RF Front-End Power Sensor Calibration for Yield Loss
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Solution Overview
Problem
Current RF front-ends in radar transceivers face challenges in accurately measuring RF power due to the limited accuracy of power sensing circuits, leading to broad guard bands and increased yield loss in production.
Innovation Solution
Incorporating a power sensor coupled to an RF signal path that receives both the RF signal and an RF test signal during calibration, allowing for the generation of a sensor signal representing the power, and using automatic testing equipment to generate and feed an RF test signal for calibration parameter calculation and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If power sensors with limited accuracy are used in RF front-ends, then the device can detect RF power levels, but the measurement precision is poor leading to broad guard bands and yield loss
Solution Approach 1:
The patent applies preliminary action by performing power sensor calibration before production testing. A calibration routine is executed that measures the actual power sensor output against a known reference power level, calculates calibration parameters, and stores these parameters for use during production testing. This preliminary calibration step improves measurement precision without affecting production yield, as it corrects sensor inaccuracies before they cause defective product classifications.
Solution Approach 2:
The patent replaces the need for complex mechanical adjustment mechanisms with an electronic calibration parameter storage and application system. Instead of physically adjusting power sensors to improve accuracy, the system uses digital calibration parameters stored in memory that are applied during production testing, substituting mechanical adjustment with electronic correction.
2Reliability
If broad guard bands are used to compensate for poor power sensing accuracy, then functional safety requirements are met, but the number of deficient products increases and yield is reduced
Solution Approach 1:
The patent implements feedback by using the calibrated power sensor measurements to adjust and narrow the guard bands applied during production testing. The calibration process provides feedback information about actual sensor performance, allowing the system to reduce excessive guard bands that were previously needed to compensate for unknown sensor inaccuracies. This feedback mechanism maintains functional safety compliance while reducing yield loss from overly conservative testing.
Solution Approach 2:
The patent applies parameter changes by modifying the guard band parameters based on calibration results. After calibrating the power sensor and determining its actual accuracy characteristics, the system adjusts the guard band width parameter to be appropriate for the calibrated sensor performance rather than using fixed broad guard bands. This dynamic parameter adjustment maintains safety compliance while improving production yield.
3Reliability
If power sensors are integrated into the RF front-end for continuous monitoring, then functional safety can be ensured, but the device complexity increases
Solution Approach 1:
The patent applies merging by integrating the power sensor calibration functionality directly into the existing RF front-end circuitry and production test system. The calibration routine uses the same signal paths, power sensors, and control logic that are already present for normal operation, combining the calibration function with existing circuit elements rather than adding separate dedicated calibration hardware. This reduces the increase in device complexity while maintaining power monitoring capability.
Solution Approach 2:
The patent implements universality by designing the power sensor and its control circuitry to serve multiple functions: normal RF power monitoring during operation, calibration measurements against reference levels, and production testing. The same hardware elements are used for different purposes at different times, reducing overall device complexity while ensuring functional safety through continuous monitoring capability.
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 enhances the accuracy of power sensing in RF front-ends, reducing yield loss and ensuring compliance with safety standards by allowing for precise calibration and monitoring of RF power levels.
Implementation Method 1
at least one power sensor, which is coupled to the RF signal path and configured to generate a sensor signal representing the power of the RF signal
Data Source
AI summary
One exemplary embodiment of the present invention relates to a circuit that includes at least one RF signal path for an RF signal and at least one power sensor, which is coupled to the RF signal path and configured to generate a sensor signal representing the power of the RF signal during normal operation of the circuit. The circuit further includes a circuit node for receiving an RF test signal during calibration operation of the circuit. The circuit node is coupled to the at least one power sensor, so that the at least one power sensor receives the RF test signal additionally or alternatively to the RF signal and generates the sensor signal as representing the power of the RF test signal.