Multimode Envelope Tracking Circuit for Wide-Bandwidth RF Amplifiers
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Solution Overview
Problem
Mobile communication devices face challenges in efficiently managing power amplifiers across a wide range of modulation bandwidths, as existing envelope tracking systems struggle to maintain efficiency and performance when switching between different communication technologies like LTE/5G-NR and legacy networks.
Innovation Solution
A multimode envelope tracking (ET) circuit that dynamically and opportunistically switches between high-, mid-, and low-modulation-bandwidth modes by utilizing multiple amplifier circuits and tracker circuits, with a control circuit to manage the switching and prevent series resonance, thereby improving efficiency and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single envelope tracking system is used for both LTE/5G-NR and legacy networks, then device complexity is reduced, but performance and efficiency deteriorate due to series resonance distortion across different modulation bandwidths
Solution Approach 1:
The envelope tracking system is segmented into multiple independent tracker circuits (first tracker circuit for LTE/5G-NR high bandwidth mode, second tracker circuit for legacy network low bandwidth mode), each optimized for specific bandwidth ranges. The system divides the operating conditions and assigns dedicated tracker circuits to different modes, preventing series resonance distortion in each mode while maintaining overall system manageability.
Solution Approach 2:
The system dynamically switches between different tracker circuits based on the detected modulation bandwidth of the RF signal. The control circuit monitors the operating mode and opportunistically selects the appropriate tracker circuit configuration, enabling the system to adapt its structure to match the current communication standard being used.
2Adaptability or versatility
If the envelope tracking system operates across a wide range of modulation bandwidths, then versatility is improved, but series resonance distortion increases causing performance degradation
Solution Approach 1:
Each tracker circuit is designed with specific local quality characteristics optimized for its target bandwidth range. The first tracker circuit has components tuned for high-bandwidth LTE/5G-NR operation, while the second tracker circuit has components optimized for low-bandwidth legacy networks. This local optimization prevents series resonance distortion in each specific operating mode.
Solution Approach 2:
The control circuit acts as an intermediary that detects the modulation bandwidth and selectively activates the appropriate tracker circuit. This intermediary function prevents the harmful series resonance distortion by ensuring that only the tracker circuit matched to the current bandwidth regime is active, filtering out incompatible operating conditions.
3Reliability
If multiple tracker circuits are used for different bandwidth modes, then performance across modes is improved, but device complexity increases
Solution Approach 1:
The control circuit provides universal management functionality by detecting the operating mode and automatically selecting the appropriate tracker circuit configuration. This multi-functional control approach handles both high-bandwidth and low-bandwidth modes through a single intelligent switching mechanism, reducing the perceived complexity despite having multiple specialized tracker circuits.
Data Source
AI summary
A multimode envelope tracking (ET) circuit and related apparatus is provided. The multimode ET circuit is configured to provide an ET voltage(s) to an amplifier circuit(s) for amplifying a radio frequency (RF) signal(s) that may correspond to a wider range of modulation bandwidth. In this regard, the multimode ET circuit is configured to switch dynamically and opportunistically between different operation modes based on the modulation bandwidth of the RF signal(s). In examples discussed herein, the multimode ET circuit is configured to support a single amplifier circuit in a high-modulation-bandwidth mode and an additional amplifier circuit(s) in a mid-modulation-bandwidth mode and a low-modulation-bandwidth mode. By switching dynamically and opportunistically between different operation modes, it may be possible to reduce undesired series resonance that may cause distortion in the ET voltage(s), thus helping to improve efficiency and performance of the amplifier circuit(s) supported by the multimode ET circuit.