Resistive Attenuator Compensation Circuit for High-Power Linearity
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Solution Overview
Problem
Existing resistive attenuators in external digital pre-distortion circuits face linearity issues when handling high-power signals, leading to AMAM and AMPM distortion, while solutions to improve linearity often compromise noise figure performance.
Innovation Solution
A resistive attenuator design incorporating a first transistor, multiple attenuation circuits, and a compensation circuit to provide varying signal paths and cancel nonlinear distortions without additional loss, maintaining noise figure performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional loss is added on signal paths to improve linearity when handling high power signals, then linearity is improved, but noise figure performance deteriorates
Solution Approach 1:
The signal path is segmented into multiple parallel paths: a first signal path through a transistor providing lower attenuation, and at least one second signal path through attenuation circuits providing higher attenuation. This segmentation allows the system to achieve good linearity by distributing the signal across paths with different attenuation characteristics, without requiring additional overall loss that would degrade noise figure.
Solution Approach 2:
The patent changes the attenuation parameter across different signal paths. By providing signal paths with different attenuation levels (first signal path with lower attenuation, second signal paths with higher attenuation), the system can optimize linearity performance without introducing excessive overall loss that would harm noise figure performance.
2Device complexity
If a transistor is used to provide signal path in resistive attenuator, then device complexity is reduced, but nonlinear distortion increases
Solution Approach 1:
The patent introduces a compensation circuit as an intermediary element that specifically targets and compensates for the nonlinear distortion generated by the transistor. This compensation circuit acts as a mediator between the transistor's nonlinear behavior and the overall system performance, canceling out the harmful nonlinear distortion while preserving the benefits of using a transistor for signal path provision.
Data Source
AI summary
A resistive attenuator and a method for improving linearity of the resistive attenuator are provided. The resistive attenuator includes a first transistor, an attenuation circuit and a compensation circuit, wherein both the first transistor and the attenuation circuit are coupled between an input terminal and an output terminal of the resistive attenuator, and the compensation circuit is coupled to the first transistor. The first transistor is configured to provide a first signal path between the input terminal and the output terminal. The attenuation circuit is configured to provide a second signal path between the input terminal and the output terminal, wherein signal attenuation of the second signal path is greater than signal attenuation of the first signal path. The compensation circuit is configured to compensate nonlinear distortion caused by the first transistor.