Supply Modulation Switch Network for Linear RF Power Amplification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radio frequency (RF) transmitters face a trade-off between energy efficiency and linearity, making it challenging to transmit data carrying RF signals with both high efficiency and high linearity, especially for modulation and coding schemes with high peak to average power ratios.
Innovation Solution
A multi-output power supply system with a pulse shaping network and configuration switch network is implemented, which includes a boost converter and a T-network of switches to selectively short the pulse shaping network, altering its transfer function and providing filtered bias voltage signals to RF amplifiers, thereby achieving efficient and linear power amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power supply system is used in RF transmitters, then the device complexity is low, but the linearity and energy efficiency cannot be simultaneously achieved
Solution Approach 1:
The power supply system is segmented into multiple independent voltage outputs (V1, V2, V3) with different voltage levels, each capable of being independently controlled and switched. This segmentation allows selective activation of specific voltage levels based on signal requirements, enabling precise control over power amplifier operating points to maintain linearity while managing complexity through modular architecture
Solution Approach 2:
The system dynamically switches between different voltage levels and power amplifier configurations based on real-time signal conditions. The switch network dynamically reconfigures the power supply connections to match the instantaneous power requirements, allowing the system to adapt its complexity level to the actual operating conditions rather than maintaining fixed high complexity
2Loss of energy
If power amplification is increased to improve signal strength, then the energy efficiency improves, but the linearity deteriorates
Solution Approach 1:
The system changes the voltage parameter dynamically by switching between multiple discrete voltage levels (V1, V2, V3) supplied to the power amplifier. By adjusting the supply voltage parameter according to the signal envelope, the system can operate the power amplifier in different regions of its characteristic curve, achieving high energy efficiency during low-power segments while maintaining linearity during high-power segments through envelope tracking
Solution Approach 2:
The power supply system employs periodic switching between different voltage levels that tracks the envelope of the modulated signal. This periodic action synchronizes the power supply variations with the signal characteristics, allowing the power amplifier to operate efficiently at peak power while maintaining linearity through controlled periodic modulation of the supply voltage
3Adaptability or versatility
If a simple switch configuration is used, then the device complexity is low, but the signal path control and filtering capability are insufficient
Solution Approach 1:
The switch network is designed with universal functionality to perform multiple operations: selecting different voltage levels, routing signal paths, and working in conjunction with the pulse shaping network for filtering. This multi-functionality allows a single switch configuration to provide adaptability for various signal conditions without requiring separate dedicated circuits for each function, thereby managing complexity while enhancing versatility
Solution Approach 2:
The pulse shaping network serves as an intermediary element between the multi-output power supply and the power amplifier. It mediates the interaction by shaping the voltage transitions from the switch network, providing filtering capability that enables precise signal path control while the switch network itself maintains relatively simple configuration. The intermediary absorbs much of the complexity required for precise control
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 allows for concurrent achievement of high efficiency and linearity in RF transmitters, effectively supporting modulation and coding schemes with high peak to average power ratios while controlling receive baseband and out-of-band emissions, suitable for mobile devices and 5G communication protocols.
Implementation Method 1
a configuration switch network having a plurality of switches to create or modify signal paths from the at least one modulator circuit to the at least one RF amplifier
Implementation Method 2
In embodiments, in which capacitive coupling (e.g., due to parasitic capacitance of a switch) is a concern
Implementation Method 3
at least one pulse shaping network (PSN) having at least one passive element, the PSN configured to shape (i.e., filter or modify the trajectory of) the modulated output signal
Implementation Method 4
The multi-output power supply may include a boost converter
Data Source
AI summary
A power supply modulator circuit includes a multi-output power supply that generates multiple power output signals; at least one power modulator circuit generates a modulated power output signal from the multiple power output signals of the multi-output power supply; at least one pulse shaping network (PSN) having at least one passive element, the PSN configured to shape the modulated power output signal; at least one power amplifier coupled to receive the modulated power signal; and a switching network having a plurality of switches to create or modify power signal paths from the at least one power modulator circuit to the at least one power amplifier.