I/Q Mismatch Calibration Using Blind Source Separation
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Solution Overview
Problem
Wideband communication receivers, particularly direct conversion receivers, suffer from signal impairments due to I/Q mismatch, which degrade the signal-to-noise ratio and overall system performance, especially for high-signal-to-noise applications like analog TV signals, as existing calibration methods leave residual artifacts.
Innovation Solution
A method and system for I/Q mismatch calibration and compensation using blind source separation algorithms to determine and correct frequency-dependent gain and phase mismatches, employing phase and amplitude tilt correction filters to mitigate these impairments, allowing for efficient compensation within the digital domain without separate calibration paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing DC offset cancellation and I/Q calibration methods are used, then signal impairments are mitigated to some extent, but residual artifacts remain visible in analog pictures for high signal-to-noise ratio applications
Solution Approach 1:
The patent performs I/Q mismatch calibration during a training period before actual signal reception. The system pre-determines calibration parameters using training sequences, then applies these parameters during normal operation to eliminate artifacts in high-quality analog pictures.
Solution Approach 2:
The patent replaces traditional analog I/Q calibration circuitry with digital signal processing methods. By using digital algorithms to calculate and apply calibration parameters, the system achieves higher precision in eliminating artifacts while maintaining reliability.
2Measurement precision
If separate calibration paths are implemented for I/Q mismatch correction, then calibration precision improves, but system complexity and implementation cost increase
Solution Approach 1:
The patent combines I/Q mismatch calibration functionality with the existing direct conversion receiver architecture. The calibration parameters are integrated into the signal processing path without requiring separate dedicated calibration hardware, thus maintaining calibration accuracy while reducing system complexity.
Solution Approach 2:
The calibration mechanism is designed to work within the universal direct conversion receiver framework. The same receiver hardware performs both normal signal reception and I/Q calibration functions by utilizing training sequences and digital signal processing, eliminating the need for separate calibration paths.
Data Source
AI summary
Methods and systems for I/Q mismatch calibration and compensation for wideband communication receivers may comprise receiving a plurality of radio frequency (RF) channels, downconverting the received plurality of received RF channels to baseband frequencies, determining and removing average in-phase (I) and quadrature (Q) gain and phase mismatch of the downconverted channels, determining a phase and amplitude tilt of the downconverted channels with removed average I and Q gain and phase mismatch, and compensating for said phase and amplitude tilt I and Q gain and phase mismatch of the downconverted channels. The determined phase tilt may be compensated utilizing a phase tilt correction filter, which may comprise one or more all-pass filters. The average I and Q gain and phase mismatch may be determined utilizing a blind source separation (BSS) estimation algorithm.