Beamformer integrated circuits with multiple-stage hybrid splitter/combiner circuits

1. A multiple-stage splitter/combiner circuit comprising:

a first splitter/combiner circuit with a first input/output (I/O) port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port; and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port connected to the second I/O port, a fifth I/O port, a sixth I/O port, and a ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other.

2. A multiple-stage splitter/combiner circuit comprising:

a first splitter/combiner circuit with a first input/output (I/O) port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port; and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port, a fifth I/O port, a sixth I/O port, and a ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other, and wherein the first and second quarter wave lines extend in parallel with each other so that the second I/O port and the third I/O port are physically separated by a distance of about a width of the first resistor.

3. The multiple-stage splitter/combiner circuit of claim 1 , wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in opposite directions from each other so that the fifth I/O port and the sixth I/O port are physically separated by a distance equal to a combined length of the third and fourth quarter wave lines.

4. The multiple-stage splitter/combiner circuit of claim 1 , wherein:

the first splitter/combiner circuit is a first-stage splitter/combiner circuit;

the second splitter/combiner circuit is a second-stage splitter/combiner circuit; and

the second I/O port is coupled to the fourth I/O port.

5. The multiple-stage splitter/combiner circuit of claim 4 , further comprising:

a third splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the third splitter/combiner circuit includes a seventh I/O port, an eighth I/O port, a ninth I/O port, and a second ring of multiple quarter wave lines that includes a seventh quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the eighth I/O port, an eighth quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the ninth I/O port, a ninth quarter wave line with a first end coupled to the eighth I/O port, and a tenth quarter wave line with a first end coupled to the ninth I/O port and a second end coupled to a second end of the ninth quarter wave line, wherein the seventh quarter wave line and the eighth quarter wave line extend from the seventh I/O port in different directions from each other.

6. The multiple-stage splitter/combiner circuit of claim 1 , wherein:

the second splitter/combiner circuit is a first-stage splitter/combiner circuit;

the first splitter/combiner circuit is a second-stage splitter/combiner circuit; and

the first I/O port is coupled to the fifth I/O port.

7. The multiple-stage splitter/combiner circuit of claim 6 , further comprising:

a third splitter/combiner circuit coupled to the second splitter/combiner circuit, wherein the third splitter/combiner circuit includes a seventh I/O port, an eighth I/O port, a ninth I/O port, a seventh quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the eighth I/O port, an eighth quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the ninth I/O port, and a second resistor with a first terminal coupled to the seventh I/O port and a second terminal coupled to the eighth I/O port.

8. A multiple-stage splitter/combiner circuit comprising:

a first splitter/combiner circuit with a first input/output (I/O) port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port; and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port, a fifth I/O port, a sixth I/O port, and a ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other, and wherein the first, second, third, fourth, fifth, and sixth quarter wave lines each include an unbalanced transmission line.

9. The multiple-stage splitter/combiner circuit of claim 8 , wherein the second splitter/combiner circuit further comprises:

a first port coupled to the second end of the fifth quarter wave line;

a second port coupled to the second end of the sixth quarter wave line;

a seventh quarter wave line coupled between the first port and a conductive node;

an eighth quarter wave line coupled between the second port and the conductive node;

a second resistor coupled between the first port and a ground reference; and

a third resistor coupled between the second port and the ground reference.

10. A multiple-stage splitter/combiner circuit comprising:

a first splitter/combiner circuit with a first input/output (I/O) port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port; and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port, a fifth I/O port, a sixth I/O port, and a ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other, and wherein the first, second, third, fourth, fifth, and sixth quarter wave lines each include a balanced transmission line.

11. The multiple-stage splitter/combiner circuit of claim 10 , wherein the second splitter/combiner circuit further comprises:

a first differential conductive node coupled to the second end of the fifth quarter wave line;

a second differential conductive node coupled to the second end of the sixth quarter wave line;

a seventh quarter wave line coupled between the first differential conductive node and a third differential conductive node;

an eighth quarter wave line coupled between the second differential conductive node and the third differential conductive node;

a second resistor coupled across the first differential conductive node; and

a third resistor coupled across the second differential conductive node.

12. The multiple-stage splitter/combiner circuit of claim 10 , wherein the second splitter/combiner circuit further comprises:

a differential conductive node cross-coupled to the second end of the fifth quarter wave line and to the second end of the sixth quarter wave line; and

a second resistor coupled across the differential conductive node.

13. A beamformer integrated circuit comprising:

a first system-side radio frequency (RF) input/output (I/O) terminal;

N first antenna-side RF I/O terminals;

N first transceiver channels electrically coupled to the N first antenna-side RF I/O terminals; and

a first multiple-stage splitter/combiner circuit electrically coupled between the first system- side RF I/O terminal and the N first transceiver channels, wherein the first multiple-stage splitter/combiner circuit includes a first splitter/combiner circuit with a first I/O port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port, and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port, a fifth I/O port, a sixth I/O port, and a ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other.

14. The beamformer integrated circuit of claim 13 , further comprising:

N first antenna elements, wherein each of the N first antenna elements includes a first connection point associated with a first polarization, and the N first antenna-side RF I/O terminals each are coupled to the first connection point of a different one of the N first antenna elements.

