Quadrature Phase Detection for Multi-Antenna Synthesizer Alignment
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Solution Overview
Problem
In multi-antenna radio circuits, quadrature phase dividers operating in different modes due to initial state mismatches result in phase noise issues, making it challenging to achieve constructive signal combining, especially at high frequencies like millimeter waves, and require careful phase detection and correction to maintain signal integrity.
Innovation Solution
A quadrature phase detector circuit is implemented to determine the in-phase or out-of-phase state of frequency synthesizers using control signal comparisons, with a correction signal circuit adjusting the phase of frequency dividers to synchronize them, thereby alleviating phase noise and ensuring correct signal combining in both analog and digital domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency dividers are used to generate quadrature phase local oscillator signals in multi-antenna systems, then signal distribution to all transceivers is achieved, but phase noise increases and signal combining fails due to uncontrolled initial states
Solution Approach 1:
The patent implements a feedback mechanism where the initial states of frequency dividers are monitored and corrected. A control circuit detects when frequency dividers settle into incorrect initial states and applies correction signals to force them into the desired state, ensuring consistent phase relationships across multiple antennas while maintaining the ability to distribute signals system-wide
Solution Approach 2:
The patent applies preliminary action by pre-controlling the initial states of frequency dividers before they are used for signal generation. The system proactively sets the initial conditions of the dividers to ensure they start in the correct phase relationship, preventing phase noise and combining issues before they can occur during normal operation
2Measurement precision
If direct sampling of high-frequency signals is performed for phase detection, then accurate phase relationship measurement is achieved, but the circuit complexity and power consumption increase significantly
Solution Approach 1:
The patent introduces an intermediary approach by using frequency dividers to down-convert high-frequency signals to lower frequencies before phase detection. This intermediary frequency conversion step allows accurate phase measurement without requiring direct sampling of the high-frequency signals, thereby reducing circuit complexity and power consumption while maintaining measurement precision
3Reliability
If individual local oscillators are placed close to antenna elements for beamforming, then phase noise between antennas becomes uncorrelated, but power consumption increases
Solution Approach 1:
The patent applies segmentation by dividing the frequency synthesis function into distributed frequency dividers placed at each antenna element. Each divider operates independently from a common reference signal, providing uncorrelated phase noise characteristics necessary for beamforming while consuming less power than individual full-featured local oscillators would require
Data Source
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AI summary
A quadrature phase detector circuit for a multi-antenna radio circuit comprising a plurality of frequency synthesizers using a common reference oscillator signal is disclosed. The quadrature phase detector comprises a first circuit arranged to collect a first state value indicating an inner state of a first quadrature signals generating frequency divider circuit of a first frequency synthesizer of the plurality of frequency synthesizers and a second state value indicating an inner state of a second quadrature signals generating frequency divider circuit of a second frequency synthesizer of the plurality of frequency synthesizers, a second circuit arranged to determine from the first state value and the second state value whether quadrature signals of the first frequency synthesizer and quadrature signals of the second frequency synthesizer are in-phase or out-of-phase, and a third circuit arranged to provide an output signal indicating whether the quadrature signals of the first frequency synthesizer and the quadrature signals of the second frequency synthesizer are in-phase or out-of-phase.