Cartesian CMOS Phase Shifter for Fine Resolution and Gain Stability
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Solution Overview
Problem
Phased array antennas face challenges in achieving high resolution phase shifting with stability over temperature variations and process variations, while also requiring low power consumption and small form factor, due to the limitations of existing passive phase shifters which exhibit high gain variations and high insertion loss.
Innovation Solution
A high resolution phase shifter design utilizing differential quadrature hybrid splitters, phase-inverting variable attenuators, and differential power combiners, fabricated on a single CMOS die, which applies phase shifts using Cartesian phase interpolation and maintains stability through controlled gate voltages and bias circuits, reducing insertion loss and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If passive phase shifters are used to reduce power consumption, then power consumption is reduced, but gain variations and insertion loss increase
Solution Approach 1:
The patent employs dynamic switching between different phase shifter modes (passive/reflective and active/transmissive) based on operational requirements. The phase shifter can transition between reflective-type configuration for power saving and transmissive-type configuration for improved gain stability, making the system adaptable to different operational conditions.
Solution Approach 2:
The invention changes the operational parameters of the phase shifter by adjusting control signals that switch between different attenuation settings and phase shift modes. This allows optimization of both power consumption and gain stability by selecting appropriate parameter sets based on system requirements.
2Use of energy by moving object
If passive phase shifters are used to reduce power consumption, then power consumption is reduced, but phase shift resolution and accuracy deteriorate
Solution Approach 1:
The system dynamically switches between passive and active phase shifter modes depending on the required phase resolution. When high precision is needed, the active mode provides finer phase control; when power saving is prioritized, the passive mode suffices for coarser adjustments.
Solution Approach 2:
The phase shifter is divided into multiple stages with different resolution capabilities. Coarse phase adjustment can be handled by passive elements while fine tuning is performed by active elements, allowing the system to achieve high overall resolution without continuously consuming high power.
3Adaptability or versatility
If cascade of attenuators is used for phase shifting, then phase shifting capability is achieved, but insertion loss and size increase with higher resolution requirements
Solution Approach 1:
The patent implements a dynamic phase shifter that can switch between reflective and transmissive configurations. The transmissive mode uses variable attenuators with complementary symmetry to achieve phase shifting with lower insertion loss compared to traditional cascade attenuator structures, especially at higher resolution settings.
Solution Approach 2:
The invention employs asymmetric bridge configurations with complementary symmetric variable attenuators that balance the signal paths. This asymmetric design allows for better control of insertion loss while maintaining phase shifting capability across different resolution requirements.
Data Source
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AI summary
The phase shifter (100) is configured to apply a phase shift to an input signal using a Cartesian phase interpolation technique. A differential input signal (110) is split into an I-component signal and a Q-component signal using the differential quadrature hybrid splitter (200). Amplitude scaling is separately applied using phase-inverting variable attenuators (400) to produce a scaled I-component signal and a scaled Q-component signal which is combined using differential power combiner (300).