Switched-Capacitor Power Amplifier Half-Amplitude Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched-capacitor power amplifiers experience efficiency degradation at lower output amplitudes due to disabled cells that attenuate the output signal and consume power, particularly for signals with a large peak-to-average power ratio, and existing solutions either have limited amplitude range, increased overhead, or require complex circuitry.
Innovation Solution
A switching scheme for switched-capacitor power amplifiers that includes a 'half amplitude' mode in addition to 'full amplitude' and 'off' modes, using a single power supply voltage, allowing for efficient operation at reduced output amplitudes without losing peak output power, by switching differential capacitors between supply voltage and ground, and utilizing additional switches to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If disabled cells are used to attenuate the output signal for amplitude modulation, then the output amplitude can be reduced, but the efficiency degrades substantially at lower output amplitudes due to power consumption in disabled cells
Solution Approach 1:
The patent introduces dynamic supply voltage modulation to the enabled cells based on the desired output amplitude. When back-off is required, the supply voltage to enabled cells is reduced proportionally, allowing them to operate at lower power levels with high efficiency rather than having disabled cells consume power while attenuating the signal
Solution Approach 2:
The patent changes the supply voltage parameter dynamically applied to enabled cells based on the output amplitude requirement. By modulating the supply voltage to enabled cells rather than disabling cells, the system achieves amplitude control without the efficiency penalty of disabled cells consuming power
2Loss of energy
If supply voltage is used to modulate the switched-capacitor power amplifier output amplitude, then the efficiency can be improved at back-off, but the resulting amplitude range is limited and the transfer is very non-linear
Solution Approach 1:
The patent segments the power amplifier into multiple independent cells that can be individually enabled or disabled. Combined with supply voltage modulation on enabled cells, this segmentation allows for finer amplitude control steps and extends the usable amplitude range while maintaining efficiency, overcoming the limited range of simple supply voltage modulation
Solution Approach 2:
The patent dynamically adjusts both the supply voltage to enabled cells and the number of enabled cells based on the desired output amplitude. This dynamic combination of voltage modulation and cell selection provides a more linear and extended amplitude range compared to static supply voltage modulation alone
3Loss of energy
If two power supplies are used to improve efficiency at back-off, then the efficiency can be enhanced, but the overhead due to the provision of the second power supply and its associated connections increases
Solution Approach 1:
The patent makes the single power supply multi-functional by dynamically modulating its voltage level to serve different output power levels. This eliminates the need for a second power supply while achieving the same efficiency benefit at back-off, as the single supply adapts its voltage to match the required output amplitude
4Loss of energy
If Doherty amplifier configuration is used to improve efficiency at back-off, then the efficiency is improved, but the amplifier works only with small frequency ranges and requires significant design effort
Solution Approach 1:
The patent employs a self-service approach where the enabled cells automatically operate at high efficiency by receiving modulated supply voltages matched to their output contribution. This eliminates the need for complex Doherty matching networks and carrier amplifier designs, achieving back-off efficiency improvement with minimal additional design effort
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution maintains efficiency at back-off levels equivalent to peak output amplitude, enhancing power amplifier efficiency across all output-power back-off values without the need for additional power supplies or complex circuitry.
Implementation Method 1
first and second differential capacitors configured for providing a differential full amplitude output signal therefrom
Implementation Method 2
the switched signal line including a further switch... the switched signal line providing a differential half amplitude output signal
Data Source
AI summary
A switched-capacitor power amplifier comprising a plurality of cells and methods for its operation are described. Switched signal lines switch supply to respective capacitors. Switches connect respective signal lines to a first supply and switches connect respective signal lines to a second supply. Pairs of switches on each signal line are switched so that one is switched off whilst the other is switched on. In a “full amplitude” mode, operation of the switches provides an output having a peak determined by the first supply. A switch signal line is provided between nodes in respective signal lines, a switch being provided in the switch signal line. In a “half amplitude” mode, switch is switched at the radio frequency in the other direction to that of switches connecting the signal lines to respective ones of the first and second supplies with the other switches being kept open.