1472 Crystal Filters Although not an active filter, crystal (Quartz) filters are very high-Q filters. Some can
Question:
14–72 Crystal Filters Although not an active filter, crystal (Quartz) filters are very high-Q filters. Some can have Q’s approaching 100,000. High Q means high selectivity; hence, crystal filters are used extensively in communications where fine-tuning is essential. In its simplest form, a quartz crystal is a rectangular cut crystal with metal plates attached to its flattest sides—imagine a parallelplate capacitor with the crystal as the dielectric. An electronic equivalent of a quartz filter is shown in Figure P14–72. CO is called the shunt capacitance, and C1, L1, and R1 are the mechanical capacitance, inductance, and resistance of the crystal, respectively.
A particular crystal has CO = 1.2 pF, C1 = 2.3 fF, L1 = 6.2 mH, and R1 = 32 Ω. Assume RL = 10 Ω. Analyze this filter and determine its Q and ω0. Use MATLAB or Multisim to examine this circuit and help calculate the requested parameters.
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The Analysis And Design Of Linear Circuits
ISBN: 9781119235385
8th Edition
Authors: Roland E. Thomas, Albert J. Rosa, Gregory J. Toussaint