RF Power Amplifier Envelope Tracking for Low-Power Efficiency
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Solution Overview
Problem
Current wireless communication apparatuses, such as mobile phones, face challenges in reducing power consumption, especially at low power levels, as existing techniques like envelope tracking mode are not effective at these levels, leading to inefficiencies in high-frequency power amplifiers.
Innovation Solution
A wireless communication apparatus with a power amplifying circuit, a source voltage generating circuit, and a bias control circuit that switches between envelope tracking mode and variable control mode based on output power levels, adjusting source voltage and bias to optimize power consumption, particularly at low power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking mode is used to improve power added efficiency at low power levels, then power consumption is reduced, but the complexity of the high-frequency signal processing apparatus increases due to additional circuits
Solution Approach 1:
The patent combines the envelope tracking function with the existing high-frequency power amplifier by integrating an envelope detecting circuit and DC-DC converter directly into the amplifier structure. This merging approach enables power consumption reduction through envelope tracking while avoiding the need for separate, additional complex circuits, thus resolving the contradiction between energy efficiency and device complexity.
Solution Approach 2:
The high-frequency power amplifier is designed to perform multiple functions: it operates as a conventional linear amplifier at high power levels and automatically switches to envelope tracking mode at low power levels. This multi-functionality allows the same apparatus to achieve both low power consumption at low output levels and high output power capability, resolving the contradiction without requiring separate dedicated circuits for each mode.
2Device complexity
If a fixed source voltage is applied to the power amplifying circuit, then the circuit structure is simple, but power consumption increases at low power levels due to unnecessary voltage overhead
Solution Approach 1:
The patent implements dynamic source voltage control by introducing a DC-DC converter that adjusts the source voltage supplied to the power amplifying circuit based on the detected envelope of the input signal. This dynamic adjustment enables the voltage to track the signal amplitude, reducing voltage overhead at low power levels while maintaining sufficient voltage for linear operation at high power levels, thus resolving the contradiction between structural simplicity and energy efficiency.
Solution Approach 2:
The source voltage parameter is changed from a fixed value to a variable value that dynamically tracks the signal envelope. By changing this critical parameter from static to dynamic, the system achieves reduced power consumption at low output levels while maintaining the simplicity of the overall circuit structure through automated voltage adjustment based on signal conditions.
3Use of energy by moving object
If the source voltage is reduced to decrease power consumption, then energy efficiency improves, but linear amplification operation cannot be maintained at low voltage levels
Solution Approach 1:
The patent employs feedback by using an envelope detecting circuit to monitor the input signal amplitude and using this detection to control the DC-DC converter's output voltage. This feedback mechanism ensures that the source voltage is reduced only when the signal envelope indicates low power levels, and maintained at sufficient levels for linear operation when needed, thus resolving the contradiction between energy efficiency and operational reliability.
Solution Approach 2:
The envelope of the input signal is detected in advance before amplification, and this preliminary detection is used to pre-adjust the source voltage via the DC-DC converter. By performing this voltage adjustment beforehand based on the detected envelope, the system ensures that the power amplifying circuit always receives the appropriate voltage level needed for linear operation at each instant, preventing distortion while minimizing power consumption.
Data Source
AI summary
A high-frequency signal processing apparatus and a wireless communication apparatus can achieve a decrease in power consumption. For example, when an indicated power level to a high-frequency power amplifier is equal to or greater than a second reference value, envelope tracking is performed by causing a source voltage control circuit to control a high-speed DCDC converter using a detection result of an envelope detecting circuit and causing a bias control circuit to indicate a fixed bias value. The source voltage control circuit and the bias control circuit indicate a source voltage and a bias value decreasing in proportion to a decrease in the indicated power level when the indicated power level is in a range of the second reference value to the first reference value, and indicate a fixed source voltage and a fixed bias value when the indicated power level is less than the first reference value.