Reconfigurable intelligent surfaces with integrated chalcogenide phase-delay elements
The technology described herein is directed towards a design and implementation of a unit cell for a reconfigurable intelligent surface/reflectarray by incorporating reconfigurability within a phase-delay element of the unit cell. Reconfigurability is directly incorporated into the unit cell via a variable length phase delay line element and PCM-based (e.g., mmWave) phase shifter that determines the unit cell's phase shift by changing the length of the phase delay line element. One implementation is directed to a monolithic integration of the element using chalcogenide materials as switch elements with pulsed actuation to switch among different available lengths that determine the length of the phase delay line element, resulting in a significant reduction in power consumption, area saving, and digital reconfigurability.
1 . A system, comprising:
a processor; and
a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, the operations comprising:
implementing a variable phase-shift unit cell, the variable phase-shift unit cell comprising a conductive metal portion electrically coupled to a variable-length conductive phase-delay transmission line element; and
controlling a phase shifter to change a phase shift of the variable phase-shift unit cell by switching among conductive and non-conductive states of chalcogenide material elements to vary a path length of the variable-length conductive phase-delay transmission line element, wherein the path length between a radio frequency (RF) input terminal and an RF output terminal determines the phase shift of the variable phase-shift unit cell,
wherein at least two of the chalcogenide material elements comprise a chalcogenide material-based single-pole, multiple throw switch.
2 . The system of claim 1 , wherein the path length of the variable-length conductive phase-delay transmission line element corresponds to a selected conductive path, selected by the phase shifter from among a group of candidate conductive paths, by determining respective conductive or non-conductive states of respective chalcogenide material elements of the chalcogenide material elements.
3 . The system of claim 2 , wherein respective candidate conductive paths correspond to respective different phase shift amounts, and wherein the respective candidate conductive paths have respective different conductive path widths that correspond to the respective different phase shifts.
4 . The system of claim 2 , wherein the phase shifter comprises a pulse code modulation-based controller coupled to a heater network to individually determine the respective conductive or non-conductive states of the respective chalcogenide material elements.
5 . The system of claim 4 , wherein the phase shift is a first phase shift, and wherein the pulse code modulation-based controller phase applies pulsed energy to latch the respective conductive or non-conductive states of the respective chalcogenide material elements without applying further energy until the variable phase-shift unit cell is changed from the first phase shift to a second phase shift that is different from the first phase shift.
6 . The system of claim 1 , wherein a subgroup of the chalcogenide material elements is configured as a single-pole, multiple-throw switch, and wherein the controlling of the phase shifter to change the phase shift comprises switching among conductive and non-conductive states of the subgroup of the chalcogenide material elements to select the path length between the RF input terminal and the RF output terminal from among multiple different candidate path lengths corresponding to multiple switch positions of the multiple-throw switch.
7 . The system of claim 6 , wherein the subgroup is a first subgroup configured as a first single-pole, multiple-throw switch at a beginning of the path length, wherein a second subgroup of the chalcogenide material elements is configured as a second single-pole, multiple-throw switch, and wherein the controlling of the phase shifter to change the phase shift comprises switching among conductive and non-conductive states of the second subgroup of the chalcogenide material elements to determine an end of the path length.
8 . The system of claim 6 , wherein the candidate path lengths comprise a first candidate path length that corresponds to a first amount of phase delay, a second candidate path length that corresponds to a second amount of phase delay, and a third candidate path length that corresponds to a reference phase delay, and wherein the first candidate path length, the second candidate path length, and the third candidate path length are different from one another.
