Phase Rotator for Wireless Transceiver IQ Imbalance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless transceivers face IQ imbalance due to phase and gain mismatches caused by impairments in transmission and reception paths, leading to crosstalk and image interference, which existing technologies struggle to accurately detect and correct.
Innovation Solution
A phase rotation technique is introduced to separate transmission and reception images by generating a second LO signal with a frequency deviation that introduces a prescribed phase shift between the first and second LO signals, allowing for accurate detection and removal of image interference without perturbing the reception path's phase and gain mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase rotation technique is introduced to separate transmission and reception images, then the accuracy of image interference removal is improved, but the complexity of the device increases due to additional LO circuits and frequency deviation mechanisms
Solution Approach 1:
The patent divides the local oscillation function into separate circuits: a first LO circuit for transmission and a second LO circuit for reception. This segmentation allows independent control of transmission and reception frequencies, enabling the phase rotation technique to separate transmission and reception images while maintaining manageable circuit complexity through functional separation.
Solution Approach 2:
The second LO circuit serves multiple functions: it generates the LO signal for the reception mixer and simultaneously provides the frequency deviation necessary for phase rotation. This multi-functionality reduces the need for additional dedicated circuits, thereby limiting the increase in device complexity while still achieving accurate image interference removal.
2Measurement precision
If a second LO circuit with frequency deviation is used to introduce phase shift, then the separation of transmission and reception images is improved, but the loss of energy increases due to additional frequency conversion operations
Solution Approach 1:
The patent changes the frequency parameter of the second LO circuit relative to the first LO circuit. By introducing a controlled frequency deviation in the second LO circuit, the system achieves phase rotation and image separation without requiring excessive energy, as the frequency change is optimized to be sufficient for separation but minimal enough to reduce energy loss.
3Measurement precision
If the phase rotation period is made sufficiently long to introduce prescribed phase shift, then the accuracy of IQ imbalance detection is improved, but the productivity decreases due to extended calibration time
Solution Approach 1:
The patent implements phase rotation as a periodic calibration process with a defined rotation period. During this period, the second LO circuit operates with frequency deviation to introduce the prescribed phase shift. The periodic nature allows the system to achieve accurate IQ imbalance detection within a predetermined time frame, balancing measurement precision with calibration speed by repeating the process efficiently.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The phase rotation technique effectively detects and corrects IQ imbalance, enhancing the accuracy of image interference removal and maintaining minimal impact on the reception path's mismatch characteristics, thereby improving signal quality.
Implementation Method 1
The phase rotation period is sufficiently long such that the frequency deviation can introduce a prescribed phase shift between the first LO signal and the second LO signal
Data Source
AI summary
A phase rotator corrects the IQ imbalance in a wireless transceiver. The phase rotator is a part of a compensation system that detects and separates reception impairment images from transmission impairment images. The disclosed phase rotator introduces a phase shift between the transmission channel and the reception channel without perturbing the phase mismatch and the gain mismatch in the reception path. The phase rotator includes a first local oscillation (LO) circuit that generates a first LO signal at a first carrier frequency and a second LO circuit that generates a second LO signal at a second carrier frequency that deviates from the first carrier frequency for a phase rotation period. The phase rotation period is sufficiently long such that the frequency deviation can introduce a prescribed phase shift between the first LO signal and the second LO signal.