Abstract: A ceramic block filter (114,118) employs a novel tuning process which avoids the necessity of etching or abrading plating on the top surface of the block. Initially, the blocks (210) are prepared from a batch of ceramic material such that their height is intentionally longer than desired, so that the filter center frequency is slightly lower than desired. Next, an artwork mask (310) designed in accordance with pre-selected frequency related characteristics and desired performance specifications is used for applying an electrically conductive material (240) to the top surface of the block (210). Then, the center frequency and resonator length of the block (210) are measured and a new resonator length is calculated using the measured values. The bottom surface of the block (210) is next lapped to the new resonator length. Then, electrically conductive material is applied to the lapped bottom surface of the block (210).

Abstract: An improved temperature compensation circuit for an oscillator circuit having a frequency response that is parabolic with respect to temperature, including a time dependent ramp signal, an AC integrator for converting the ramp signal to single-sided parabolic voltage functions and means for sampling the resulting time dependent one-sided parabolic voltage functions with respect to a time base at selected times corresponding to ambient temperatures.