When the frequency range is expanded shown below in

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Unformatted text preview: 0.2 8e7 8.5e7 9e7 9.5e7 1e8 1.05e8 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. 2 0.5 0.4 0.3 0.2 0.1 0 0 2e7 4e7 6e7 8e7 1e8 1.2e8 1.4e8 1.6e8 1.8e8 acfrequency 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.

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