Acoustic filter for antennas

Patent metadata

Field	Value
Publication number	US-10141644-B2
Application number	US-201715490381-A
Country	US
Kind code	B2
Filing date	Apr 18, 2017
Priority date	Apr 18, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

Filter circuitry is used in communication systems that employ multiple antennas. In general, a communication system may have a transmit path and a receive path. The transmit path extends to a first antenna port and is configured to present signals for transmission in a first communication band and a second communication band to the first antenna port for transmission via a first antenna that is coupled to the first antenna port. The receive path extends to a second antenna port and comprises a first multiple passband/multiple stopband filter that provides a plurality of passbands and a plurality of stopbands interleaved with one another, wherein a first stopband and a second stopband of the plurality of stopbands correspond respectively to the first communication band and the second communication band and are separated by a first passband of the plurality of passbands.

First claim

What is claimed is:

1. An apparatus comprising:
a transmit path extending to a first antenna port and configured to present signals for transmission in a first communication band and a second communication band to the first antenna port for transmission via a first antenna that is coupled to the first antenna port; and
a receive path extending to a second antenna port and comprising a first multiple passband/multiple stopband (MPMS) filter that provides a plurality of passbands and a plurality of stopbands interleaved with one another, wherein a first stopband and a second stopband of the plurality of stopbands correspond respectively to the first communication band and the second communication band and are separated by a first passband of the plurality of passbands.

2. The apparatus of claim 1 wherein the first passband of the plurality of passbands corresponds to a third communication band, and the receive path is configured to receive signals received via a second antenna coupled to the second antenna port.

3. The apparatus of claim 2 further comprising radio frequency circuitry configured to generate the signals for transmission as well as demodulate the signals received via the second antenna.

4. The apparatus of claim 3 further comprising a first coaxial cable electrically coupled between the radio frequency circuitry and the transmit path, and a second coaxial cable electrically coupled between the radio frequency circuitry and the receive path.

5. The apparatus of claim 4 further comprising a rigid printed circuit board on which the radio frequency circuitry is provided and a flexible printed circuit board on which the receive path, including the first MPMS filter, is provided.

6. The apparatus of claim 5 wherein the transmit path is provided on the flexible printed circuit board and the first coaxial cable extends between the rigid printed circuit board and the flexible printed circuit board.

7. The apparatus of claim 6 wherein the first antenna is coupled to a first antenna port of the flexible printed circuit board, and the second antenna is coupled to a second antenna port of the flexible printed circuit board.

8. The apparatus of claim 3 wherein the radio frequency circuitry is further configured to receive signals being received via the first antenna and demodulate the signals received via the second antenna and the signals received via the first antenna together using multiple input multiple output processing.

9. The apparatus of claim 1 further comprising a low noise amplifier in the receive path and configured to amplify signals received via a second antenna coupled to the second antenna port.

10. The apparatus of claim 1 wherein the first stopband and second stopband reside entirely above 2 GHz.

11. The apparatus of claim 10 wherein a bandwidth of the first passband is at least 20 MHz and a bandwidth of the second stopband is at least 20 MHz.

12. The apparatus of claim 10 wherein a bandwidth of the first passband is at least 100 MHz.

13. The apparatus of claim 12 wherein a bandwidth of the second stopband is at least 20 MHz.

14. The apparatus of claim 1 wherein the first MPMS filter comprises:
a first node and a second node;
a first plurality of acoustic resonators coupled in parallel between the first node and the second node;
a first shunt path comprising a series combination of a second plurality of acoustic resonators and a first inductor coupled between the first node and a fixed voltage node; and
a second shunt path comprising a second inductor coupled between the second node and the fixed voltage node, wherein the first inductor and the second inductor are negatively coupled with one another.

15. The apparatus of claim 1 wherein the first MPMS filter comprises:
a first node and a second node;
a first plurality of acoustic resonators coupled in parallel between the first node and the second node;
a first shunt path comprising a series combination of a second plurality of acoustic resonators and a first inductor coupled between the first node and a fixed voltage node; and
a second shunt path comprising a second inductor coupled between the second node and the fixed voltage node, wherein the first inductor and the second inductor are negatively coupled with one another.

16. The apparatus of claim 1 wherein the first MPMS filter comprises:
a first node and a second node;
a first plurality of acoustic resonators coupled in parallel between the first node and the second node;
a first shunt path comprising a series combination of a second plurality of acoustic resonators and a first inductor coupled between the first node and a common node;
a second shunt path comprising a second inductor coupled between the second node and the common node, wherein the first inductor and the second inductor are negatively coupled with one another; and
a third plurality of acoustic resonators coupled between the common node and a fixed voltage node.

17. The apparatus of claim 1 wherein the first MPMS filter comprises:
a first node and a second node;
at least one series acoustic resonator coupled between the first node and the second node, wherein at least one main series resonance is provided between the first node and the second node at a main resonance frequency through the at least one series acoustic resonator; and
a compensation circuit comprising:
a first inductor and a second inductor coupled in series between the first node and the second node, wherein the first inductor and the second inductor are negatively coupled with one another and a common node is provided between the first inductor and the second inductor;
a first shunt acoustic resonator coupled between the common node and a fixed voltage node; and
a second shunt acoustic resonator coupled between the common node and the fixed voltage node, wherein a first series resonance at a first resonance frequency and a second series resonance at a second resonance frequency, which is different from the first resonance frequency and the main resonance frequency, are provided between the first node and the second node through the compensation circuit.

18. The apparatus of claim 17 wherein at least one of the first resonance frequency and the second resonance frequency is greater than the main resonance frequency.

19. The apparatus of claim 17 wherein the first resonance frequency is less than the main resonance frequency, and the second resonance frequency is greater than the main resonance frequency.

20. The apparatus of claim 17 wherein the at least one series acoustic resonator comprises a plurality of acoustic resonators that are coupled in parallel with one another, and each of the plurality of acoustic resonators has a different series resonance frequency.

21. The apparatus of claim 20 wherein the compensation circuit comprises at least one additional shunt acoustic resonator coupled between the common node and the fixed voltage node.

22. The apparatus of claim 17 wherein the at least one series acoustic resonator, the first shunt acoustic resonator, and the second shunt acoustic resonator are at least one of a group consisting of bulk acoustic wave (BAW) resonator and a surface acoustic wave (SAW).

23. The apparatus of claim 1 wherein first MPMS filter comprises at least one acoustic resonator of a group consisting of bulk acoustic wave (BAW) resonator and a surface acoustic wave (SAW).

Assignees

• Qorvo Us Inc

Inventors

• Khlat Nadim
• Aigner Robert

Classifications

• H04B1/525

  with means for reducing leakage of transmitter signal into the receiver · CPC title

• H04B11/00

  Transmission systems employing ultrasonic, sonic or infrasonic waves · CPC title

• H03H9/542

  including passive elements (H03H9/545 takes precedence) · CPC title

• H03H9/703

  Networks using bulk acoustic wave devices · CPC title

• H03H9/72

  Networks using surface acoustic waves · CPC title