Dual-Tracker Envelope Tracking With Switchable Notch Filters
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Solution Overview
Problem
The output impedance of envelope tracking integrated circuits (ETICs) interacts nonlinearly with power amplifiers at higher modulation bandwidths, leading to degradation of modulated voltage and the creation of harmonic frequencies outside the modulation bandwidth, particularly in advanced wireless communication technologies like 5G-NR.
Innovation Solution
A dual tracker envelope tracking system with a switch controller that configures notch filters to either couple or decouple them in parallel, depending on the operating mode, to better control output impedance and attenuate harmonic frequencies. This system includes a first and second tracker with notch filters and a switch controller to manage the coupling of these filters based on the ETIC's operating mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single tracker is used in the ETIC, then the device complexity is reduced, but the ability to control output impedance and attenuate harmonic frequencies at higher modulation bandwidths is insufficient
Solution Approach 1:
The ETIC is divided into multiple independent tracker circuits (first tracker and second tracker), each with its own notch filter. This segmentation allows each tracker to handle specific frequency ranges or operational modes, improving output impedance control and harmonic attenuation while maintaining manageable complexity through modular design
Solution Approach 2:
The switch dynamically reconfigures the connection between trackers and notch filters based on operational mode. In the first mode, the switch couples both trackers with their respective notch filters to maximize impedance control. In the second mode, the switch decouples them to reduce complexity. This dynamic reconfiguration resolves the contradiction by adapting the system complexity to the current operational requirements
2Reliability
If multiple trackers with notch filters are always coupled in parallel, then output impedance control and harmonic attenuation are improved, but the device complexity and power consumption increase
Solution Approach 1:
The switch enables dynamic reconfiguration of the tracker and filter network based on operational mode. In the first mode, both trackers are coupled with their notch filters in parallel to maximize harmonic attenuation. In the second mode, the switch decouples the filters to reduce device complexity and power consumption. This dynamic approach resolves the contradiction by adapting the system configuration to current operational needs
Solution Approach 2:
Each tracker has its own dedicated notch filter tailored to specific frequency ranges or operational requirements. This local optimization allows each tracker-filter pair to be optimized for its specific function, improving overall harmonic attenuation while allowing the system to selectively engage only the necessary tracker-filter combinations in different modes, thereby managing device complexity
3Productivity
If the ETIC operates in higher modulation bandwidth modes, then the data rate and communication capability are improved, but the nonlinear interaction with power amplifiers increases, creating more harmonic frequencies
Solution Approach 1:
The notch filters are segmented into multiple independent circuits, each designed to target specific harmonic frequency ranges generated at different modulation bandwidths. This segmentation allows the system to effectively attenuate harmonics across the entire extended bandwidth range by engaging the appropriate filter circuits based on the current operational mode
Solution Approach 2:
The switch dynamically activates or deactivates specific tracker and filter combinations based on the current modulation bandwidth and operational mode. When operating at higher bandwidths, the system engages the appropriate notch filters to attenuate the increased harmonic content. When operating at lower bandwidths, the system decouples unnecessary filters to reduce complexity, thus resolving the contradiction between productivity and harmful factors
Data Source
AI summary
An envelope tracking system is disclosed having an envelope tracking integrated circuit (ETIC) with a first tracker having a first supply output and a second tracker having a second supply output, wherein the ETIC has a first mode in which only one of the first and second trackers supplies voltage and a second mode in which the first and second trackers both supply voltage. A first notch filter is coupled to the first supply output and a second notch filter is coupled to the second supply output. A mode switch coupled between the first supply output and the second supply output is configured to couple the first notch filter and the second notch filter in parallel in the first mode and open the mode switch to decouple the first notch filter from the second notch filter in the second mode in response to first and second switch control signals, respectively.