First and Second Order Group Timing Tank Ceramic Filters for PCM Carrier Systems

Abstract

Timing extraction use ceramic bandpass filters for 1st (1.544 Mbit/s) and 2nd (6.312 Mbit/s) order group PCM carrier systems were examined. Two trapped energy piezoelectric ceramic strip resonators operated with thickness shear vibration mode and three ceramic capacitors were used for each filter. Gaussian approximated effective parameter theory is applied in a circuit design. For both filters, temperature coefficients of the center frequencies are below 10 ppm/°C. The aging rates are 0.01%/decade. Both filter sizes are reduced to 1/5 that of the usual LC filters.