Radio frequency filter, high selectivity triplexer, and communications device

Patent metadata

Field	Value
Publication number	US-10038424-B2
Application number	US-201715672083-A
Country	US
Kind code	B2
Filing date	Aug 8, 2017
Priority date	Apr 8, 2016
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

Communications devices, triplexers, high-pass filters, and low-pass filters are disclosed. A communications device includes a triplexer having a common port and first, second, and third branch ports. A hybrid LC/SAW high-pass filter is connected between the common port and the third branch port, a hybrid LC/SAW low-pass filter is connected between the common port and an internal node, an LC high-pass filter is connected between the internal node and the second branch port, and an LC low-pass filter is connected between the internal node and the first branch port.

First claim

It is claimed:

1. A communications device, comprising:
a triplexer having a common port and first, second, and third branch ports;
wherein the triplexer comprises:
a hybrid LC/SAW high-pass filter connected between the common port and the third branch port;
a hybrid LC/SAW low-pass filter connected between the common port and an internal node;
an LC high-pass filter connected between the internal node and the second branch port; and
an LC low-pass filter connected between the internal node and the first branch port.

2. The communications device of claim 1 , wherein
the hybrid LC/SAW low-pass filter and the LC low-pass filter are collectively configured to pass radio frequency signals in a frequency range of 450 MHz to 960 MHz between the common port and the first branch port,
the hybrid LC/SAW low pass filter and the LC high-pass filter are collectively is configured to pass radio frequency signals in a frequency range of 1500 MHz to 2200 MHz between the common port and the second branch port, and
the hybrid LC/SAW high pass filter is configured to pass radio frequency signals in a frequency range above 2300 MHz between the common port and the third branch port.

3. The communications device of claim 2 , further comprising:
an antenna coupled to the common port;
a first radio coupled to the first branch port, the first radio configured to communicate over one or more channels within the frequency range of 450 MHz to 960 MHz;
a second radio coupled to the second branch port, the second radio configured to communicate over one or more channels within the frequency range of 1500 MHz to 2200 MHz; and
a third radio coupled to the third branch port, the third radio configured to communicate over one or more channels with frequencies above 2300 MHz.

4. The communications device of claim 2 , wherein
the hybrid LC/SAW low-pass filter is configured to pass radio frequency signals in a range from 450 MHz to 2200 MHZ and to stop radio frequency signals in a range from 2300 MHz to at least 4000 MHz, and
the hybrid LC/SAW high pass filter is configured to pass radio frequency signals in a frequency range from 2300 MHz to at least 4000 MHz and to stop radio frequency signals in a range from 450 MHz to 2200 MHZ.

5. The communications device of claim 1 , wherein the hybrid LC/SAW high-pass filter comprises:
an LC high-pass filter defining a stop-band and a pass-band separated by a transition frequency region; and
a SAW resonator connected in parallel with at least a portion of the LC high-pass filter, a resonance frequency of the first SAW resonator within the transition frequency region.

6. The communications device of claim 5 , wherein
the LC high-pass filter comprises two or more series capacitors and two or more shunt inductors, and
the SAW resonator is connected in parallel with at least one of the two or more series capacitors.

7. The hybrid LC/SAW high-pass filter of claim 6 , wherein
the LC high-pass filter comprises two series capacitors and two shunt inductors,
the first SAW resonator is connected in parallel with the two series capacitors, and
the hybrid LC/SAW filter further comprises a second SAW resonator connected in parallel with one of the shunt inductors.

8. The hybrid LC/SAW high-pass filter of claim 6 , wherein
the LC high-pass filter comprises four series capacitors and three shunt inductors, and
the first SAW resonator is connected in parallel with three of the series capacitors.

9. The communications device of claim 1 , wherein the hybrid LC/SAW low-pass filter comprises:
a bridged-T circuit including two inductors connected in series, a capacitor connected in parallel with the series-connected inductors, and a SAW resonator connected from a junction between the two inductors to ground.

10. The communications device of claim 9 , further comprising:
a second capacitor and a third inductor forming a low-pass filter section in series with the bridged-T circuit.

11. A hybrid LC/SAW high-pass filter comprising:
an LC high-pass filter defining a stop-band and a pass-band separated by a transition frequency region, the LC high-pass filter comprising two or more series capacitors and two or more shunt inductors; and
a first SAW resonator connected in parallel with at least one of the two or more series capacitors, a resonance frequency of the first SAW resonator within the transition frequency region.

12. The hybrid LC/SAW high-pass filter of claim 11 , wherein
the LC high-pass filter comprises four series capacitors and three shunt inductors, and
the first SAW resonator is connected in parallel with three of the series capacitors.

13. The hybrid LC/SAW high-pass filter of claim 11 , wherein
the LC high-pass filter comprises two series capacitors and two shunt inductors,
the first SAW resonator is connected in parallel with the two series capacitors, and
the hybrid LC/SAW filter further comprises a second SAW resonator connected in parallel with one of the shunt inductors.

14. A hybrid LC/SAW low-pass filter defining a stop-band and a pass-band separated by a transition region, comprising:
a bridged-T circuit including first and second inductors connected in series, a first capacitor connected in parallel with the series-connected first and second inductors; and
a shunt SAW resonator connected from a junction between the first and second inductors to ground, a resonance frequency of the shunt SAW resonator within the transition frequency region.

15. The hybrid LC/SAW low-pass filter of claim 14 , further comprising:
a second capacitor and a third inductor forming a low-pass filter section in series with the bridged-T circuit.

16. A communications device, comprising:
a triplexer having a common port and first, second, and third branch ports;
wherein the triplexer comprises:
a hybrid LC/SAW high-pass filter connected between the common port and the third branch port;
a hybrid LC/SAW low-pass filter connected between the common port and an internal node;
an LC high-pass filter connected between the internal node and the second branch port; and
an LC low-pass filter connected between the internal node and the first branch port, and

the hybrid LC/SAW high-pass filter comprises:
an LC high-pass filter comprising two or more series capacitors and two or more shunt inductors, the LC high-pass filter defining a stop-band and a pass-band separated by a transition frequency region; and
a first SAW resonator connected in parallel with at least one of the two or more series capacitors, a resonance frequency of the SAW resonator within the transition frequency region.

17. The communications device of claim 16 , wherein
the LC high-pass filter comprises two series capacitors and two shunt inductors,
the first SAW resonator is connected in parallel with the two series capacitors, and
the hybrid LC/SAW filter further comprises a second SAW resonator connected in parallel with one of the shunt inductors.

18. The communications device of claim 16 , wherein
the hybrid LC/SAW low-pass filter and the LC low-pass filter are collectively configured to pass radio frequency signals in a frequency range of 450 MHz to 960 MHz between the common port and the first branch port,
the hybrid LC/SAW low pass filter and the LC high-pass filter are collectively configured to pass radio frequency signals in a frequency range of 1500 MHz to 2200 MHz between the common port and the second branch port, and
the hybrid LC/SAW high pass filter is configured to pass radio frequency signals in a frequency range abo

Assignees

• Resonant Inc

Inventors

• Hey-Shipton Gregory L
• Guyette Andrew

Classifications

• H03H9/72 Primary

  Networks using surface acoustic waves · CPC title

• H03H9/70

  Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source · CPC title

• H04B1/40

  Circuits · CPC title

• H03H9/6489

  Compensation of undesirable effects · CPC title

• H04W88/06

  adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals · CPC title