The Influence of Filter Parameters on the Response of Ceramic Filters Operating in the Thickness-Twist Mode

Starting with common equivalent circuits, computer programs have been designed to enable the calculation of filter responses from the parameters of the ceramic material and the dimensions of the electrodes. By varying the parameter values their effect on the filter response is shown. To test the calculated results a number of test filters have been made and their responses measured. The filter responses have behaved as predicted by the calculations. It has been possible to calculate the response of thickness-twist mode filters with a centre frequency in the range 1 to 5 MHz, a bandwidth of 1 to 10%, a load impedance of 100 to 600 Ω and a comparatively linear phase response.