Transmitter IQMM Decoupling via Phase Delay Rotation
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Solution Overview
Problem
Existing radio architectures face challenges in accurately determining and correcting in-phase (I) and quadrature (Q) mismatch (IQMM) in transmitter-receiver loops, which degrades the error vector magnitude (EVM) of QAM signals due to impairments like non-linearity and phase noise, and current methods using fast Fourier transforms are computationally complex.
Innovation Solution
A method that introduces phase delays or rotations in the transmitter-receiver loop to decouple the IQMM of the transmitter and auxiliary receiver, allowing for the estimation and correction of transmitter IQMM in the time domain using an indirect adaptive algorithm, thereby separating transmitter and receiver IQMM and correcting for frequency-dependent impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fast Fourier transform methods are used to determine IQMM in transmitter-receiver loops, then measurement precision is improved, but device complexity increases due to computational requirements
Solution Approach 1:
The patent replaces the computational FFT-based IQMM determination method with a time-domain measurement approach using phase delay and signal rotation. Instead of using complex frequency-domain transformations, the system uses a delay element to introduce phase delays and a controller to rotate signals, thereby simplifying the measurement apparatus while maintaining measurement precision.
Solution Approach 2:
The patent introduces a delay element as an intermediary component that introduces controlled phase delays between the transmitter and receiver signals. This intermediary enables the decoupling of transmitter and receiver IQMM components, allowing for simplified time-domain measurement without requiring complex computational algorithms.
2Device complexity
If phase delay methods are used to decouple transmitter and receiver IQMM, then device complexity is reduced by operating in time domain, but measurement precision may be affected by phase delay accuracy
Solution Approach 1:
The patent employs feedback mechanisms where the controller measures the phase delay introduced by the delay element and uses this information to calculate the required rotation angle. The system continuously adjusts the rotation based on the measured phase delay, ensuring that the decoupling of transmitter and receiver IQMM is accurate despite variations in the delay element characteristics.
Solution Approach 2:
The patent changes the operational parameters by working in the time domain rather than the frequency domain. By introducing phase delays as a controllable parameter and using rotation to decouple the IQMM components, the system achieves simplified measurement while maintaining precision through parameter-based control rather than complex computational processing.
3Ease of operation
If transmitter and receiver IQMM are not decoupled, then ease of operation is improved by direct measurement, but manufacturing precision suffers due to inability to correct transmitter-specific IQMM
Solution Approach 1:
The patent segments the total loop IQMM into transmitter-specific and receiver-specific components by introducing phase delays and using rotation to decouple them. This segmentation allows for separate identification and correction of transmitter IQMM, improving manufacturing precision while maintaining ease of operation through a systematic measurement approach.
Solution Approach 2:
The patent performs preliminary actions by introducing controlled phase delays before the actual IQMM measurement. This preliminary phase delay introduction enables the controller to rotate the signals and separate the transmitter and receiver contributions, thereby preparing the measurement system to accurately identify and correct transmitter-specific IQMM without complicating the overall measurement process.
Data Source
AI summary
In an example, a system includes a transmitter configured to transmit a quadrature amplitude modulation (QAM) signal, where the QAM signal includes an in-phase (I) chain signal and a quadrature (Q) chain signal. The system includes a receiver configured to receive the QAM signal from the transmitter. The system includes a delay element configured to introduce a phase delay between the transmitter and the receiver. The system includes a controller configured to determine an IQ mismatch (IQMM) of a transmitter-receiver loop without a phase delay, and to determine an IQMM of the transmitter-receiver loop with a phase delay introduced by the delay element. The controller is configured to determine an IQMM of the transmitter based on the IQMM of the transmitter-receiver loop without the phase delay and the IQMM of the transmitter-receiver loop with the phase delay. The controller is configured to correct the IQMM of the transmitter.