15. The beamformer integrated circuit of claim 13 , wherein:

the first splitter/combiner circuit is a first-stage splitter/combiner circuit;

the second splitter/combiner circuit is a second-stage splitter/combiner circuit;

the second I/O port is coupled to the fourth I/O port; and

the multiple-stage splitter/combiner circuit further includes

a third splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the third splitter/combiner circuit includes a seventh I/O port, an eighth I/O port, a ninth I/O port, and a second ring of multiple quarter wave lines that includes a seventh quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the eighth I/O port, an eighth quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the ninth I/O port, a ninth quarter wave line with a first end coupled to the eighth I/O port, and a tenth quarter wave line with a first end coupled to the ninth I/O port and a second end coupled to a second end of the ninth quarter wave line, wherein the seventh quarter wave line and the eighth quarter wave line extend from the seventh I/O port in different directions from each other.

16. The beamformer integrated circuit of claim 13 , wherein:

the second splitter/combiner circuit is a first-stage splitter/combiner circuit;

the first splitter/combiner circuit is a second-stage splitter/combiner circuit;

the first I/O port is coupled to the fifth I/O port; and

the multiple-stage splitter/combiner circuit further includes

a third splitter/combiner circuit coupled to the second splitter/combiner circuit, wherein the third splitter/combiner circuit includes a seventh I/O port, an eighth I/O port, a ninth I/O port, a seventh quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the eighth I/O port, an eighth quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the ninth I/O port, and a second resistor with a first terminal coupled to the seventh I/O port and a second terminal coupled to the eighth I/O port.

17. The beamformer integrated circuit of claim 13 , wherein:

the first, second, third, fourth, fifth, and sixth quarter wave lines are differential quarter wave lines; and

the second splitter/combiner circuit further includes

a differential conductive node cross-coupled to the second end of the fifth quarter wave line and to the second end of the sixth quarter wave line, and

a second resistor coupled across the differential conductive node.

18. A communication system comprising:

a beamformer that includes

a first system-side radio frequency (RF) input/output (I/O) terminal,

N first antenna-side RF I/O terminals,

N first transceiver channels electrically coupled to the N first antenna-side RF I/O terminals, and

a first multiple-stage splitter/combiner circuit electrically coupled between the first system-side RF I/O terminal and the N first transceiver channels, wherein the first multiple-stage splitter/combiner circuit includes

a first splitter/combiner circuit with a first I/O port, a second I/O port, a third I/O port, a first quarter wave line with a first end coupled to the first I/O port and a second end coupled to the second I/O port, a second quarter wave line with a first end coupled to the first I/O port and a second end coupled to the third I/O port, and a first resistor with a first terminal coupled to the second I/O port and a second terminal coupled to the third I/O port, and

a second splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a fourth I/O port, a fifth I/O port, a sixth I/O port, and a first ring of multiple quarter wave lines that includes a third quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the fifth I/O port, a fourth quarter wave line with a first end coupled to the fourth I/O port and a second end coupled to the sixth I/O port, a fifth quarter wave line with a first end coupled to the fifth I/O port, and a sixth quarter wave line with a first end coupled to the sixth I/O port and a second end coupled to a second end of the fifth quarter wave line, wherein the third quarter wave line and the fourth quarter wave line extend from the fourth I/O port in different directions from each other; and

N first antenna elements, wherein each of the N first antenna elements includes a first connection point associated with a first polarization, and the N first antenna-side RF I/O terminals each are coupled to the first connection point of a different one of the N first antenna elements.

19. The communication system of claim 18 , wherein:

each of the N first antenna elements also includes a second connection point associated with a second polarization that is different from the first polarization; and

the beamformer further comprises

a second system-side RF I/O terminal,

N second antenna-side RF I/O terminals,

N second transceiver channels electrically coupled to the N second antenna-side RF I/O terminals, and

a second multiple-stage splitter/combiner circuit electrically coupled between the second system-side RF I/O terminal and the N second transceiver channels, wherein the second multiple-stage splitter/combiner circuit includes

a third splitter/combiner circuit with a seventh I/O port, an eighth I/O port, a ninth I/O port, a seventh quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the eighth I/O port, an eighth quarter wave line with a first end coupled to the seventh I/O port and a second end coupled to the ninth I/O port, and a second resistor with a first terminal coupled to the eighth I/O port and a second terminal coupled to the ninth I/O port, and

a fourth splitter/combiner circuit coupled to the first splitter/combiner circuit, wherein the second splitter/combiner circuit includes a tenth I/O port, an eleventh I/O port, a twelfth I/O port, and a second ring of multiple quarter wave lines that includes a ninth quarter wave line with a first end coupled to the tenth I/O port and a second end coupled to the eleventh I/O port, a tenth quarter wave line with a first end coupled to the tenth I/O port and a second end coupled to the twelfth I/O port, an eleventh quarter wave line with a first end coupled to the tenth I/O port, and a twelfth quarter wave line with a first end coupled to the eleventh I/O port and a second end coupled to a second end of the eleventh quarter wave line, wherein the ninth quarter wave line and the tenth quarter wave line extend from the tenth I/O port in different directions from each other; and

the N second antenna-side RF I/O terminals each are coupled to the second connection point of a different one of the N first antenna elements.

20. The communication system of claim 18 , wherein N equals 4.