Acoustic galvanic isolator incorporating single decoupled stacked bulk acoustic resonator
View Patent ↗Embodiments of the acoustic galvanic isolator comprise a carrier signal source, a modulator connected to receive an information signal and the carrier signal, a demodulator, and an electrically-isolating acoustic coupler connected between the modulator and the demodulator. The acoustic coupler comprises no more than one decoupled stacked bulk acoustic resonator (DSBAR). An electrically-isolating acoustic coupler based on a single DSBAR is physically small and is inexpensive to fabricate yet is capable of passing information signals having data rates in excess of 100 Mbit/s and has a substantial breakdown voltage between its inputs and its outputs.
1. An acoustic galvanic isolator, comprising:
a carrier signal source;
a modulator connected to receive an information signal and the carrier signal;
a demodulator; and
connected between the modulator and the demodulator, an electrically-isolating acoustic coupler comprising exactly one decoupled stacked bulk acoustic resonator (DSBAR),
wherein the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an electrically-insulating acoustic decoupler between the FBARs, and
wherein the electrically-insulating acoustic decoupler comprises at least one of: (1) an electrically-insulating acoustic Bragg structure; (2) a quarter-wave thick layer of acoustic coupling material; and (3) at least one layer of crosslinked polyphenylene polymer.
2. The acoustic galvanic isolator of claim 1 , additionally comprising:
a first electrical circuit electrically connecting the modulator to the first FBAR; and
a second electrical circuit electrically connecting the demodulator to the second FBAR.
3. The acoustic galvanic isolator of claim 2 , in which:
each FBAR comprises opposed planar electrodes and a piezoelectric element between the electrodes;
the first electrical circuit electrically connects the modulator to the electrodes of the first FBAR; and
the second electrical circuit electrically connects demodulator to the electrodes of the second FBAR.
4. The acoustic galvanic isolator of claim 1 , wherein the electrically-insulating acoustic decoupled comprises the electrically-insulating acoustic Bragg structure, and wherein the electrically-insulating acoustic Bragg structure comprises first, second, and third Bragg elements, the second Bragg element being disposed in between the first and third Bragg elements and having a lower acoustic impedance than the first and third Bragg elements, respectively, at least one of the Bragg elements comprising a layer of electrically-insulating material.
5. The acoustic galvanic isolator of claim 4 , wherein the first Bragg element is a quarter-wave thick layer of a same material as an electrode of the first FBAR, and the third Bragg element is a quarter-wave thick layer of a same material as an electrode of the second FBAR.
6. The acoustic galvanic isolator of claim 1 , wherein the electrically-insulating acoustic decoupler comprises the electrically-insulating acoustic Bragg structure, and wherein the electrically-insulating acoustic Bragg structure comprises one or more layers of crosslinked polyphenylene polymer interleaved with layers of silicon dioxide.
7. The acoustic galvanic isolator of claim 1 , wherein the electrically-insulating acoustic decoupler comprises the quarter-wave thick layer of acoustic coupling material.
8. The acoustic galvanic isolator of claim 1 , wherein the electrically-insulating acoustic decoupler comprises the at least one layer of crosslinked polyphenylene polymer.
9. A method for galvanically isolating an information signal, the method comprising:
providing an electrically-isolating acoustic coupler comprising exactly one decoupled stacked bulk acoustic resonator (DSBAR), the DSBAR comprising a first film bulk acoustic resonator (FBAR), a second FBAR, and an electrically-insulating acoustic decoupler between the FBARs, wherein the electrically-insulating acoustic decoupler comprises at least one of: (1) an electrically-insulating acoustic Bragg structure; (2) a quarter-wave thick layer of acoustic coupling material; and (3) at least one layer of crosslinked polyphenylene polymer;
providing a carrier signal;
modulating the carrier signal with the information signal to form a modulated electrical signal;
acoustically coupling the modulated electrical signal through the electrically-isolating acoustic coupler; and
recovering the information signal from the modulated electrical signal acoustically coupled through the electrically-isolating acoustic coupler.
10. The method of claim 9 , in which the recovering comprises performing clock and data recovery on the modulated electrical signal acoustically coupled through the electrically-isolating acoustic coupler.
11. The method of claim 9 , wherein the electrically-insulating acoustic decoupler comprises the electrically-insulating acoustic Bragg structure, and wherein the electrically-insulating acoustic Bragg structure comprises first, second, and third Bragg elements, the second Bragg element being disposed in between the first and third Bragg elements and having a lower acoustic impedance than the first and third Bragg elements, respectively, at least one of the Bragg elements comprising a layer of electrically-insulating material.
12. The method of claim 11 , wherein the first Bragg element is a quarter-wave thick layer of a same material as an electrode of the first FBAR, and the third Bragg element is a quarter-wave thick layer of a same material as an electrode of the second FBAR.
13. The method of claim 9 , wherein the electrically-insulating acoustic decoupler comprises the quarter-wave thick layer of acoustic coupling material.
14. The method of claim 9 , wherein the electrically-insulating acoustic decoupler comprises the at least one layer of crosslinked polyphenylene polymer.
15. An acoustic galvanic isolator, comprising:
a semiconductor substrate having an insulating layer formed on a top surface thereof;
a carrier signal source disposed on the substrate;
a modulator disposed on the substrate and connected to receive an information signal and the carrier signal and to modulate the information signal onto the carrier signal to produce a modulated signal;
a demodulator disposed on the substrate; and
an electrically-isolating acoustic coupler disposed on the substrate and connected between the modulator and the demodulator, the electrically-isolating acoustic coupler comprising exactly one decoupled stacked bulk acoustic resonator (DSBAR),
wherein the demodulator is adapted to receive the modulated signal from the electrically-isolating acoustic coupler and in response thereto outputs the information signal.
16. The acoustic galvanic isolator of claim 15 , wherein the DSBAR comprises a first film bulk acoustic resonator (FBAR), a second FBAR, and an electrically-insulating acoustic decoupler between the FBARs the electrically-insulating acoustic decoupler comprises at least one of: (1) an electrically-insulating acoustic Bragg structure; (2) a quarter-wave thick layer of acoustic coupling material; and (3) at least one layer of crosslinked polyphenylene polymer.
17. The acoustic galvanic isolator of claim 16 , wherein the electrically-insulating acoustic decoupler comprises the quarter-wave thick layer of acoustic coupling material.
18. The acoustic galvanic isolator of claim 16 , wherein the electrically-insulating acoustic decoupler comprises the at least one layer of crosslinked polyphenylene polymer.
19. The acoustic galvanic isolator of claim 16 , wherein the electrically-insulating acoustic decoupler comprises the electrically-insulating acoustic Bragg structure, and wherein the electrically-insulating acoustic Bragg structure comprises first, second, and third Bragg elements, the second Bragg element being disposed in between the first and third Bragg elements and having a lower acoustic impedance than the first and third Bragg elements, respectively, at least one of the Bragg elements comprising a layer of electrically-insulating material.
20. The acoustic galvanic isolator of claim 19 , wherein the first Bragg element is a quarter-wave thick layer of a same material as an electrode of the first FBAR, and the third Bragg element is a quarter-wave thick layer of a same material as an electrode of the second FBAR.