RF Transmit Power Control Through Detector Feedback for OTA Testing
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Solution Overview
Problem
Manufacturing wireless devices, particularly wearable devices, faces challenges in achieving consistent and reliably-calibrated maximum transmit power due to device-to-device variations, which is essential for performance and regulatory compliance, and existing calibration methods using call boxes are costly and time-consuming.
Innovation Solution
A method for RF transmit power control in wearable devices involves creating a power response lookup table during RF calibration, allowing direct control of transmit power through a transmitter gain setting, and using a power detector to indirectly measure power, enabling automatic setting of transmit power to meet regulatory requirements without expensive call boxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional call box methods are used for transmit power calibration, then measurement accuracy is improved, but manufacturing cost and time consumption increase
Solution Approach 1:
The patent creates a power response lookup table that copies and stores the relationship between transmitter gain settings and actual transmit power values. This allows the device to reference pre-characterized power responses during manufacturing, eliminating the need for expensive call box equipment while maintaining calibration accuracy through the stored power response data
Solution Approach 2:
The patent performs preliminary power response characterization during device manufacturing by measuring the actual transmit power at various transmitter gain settings and storing these relationships in a lookup table. This preliminary action enables subsequent automatic transmit power control without requiring real-time call box equipment, thereby improving manufacturing efficiency
2Manufacturing precision
If device-to-device variations are addressed through manual calibration, then transmit power consistency is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent enables devices to self-calibrate their transmit power by automatically querying the power response lookup table and adjusting their transmitter gain settings based on stored power response data. This self-service capability eliminates the need for complex manual calibration procedures and expensive external equipment, allowing each device to independently achieve consistent transmit power
Solution Approach 2:
The patent implements a feedback mechanism where the device queries the power response lookup table with desired power values and receives corresponding transmitter gain settings as feedback. This closed-loop feedback process automatically compensates for device-to-device variations in power amplifier characteristics, achieving consistent transmit power across all manufactured devices
Data Source
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AI summary
A computer-implemented method for setting RF transmit power of a wireless device includes obtaining power response data for a power detector of the wireless device, the power response data providing a relationship between power detector readings from the power detector and measured transmit power of a transmitter of the wireless device; identifying a target power detector reading value corresponding to a target transmit power based at least in part on the power response data; initializing a transmitter gain of the transmitter to an initial transmitter gain value; obtaining a power detector reading value from the power detector; determining that a difference between the power detector reading value and the target power detector reading value is greater than a tolerance margin; and adjusting a transmitter gain value of the transmitter in a direction of the difference between the power detector reading value and the target power detector reading value.