50Ω-terminated 900MHz monolithic lateral-extensional piezoelectric filters on ultrananocryslalline diamond

For the first time, very low insertion loss (3.7 dB) 900 MHz micromachined bulk-lateral mode filters are reported with 50 Ω termination impedance. Two lateral-extensional modes of a single resonant structure are coupled together to enable low insertion loss (IL) while maintaining a very small footprint (~ 2666 μm × 2666 μm). These narrow-band filters are fabricated on a thin-film piezoelectric-on-diamond (TPoD) platform and demonstrate an adjustable fractional bandwidth between ~0.1 to 0.4 percent.