RF Power Amplifier Supply Control for ACLR Compliance
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Solution Overview
Problem
Current RF transmitter power amplifiers (PAs) consume excess power due to a supply voltage margin added to ensure compliance with spectral mask and Adjacent Channel Leakage Ratio (ACLR) requirements, which is not optimized for variations in temperature, process, and load impedance.
Innovation Solution
Implementing a feedback system to dynamically adjust the PA supply voltage based on real-time measurements of in-channel and out-of-band emissions, and ACLR, allowing for reduced voltage margins while maintaining compliance with spectrum emission requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply voltage to the power amplifier is increased by a margin above the nominal supply voltage, then compliance with spectral mask and ACLR requirements is ensured, but power dissipation of the power amplifier increases beyond what is needed to generate the desired output power
Solution Approach 1:
The patent implements dynamic adjustment of the power amplifier supply voltage based on real-time measurements of output emissions and ACLR. The voltage is adjusted from a fixed margin-based approach to a dynamic value that maintains compliance while minimizing power dissipation under varying operating conditions including temperature, process variations, and load impedance changes.
Solution Approach 2:
The patent employs a feedback mechanism where the output emissions and ACLR are measured and used to adjust the supply voltage to the power amplifier. This closed-loop control system continuously monitors performance and adjusts the voltage to maintain compliance with spectral mask and ACLR requirements while optimizing power efficiency, eliminating the need for excessive voltage margins.
2Adaptability or versatility
If the supply voltage is increased to account for variations in temperature, process, and load impedance, then compliance under varying conditions is maintained, but power consumption increases under all conditions
Solution Approach 1:
The system transitions from a static voltage margin approach to a dynamic adjustment mechanism that adapts the supply voltage to actual operating conditions. The voltage is adjusted in real-time based on measured emissions and ACLR, allowing the system to maintain compliance across temperature, process, and load variations without consuming excessive power under all conditions.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on measured output characteristics and operating conditions. By adjusting this key parameter in response to actual emissions and ACLR measurements, the system adapts to temperature, process, and load variations while optimizing power consumption, rather than using a fixed elevated voltage for all conditions.
Data Source
AI summary
Methods and systems for controlling the supply voltage provided to a power amplifier (PA) in a radio frequency (RF) transmitter based on measured output spectrum emissions are provided. In an embodiment, the PA supply voltage is adjusted such that spectrum emission limits are satisfied with predetermined margins. In another embodiment, the predetermined margins are reduced to lower power consumption of the PA.