Envelope Tracking Linear Amplifier With Switchable Gain-Bandwidth Modes
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Solution Overview
Problem
Power amplifiers in portable electronic devices face efficiency degradation due to high peak-to-average power ratio in LTE-A services and the need to cover wide frequency ranges, especially in LTE-A systems with contiguous carrier aggregation, which complicates envelope tracking modulation and reduces amplifier efficiency.
Innovation Solution
A linear amplifier design featuring a first stage amplifier circuit with switchable impedance configurations and a cascode output stage, allowing operation in high bandwidth or high gain modes, and dynamically adjusting the supply voltage to optimize efficiency across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power amplifier is configured to cover a wide frequency range, then the frequency coverage is improved, but the efficiency of the power amplifier deteriorates
Solution Approach 1:
The patent implements dynamic switching between different amplifier circuits based on operating conditions. The system selectively activates specific amplifier circuits depending on the required bandwidth and frequency range, allowing the power amplifier to adapt its configuration in real-time. This dynamic reconfiguration enables the system to maintain high efficiency by activating only the necessary amplifier circuits for the current operating mode, rather than continuously operating all circuits across the entire frequency range.
2Use of energy by stationary object
If envelope tracking modulation is used to lower power consumption, then power consumption is reduced, but efficiency is degraded due to high PAPR in LTE-A services
Solution Approach 1:
The patent divides the power amplifier into multiple independent amplifier circuits, each optimized for specific operating conditions. Instead of using a single amplifier circuit that must handle all scenarios, the system segments the amplification function across multiple specialized circuits. This segmentation allows each circuit to be optimized for particular bandwidth and efficiency requirements, reducing overall power consumption while maintaining high efficiency in each operating mode through selective activation.
3Speed
If a contiguous carrier aggregation is implemented to increase bandwidth, then the data rate is improved, but the complexity of envelope tracking modulation increases and efficiency is reduced
Solution Approach 1:
The system dynamically selects and switches between different amplifier circuits based on the required carrier aggregation configuration. When contiguous carrier aggregation is activated for high data rate requirements, the system selectively engages specific amplifier circuits designed for wideband operation. This dynamic adaptation reduces the complexity of envelope tracking modulation by activating only the necessary circuits for the current aggregation mode, rather than requiring all circuits to simultaneously handle the full complexity of tracking across all frequency bands.
Data Source
AI summary
A linear amplifier is provided to have higher efficiency for an envelope tracking modulator. In one embodiment, a first stage amplifier circuit can be simply operated in a high gain mode or a high bandwidth mode for different applications, without using large chip area. In another embodiment, an output stage has a cascode structure whose dynamic range is controlled according to a voltage level of a supply voltage, to make a core device within the output stage have better protection and suitable dynamic range.