In-Situ RF Envelope Delay Detection for Envelope-Tracking Amplifiers
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Solution Overview
Problem
In envelope-tracking systems, the delay between the RF path and the envelope path leads to synchronization issues, causing non-linearities and distortion due to processing delays and non-idealities, which increases power consumption and affects performance metrics like ACLR.
Innovation Solution
An in-situ delay measurement circuit measures the delay between the RF input and output signals or between the envelope signal and the envelope-tracking power supply voltage, allowing for synchronization without the need for downconversion and ADC, thereby reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope-tracking power supply is used to improve RF power amplifier efficiency, then power consumption is reduced, but delay between envelope path and RF path causes synchronization issues leading to non-linearities and distortion
Solution Approach 1:
The delay measurement circuit measures the delay between the envelope path and RF path in advance, allowing the system to pre-compensate for the delay by adjusting the envelope path timing before it causes synchronization issues, thus maintaining signal linearity while using envelope-tracking power supply
Solution Approach 2:
The delay measurement circuit continuously monitors the delay between envelope and RF paths, providing feedback to the envelope-tracking power supply to dynamically adjust the envelope path timing, ensuring synchronization is maintained under varying operating conditions
2Measurement precision
If downconversion and ADC are used to measure delay between RF and envelope paths, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts only the envelope information from the RF signal using a simple envelope detector, rather than performing full downconversion and ADC processing. This extracts the necessary delay measurement data while eliminating complex processing stages, achieving adequate measurement precision with reduced complexity
Solution Approach 2:
The envelope detector uses simple, low-cost components compared to downconversion and ADC systems. The measurement approach uses inexpensive envelope detection circuitry instead of expensive RF processing equipment, reducing device complexity and cost while providing sufficient measurement accuracy for delay compensation
Data Source
AI summary
An in-situ delay measurement is performed for an envelope-tracking power amplifier of an RF input signal. Because the delay measurement is in-situ, the delay measurement avoids the necessity to down convert and digitize a version of an RF output signal from the envelope-tracking power amplifier.