A 3-TERMINAL AT-CUT QUARTZ RESONATOR WITH SHIELD ELECTRODES

In this paper a 3-terminal AT-cut quartz crystal resonator with shield electrodes is proposed. The resonator has three terminals connected t o three electrodes on the quartz substrate. The Ist and 2nd terminals are connected to two main electrodes to drive piezoelectrically, and t he 3rd terminal is connected to a shield electrode which is located ju st outside the main electrodes. The resonator with shield electrodes e nables the separation of the intrinsic capacitance from the stray capa citance which affects the increase of effective resistance. Experiment al data show fairly good agreement with the intrinsic capacitance pred icted by material constants of AT-cut quartz crystal. In the applicati on of oscillators, a common-emitter Colpitz oscillator circuit is prop osed in this paper instead of the widely used ''common-corrector'' one , because the stray capacitance can be included in 2-phase inverting c apacitors. Experimental data on the resonator having a 2-divided elect rode connected in a lattice with shield electrodes is also presented.