RF Amplifier Clipping Circuit in Load-Modulated Balanced Architecture
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Solution Overview
Problem
Existing RF amplifier architectures, such as Doherty and LMBA, face challenges in bandwidth expansion and require complex, costly solutions for phase shift optimization, particularly in wideband systems.
Innovation Solution
A simplified RF amplifier circuit using a passive RF signal splitting circuit, RF signal clipping circuit with diode limiters, and a load modulated balanced amplifier (LMBA) with a 3-dB quadrature hybrid coupler for analog phase-to-amplitude transformation, eliminating the need for complex digital controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a load modulated balanced amplifier is used to achieve high efficiency and linearity, then power efficiency is improved, but device complexity increases due to the need for multiple amplifiers and precise phase shift control
Solution Approach 1:
The patent combines the phase shift control function into the quadrature hybrid coupler itself, which naturally provides 90-degree phase shifts between its output ports. This eliminates the need for separate phase shifters and reduces device complexity while maintaining the load modulated balanced amplifier's high efficiency and linearity performance.
Solution Approach 2:
The quadrature hybrid coupler automatically provides the required phase shifts between amplifier inputs without requiring external control signals or additional active components. This self-service capability reduces control signal power requirements and simplifies the overall device architecture.
2Manufacturing precision
If multiple baseband inputs or digitally controlled precision level inputs are used for phase shift optimization, then phase shift precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses passive RF signal splitting circuitry with simple resistive or transformer-based phase splitting that provides sufficient phase accuracy without requiring expensive digitally controlled precision level inputs or multiple baseband processing paths. This approach achieves adequate phase shift precision at significantly lower manufacturing cost.
3Power
If Doherty power amplifier architecture is used for high power applications, then power output is improved, but bandwidth capability deteriorates making design difficult for wideband systems
Solution Approach 1:
The load modulated balanced amplifier architecture provides universal applicability across wide bandwidths while maintaining high power output capability. The quadrature hybrid coupler and balanced topology enable the amplifier to function effectively across multiple frequency bands, making it suitable for both high power and wideband requirements simultaneously.
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 configuration provides a cost-effective and efficient RF amplifier solution with improved bandwidth and reduced complexity, maintaining high efficiency and linearity for modern wireless communications.
Implementation Method 1
The 3-dB quadrature hybrid coupler is performing an analog Fourier transformation which means that a phase difference between the two input signals of the hybrid coupler is transformed in an amplitude difference at the output side and vice versa
Implementation Method 2
The RF signal clipping circuit is configured to clip the first RF input signal to a predetermined clipping level
Data Source
AI summary
The present invention relates to a RF amplifier circuit arrangement for amplifying at least one RF input signal to an output signal for delivery to a load. The RF amplifier circuit arrangement uses a simple and low-cost RF clipping circuit within a load modulated balanced amplifier arrangement which passes RF input signals to output linearly up to the signal input reaches a predefined amplitude. Beyond that predefined amplitude the clipping circuit clips excess amplitudes. The present invention further relates to an electronic device.