Envelope Tracking Power Supply Using Split AC/DC Modulation
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Solution Overview
Problem
The fixed drain bias approach in power amplifiers results in significant power loss and thermal issues due to constant supply voltage, leading to reduced battery lifetime, especially in wide frequency-range applications where tracking the instantaneous signal envelope is challenging.
Innovation Solution
A power supply with an AC and DC component generator, along with a transition accelerator, dynamically adjusts the voltage to match the power amplifier's operational needs, using a modulated voltage that includes a DC and AC component, and includes pull-up and pull-down circuits to accelerate voltage transitions, ensuring efficient power utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed supply voltage is provided to the power amplifier, then the circuit design is simple, but significant power loss and thermal issues occur
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed supply voltage to a dynamically modulated supply voltage that tracks the instantaneous envelope of the power amplifier's output signal. The envelope tracking power supply continuously adjusts the DC component voltage based on the detected signal envelope, ensuring the power amplifier receives exactly the power it needs at any given moment, thereby eliminating unnecessary power dissipation while maintaining circuit functionality
Solution Approach 2:
The patent changes the voltage parameter from a constant fixed value to a time-varying modulated value. The DC component generator produces a variable DC voltage that dynamically changes according to the signal envelope detection, allowing the supply voltage to match the instantaneous power requirements of the power amplifier across different operating conditions and frequency ranges
2Loss of energy
If a modulated voltage is supplied to reduce power loss, then power efficiency improves, but tracking the instantaneous signal envelope becomes difficult in high frequency bands
Solution Approach 1:
The patent segments the modulated voltage into two distinct components: a DC component and an AC component. The DC component generator handles the bulk power delivery with voltage levels corresponding to different power amplifier operating ranges, while the AC component generator provides fine-grained envelope tracking adjustments. This segmentation allows each component to be optimized independently for its specific function, making high-frequency envelope tracking feasible
Solution Approach 2:
The patent introduces an intermediary envelope detection and control mechanism that bridges the power supply and power amplifier. The envelope detector extracts the instantaneous signal envelope from the high-frequency RF signal, and the control circuit processes this information to generate appropriate control signals for both DC and AC component generators, enabling accurate power delivery tracking even at high frequencies
3Stability of the object's composition
If the DC component transitions slowly, then the circuit is stable, but the power supply cannot respond to rapid changes in the signal envelope
Solution Approach 1:
The patent applies dynamics by implementing pull-up and pull-down circuits that actively accelerate the transition of the DC component voltage. These circuits provide additional current paths during voltage transitions, enabling the DC component to rapidly follow the AC component's envelope variations without compromising the overall circuit stability, thus achieving both speed and stability
Data Source
AI summary
A power supply configured to supply a modulated voltage to a power amplifier is shown. The power supply has an alternating current (AC) component generator, a direct current (DC) component generator, and a transition accelerator. The AC component generator generates an AC component of the modulated voltage according to an envelope tracking signal. The DC component generator generates a DC component of the modulated voltage according to the operational voltage range of the power amplifier. The transition accelerator is coupled to an output terminal of the DC component generator to speed up the transition of the modulated voltage.