Envelope Tracking Delay Compensation for 5G-NR Linearity
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Solution Overview
Problem
Envelope tracking systems in mobile communication devices face limitations in maintaining linearity and efficiency with the advent of 5G-NR technology, which modulates RF signals with higher bandwidths exceeding the inherent bandwidth limits, leading to reduced performance.
Innovation Solution
The implementation of a delay compensation circuitry within the envelope tracking system that generates delay compensation values based on the peak-to-average ratio of modulation types and gain control signals, allowing for precise envelope tracking and synchronization between RF signals and operating voltages, even at wide modulation bandwidths like 5G-NR 100 MHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If envelope tracking system operates at higher bandwidth to support 5G-NR technology, then the system can handle higher data rates, but linearity and efficiency deteriorate due to exceeding inherent bandwidth limits
Solution Approach 1:
The system pre-calculates and stores delay compensation values in a lookup table before operation. The lookup table contains pre-computed delay compensation values corresponding to different peak-to-average ratios and modulation types, allowing the system to quickly retrieve and apply the appropriate compensation without real-time computation delays
Solution Approach 2:
A delay compensation mechanism is introduced as an intermediary between the envelope tracking signal generation and the power amplifier modulation. This intermediary applies retrieved delay compensation values to adjust the timing of voltage adjustments, compensating for the group delay effects that cause linearity and efficiency deterioration at high bandwidths
2Speed
If envelope tracking system increases supply voltage adjustment speed to track high bandwidth RF signals, then bandwidth capability improves, but synchronization between RF signal and operating voltage deteriorates due to delay effects
Solution Approach 1:
The system pre-calculates and stores delay compensation values in a lookup table before operation. The lookup table contains pre-computed delay compensation values corresponding to different peak-to-average ratios and modulation types, allowing the system to quickly retrieve and apply the appropriate compensation without real-time computation delays
Solution Approach 2:
The system continuously monitors the RF signal characteristics including peak-to-average ratio and modulation type, uses this feedback to query the lookup table for appropriate delay compensation values, and dynamically adjusts the timing of supply voltage changes accordingly to maintain synchronization
Data Source
AI summary
An envelope tracking system having delay compensation circuitry is disclosed. The envelope tracking system includes transmit circuitry configured to receive an input transmit signal, a gain control signal, and delay compensation values. The envelope tracking system is further configured to generate an envelope tracking signal based on the input transmit signal, the gain control signal, and the delay compensation values, and generate an output transmit signal based on the input transmit signal. The envelope tracking system also includes a power amplifier configured to generate an amplified transmit signal based on the output transmit signal and an operating voltage. The envelope tracking system further includes an envelope tracking integrated circuit configured to control the operating voltage based on the envelope tracking signal. The delay compensation circuitry is configured to generate the delay compensation values based on a peak-to-average ratio of a given modulation type and the gain control signal.