Fundamental mode 155 MHz with flat blank in the crystal unit using VCXO

Fundamental mode At-cut 155.52 MHz crystal units are used in the VCXO (Voltage Controlled Crystal Oscillator) for the base station. To this oscillator, both high frequency stability and wide frequency trim range are required. One of the solutions is to use flat wafer, which are used in 10 MHz, 20 MHz and etc. crystal units. Because the thickness of AT-cut 155.52 MHz blank is about 10-micron meter, to realize make such thin blank is about 10-micron meter, to realize make such thin blank, it is necessary to review and use method of the wafer. Also it is necessary to study blank protection against external shock. This paper shows the results of these above and oscillator's frequency stability. At first, lapping method of this wafer is discussed. Next, as an applied examples, fundamental mode AT-CUT 155.52 MHz, drive level characteristics, temperature characteristics, equivalent characteristics are discussed. Also as further step applied example, crystal oscillator's temperature characteristics, and long term frequency stability are shown.