When designing a second-order RLC band pass filter, how can we choose whether to use the series form or parallel form?
One wishes to choose a resonating inductance that is as small as possible, since the iron or ferrite required to achieve high-inductance often has undesirable characteristics. A large inductance may also require many windings of copper wire.
A resonator sometimes is mechanical, such as a piezoelectric crystal, or ceramic resonator. In these cases, inductance is often quite high, but cannot be easily chosen by the designer.
Both source resistance and load resistance must be considered, one or both are usually out of control of the designer. When both are low, the series RLC resonator yields a high-Q resonator with least inductance:



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When both source and load resistance are high, parallel RLC resonator yields a high-Q resonator with least inductance (below). Both these series and parallel example circuits  have similar &quot;loaded&quot; Q.



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Where you have a crystal resonator, the equivalent inductive reactance is often very, very high. For reasonable source and load resistances found in electronic circuits, the series form is more reasonable than the parallel form:



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