I'm curious about how MURATA variable capacitors work, for example, parts from the family LXRW0YV330-056. As far as I can tell, these are not semiconductor varactors, but based on some other physical principle; does anyone know what it is? There is no information on the data sheets except that they are "ceramic".
My interest is that I would like a voltage-tuned capacitor where the input capacitance on the control voltage line is as small as possible, but the capacitance swing per input volt is as large as possible. Also, I would like these to work at cryogenic temperatures, where semiconductor varactors tend to fail. Any input would be greatly appreciated!