620 MHz AT-cut fundamental crystal resonator

This study succeeded in making 620 MHz AT-cut fundamental resonators, which used inverted mesa blanks of approximately 2.5 μm thickness, produced by a uniquely developed dry etching process using magnetron plasma. The electrode of this resonator is aluminum with has similar gravity to the crystal (2.65), and the blank is put into 7.5 mm×5.0 mm and 5.0 mm×3.2 mm ceramic packages. A voltage controlled crystal oscillator (VCXO) using this resonator shows excellent electrical characteristics.