Reflective Hybrid Coupler Linearizer for AM-PM Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power amplifiers face challenges in achieving good amplitude-to-amplitude (AM-AM) and amplitude-to-phase (AM-PM) metrics while maintaining high power added efficiency (PAE) and error vector magnitude (EVM) performance, often requiring complex digital pre-distortion and operating far from the 1 dB compression point, which degrades efficiency.
Innovation Solution
A linearization approach using a reflective hybrid coupler and non-linear termination circuit to pre-process input signals, altering the AM-PM profile to compensate for the amplifier's non-linear distortion, thereby extending the 1 dB compression point and improving linearity and EVM performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital pre-distortion is used to improve linearity and EVM performance, then AM-AM and AM-PM metrics are improved, but device complexity increases due to feedback loop and complex circuitry requirements
Solution Approach 1:
The patent applies preliminary action by pre-processing the input signal through a non-linear termination circuit that anticipates and compensates for amplifier non-linearities before the signal enters the power amplifier. This pre-distortion approach eliminates the need for complex feedback loops while achieving improved AM-AM and AM-PM metrics, thereby reducing device complexity while maintaining linearity performance.
2Manufacturing precision
If the amplifier operates further away from the 1 dB compression point to reduce non-linear distortion, then AM-AM and AM-PM metrics are improved, but power added efficiency degrades significantly
Solution Approach 1:
The non-linear termination circuit performs preliminary distortion compensation on the input signal, allowing the power amplifier to operate closer to its 1 dB compression point where power added efficiency is higher. By pre-correcting the signal characteristics, the amplifier can maintain improved AM-AM and AM-PM metrics while operating at more efficient power levels, thus resolving the trade-off between linearity and efficiency.
3Manufacturing precision
If high current density is used in IC FET fabrication to achieve good AM-AM and AM-PM metrics, then linearity is improved, but thermal performance and power efficiency deteriorate
Solution Approach 1:
The patent implements preliminary signal processing through the non-linear termination circuit that compensates for distortion before amplification. This allows the use of lower current density FETs that generate less heat, thereby improving thermal performance and power efficiency while maintaining good AM-AM and AM-PM metrics through the pre-applied distortion compensation rather than relying on high current density operation.
Data Source
AI summary
Circuits and methods for achieving good amplifier AM-AM and AM-PM metrics while achieving good power, PAE, linearity, and EVM performance. Embodiments compensate for a non-linear distortion profile (e.g., an AM-PM and/or AM-AM profile) in an amplifier by pre-processing an input signal, such as a radio-frequency signal, to alter the non-linear distortion profile of the input signal so as to compensate for the non-linear distortion profile imposed by a coupled device, such as an amplifier. An inventive aspect includes linearizing an output from an amplifier having a first non-linear distortion profile, including passing an input signal having a second non-linear distortion profile through a reflective hybrid coupler to a non-linear termination circuit, and reflecting a modified input signal from the non-linear termination circuit back through the reflective hybrid coupler as an output signal, the output signal having a third non-linear distortion profile shaped to compensate for the first non-linear distortion profile.