Envelope Tracking Modulator Resonance Suppression
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Solution Overview
Problem
Prior art envelope tracking modulated power supplies for RF power amplifiers face efficiency and tracking accuracy issues due to resonance in the output of switched mode amplifiers and combiners at certain frequencies.
Innovation Solution
The implementation of sensing circuitry to detect resonance in the power supply paths, using difference amplifiers and feedback loops to adjust control signals and combine resonance signals with control signals, thereby reducing resonance and improving tracking accuracy by varying the pulse width modulator and feedback loops to manage voltage and current feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a frequency selective combiner is used to combine LF and HF path signals, then the envelope tracking power supply can generate modulated supply voltage, but resonance occurs in the output of switched mode amplifier and/or combiner at certain frequencies reducing efficiency and tracking accuracy
Solution Approach 1:
The patent introduces feedback loops that sense the output signals from both the LF and HF paths and feed them back to adjust the control signals. This feedback mechanism enables the system to detect and compensate for resonance conditions by dynamically adjusting the control signals to counteract resonant effects, thereby maintaining efficiency and tracking accuracy across different operating frequencies
Solution Approach 2:
The patent employs variable control signals whose parameters (amplitude, phase, frequency) are dynamically adjusted based on the operating frequency and detected resonance conditions. By changing these parameters in real-time, the system can optimize performance and minimize resonance effects at different frequency points
2Measurement precision
If feedback path is added to subtract signal from combiner output to improve tracking accuracy, then tracking accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the feedback mechanism into separate feedback paths for the LF and HF signals, allowing independent optimization and control of each path. This segmentation simplifies the overall feedback control by breaking down the complex single feedback loop into manageable independent segments that can be tuned separately
Solution Approach 2:
The patent introduces intermediate control signals and buffer stages between the feedback path and the main signal paths. These intermediaries help to isolate and decouple the feedback mechanism from the main signal flow, reducing the impact of feedback on signal integrity while maintaining tracking accuracy
Data Source
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Figure 3
Figure 4(a)~4(b)
AI summary
An envelope tracking power supply arranged to generate a modulated supply voltage in dependence on a reference signal, comprising a first path for tracking low frequency variations in the reference signal and a second path for tracking high frequency variations in the reference signal, and further comprising a combiner having a low frequency combining element for the first path and a high frequency combining element for the second path, and for generating the modulated supply voltage, wherein there is further provided sensing circuitry for sensing a resonance signal in the low or high frequency combining element, and adjusting circuitry for adjusting a signal in the first path in dependence on the sensed resonance signal.