Receiver Distortion Reduction via Correlation-Based Mixer Calibration
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Solution Overview
Problem
In communication devices where a transmit path and a receive path share a common antenna, strong transmission signals cause crosstalk, leading to significant distortion in the receive signal due to the non-linearity of mixers, particularly affecting the Signal-to-Noise Ratio (SNR) and requiring offline calibration which is not optimal for regular operation.
Innovation Solution
A receiver system with a distortion meter and correlation unit that adjusts mixer settings, such as bias voltage, based on correlation results to reduce distortion components in the baseband receive signal, allowing for online calibration during regular operation without additional analog elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If offline calibration is performed to improve mixer linearity, then distortion components are reduced, but the device requires additional complexity and space for calibration equipment
Solution Approach 1:
The receiver uses its own receive signal to perform self-calibration of the mixer, eliminating the need for external calibration equipment. The correlation unit correlates the receive signal with a synthesized version of the transmit signal to detect distortion components and adjust mixer settings accordingly.
Solution Approach 2:
The correlation unit serves multiple functions: it detects distortion components, determines correlation results, and controls mixer settings adjustments. This multi-functional approach eliminates the need for separate calibration equipment while achieving the same calibration objective.
2Power
If strong transmission signals are used, then transmission power is increased, but crosstalk causes significant distortion in the receive signal
Solution Approach 1:
The system continuously monitors the receive signal for distortion components caused by crosstalk and feeds this information back to the correlation unit. The correlation unit then adjusts mixer settings in real-time to compensate for the distortion, enabling the system to maintain high transmission power while minimizing its harmful effects on receive signal quality.
3Measurement precision
If additional analog elements are added for calibration, then calibration accuracy is improved, but chip space requirements increase
Solution Approach 1:
The patent replaces physical analog calibration elements with digital signal processing functions implemented in the correlation unit. The correlation unit uses digital correlation algorithms to detect distortion components and determine adjustment settings, eliminating the need for additional analog calibration circuitry while maintaining calibration accuracy.
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
This approach effectively minimizes second-order InterModulation Distortion (IMD) components, enhancing the Signal-to-Noise and Distortion Ratio (SNDR) and reducing the complexity and space requirements on the chip, while enabling optimal mixer linearity without dedicated calibration during standby operations.
Implementation Method 1
a correlation unit (111) configured to correlate a signal that depends on the baseband receive signal (140) and a signal that depends on the baseband transmit signal (150)
Data Source
AI summary
A receiver for reducing a distortion component related to a baseband transmit signal in a baseband receive signal is provided. The receiver includes a distortion meter including a correlation unit configured to correlate a signal that depends on the baseband receive signal and a signal that depends on the baseband transmit signal. The receiver further includes a combiner configured to provide the baseband receive signal using the received radio frequency signal and a plurality of settings based on a correlation result of the distortion meter.