ET Modulator Load Current Sensing Without Feedback Loops
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Solution Overview
Problem
Existing wireless transmitter systems using envelope tracking (ET) modulators face challenges in maintaining efficiency and signal quality due to variations in load impedance, which require complex feedback loops and error amplifiers, leading to reduced efficiency and increased power consumption.
Innovation Solution
The system reconfigures the switching regulator in the ET modulator to operate as a linear regulator during calibration, allowing for direct measurement of load current and impedance, enabling predistortion to compensate for frequency response and non-linearity without the need for feedback loops or error amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback loops and error amplifiers are used to compensate for load impedance variations, then signal quality is maintained, but power consumption increases and efficiency decreases
Solution Approach 1:
The patent extracts and removes the feedback loop and error amplifier components from the ET modulator circuit. By eliminating these power-consuming components, the system achieves higher efficiency while maintaining signal quality through alternative means (precise impedance measurement and predistortion techniques)
Solution Approach 2:
The patent replaces the traditional feedback-based control mechanism with a measurement-and-predistortion approach. Instead of using continuous feedback loops, the system measures load impedance characteristics and applies predistortion to compensate for variations, thereby eliminating the need for power-consuming feedback circuitry
2Reliability
If feedback loops and error amplifiers are added to the circuit, then load impedance variations are compensated, but device complexity increases
Solution Approach 1:
The patent removes the complex feedback loop and error amplifier components from the circuit. By extracting these unnecessary elements, the design achieves load impedance compensation through a simpler measurement and predistortion approach, thereby reducing overall circuit complexity
3Loss of energy
If switching regulator is used in ET modulator, then efficiency is improved, but load current measurement becomes difficult
Solution Approach 1:
The patent implements a reconfigurable regulator that can dynamically switch between switching mode (for high efficiency) and linear mode (for accurate current measurement). This dynamic capability allows the system to optimize for efficiency during normal operation while enabling precise load current measurement when needed for impedance characterization
Data Source
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AI summary
An apparatus and method for sensing load current of an envelope tracking (ET) modulator enables load impedance of a power amplifier to be measured. Impairments associated with the load impedance characteristic can be suppressed by calibration and predistortion instead of by feedback (as done in the prior art). The ET modulator provides a switching regulator that can be reconfigured as a linear regulator for the purpose of sensing the load current. This allows the ET modulator to be operated open-loop, thereby eliminating the power consumption overhead resulting from utilization of a loop filter and error amplifier (used in the prior art) and achieving a higher overall efficiency.