Asymmetric Second-Harmonic Terminations for RF Amplifier Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current amplifier circuits face challenges in reducing AM-AM and AM-PM distortion when handling single tone RF signals, as existing harmonic termination methods tuned at fundamental frequencies are insufficient in improving linearity and efficiency metrics.
Innovation Solution
The implementation of RF amplification circuits with input and output harmonic terminations tuned at frequencies near but not equal to the second harmonic frequency, with the input termination resonant frequency being smaller than and the output termination resonant frequency being greater than the second harmonic frequency, allowing for asymmetric tuning to reduce distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If harmonic terminations are tuned at the second harmonic frequency to attenuate harmonic components, then linearity is improved, but AM-AM and AM-PM distortion reduction is insufficient for single tone RF signals
Solution Approach 1:
The patent applies asymmetry by detuning the input and output harmonic terminations in opposite directions from the second harmonic frequency. The input termination is tuned below the second harmonic frequency while the output termination is tuned above it, creating an asymmetric configuration that specifically addresses AM-AM and AM-PM distortion in single tone RF signals while maintaining linearity improvement.
2Reliability
If harmonic terminations are tuned at harmonic frequencies to reduce intermodulation products, then linearity is improved, but performance in AM-AM and AM-PM metrics is not sufficiently increased
Solution Approach 1:
The patent changes the frequency parameter of the harmonic terminations from being exactly at the second harmonic frequency to being detuned below (input) and above (output) the second harmonic frequency. This parameter modification enables the terminations to effectively reduce AM-AM and AM-PM distortion while maintaining their linearity improvement benefits.
3Reliability
If asymmetric tuning of harmonic terminations is used to reduce AM-AM and AM-PM distortion, then overall amplifier performance is enhanced, but harmonic component attenuation may be slightly sacrificed
Solution Approach 1:
The asymmetric tuning configuration accepts a slight trade-off in harmonic component attenuation to achieve superior AM-AM and AM-PM distortion reduction. By positioning the input termination below and output termination above the second harmonic frequency, the system prioritizes overall performance enhancement in single tone RF signal handling over maximum harmonic attenuation.
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 reduces AM-AM and AM-PM distortion while maintaining or slightly sacrificing harmonic component attenuation, thereby enhancing the overall performance of the amplifier circuit.
Implementation Method 1
the input harmonic termination has a resonant frequency fIN that is near to, but smaller than, the second harmonic frequency 2f0 of the operating frequency
Implementation Method 2
the output harmonic termination has a resonant frequency fOUT that is near to, but greater than, the second harmonic 2f0 frequency of the operating frequency
Implementation Method 3
This approach effectively reduces AM-AM and AM-PM distortion while maintaining or slightly sacrificing harmonic component attenuation
Data Source
AI summary
Methods and devices for improving AM-AM and AM-PM performance of an RF amplifier are presented. According to one aspect, input and output harmonic terminations coupled to the input and output of the amplifier are tuned at frequencies near to, but different than, a second harmonic frequency of an RF signal to be amplified. Improved AM-AM and AM-PM performance is obtained when i) the input harmonic termination is tuned at a frequency that is below the second harmonic frequency and the output harmonic termination is tuned at a frequency that is above the second harmonic frequency, and ii) the input harmonic termination is tuned at a frequency that is farther away from the second harmonic frequency than the frequency used for tuning of the output harmonic termination.