Scalable Phased-Array Beamforming With Spur-Canceling Phase Control
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Solution Overview
Problem
Conventional phased-array architectures are limited by lossy phase shifters and high-frequency constraints, leading to signal distortion and interference issues above 100 GHz, and require extensive chip area and power consumption for high-frequency drivers, making them unsuitable for high-order modulation and phase-shifting functions.
Innovation Solution
A scalable phased-array system utilizing time division duplexing (TDD) with a frequency multiplier and low-frequency phase shifter for linear up-conversion, allowing phase control of desired and undesired signals, and incorporating a multifunctional resonator-coupled network for phase shifting, impedance matching, and signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a frequency multiplier is used to expand working frequency above 100 GHz, then the working frequency is improved, but signal constellation distortion occurs due to extreme nonlinearity
Solution Approach 1:
The frequency multiplication process is segmented into multiple stages with intermediate filtering and amplification. The patent divides the frequency multiplication into cascaded stages (e.g., x2, x2, x2.5) with buffer amplifiers and filters between stages to maintain signal integrity and reduce distortion accumulation.
Solution Approach 2:
Intermediate frequency stages and buffer amplifiers are introduced as mediators between frequency multiplication stages. These intermediaries condition the signal at each stage, preventing direct propagation of distortion from one stage to the next.
2Manufacturing precision
If a cubic mixer is used with adjusted LO and IF power to improve desired signals, then signal quality is improved, but undesired spurs are reduced only to maximum extent and still cause interference
Solution Approach 1:
The patent converts the harmful spurs generated by the cubic mixer into beneficial cancellation opportunities by using multiple parallel mixers with controlled phases. The spurs from different mixers are made to cancel each other through destructive interference, while desired signals add constructively.
Solution Approach 2:
Multiple mixer outputs are merged in a combiner network where phase control allows desired signals to combine constructively while spurs combine destructively. This merging process with proper phase management simultaneously improves signal quality and reduces harmful interference.
3Object-generated harmful factors
If a square mixer is used to solve spur problems, then spurs are eliminated, but many high frequency drivers are required which occupy large chip area and consume high power
Solution Approach 1:
The patent makes the phase shifters perform multiple functions: they control the phase of desired signals for beamforming and simultaneously control the phase of spurs for cancellation. This multi-functionality eliminates the need for separate spur cancellation circuits, reducing chip area.
Solution Approach 2:
The functions of signal phase control and spur phase control are merged into a single phase shifter network. By controlling the relative phases between mixer outputs, the system simultaneously achieves beamforming and spur cancellation without requiring separate driver circuits.
4Speed
If conventional phased-array architecture is used above 100 GHz, then frequency operation is achieved, but lossy phase shifters and limited transistor speeds cause performance degradation
Solution Approach 1:
The patent employs periodic switching between transmit and receive modes in TDD operation, allowing the use of lower frequency components during each mode. This periodic action at baseband frequencies avoids the limitations of high-frequency phase shifters while achieving high-frequency wireless operation through frequency multiplication.
Solution Approach 2:
The patent replaces high-frequency mechanical/electrical phase shifters with low-frequency digital phase control. Phase shifting is achieved through digital signal processing and baseband phase modulation rather than high-frequency analog phase shifters, avoiding transistor speed limitations.
5Power
If high frequency drivers are added to provide acceptable output power, then output power is improved, but direct current power consumption increases significantly
Solution Approach 1:
TDD operation allows the system to use low-frequency amplifiers periodically at baseband frequencies during transmit and receive modes, avoiding the need for continuous high-frequency power amplification. This periodic low-frequency operation significantly reduces power consumption compared to continuous high-frequency operation.
Solution Approach 2:
The patent changes the operating frequency parameter of amplifiers from high frequency to low frequency where amplification is more efficient. By performing amplification at lower frequencies and then frequency-multiplying the output, the system achieves high-frequency output power with lower power consumption.
Data Source
AI summary
A scalable phased-array system for a wireless system includes: a plurality of transceivers, which are switched to form a transmitter mode and a receiver mode by means of time division duplexing (TDD), wherein each transceiver includes: a millimeter wave (mmWave) up-conversion circuit used to convert a baseband (BB) transmitter signal into an intermediate frequency (IF) transmitter signal; a power divider/combiner circuit used to divide the IF transmitter signal into a plurality of pairs of IF transmitter differential signals in the transmitter mode, and combine a plurality of pairs of BB receiver differential signals into a BB receiver signal in the receiver mode; and a beamforming circuit used to convert the pairs of the IF transmitter differential signals into a plurality of radio frequency (RF) transmitter signals in the transmitter mode, and convert a plurality of RF receiver signals into the pairs of the BB receiver differential signals in the receiver mode.