Mobile Transceiver Self-Calibration for DC Offset and I/Q Mismatch
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Solution Overview
Problem
Mobile transceivers are degraded by DC offset and mismatch issues, leading to reduced signal-to-noise ratio and increased bit error rate, which existing calibration methods fail to accurately address without increasing power consumption and mixer size.
Innovation Solution
A self-calibration method that estimates and calibrates DC offset and mismatch using test signals in a single path, applying them through both transmission and reception stages with specific carrier frequencies to accurately determine and correct these issues without additional circuitry or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mixers of I and Q channel demodulators are designed to be symmetrical to reduce mismatch, then mismatch is reduced, but current consumption and mixer size increase
Solution Approach 1:
The patent implements self-calibration functionality within the transceiver system that automatically detects and corrects mismatch and DC offset without requiring manual intervention or additional external calibration equipment. The system uses its own transmitted signals and received echoes to perform calibration, making the system self-sufficient and avoiding the need for oversized symmetrical mixers that would consume more power.
Solution Approach 2:
The patent changes the operating parameters by using specific test signals (I-channel and Q-channel test signals with known characteristics) and processing the received signals through mathematical operations to extract mismatch and DC offset information. This allows calibration without physically modifying the mixer symmetry, thereby avoiding increased power consumption and device size.
2Manufacturing precision
If mixers of I and Q channel demodulators are designed to be symmetrical to reduce mismatch, then mismatch is reduced, but mixer size increases
Solution Approach 1:
The transceiver performs self-calibration using its own transmitted signals and received echoes, eliminating the need for external calibration equipment and avoiding the requirement for oversized symmetrical mixers. The calibration is performed digitally through signal processing operations on the received test signals.
Solution Approach 2:
The patent replaces the mechanical/physical approach of designing symmetrical mixers with a digital signal processing approach. Instead of physically adjusting mixer symmetry, the system uses mathematical operations on the received signals to detect and correct mismatch, thereby reducing mixer size while maintaining calibration accuracy.
3Measurement precision
If conventional calibration methods are used to estimate DC offset and mismatch, then calibration is performed, but additional circuitry and power consumption increase
Solution Approach 1:
The patent makes the transceiver system perform multiple functions: normal communication and self-calibration. The same transmit and receive paths are used for both communication and calibration purposes. The calibration process reuses existing components (mixers, amplifiers, antennas) rather than adding dedicated calibration circuitry, thereby reducing device complexity.
Solution Approach 2:
The system performs self-calibration without requiring external calibration equipment or additional dedicated calibration circuits. The transceiver uses its own transmitted signals and the echoes received through the same path to detect and correct its own mismatches and DC offsets, eliminating the need for separate calibration hardware.
4Measurement precision
If conventional calibration methods are used to estimate DC offset and mismatch, then calibration is performed, but power consumption increases
Solution Approach 1:
The transceiver uses the same transmit and receive paths for both normal communication and calibration operations. The calibration process does not require separate power-intensive calibration circuits but instead uses the existing RF path and baseband processing resources, thereby minimizing additional power consumption.
Solution Approach 2:
The system performs self-calibration using its own transmitted signals and received echoes, avoiding the need for external calibration equipment that would consume additional power. The calibration is performed digitally through signal processing operations that reuse existing processing resources rather than activating additional power-hungry hardware.
Data Source
AI summary
A method is provided for self-calibrating the mismatch and the direct current (DC) offset occurring in a mobile transceiver. The transmitter of the mobile terminal is used as a signal generator and the receiver thereof is used as a response characteristic measurer. The baseband processor calibrates the mismatch and the DC offset for the receiving and transmitting sides using a test signal received from the transmitter. When multiple input subcarriers are used in a mixer present on a reception stage, self-calibration is performed using multiple received test signals obtained from one transmission test signal.