Bidirectional Converter Power Supply for RF Envelope Tracking
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Solution Overview
Problem
Existing high frequency power amplification circuits face challenges in efficiently following the envelope of high frequency signals due to complex circuit configurations and voltage switching, leading to waveform distortion and increased adjacent channel leakage power ratio, which limits their application in products with strict frequency band allocation.
Innovation Solution
A power supply device with bidirectional converters and an amplitude change monitor circuit that varies the power supply voltage in accordance with the amplitude change of the high frequency signal, enabling precise adjustment of the output voltage's amplitude and phase to follow the input signal, thereby simplifying the configuration and improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple voltage sources are prepared and voltage source selection is used to follow the envelope of the high frequency signal, then the power efficiency of the high frequency amplification circuit is improved, but the circuit configuration becomes complex and waveform distortion increases
Solution Approach 1:
The patent merges multiple voltage source functions into a single voltage source by adding a capacitor parallel to the load. This capacitor stores energy and enables the single voltage source to provide variable voltage output by combining its output with the stored energy, thereby simplifying the circuit while maintaining the ability to follow the signal envelope and improve power efficiency.
Solution Approach 2:
The patent changes the operational parameters of a single voltage source by controlling it to operate in different modes (constant voltage mode and variable voltage mode) based on the signal envelope. This allows the single voltage source to dynamically adjust its output characteristics, replacing the need for multiple fixed voltage sources and reducing circuit complexity.
2Use of energy by moving object
If voltage source selection is used to follow the envelope of the high frequency signal, then power efficiency is improved, but waveform distortion increases and adjacent channel leakage power ratio worsens
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during constant voltage periods before the variable voltage period begins. This ensures that when the variable voltage mode starts, the capacitor is already charged and ready to immediately combine its energy with the voltage source output, enabling smooth and accurate waveform transition without distortion or delays that would affect adjacent channel leakage.
Solution Approach 2:
The patent ensures continuity of useful action by designing the circuit to maintain continuous energy supply to the load. The capacitor continuously stores energy during constant voltage periods and continuously releases it during variable voltage periods, creating a seamless energy delivery process that maintains waveform accuracy and prevents gaps or distortions in the power supply to the amplification circuit.
3Use of energy by moving object
If multiple voltage sources and switching control are used, then power efficiency is improved, but the control system becomes extremely complex
Solution Approach 1:
The patent extracts the energy storage function from the voltage source selection system and places it in a dedicated capacitor. This separation allows the voltage source to be controlled independently based on the signal envelope, while the capacitor automatically provides the necessary energy supplementation. The control system only needs to manage a single voltage source and a simple switch, dramatically reducing control complexity compared to managing multiple voltage sources.
4Use of energy by moving object
If voltage source switching is used to follow the envelope, then power efficiency is improved, but adjacent channel leakage power ratio increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor before the variable voltage period. This advance preparation ensures that when the voltage source transitions to variable output, the capacitor is ready to immediately supplement the energy, creating a smooth and accurate voltage waveform that precisely follows the signal envelope. This eliminates waveform inaccuracies that would cause spectral regrowth and increase adjacent channel leakage power ratio.
Data Source
AI summary
In a power supply device, bidirectional converters that are each capable of supplying or regenerating an electric charge are provided between an input section for an input voltage and an output section for an output voltage. An amplitude change monitor circuit detects an envelope of an RF input signal. A converter switching circuit controls supply and regeneration of electric charges by the bidirectional converters so that the output voltage follows an amplitude change of the input signal. An output capacitor capacitance estimation unit estimates the capacitance of an output capacitor from its voltage and current. A delay time detection circuit grasps a delay time of a power supply device for a high frequency power amplification circuit and makes an adjustment through a delay adjustment circuit.