I/Q Phase Imbalance Calibration Using Dual-Path Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic devices face performance degradation due to phase imbalances between inphase and quadrature signal branches, which existing calibration methods struggle to accurately correct, especially in analog domains without introducing gain imbalances or high power consumption.
Innovation Solution
A phase imbalance calibration circuit that includes a detection circuit with a limiter and a correction circuit using dual-direction coupling between inphase and quadrature paths, employing current buffer replicas and switches controlled by a controller to adjust coupling and reduce phase imbalance in the analog domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used to correct phase imbalance, then phase imbalance may be reduced, but gain imbalance is introduced or performance is degraded
Solution Approach 1:
The calibration system is segmented into independent detection and correction modules. The detection circuit uses limiters to convert I and Q signals into separate digital signals that are processed independently through XOR operations, allowing phase imbalance measurement without being affected by gain variations in the analog domain.
Solution Approach 2:
Digital signals serve as an intermediary between the analog I/Q signals and the correction mechanism. The limiters convert analog signals to digital form, and the XOR gate produces a digital error signal that drives the correction circuit, isolating the measurement process from gain imbalance effects.
2Measurement precision
If calibration circuits are added to correct phase imbalance, then phase accuracy is improved, but device complexity increases
Solution Approach 1:
The phase imbalance correction is merged with the existing I/Q signal paths by coupling the inphase buffer replica to the quadrature path and the quadrature buffer replica to the inphase path. This integrated approach corrects phase errors without requiring completely separate calibration circuits.
Solution Approach 2:
Buffer replicas are used to create copies of the I and Q signals for the correction circuit. The inphase buffer replica and quadrature buffer replica provide signal copies that can be coupled back into the opposite paths without disrupting the original signal flow, simplifying the correction architecture.
3Productivity
If analog domain calibration is performed, then real-time correction is achieved, but power consumption increases
Solution Approach 1:
The calibration system performs periodic calibration operations rather than continuous correction. The switch controlled by the error signal enables coupling only when correction is needed, allowing the system to alternate between calibration mode and normal operation, reducing average power consumption while maintaining real-time correction capability.
Data Source
AI summary
A circuit for performing a residual side band calibration is described. The circuit generally includes a phase imbalance detection circuit. The phase imbalance detection circuit may include a limiter. The phase imbalance detection circuit may be independent of gain imbalance. The circuit may also include a phase imbalance correction circuit. The phase imbalance detection circuit may control coupling between an inphase path and a quadrature path.