Single stack coupled resonators having differential output
View Patent ↗A coupled acoustic resonator adapted for single-ended input to differential output signal transformation, comprises a single stack. The single stack comprises: a first film bulk acoustic resonator (FBAR) comprising a single-ended input; a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output; an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and a resonant element comprising a resonant inductor and a parasitic capacitor connected in parallel. The resonant element is connected to the first differential output and is operative to substantially balance a signal from the first differential output with a signal from the second differential output. The first differential output is connected to an external circuit comprising a parasitic impedance, and the resonant inductor has an inductance selected to substantially maintain the balance.
1. A coupled acoustic resonator adapted for single-ended to differential signal transformation, comprising a single stack, the single stack comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element comprising a resonant inductor and a parasitic capacitor connected in parallel, the resonant element being connected to the first differential output and operative to substantially balance a signal from the first differential output with a signal from the second differential output, wherein the first differential output is connected to an external circuit comprising a parasitic impedance, and the resonant inductor has an inductance selected to substantially maintain the balance.
2. A coupled acoustic resonator as claimed in claim 1 , wherein the resonant inductor is connected between the first differential output and a ground.
3. A coupled acoustic resonator as claimed in claim 1 , wherein the parasitic capacitor comprises the acoustic decoupling layer, an upper electrode of the first FBAR and a lower electrode of the second FBAR.
4. A coupled acoustic resonator as claimed in claim 1 , wherein the resonant element has a passband selected substantially to match a passband of the resonator.
5. A coupled acoustic resonator as claimed in claim 1 , wherein the parasitic impedance comprises a parasitic inductor, and the parasitic inductor is connected in series with a tank circuit comprising the parasitic capacitor and the resonant inductor.
6. A coupled acoustic resonator as claimed in claim 1 , wherein the coupled acoustic resonator is a coupled resonator filter (CRF).
7. A communication device, comprising:
a transmitter;
a receiver; and
a single stack coupled resonator filter (CRF), adapted for single-ended to differential signal transformation, the CRF comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element comprising a resonant inductor and a parasitic capacitor connected in parallel, the resonant element being connected to the first differential output and operative to substantially balance a signal from the first differential output with a signal from the second differential output, wherein the first differential output is connected to an external circuit comprising a parasitic impedance; and the resonant inductor has an inductance selected to substantially maintain the balance.
8. A communication device as claimed in claim 7 , wherein the parasitic impedance comprises a parasitic inductor, and the parasitic inductor is connected in series with a tank circuit comprising the parasitic capacitor and the resonant inductor.
9. A communications device as claimed in claim 7 , wherein the resonant inductor is connected between the first differential output and a ground.
10. A communications device as claimed in claim 7 , wherein the parasitic capacitor comprises the acoustic decoupling layer, an upper electrode of the first FBAR and a lower electrode of the second FBAR form a parasitic capacitor.
11. A communications device as claimed in claim 7 , wherein an S parameter of the signal of the first differential output and an S parameter of the signal of the second differential output have a differential of less than approximately 1.0 dB to approximately 0.3 dB.
12. An electronic device, comprising:
a single stack coupled resonator filter (CRF), adapted for single-ended to differential signal transformation, the CRF comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element comprising a resonant inductor and a parasitic capacitor connected in parallel, the resonant element being connected to the first differential output and operative to substantially balance a signal from the first differential output with a signal from the second differential output, wherein the first differential output is connected to an external circuit comprising a parasitic impedance, and the resonant inductor has an inductance selected to substantially maintain the balance.
13. An electronic device as claimed in claim 12 , wherein the electronic device is one of an oscillator circuit; a mixer; or a transformer.
14. A coupled acoustic resonator adapted for single-ended to differential signal transformation, comprising a single stack, the single stack comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element comprising a resonant inductor and the parasitic capacitor connected in parallel, the resonant element being connected to the first differential output and operative to substantially balance a signal from the first differential output with a signal from the second differential output, wherein the second differential output is connected to an external circuit comprising a parasitic impedance; and the resonant inductor has an inductance selected to substantially maintain the balance.
15. A communication device, comprising:
a transmitter;
a receiver; and
a single stack coupled resonator filter (CRF), adapted for single-ended to differential signal transformation, the CRF comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element comprising a resonant inductor and a parasitic capacitor connected in parallel, the resonant element being connected to the first differential output and operative to balance substantially a signal from the first differential output with a signal from the second differential output, wherein the second differential output is connected to an external circuit comprising a parasitic impedance, and the resonant inductor has an inductance selected to substantially maintain the balance.
16. A coupled acoustic resonator adapted for single-ended to differential signal transformation, comprising a single stack, which comprises:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element connected to the first differential output and operative to balance substantially a signal from the first differential output with a signal from the second differential output, wherein an S parameter of the signal of the first differential output and an S parameter of the signal of the second differential output have a differential of less than approximately 1.0 dB to approximately 0.3 dB.
17. A communication device, comprising:
a transmitter;
a receiver; and
a single stack coupled resonator filter (CRF), adapted for single-ended to differential signal transformation, the CRF comprising:
a first film bulk acoustic resonator (FBAR) comprising a single-ended input;
a second FBAR disposed over the first FBAR comprising a first differential output and a second differential output;
an acoustic decoupling layer disposed between the first FBAR and the second FBAR; and
a resonant element connected to the first differential output and operative to balance substantially a signal from the first differential output with a signal from the second differential output, wherein an S parameter of the signal of the first differential output and an S parameter of the signal of the second differential output have a differential of less than approximately 1.0 dB to approximately 0.3 dB.