Outphasing Power Amplifier Switching Pulses for Wider RF Range
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Solution Overview
Problem
Conventional outphasing power amplification using class-D power amplifiers is limited by the accuracy of switching signal timing, which results in noise and degraded characteristics such as spurious emissions and Error Vector Magnitude (EVM), due to constraints on the operating clock of digital circuits, making it difficult to increase the radio frequency range effectively.
Innovation Solution
The implementation of a switching signal generating circuit that includes sin and cos calculation units for quadrature format conversion, a DA converter, filters to remove aliasing, an analogue quadrature modulator, and a comparator to generate switching pulse signals, allowing for updated phase information and increased radio frequency range without constraints on the operating clock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional digital circuit switching signal generation is used, then the circuit structure is simple, but the operating clock is constrained which limits radio frequency range and reduces switching signal accuracy
Solution Approach 1:
The patent replaces the conventional digital circuit switching signal generation with an analog signal generation approach using sinusoidal wave generation, quadrature format conversion, and analog quadrature modulation. This substitution eliminates the operating clock constraints of digital circuits while maintaining signal generation functionality, thereby expanding the applicable radio frequency range without being limited by digital circuit speed.
Solution Approach 2:
The patent changes the fundamental parameters of signal generation from digital domain (discrete, clock-synchronized) to analog domain (continuous, frequency-agile). By using analog sinusoidal waves and quadrature modulation, the system achieves frequency independence from fixed clock rates, enabling operation across a broader radio frequency spectrum.
2Measurement precision
If digital circuit operating clock is constrained, then the circuit structure remains simple, but switching signal timing accuracy deteriorates causing noise and degraded EVM characteristics
Solution Approach 1:
The patent substitutes digital pulse generation with analog sinusoidal wave generation followed by quadrature modulation and comparison. This analog approach provides continuous timing control without quantization errors inherent in digital systems, achieving superior switching signal timing accuracy and eliminating noise and spurious emissions caused by digital clock constraints.
3Adaptability or versatility
If conventional switching signal generation is used, then the device complexity is low, but the radio frequency range application is limited
Solution Approach 1:
The patent replaces the conventional digital switching signal generation system with an analog signal generation system based on sinusoidal waves and quadrature modulation. This substitution enables the system to operate across a broader radio frequency range while maintaining reliable performance characteristics, as the analog approach is not constrained by digital circuit operating frequencies.
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
This solution eliminates constraints on the operating clock of digital circuits, enabling the application of outphasing power amplification to a broader radio frequency range and improving the accuracy of switching signals, thereby reducing noise and enhancing performance metrics like EVM and spurious characteristics.
Implementation Method 1
a DA converter configured to convert the quadrature-format phase information from each of the sin calculation unit and the cos calculation unit into an analogue signal
Implementation Method 2
a first filter configured to remove an aliasing component from the analogue signal inputted from the DA converter
Implementation Method 3
an analogue quadrature modulator configured to generate a sinusoidal wave from the analogue signals inputted from the first filter by using a local signal
Implementation Method 4
a second filter configured to allow a predetermined radio frequency and a component in the vicinity thereof in the sinusoidal wave inputted from the analogue quadrature modulator to pass therethrough
Implementation Method 5
a comparator configured to convert the sinusoidal wave inputted from the second filter into a switching pulse signal by comparison with a reference voltage
Data Source
AI summary
An outphasing power amplifying device includes a switching signal generating circuit configured to generate a switching pulse signal for switching a class-D power amplifier from two types of sinusoidal wave generated based on amplitude and phase of a modulated wave to be transmitted. The switching signal generating circuit includes: a sin calculation unit and a cos calculation unit for converting phase information of the two types of sinusoidal wave into a quadrature format; a DA converter for converting the quadrature-format phase information; a first filter for removing an aliasing component from the analogue signal; an analogue quadrature modulator for generating a sinusoidal wave from the analogue signals by using a local signal; a second filter for allowing a radio frequency and a component in the vicinity thereof to pass therethrough; and a comparator for converting the sinusoidal wave into a switching pulse signal by comparison with a reference voltage.