Narrowband EVM Estimation for RF Amplifier Supply Control
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Solution Overview
Problem
Determining an optimal supply voltage for radio-frequency power amplifiers in electronic devices with wireless communications circuitry is challenging, especially for baseband signals with bandwidths exceeding a certain threshold, where envelope tracking techniques are no longer effective, leading to inefficiencies and excessive power consumption.
Innovation Solution
The implementation of error vector magnitude (EVM) estimation circuitry, which includes filters, signal extraction circuits, and comparison circuits to compute a figure of merit used to adjust the power supply voltage of the radio-frequency power amplifier, optimizing power efficiency by isolating amplitude components and measuring energy levels to adjust the supply voltage based on the calculated EVM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking techniques are used to adjust power supply voltage, then power efficiency is improved, but this technique is no longer effective for baseband signals with bandwidth exceeding a certain threshold
Solution Approach 1:
The patent changes the measurement parameter from wideband EVM to narrowband EVM, allowing the system to maintain effective voltage adjustment mechanisms for wideband signals by measuring performance in narrow frequency slices where envelope tracking remains effective.
Solution Approach 2:
The patent segments the wideband signal measurement into multiple narrowband measurements across different frequency slices. This allows the system to apply envelope tracking techniques to each narrowband segment individually, overcoming the limitation that envelope tracking is ineffective for wideband signals as a whole.
2Device complexity
If a fixed supply voltage is set for radio-frequency power amplifier, then device complexity is reduced, but power consumption increases and cannot be optimized for different signal conditions
Solution Approach 1:
The system performs self-diagnosis by measuring narrowband EVM and automatically adjusting the supply voltage based on the measured performance, eliminating the need for complex external voltage control mechanisms while optimizing power consumption.
Solution Approach 2:
The patent implements a feedback mechanism where the narrowband EVM measurement results are used to adjust the supply voltage of the power amplifier. This closed-loop control optimizes power consumption while maintaining signal quality without requiring complex open-loop control systems.
3Measurement precision
If wideband EVM measurement is performed, then overall signal quality is assessed, but the measurement complexity and required processing bandwidth increase significantly
Solution Approach 1:
The patent divides the wideband EVM measurement into multiple narrowband measurements across different frequency slices. This segmentation reduces the processing bandwidth requirements for each measurement while collectively providing comprehensive signal quality assessment across the entire wideband signal.
Solution Approach 2:
Instead of measuring the entire wideband signal at once, the patent performs partial measurements in narrow frequency slices. This approach reduces measurement complexity and processing requirements while still providing sufficient information for voltage optimization through the narrowband EVM metric.
Data Source
AI summary
Wireless circuitry can include a processor that generates a reference baseband signal, an upconversion circuit that upconverts the baseband signals to radio-frequency signals, an amplifier that amplifies the radio-frequency signals, and an antenna. The amplifier can be adjusted based on an estimated value computed using error vector magnitude (EVM) estimation circuitry. The EVM estimation circuitry may include a first filter configured to receive the reference signal, a second filter configured to receive a measured signal coupled from the output of the amplifier, a first signal extraction circuit coupled to an output of the first filter, a second signal extraction circuit coupled to an output of the second filter, and a comparison circuit having a first input that receives signals from the first signal extraction circuit, a second input that receives signals from the second signal extraction circuit, and an output on which the estimated value is provided.