Jonathan Kayne, KM4CFT
I am in the process of trying to run some LTspice simulations of the crystal filters.
I am aware that one can model a quartz crystal using a series combination of a resistor, inductor and capacitor all in parallel with another capacitor.
What I want to know is if there is a way to find out the motion parameters of a crystal given a datasheet, or if there is a set of "typical" values I can use.
Please keep in mind that this is a simulation, and I am not looking for an exact replica. (I expect the values to be different from what is measured)
The point of this is purely for educational purposes, as I want to learn about how these filters work and how to possibly design them in the future.
I appreciate your interest. Start with this article, let me know if you have any issues getting it --
These parameters typically are not listed on a datasheet. The article describes a 4915 kHz crystal - widely used by hams to build CW narrow filters. Also in some designs varactors are placed between the crystals to allow variable bandwidth, but a caution this also moves the center frequency (so a receiver may use an oscillator after the crystal filter to compensate for this - the K2 does this).
in practice these parameters have to be measured - and some hams have made simple test equipment to make these measurements - or maybe suitable gear maybe there at your university.
my email is listed at qrz.com. glad to dialog further - and maybe I can help you with some crystals for your project. I can also share that I once worked with some specialists who learned to make these things - they are called bulk acoustic wave - onto a chip - they are inside your cell phone! I can share other info via email.
73 Curt wb8yyy