Phased Array LO Stage with Split Phase Shifting for I/Q Accuracy
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Solution Overview
Problem
Conventional phased array transceiver elements face challenges in generating accurate in-phase and quadrature local oscillator signals, particularly at high frequencies, due to complex modulation schemes and the need for precise phase shifts, which increases design complexity.
Innovation Solution
A phased array transceiver element with a local oscillator stage that applies a first phase shift before frequency multiplication, followed by phase-splitting and secondary frequency multiplication to generate in-phase and quadrature local oscillator signals, allowing for independent adjustment of phase shifts and reducing design complexity by performing beamforming phase shifts at lower frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase shifts are applied at the local oscillator frequency directly, then the beamforming phase shift accuracy is improved, but the design complexity increases significantly
Solution Approach 1:
The phase shifting operation is segmented into two distinct stages: a first phase shifter operating at a lower frequency to apply the beamforming phase shift, and a second phase shifter operating at the local oscillator frequency to apply the quadrature phase shift. This segmentation allows each phase shifter to be optimized for its specific function, reducing the overall design complexity while maintaining accuracy.
Solution Approach 2:
The beamforming phase shift is applied in advance at a lower frequency before the signal reaches the local oscillator stage. This preliminary action simplifies the subsequent quadrature generation, as the second phase shifter only needs to provide the 90-degree phase difference without needing to accommodate large beamforming phase shifts, thereby reducing design complexity.
2Adaptability or versatility
If complex modulation schemes are supported, then the transceiver functionality is improved, but the requirement for precise phase shifts increases design complexity
Solution Approach 1:
The phase shifting function is divided between two independent phase shifters operating at different frequencies. The first phase shifter handles beamforming requirements, while the second phase shifter handles quadrature generation. This segmentation enables the system to support complex modulation schemes with precise phase requirements without overwhelming design complexity, as each phase shifter can be independently optimized.
3Device complexity
If a single phase shifter is used at the local oscillator frequency, then the device structure is simplified, but the adjustment range and precision for beamforming phase shifts are limited
Solution Approach 1:
Instead of using a single phase shifter, the system employs two phase shifters operating at different frequencies. The first phase shifter at lower frequency provides the beamforming phase shift with a wide adjustment range, while the second phase shifter at local oscillator frequency provides the precise 90-degree quadrature phase shift. This segmentation achieves both structural simplicity and high precision.
Solution Approach 2:
The system changes the operating frequency parameter between the two phase shifters. The first phase shifter operates at a lower frequency to provide large phase shifts for beamforming, while the second phase shifter operates at the higher local oscillator frequency to provide precise quadrature phase shifts. This parameter change enables each phase shifter to be optimized for its specific phase shift range and precision requirements.
Data Source
AI summary
A phased array transceiver element comprises a local oscillator stage for generating beamformed in-phase and quadrature local oscillator signals, the local oscillator stage comprising a phase shifter connectable to a reference frequency source and applying a first phase shift; a primary frequency multiplier input from the phase shifter and applying a primary frequency multiplication factor; a phase-splitting arrangement input from the primary frequency multiplier and having a first output and a second output, the phase-splitting arrangement applying a second phase shift at the first output and a third phase shift at the second output; a first secondary frequency multiplier input from the first output of the phase-splitting arrangement, having an output for the in-phase local oscillator signal, and applying a secondary frequency multiplication factor; and a second secondary frequency multiplier input from the second output of the phase-splitting arrangement, having an output for the quadrature local oscillator signal, and applying the secondary frequency multiplication factor.