Multi-Level PA Supply Control With Decimated Envelope Tracking
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Solution Overview
Problem
Current RF power amplifiers in wireless communication systems face inefficiencies due to non-linear operation, leading to low DC to RF power conversion efficiency, especially in portable devices and base stations, and are further challenged by the demands of wider bandwidth applications.
Innovation Solution
A communication unit with a decimator and multi-level power supply (MLPS) is introduced, which reduces the bandwidth of control signals to improve PA efficiency by dynamically adapting sampling rates and selecting optimal supply voltages, and an adaptive quantizer is used to maintain efficiency while ensuring good adjacent channel leakage ratio (ACLR) performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear amplification is used to minimize out-of-band emissions, then spectral efficiency is improved, but DC to RF power conversion efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the power amplifier supply voltage time-varying through envelope tracking. The supply voltage dynamically follows the envelope of the modulated signal, allowing the PA to operate in a more efficient region while maintaining linear amplification performance. This resolves the contradiction by enabling the PA to adapt its operating point in real-time rather than being fixed in the inefficient linear region.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically to improve efficiency. By adjusting the supply voltage to track the signal envelope, the system achieves better DC to RF conversion efficiency while maintaining the linear amplification needed for spectral efficiency. This parameter change allows the PA to operate more efficiently across different signal conditions.
2Use of energy by moving object
If supply voltage is reduced to improve PA efficiency, then power consumption is reduced, but linearity deteriorates
Solution Approach 1:
The patent uses feedback through envelope tracking where the supply voltage is continuously adjusted based on the detected signal envelope. This feedback mechanism ensures that the PA maintains optimal operating conditions for linearity while operating at reduced supply voltages to improve efficiency. The real-time adjustment compensates for any linearity degradation that would occur with fixed voltage reduction.
Solution Approach 2:
The dynamic adjustment of supply voltage through envelope tracking allows the system to maintain linearity by adapting the voltage to the instantaneous signal conditions. Rather than using a fixed reduced voltage that would degrade linearity, the voltage dynamically follows the signal envelope, preserving linearity while improving overall efficiency.
3Use of energy by moving object
If envelope tracking is used to improve PA efficiency, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the power supply function into multiple discrete voltage levels rather than using a continuous analog supply. The multi-level power supply architecture divides the complex envelope tracking function into manageable discrete states, reducing the overall system complexity while maintaining the efficiency benefits of envelope tracking.
Solution Approach 2:
The patent discretizes the supply voltage parameter into multiple fixed levels, transforming the continuous envelope tracking problem into a discrete selection problem. This parameter change from continuous to discrete reduces the complexity of the power supply control while preserving the essential efficiency improvements of envelope tracking.
4Device complexity
If decimation is applied to reduce control signal bandwidth, then processing complexity is reduced, but control precision deteriorates
Solution Approach 1:
The patent changes the control signal from continuous to discrete by applying decimation, reducing the sampling rate to match the bandwidth requirements of the power supply control. This parameter change reduces processing complexity while the multi-level voltage architecture compensates for any precision loss by providing optimized discrete voltage steps.
Solution Approach 2:
The patent applies partial decimation that reduces the control signal bandwidth to the necessary level for power supply control, rather than maintaining full signal bandwidth. This partial action is sufficient for the power control function while significantly reducing processing complexity, and the multi-level voltage selection compensates for any lost precision.
Data Source
AI summary
A communication unit comprises a decimator configured to sample a variable control signal and output a reduced bandwidth variable control signal; and a multi-level power supply, MLPS, comprising an input and an output, wherein the input is coupled to the decimator and configured to receive the reduced bandwidth variable control signal and, in response thereto, the output delivers multi-level output voltages to supply a power amplifier, PA, module.