Large phased arrays using balance-impedance phase shifters
A balanced-impedance phase shifter (BIPS) beamformer design that can be scaled to realize large phased arrays (e.g., arrays with element counts greater than four) while minimizing power consumption and cost is provided. The beamformer design includes multiple beamforming ports, a summation port, a first set of two or more of BIPS beamforming circuits receiving port signals from the beamforming ports to generate multiple intermediate signals, and a second set of one or more beamforming circuit receiving the multiple intermediate signals to generate a combined signal at the summation port. The second set of beamforming circuits may include a BIPS beamforming circuit. The second set of beamforming circuits may include or multiple radio frequency (RF) beamforming circuits. The first and second sets of beamforming circuits are configured to perform phase shifting based on a desired beamforming characteristics and array geometry.
1 . A beamforming system comprising:
a plurality of beamforming ports;
a summation port;
a first set of two or more of balanced-impedance phase shifter (BIPS) beamforming circuits interconnecting the plurality of beamforming ports with a plurality of intermediate nodes, wherein each BIPS beamforming circuit of the first set of two or more BIPS beamforming circuits combines or splits signals between two or more of the plurality of beamforming ports and one of the intermediate nodes; and
a second set of one or more beamforming circuits interconnecting the plurality of intermediate nodes with the summation port to combine or split signals between the first set of two or more BIPS beamforming circuits and the summation port.
2 . The beamforming system of claim 1 , wherein the first set of two or more BIPS beamforming circuits receives a plurality of port signals from the plurality of beamforming ports to generate a plurality of intermediate signals at the plurality of intermediate nodes and the second set of one or more beamforming circuits receives the plurality of intermediate signals to generate a combined signal at the summation port.
3 . The beamforming system of claim 1 , wherein the second set of one or more beamforming circuits receives a source signal from the summation port to generate a plurality of intermediate signals and the first set of two or more BIPS beamforming circuits receives the plurality of intermediate signals at the plurality of intermediate nodes to generate a plurality of port signals at the plurality of beamforming ports.
4 . The beamforming system of claim 1 , wherein each of the two or more BIPS beamforming circuits comprises:
a plurality of phase shifters; and
a summing node at which the plurality of phase shifters is connected in series,
wherein each phase shifter comprises a programmable admittance controlling phase shifting.
5 . The beamforming system of claim 1 , wherein each of the two or more BIPS beamforming circuits comprises:
a plurality of phase shifters; and
a summing node at which the plurality of phase shifters is connected in shunt,
wherein each phase shifter comprises a programmable impedance controlling phase shifting, and
wherein the summing node is connected to one of the plurality of intermediate nodes.
6 . The beamforming system of claim 1 , wherein the second set of one or more beamforming circuits comprises a BIPS beamforming circuit.
7 . The beamforming system of claim 1 , wherein the second set of one or more beamforming circuits does not comprise a BIPS beamforming circuit.
8 . The beamforming system of claim 1 , wherein the second set of one or more beamforming circuits comprises a plurality of radio frequency (RF) beamforming circuits, each RF beamforming circuit receiving an intermediate signal from a corresponding BIPS beamforming circuit to generate an output signal.
9 . The beamforming system of claim 8 , wherein each RF beamforming circuit in the second set of one or more beamforming circuits comprises an active amplifier.
10 . The beamforming system of claim 8 , wherein each RF beamforming circuit in the second set of one or more beamforming circuits utilizes local oscillator (LO), intermediate frequency (IF), or baseband (BB) beamforming techniques.
11 . The beamforming system of claim 8 , further comprising a power combiner circuit for combining amplified signals generated by the plurality of RF beamforming circuits to generate a combined signal at the summation port.
12 . The beamforming system of claim 1 , wherein the plurality of beamforming ports supports more than eight antenna elements.
13 . The beamforming system of claim 1 , wherein the first set of two or more BIPS beamforming circuits and the second set of one or more beamforming circuits are configured to perform phase shifting based on desired beamforming characteristics and array geometry, wherein phase shifters in the first set of two or more BIPS beamforming circuits are configured to perform a first stage of phase shifting and phase shifters in the second set of one or more beamforming circuits are configured to perform a second stage of phase shifting.
14 . The beamforming system of claim 1 , wherein each of the first set of two or more BIPS beamforming circuits comprises a plurality of phase shifters, each phase shifter comprising a programmable admittance or impedance for controlling phase shifting and a crossover switch for selectively introducing one of a 0° phase shift and a 180° phase shift.
15 . The beamforming system of claim 14 , wherein the second set of one or more beamforming circuits comprises a BIPS beamforming circuit having a plurality of phase shifters that does not comprise a crossover switch.
16 . The beamforming system of claim 15 , wherein the crossover switch in each phase shifter of the first set of two or more BIPS beamforming circuits is configured to introduce an additional 180° phase shift.
17 . The beamforming system of claim 14 , wherein the second set of one or more beamforming circuits comprises a plurality of radio frequency (RF) beamforming circuits, each RF beamforming circuit comprising a phase shifter that is limited to less than 360° of phase shifting.
18 . The beamforming system of claim 14 , wherein the second set of one or more beamforming circuits comprise a plurality of radio frequency (RF) beamforming circuits, each RF beamforming circuit comprising a phase shifter that is limited to 180° or less phase shifting.