Envelope Tracking Modulator With Accelerated Voltage Transitions
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Solution Overview
Problem
In wide frequency-range applications, such as 5G, the fixed drain bias approach to power amplifiers results in significant power loss and thermal issues due to constant supply voltage, leading to reduced battery lifetime and inefficient power utilization.
Innovation Solution
A power supply with a modulated voltage system that includes an AC component generator, a DC component generator, and a transition accelerator, which dynamically adjusts the voltage based on the instantaneous signal envelope of the power amplifier, using step-up and step-down converters and pull-up/pull-down circuits to enhance transition speed and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed supply voltage is provided to the power amplifier, then the power amplifier can operate with simple power supply circuitry, but significant power loss and thermal issues occur due to constant voltage supply
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 tracker circuit continuously adjusts the supply voltage level according to the signal envelope, enabling the power amplifier to operate efficiently across varying power levels while minimizing power loss and thermal issues.
2Loss of energy
If envelope tracking is implemented to reduce power loss, then power utilization efficiency improves, but the system complexity increases due to additional modulated voltage generation circuits
Solution Approach 1:
The patent applies segmentation by dividing the modulated voltage generation into distinct functional modules: an envelope detector that extracts the signal envelope, a modulator that generates the modulated supply voltage, and an envelope tracker that dynamically adjusts the voltage level. This modular segmentation allows each component to be optimized independently while working together to achieve efficient power delivery with reduced overall system complexity.
3Loss of energy
If the supply voltage is dynamically adjusted to track the instantaneous signal envelope, then power loss is reduced, but tracking difficulty increases in high frequency bands
Solution Approach 1:
The patent introduces an intermediary envelope tracker circuit that acts as a mediator between the high-frequency power amplifier output and the lower-frequency power supply control. This envelope tracker converts the high-frequency signal variations into a lower-frequency envelope signal that is easier to process and track, effectively bridging the frequency gap and enabling accurate power supply modulation without direct high-frequency tracking complexity.
4Measurement precision
If fast transition of modulated voltage is achieved to track short cyclic prefixes in 5G, then envelope tracking accuracy improves, but the circuit response time requirements become more stringent
Solution Approach 1:
The patent applies preliminary action by pre-charging and pre-discharging capacitive elements in the envelope tracker and modulator circuits during idle or low-activity periods. This preliminary preparation ensures that when rapid voltage transitions are required to track short 5G cyclic prefixes, the circuits are already in an optimal state to respond quickly, thereby achieving both high tracking accuracy and fast response times without requiring continuously high-speed circuit operation.
Data Source
Figure 1A~1B
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Figure 3
AI summary
A power supply (300) configured to supply a modulated voltage to a power amplifier (302) is shown. The power supply (300) has an alternating current (AC) component generator, a direct current (DC) component generator, and a transition accelerator (316). The AC component generator generates an AC component of the modulated voltage according to an envelope tracking signal (Venv). The DC component generator generates a DC component of the modulated voltage according to the operational voltage range of the power amplifier (302). The transition accelerator (316) is coupled to an output terminal of the DC component generator to speed up the transition of the modulated voltage.