7
1e8 1.2e8 1.4e8 1.6e8 1.8e8
acfrequency 2e8 The reason for this is that we designed the ﬁlter by transforming the actual circuit to a an equivalent series
RLC circuit at the center frequency of the ﬁlter. The equivalence between the transformed circuit and a
“pure” RLC circuit only holds up in the vicinity of the design frequency. Away from the center frequency,
the equivalence breaks down. Obviously, this procedure doesn’t work very well for low-Q (relatively widebandwidth) circuits like this one — the loaded Q of this ﬁlter is only 5 (fractio...
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This homework help was uploaded on 03/13/2014 for the course ECE 453 taught by Professor Staff during the Spring '08 term at University of Illinois, Urbana Champaign.
- Spring '08