Self-Correction Modulator for I/Q Linearity
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Solution Overview
Problem
Wireless transmitters in automotive radar systems face non-linear distortion issues due to transconductance errors, leading to poor bitrate performance and radar detection, which existing technologies have not adequately addressed.
Innovation Solution
A self-correction modulator with a calibration correction unit is employed, using in-phase and quadrature signals to generate correction currents that compensate for errors at the output of the core I/Q modulator, thereby improving the linearity and reducing distortion in the modulated signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If advanced digital modulation schemes are implemented to enable MIMO capabilities, then radar performance and encryption capability are improved, but transmitter linearity requirements increase leading to non-linear distortion
Solution Approach 1:
The patent implements a feedback mechanism where the modulator output is monitored and correction signals are generated to compensate for non-linear distortion. The system uses the output signal itself to generate correction currents that are fed back to cancel distortion, enabling advanced modulation schemes to operate with improved linearity.
Solution Approach 2:
The patent introduces correction currents as an intermediary element that mediates between the modulator output and the desired linear output. These correction currents act as a bridge to cancel non-linear distortion components without requiring complete redesign of the modulation scheme.
2Device complexity
If transconductance errors are present in the core I/Q modulator, then device complexity is reduced, but signal linearity deteriorates leading to poor bitrate performance
Solution Approach 1:
The patent extracts the linearity correction function from the core modulator structure by generating separate correction currents. This allows the core I/Q modulator to maintain its simpler structure with transconductance errors while the extraction and cancellation of distortion occurs in a dedicated correction path.
Solution Approach 2:
The patent segments the modulation function into a core I/Q modulator that handles the primary modulation with acceptable complexity, and a separate correction path that handles linearity enhancement. This segmentation allows each part to be optimized independently for its specific function.
3Manufacturing precision
If correction currents are generated to compensate for errors, then signal linearity is improved, but device complexity increases
Solution Approach 1:
The patent designs the calibration correction unit to perform multiple functions: generating correction currents, adjusting their amplitude and phase, and injecting them into the modulator output. This multi-functionality reduces the need for separate dedicated circuits for each correction task, thereby limiting the increase in device complexity.
Data Source
AI summary
A wireless transceiver system includes a transmitter and a receiver. The transmitter includes a digital processor and a self-correction modulator coupled to the digital processor, wherein based upon a calibration correction assessment of an in-phase (I) signal and a quadrature (Q) signal received from the digital processor, the self-correction modulator generates a calibrated modulated signal. The self-correction modulator includes a core modulator and a calibration correction unit. The calibration correction unit is configured to correct an output of the core modulator based upon the calibration correction assessment. The calibration correction unit includes a calibration processing unit and a calibration modulator, wherein the calibration processing unit provides correction quantities that are used to program the calibration modulator to provide the self-corrected modulated signal.