Tracker Circuit Filtering for Low-Spur Multi-Band Power Amplifiers
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Solution Overview
Problem
Existing power amplifier technologies using discrete voltage supply modes, such as digital ET mode, result in increased noise and spurious emissions due to intermodulation distortion, leading to degradation of adjacent channel power ratio and increased circuit size.
Innovation Solution
A tracker circuit with an output switching circuit, voltage supply paths, and a filter circuit that selectively outputs discrete voltages to power amplifiers, and connects/disconnects a filter circuit based on channel bandwidth to reduce noise and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If discrete voltage supply mode is used in power amplifier, then power-added efficiency is improved, but distortion and spurious emissions increase
Solution Approach 1:
A filter circuit is introduced as an intermediary component between the discrete voltage supply and the power amplifier. This filter circuit suppresses the harmful intermodulation distortion and spurious emissions generated by the discrete voltage switching, while allowing the efficient discrete voltage supply mode to continue operating. The filter acts as a mediator that preserves the benefits of discrete voltage supply while eliminating its adverse effects on signal quality.
Solution Approach 2:
The invention converts the harmful intermodulation distortion products generated by discrete voltage switching into beneficial filtered outputs. By using the filter circuit to selectively remove unwanted frequency components while preserving the fundamental signal, the harmful distortion is transformed into a design feature where the filter's frequency-selective properties are used to enhance overall system performance.
2Object-generated harmful factors
If filter circuit is added to reduce distortion, then signal quality is improved, but circuit size increases
Solution Approach 1:
The filter circuit is designed with a segmented structure that processes different frequency components separately. This segmentation allows the filter to achieve effective distortion reduction while maintaining a compact form factor, as each segment can be optimized for specific frequency ranges rather than requiring a single large-scale filter structure.
Solution Approach 2:
The filter circuit incorporates dynamic switching capabilities that allow it to adapt its configuration based on operating conditions. This dynamic behavior enables the filter to achieve high performance when needed while minimizing its impact on circuit size during normal operation, resolving the contradiction between filter effectiveness and circuit compactness.
Data Source
AI summary
A tracker circuit includes an output switching circuit, a first voltage supply path, a second voltage supply path and a first filter circuit. The output switching circuit is configured to selectively output at least one of a plurality of discrete voltages as a power supply output. The first voltage supply path is configured to provide the power supply output to a first power amplifier, the first power amplifier is configured to amplify a first radio frequency signal of a first band. The second voltage supply path is configured to provide the power supply output to a second power amplifier, the second power amplifier is configured to amplify a second radio frequency signal of a second band. The first filter circuit is configured to be connected in shunt with the first voltage supply path and/or the second voltage supply path.