9 . The system of claim 1 , wherein a first subgroup of the chalcogenide material elements is configured as a first single-pole, multiple-throw switch, wherein a second subgroup of the chalcogenide material elements is configured as a second single-pole, multiple-throw switch, wherein a third subgroup of the chalcogenide material elements is configured as a third single-pole, multiple-throw switch, and wherein a fourth subgroup of the chalcogenide material elements is configured as a fourth single-pole, multiple-throw switch,
wherein the controlling of the phase shifter to change the phase shift comprises:
switching among conductive and non-conductive states of the first subgroup and among conductive and non-conductive states of the second subgroup to select a first sub-path length from among multiple different candidate first sub-path lengths that correspond to multiple throw positions of the first single-pole, multiple-throw switch and multiple throw positions of the second single-pole, multiple-throw switch; and
switching among conductive and non-conductive states of the third subgroup and among conductive and non-conductive states of the fourth subgroup to select a second sub-path length from among multiple different candidate second sub-path lengths that correspond to multiple throw positions of the third single-pole, multiple-throw switch, and multiple throw positions of the second single-pole, multiple-throw switch, and
wherein an output terminal of the second single-pole, multiple-throw switch is coupled to an input terminal of the third single-pole, multiple-throw switch to add the first sub-path length to the second sub-path length to determine the path length between the RF input terminal and the RF output terminal.
10 . The system of claim 1 , wherein the variable phase-shift unit cell is one unit cell of a group of unit cells that form a reconfigurable intelligent surface, and wherein the phase shift of the variable phase-shift unit cell determines part of a beam reflected as a beam by the reconfigurable intelligent surface from an electromagnetic wave impinging on the reconfigurable intelligent surface.
11 . The system of claim 10 , wherein the group of unit cells comprise respective unit cells comprising respective conductive metal portions, and wherein the respective conductive metal portions are matching or substantially matching in size.
12 . A method, comprising:
obtaining, by a system comprising a processor, a phase shift value for a unit cell; and
changing, by the system, a phase shift of the unit cell to match the phase shift value, comprising determining respective states of respective individual chalcogenide components of respective switches of the unit cell to vary a transmission line path length of a variable phase-delay line element, corresponding to a phase delay, from a first path length to a second path length,
wherein the transmission line path length comprises a first sub-path length plus a second sub-path length, and wherein the changing of the respective states of the respective chalcogenide components comprises controlling at least some of the respective states to change the first sub-path length to a different first sub-path length.
13 . The method of claim 12 , wherein the changing of the respective states of the respective individual chalcogenide components comprises controlling a controllable heater network that selectively transfers heat to at least some of the respective individual chalcogenide components.
14 . The method of claim 12 , wherein the transmission line path length corresponds to a first sub-path length of the variable phase-delay line element corresponding to a first amount of phase shift, and a second sub-path length of the variable phase-delay line element corresponding to a second amount of phase shift, and wherein the changing of the respective states of the respective chalcogenide components comprises controlling at least some of the respective states to add the first sub-path length of the variable phase-delay line element to the second sub-path length of the variable phase-delay line element to vary the transmission line path length of the variable phase-delay line element.
15 . A unit cell, comprising:
a conductive patch;
a phase delay element coupled to the conductive patch; and
a phase shifter, the phase shifter comprising respective switches comprising respective chalcogenide material parts in respective low-resistance or high-resistance states, the phase shifter changing at least some of the respective low-resistance or high-resistance states of the respective chalcogenide material parts to select among available transmission paths that determine a length of the phase delay element, resulting in a phase shift of the unit cell with respect to redirecting an electromagnetic wave impinging on the unit cell,
wherein the phase shifter comprises a pulse code modulation-based controller that controls a heater network for changing the at least some of the respective low-resistance or high-resistance states of the respective chalcogenide material parts.
16 . The unit cell of claim 15 , wherein the length of the phase delay element comprises a first sub-path length determined by the phase shifter, and a second sub-path length determined by the phase shifter.
17 . The unit cell of claim 15 , wherein the unit cell is one unit cell of a group of unit cells that form a reconfigurable intelligent surface, and wherein the phase shift of the unit cell determines part of a beam reflected by the reconfigurable intelligent surface based on an electromagnetic wave impinging on the unit cell.
18 . The system of claim 1 , wherein the path length comprises a first sub-path length plus a second sub-path length, and wherein the controlling of the phase shifter comprises controlling at least some of respective states to change the first sub-path length to a different first sub-path length.
19 . The system of claim 1 , wherein the phase shifter comprises a pulse code modulation-based controller that controls a heater network for changing the at least some of respective low-resistance or high-resistance states of the chalcogenide material elements.
20 . The unit cell of claim 15 , wherein at least two of the chalcogenide material parts comprise a chalcogenide material-based single-pole, multiple throw switch.