Reflective Hybrid Coupler Linearizer for Power Amplifier Distortion
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Solution Overview
Problem
Existing power amplifiers face challenges in achieving good AM-AM and AM-PM metrics while maintaining high power, power added efficiency (PAE), linearity, and error vector magnitude (EVM) performance.
Innovation Solution
A new linearization approach is introduced, which involves pre-processing an input signal using a reflective hybrid coupler and a non-linear termination circuit to alter the AM-PM profile, thereby compensating for the AM-PM variation imposed by the amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amplifier operates closer to the 1 dB compression point to improve power efficiency, then power added efficiency (PAE) is improved, but linearity and AM-AM/AM-PM metrics deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-distorting the input signal before it enters the power amplifier. The linearizer circuit modifies the input signal's amplitude and phase characteristics in advance to counteract the expected non-linear distortion that will occur when the amplifier operates near its compression point. This allows the amplifier to operate at high efficiency while the pre-applied distortion compensation maintains linearity of the overall system.
2Manufacturing precision
If the amplifier operates at high current density to achieve good AM-AM and AM-PM metrics, then linearity is improved, but power added efficiency and thermal performance deteriorate
Solution Approach 1:
The patent introduces an intermediary linearizer circuit between the signal source and the power amplifier. This intermediary device performs the function of signal conditioning and distortion compensation, allowing the power amplifier to operate at high current density for efficiency without directly承受 the full burden of maintaining linearity. The linearizer acts as a mediator that handles the linearity requirements separately from the amplifier's power conversion function.
3Manufacturing precision
If digital pre-distortion is used to improve linearity, then AM-AM and AM-PM metrics are improved, but device complexity and circuit requirements increase
Solution Approach 1:
The patent replaces complex digital signal processing systems with an analog circuit-based linearizer. Instead of using digital pre-distortion algorithms that require feedback loops, ADCs, DACs, and complex computational resources, the invention uses analog circuitry (including voltage-controlled attenuators, phase shifters, and lookup tables implemented in analog form) to achieve the same linearity improvement. This substitution reduces device complexity while maintaining the linearity enhancement benefit.
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.