Wireless Transmitter Power Calibration With Shared ADC Feedback
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Solution Overview
Problem
Existing wireless transceiver systems face challenges in maintaining accurate output power control across varying temperatures and manufacturing processes, especially when dealing with standards that require variable power levels, as current closed-loop systems are inadequate for accounting for process variations and are cumbersome due to the need for extensive characterization of each device.
Innovation Solution
A closed-loop power output calibration system is implemented, utilizing power detection circuitry, analog to digital conversion, a power signal processor, and a power correction circuit to adjust output gain based on feedback signals, minimizing additional circuitry and memory storage by reusing existing components and employing digital signal processing to correct for temperature and manufacturing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a closed-loop power sensing scheme is used to regulate output power, then output power control accuracy is improved, but device complexity increases due to additional power detection circuitry and feedback mechanisms
Solution Approach 1:
The patent combines the power detection function with the existing receive core by sharing the low-pass filter and analog-to-digital converter between the power detection path and the signal reception path. This merging eliminates duplicate components and reduces overall device complexity while maintaining closed-loop power control accuracy through the shared measurement infrastructure.
Solution Approach 2:
The receive core components, specifically the low-pass filter and ADC, are designed to serve dual purposes: processing received communication signals and measuring the power of transmitted signals through the power detection circuitry. This multi-functionality allows the system to achieve accurate power measurement without adding dedicated measurement-only components, thereby reducing device complexity.
2Manufacturing precision
If extensive characterization of each device is performed to account for process variations, then manufacturing precision is improved, but productivity decreases due to time-consuming calibration procedures
Solution Approach 1:
The patent implements a closed-loop feedback system that continuously measures the actual output power and automatically adjusts the transmit gain to compensate for process variations. This real-time feedback mechanism eliminates the need for extensive pre-characterization and calibration of each device during manufacturing, as the system self-corrects for variations during operation, thereby maintaining manufacturing precision while improving productivity.
Solution Approach 2:
The power control system performs self-calibration by using its own output signal to measure and correct its performance. The transmit path generates a test signal, the power detection circuitry measures its power level, and the system automatically adjusts its gain to achieve the desired output. This self-service approach eliminates the need for external characterization equipment and time-consuming manual calibration procedures, thus improving productivity while maintaining precision.
3Adaptability or versatility
If variable gain amplifier is used to adjust transmit power, then adaptability is improved for different power levels, but reliability decreases due to sensitivity to temperature and process variations
Solution Approach 1:
The patent employs a closed-loop feedback system where the actual output power of the variable gain amplifier is continuously measured by the power detection circuitry and fed back to adjust the gain control. This feedback mechanism compensates for temperature and process variations in real-time, ensuring that the amplifier maintains reliable and accurate output power levels across different operating conditions while preserving its adaptability for variable power requirements.
Solution Approach 2:
The system dynamically adjusts the gain parameter of the variable gain amplifier based on measured output power and operating conditions such as temperature. By continuously monitoring and modifying the gain parameter in response to environmental changes, the system maintains reliable performance across varying temperatures and processes while retaining the ability to adapt to different required power levels.
Data Source
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AI summary
A closed loop power output calibration system for variable power output wireless devices. The wireless device includes a wireless transceiver having a transmit core coupled to a discrete power amplifier. Power detection circuitry formed in the wireless transceiver provides a detected power level of the power amplifier, and a reference power level, both of which are converted to digital signals using existing I and Q signal analog to digital converters in the receiver core. The digital signals are processed to cancel power distortion and temperature effects to provide a resulting power feedback signal. Corrective control signals are generated in response to the power feedback signal relative to a desired power output level. The gain in the transmit core is then adjusted in response to the corrective control signals such that the power amplifier outputs the target output power level.