RF Power Amplifier Control for Low-Power Envelope Tracking
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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 a DC-DC converter directly into the amplifier structure. This merging approach enables power consumption reduction through envelope tracking while avoiding the need for completely separate control circuits, thus reducing overall system 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 circuit to achieve power savings across different operating conditions without requiring separate dedicated circuits for each mode.
2Device complexity
If a fixed source voltage is applied to the high-frequency power amplifier, then the circuit is simple, but power added efficiency deteriorates at low power levels due to unnecessary DC power loss
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 amplifier based on the instantaneous power level. At low power levels, the source voltage is reduced to match the signal amplitude, eliminating the DC power loss that occurs with fixed voltage operation. This dynamic adjustment maintains circuit simplicity while dramatically improving power added efficiency at low power levels.
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.