Differential Power Amplifier Gain Control for Waveform Symmetry
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Solution Overview
Problem
Existing power amplifier circuits fail to achieve appropriate gain dispersion with symmetry of waveforms for differential signals, particularly in the context of envelope tracking technology for fifth generation mobile communication systems.
Innovation Solution
A power amplifier circuit is designed with a differential amplifier circuit activated by a variable supply voltage, accompanied by a bias circuit and first and second dispersion circuits to control the gain dependence on supply voltage, ensuring symmetry in differential signal waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single dispersion circuit is used to control gain dependence on supply voltage, then power amplifier circuits can improve gain dispersion, but symmetry of differential signal waveforms deteriorates
Solution Approach 1:
The single dispersion circuit is divided into two separate dispersion circuits, each independently controlling one differential signal path. This segmentation allows each circuit to optimize gain dispersion for its respective path without disrupting the symmetry of the differential pair, as each side can be independently adjusted while maintaining overall balance.
Solution Approach 2:
Each dispersion circuit is tailored to its specific differential signal path with locally optimized components and configuration. The first dispersion circuit handles the first differential signal with specific gain characteristics, while the second dispersion circuit handles the second differential signal with matching characteristics, ensuring local optimization while maintaining global symmetry.
2Use of energy by moving object
If envelope tracking is used to control supply voltage according to signal amplitude, then power efficiency improves, but gain dispersion increases
Solution Approach 1:
The dispersion circuits provide feedback control by monitoring the supply voltage variations caused by envelope tracking and adjusting the gain of each differential path accordingly. This feedback mechanism compensates for the gain dispersion introduced by variable supply voltage, maintaining consistent gain performance across different power efficiency operating points.
Solution Approach 2:
The dispersion circuits dynamically adjust circuit parameters such as bias currents and transistor operating points in response to supply voltage changes from envelope tracking. By changing these parameters adaptively, the system maintains optimal gain characteristics while benefiting from the power efficiency improvements of envelope tracking.
Data Source
AI summary
A power amplifier circuit according to the present disclosure includes an amplifier circuit serving as a differential amplifier circuit configured to be activated by a supply voltage that is variable in accordance with amplitude of a signal, a bias circuit configured to output a bias to be supplied to the amplifier circuit, and first and second dispersion circuits respectively provided for a pair of differential signals outputted from the amplifier circuit and configured to control dependence of gain of the differential amplifier circuit on the supply voltage.