Receiver Phase Error Reduction via IQ Feedback Control
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Solution Overview
Problem
Communication modulation techniques involving in-phase (I) and quadrature (Q) signals often experience phase errors, which limit the image response rejection ratio (IMRR) due to deviations in the predetermined 90-degree phase difference between I and Q signals in receivers.
Innovation Solution
A receiver circuit is designed with a quadrature signal generator and an IQ phase sense and control circuit to detect and correct phase errors by generating a phase adjustment code, utilizing a phase corrector to adjust the phase difference between I and Q signals, ensuring they remain within a predetermined level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase error correction is not implemented, then the receiver circuit is simpler, but the image response rejection ratio is limited
Solution Approach 1:
The patent implements feedback by using the IQ phase sense and control circuit to continuously monitor the phase difference between I and Q signals, generate a phase adjustment code based on detected phase error, and feed this code to the phase corrector to dynamically adjust the local oscillator signals, creating a closed-loop system that automatically maintains the correct 90-degree phase relationship
Solution Approach 2:
The patent introduces an intermediary phase corrector circuit that acts as a mediator between the quadrature signal generator and the mixers. This phase corrector receives local oscillator signals, applies phase adjustment based on the phase adjustment code, and outputs corrected signals, thereby isolating the complexity of phase error correction from the core demodulation function
2Measurement precision
If phase error correction is implemented, then the image response rejection ratio is improved, but the device complexity increases
Solution Approach 1:
The patent segments the phase correction function into distinct modular components: the IQ phase sense and control circuit that detects phase error and generates adjustment codes, and the phase corrector that applies the correction. This segmentation allows each component to be optimized independently and simplifies the overall system architecture by separating detection and correction functions
3Adaptability or versatility
If dynamic phase adjustment is used, then phase error is reduced across different frequencies, but the circuit complexity increases
Solution Approach 1:
The patent implements dynamics by making the phase correction capability adjustable and adaptive rather than fixed. The phase corrector can dynamically modify the phase of local oscillator signals based on the phase adjustment code, allowing the system to adapt to different operating frequencies and conditions while maintaining accurate phase relationship through real-time control
Data Source
AI summary
A receiver circuit includes a quadrature signal generator to generate an in-phase (I) signal and a quadrature (Q) signal from a local oscillator signal and an IQ phase sense and control circuit to generate a phase adjustment code responsive to a phase error between quadrature signals generated by a plurality of mixers. The receiver circuit also includes a phase corrector to adjust a phase difference between the I and Q signals from the quadrature signal generator to generate corrected I and Q signals to be provided to the plurality of mixers.