Thin Film Bulk Acoustic FBAR Resonator With Spurious Mode Suppression Mechanism

An electronic signal filter having an input and an output, the filter comprising:

• at least one series connected resonator having a first node connected to the filter input and a second node connected to the filter output;
• at least one parallel connected resonator having a first node connected to the second node of the series connected resonator and a second node connected to ground;
• wherein each of the series connected resonator and the parallel connected resonator further comprise a first electrode having a first planar portion, a second electrode having a second planar portion disposed substantially parallel to the first planar portion;
• and a piezoelectric layer disposed between and contacting both the first and second planar portions, wherein at least a portion of an edge of one of the electrodes is formed with a plurality of peaks and valleys which are operable to increase an effective resonance length of the electrode, thereby altering a frequency response characteristic of an electromagnetic resonance of the resonator.

An electronic signal filter having an input and an output, the filter comprising:

• a plurality of series connected resonators, a first resonator of the plurality having a first node connected to the filter input and a last of the series connected resonators having a second node connected to the filter output;
• a plurality of parallel connected resonators, each of the parallel connected resonators having a first node connected in between two of the series connected resonators, each of the parallel connected resonators having a second node connected to ground;
• wherein each of the series connected resonators and the parallel connected resonators further comprise a first electrode having a first planar portion, a second electrode having a second planar portion disposed substantially parallel to the first planar portion;
• and a piezoelectric layer disposed between and contacting both the first and second planar portions, wherein at least a portion of an edge of one of the electrodes is formed with a plurality of peaks and valleys which are operable to increase an effective resonance length of the electrode, thereby altering a frequency response characteristic of an electromagnetic resonance of the resonator.