Design and construction of monolithic-crystal filters using lithium tantalate

Owing to its larger electromechanical coupling coefficient, the use of lithium-tantalate substrates in place of quartz for the construction of monolithic-crystal filters provides a useful increase in available filter bandwidth. Crystal plate orientations are identified with piezoelectric properties suitable for filter applications, and filterdesign criteria are derived and confirmed experimentally for a number of selected orientations in lithium tantalate. Applying these criteria to the 163° rotated Y-cut plate, third-overtone monolithic-crystal filters have been constructed operating in the frequency range 35¿55 MHz with bandwidths up to 0.75%.