Transmit Power Sensor Calibration Using EVM-Based Correlation
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Solution Overview
Problem
Existing wireless communication systems face challenges in accurately calibrating transmit power sensors, leading to inconsistencies in power output, which affect signal quality and emission requirements, particularly due to variations in coupler designs and manufacturing processes, necessitating time-consuming and costly calibration for each device.
Innovation Solution
A method and apparatus that derive a characteristic correlation between actual output power of transmit amplifiers and power detection circuits across a range of power levels, allowing for the storage of this correlation in wireless devices, enabling the estimation of actual output power and adjustment of gain settings based on this correlation, thereby eliminating the need for per-device calibration using external test equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If per-device calibration using external test equipment is performed, then measurement precision of transmit power sensor is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-characterizing a set of transmit amplifiers and power detection circuits to derive a characteristic correlation before actual device manufacturing. This correlation is stored in memory and used during production to eliminate time-consuming per-device calibration procedures, thereby resolving the contradiction between measurement precision and manufacturing time
Solution Approach 2:
The patent uses copying by creating a representative model through characterizing a set of amplifiers and detectors. The derived characteristic correlation from this set serves as a copy that can be applied to multiple devices, eliminating the need to perform actual calibration on each individual device while maintaining accuracy
2Measurement precision
If per-device calibration using external test equipment is performed, then measurement precision of transmit power sensor is improved, but manufacturing cost increases
Solution Approach 1:
The patent performs the characterization and correlation derivation in advance during a setup phase, rather than during individual device manufacturing. This preliminary action allows the same correlation data to be reused across multiple devices, significantly reducing per-unit manufacturing cost while maintaining calibration precision
Solution Approach 2:
By creating a master correlation profile from a characterized set of components and copying this profile to multiple devices, the patent eliminates the need for expensive external test equipment and per-device calibration procedures, thereby reducing manufacturing cost while preserving measurement precision
3Device complexity
If characteristic correlation is derived from a set of devices, then device complexity is reduced, but measurement precision may worsen due to variations in coupler designs and manufacturing processes
Solution Approach 1:
The patent addresses measurement precision concerns by characterizing a set of amplifiers and detectors across multiple parameters and power levels to derive a comprehensive characteristic correlation. This correlation captures variations in coupler designs and manufacturing processes, allowing the system to maintain accuracy despite device variations while keeping the implementation simple
Data Source
AI summary
Systems, methods and apparatus a provided for calibrating actual output power of a transmit power sensor for closed loop power control using a quality metric such as error vector magnitude (EVM) to improve power detection accuracy. In aspects, a method for correlating an output of a transmit power sensor with actual output power of a wireless transmitter includes deriving a characteristic correlation between an actual output power of a set of transmit amplifiers and an output power and of a set of corresponding power detection circuits over a range of transmit power levels in a corresponding set of wireless devices; storing the characteristic correlation in a wireless device that is not part of the set from which the characteristic correlation was derived; and sensing an output of a transmit power sensor of the device while the transmitter of the device transmits according to one or more gain settings.