RF Amplifier Circuit Resistor Isolation for Oscillation Stability
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Solution Overview
Problem
High-output radio frequency amplifier circuits face challenges in achieving high efficiency due to low-output transistors being short-circuited in parallel, leading to reduced output impedance and potential oscillation issues from unnecessary current loops.
Innovation Solution
A radio frequency amplifier circuit design that connects output terminals of low-output transistors via a resistor, incorporating an output-side harmonic processing circuit that processes even or odd harmonics, and includes input and output matching elements to enhance isolation and impedance, allowing for stable class-F or inverse class-F operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If output terminals of low-output transistors are short-circuited in parallel to increase output, then output power is improved, but output impedance decreases and oscillation issues occur
Solution Approach 1:
The patent introduces an output-side resistor as an intermediary element connected to the output terminals of the parallel-connected transistors. This resistor serves as a mediator that maintains high output impedance while allowing the transistors to operate in parallel for increased power output, thereby preventing oscillation issues without sacrificing power amplification capability.
2Loss of energy
If class-F circuit is used to improve efficiency by short-circuiting even harmonics, then power added efficiency is improved, but circuit complexity increases
Solution Approach 1:
The patent combines the harmonic processing function with the output matching circuit by integrating the output-side resistor into the existing output structure. This merging approach allows the circuit to achieve class-F efficiency through even harmonic short-circuiting while avoiding the need for separate, complex harmonic processing components, thus reducing overall circuit complexity.
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 achieves high efficiency and stability by maintaining a high output impedance and preventing oscillations, enabling effective harmonic processing and efficient operation of the radio frequency amplifier circuit.
Implementation Method 1
an output-side harmonic processing circuit provided for each of the first transistors to be connected to the output terminal of the first transistor, the output-side harmonic processing circuit processing even harmonics or odd harmonics both included in the amplified radio frequency signal
Implementation Method 2
the secondary harmonic processing circuit 702 including the inductor 702A and the capacitor 702B are set so that the secondary harmonic processing circuit 702 serving as a series resonant circuit resonates at a frequency twice as high as the fundamental
Implementation Method 3
an output-side resistor connected to the output terminal of each of the first transistors, in which the output terminal of each of the first transistors is connected to the output terminal of the other one of the first transistors via the output-side resistor
Implementation Method 4
the input terminal of each of the first transistors is connected to an input terminal of the radio frequency amplifier circuit via an input matching element, and the output terminal of each of the first transistors is connected to an output terminal of the radio frequency amplifier circuit via an output matching element
Data Source
AI summary
A radio frequency amplifier circuit includes: low-output transistors, each of which includes an input terminal, an output terminal, and a ground terminal, and amplifies a radio frequency signal; a harmonic processing circuit provided for each of the low-output transistors to be connected to the output terminal of the low-output transistor, and processing a secondary harmonic included in an amplified radio frequency signal, and a resistor connected to the output terminal of each of the low-output transistors. The input terminal of each of the low-output transistors is connected to an input terminal of the radio frequency amplifier circuit via an inductor, and the output terminal of each of the low-output transistors is connected to the other output terminal via the resistance and is further connected to an output terminal of the radio frequency amplifier circuit via an inductor.