Envelope Tracker PMIC State Mapping for Fast PA Mode Switching
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Solution Overview
Problem
Existing envelope tracking systems for power amplifiers in wireless communication systems face limitations in transitioning between operational modes quickly, particularly in applications like Wi-Fi, where rapid mode changes are necessary due to the constraints of typical 2-bit digital signals that can only signal 4 voltage levels, leading to slower transition times using MIPI RFFE writings.
Innovation Solution
Implementing a state machine circuit within the tracker circuit that utilizes a predefined mapping scheme to identify operational modes and voltage levels, allowing transitions between modes based on digital selection signals, including forbidden transitions, to facilitate faster and more efficient mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MIPI RFFE writings are used to control envelope tracking systems, then the system can operate with standard digital interfaces, but the transition time between operational modes becomes too slow for applications like Wi-Fi
Solution Approach 1:
The patent segments the voltage control into discrete levels (e.g., 4 voltage levels using 2-bit digital signals) and assigns specific operational modes to each level. This segmentation allows the system to jump between predefined voltage states rapidly without requiring gradual transitions, thereby achieving fast mode switching while maintaining compatibility with standard digital interfaces like MIPI RFFE.
Solution Approach 2:
The patent pre-defines mapping schemes that associate specific digital signal values with operational modes and voltage levels. By preparing these mappings in advance, the system can immediately transition to the required mode when a digital signal is received, eliminating the need for complex real-time calculations and achieving rapid transitions.
2Device complexity
If a 2-bit digital interface is used to control voltage levels, then the system maintains simplicity and compatibility, but only 4 voltage levels can be signaled which is insufficient for rapid mode changes
Solution Approach 1:
The patent introduces an additional dimension by implementing a state machine circuit that tracks the current operational mode and combines it with the 2-bit digital signal. This creates a multi-dimensional control space where the same 2-bit signal can transition to different voltage levels depending on the current state, effectively expanding the number of identifiable voltage levels and operational modes beyond the limited 4 levels of a simple 2-bit interface.
Solution Approach 2:
The state machine circuit acts as an intermediary between the simple 2-bit digital interface and the envelope tracking system. It interprets the limited 2-bit signals in the context of the current state, enabling the system to access a larger set of operational modes and voltage levels than the interface would suggest, thereby bridging the gap between interface simplicity and system versatility.
Data Source
AI summary
A tracker circuit configured to provide a variable supply voltage to a power amplifier (PA) circuit is disclosed. The tracker circuit includes a state machine circuit comprising a plurality of states mapped in accordance with transitions associated with a mapping scheme. In some embodiments, the plurality of states of the state machine circuit identify one or more operational modes associated with the tracker circuit, wherein at least one operational mode comprises one or more voltage levels respectively associated therewith. In some embodiments, the one or more operational modes includes at least two active operational modes. In some embodiments, a transition between the one or more operational modes of the tracker circuit is controlled by a digital selection signal received from a digital communication interface associated therewith.