A Microwave Acoustic QPSK Modulator Leveraging Poled Ferroelectrics

This paper reports on the first microwave acoustic quadrature phase-shift keying (QPSK) modulator. Phase modulation is achieved via acoustic phase inversion (API) through electric field control over piezoelectric coefficient in ferroelectric stacked crystal filters (SCF). A proof-of-principle device is fabricated and measured. QPSK constellation diagram is presented along with two-port S-parameters for each of the four data states. The microwave acoustic QPSK modulator demonstrates a step towards an ultra compact all-acoustic transceiver.