Envelope Tracking Ripple Control for RF Sideband Compliance
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Solution Overview
Problem
Cellular communication systems face interference issues due to RF spectral emissions that bleed into adjacent non-cellular communication bands, necessitating a solution to modify these emissions to prevent protocol violations and meet stricter spurious emission requirements in bands like the Public Safety Band.
Innovation Solution
The RF transmitter circuitry employs an envelope tracking power supply that operates in either normal or modified switching ripple modes, allowing for frequency modification and active ripple cancellation to ensure that switching ripple sidebands do not violate communications protocols, particularly by moving them outside stricter emission bands or reducing their magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the envelope tracking power supply operates in normal switching ripple mode, then power efficiency is improved, but RF spectral emissions violate communications protocols
Solution Approach 1:
The patent changes the frequency parameter of the switching ripple by adjusting the switching frequency of the power supply. This shifts the location of switching ripple sidebands in the frequency spectrum, moving them away from adjacent non-cellular bands to reduce RF spectral emissions while maintaining power efficiency benefits of envelope tracking operation.
Solution Approach 2:
The patent introduces an intermediary filtering mechanism that selectively attenuates switching ripple sidebands falling within non-cellular communication bands. This filter acts as a mediator between the power supply switching ripple and the RF output, allowing the system to maintain normal switching operation while reducing harmful spectral emissions in specific frequency ranges.
2Reliability
If the switching ripple frequency is modified to move sidebands outside stricter emission bands, then compliance with communication protocols is improved, but power supply complexity increases
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the power supply switching frequency is varied based on the operating conditions and spectral requirements. The system dynamically selects between different switching frequencies to position sidebands in acceptable spectral regions, allowing protocol compliance without requiring permanently complex circuitry for all operating modes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively minimizes interference by adjusting the frequency and magnitude of switching ripple sidebands, ensuring compliance with stricter emission standards in adjacent communication bands, thereby enhancing the operational efficiency and reliability of both cellular and non-cellular communication systems.
Implementation Method 1
the switching ripple of the envelope power supply signal may at least partially amplitude modulate the RF transmit signal, thereby adding switching ripple sidebands to the RF transmit signal
Data Source
AI summary
Radio frequency (RF) transmitter circuitry, which includes an RF power amplifier (PA) and an envelope tracking power supply, is disclosed. The RF PA receives and amplifies an RF input signal to provide an RF transmit signal using an envelope power supply signal. The envelope tracking power supply provides the envelope power supply signal, which has switching ripple. Further, the envelope tracking power supply operates in either a normal switching ripple mode or a modified switching ripple mode, such that during the normal switching ripple mode, the envelope power supply signal has normal switching ripple, and during the modified switching ripple mode, the envelope power supply signal has modified switching ripple. When the modified switching ripple is required, the envelope tracking power supply operates in the modified switching ripple mode.