Switched Mode Power Amplifier Baseband Modulation
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Solution Overview
Problem
Current RF power amplifier and modulation systems in base stations have low efficiency, typically around 30%, due to the need for 'quasi-linear' high-frequency power amplifiers to meet linearity requirements, leading to high production and operation costs.
Innovation Solution
The implementation of a power amplifier system using switched mode amplifiers, baseband modulation, complex up-conversion, and filtering to efficiently amplify and modulate complex carrier signals, suppressing image components and achieving higher efficiency by coding time-dependent phase and amplitude in the baseband domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If quasi-linear high-frequency power amplifiers are used to meet linearity requirements, then linearity is improved, but efficiency deteriorates
Solution Approach 1:
The patent segments the amplification process into multiple parallel switched-mode power amplifiers, each handling a portion of the signal spectrum. This allows each amplifier to operate efficiently in switched mode while collectively meeting linearity requirements through the combination of multiple channels.
Solution Approach 2:
The patent transforms the signal from time-domain baseband modulation to frequency-domain representation through FFT processing. This dimensional transformation enables parallel processing of different frequency components, allowing switched-mode amplification to achieve both efficiency and linearity by operating on spectral components rather than time-domain waveforms.
2Loss of energy
If switched mode amplifiers are used to improve efficiency, then efficiency is improved, but linearity deteriorates
Solution Approach 1:
The signal spectrum is segmented into multiple frequency bins through FFT processing, with each bin assigned to a separate switched-mode power amplifier. This segmentation allows each amplifier to operate in efficient switched mode while the collective output, after inverse FFT processing, maintains linearity by preserving the phase and amplitude relationships of all spectral components.
Solution Approach 2:
The patent replaces traditional time-domain linearization circuits with frequency-domain processing using FFT and IFFT transforms. This substitution enables switched-mode amplifiers to achieve linearity through digital signal processing in the frequency domain rather than through analog linearization circuits, thereby maintaining both efficiency and linearity.
3Loss of energy
If baseband modulation with switched amplifiers is implemented, then efficiency is improved to 60%, but device complexity increases
Solution Approach 1:
The patent implements a universal processing architecture where a single set of FFT-based frequency domain processing circuits handles multiple signal channels and modulation schemes. The same switched-mode power amplifier blocks process different frequency components across multiple carriers, reducing overall system complexity compared to implementing separate processing chains for each function.
Data Source
AI summary
A power amplifier includes a baseband modulator configured to receive a baseband amplitude component and generate a baseband modulated pulse string, an oscillator configured to receive a baseband phase component and generate phase modulated complex carrier signals, a complex up-converter configured to receive and mix the baseband modulated pulse string with the phase modulated complex carrier signals into mixed product signals, and two or more switched mode power amplifiers coupled to the complex up-converter, configured to amplify and switch the mixed product signals at the carrier frequency. The power amplifier further comprises complex filters individually coupled to one of the switch mode power amplifiers, configured to suppress image components in the amplified and switched mixed product signals, and a power combiner coupled to the two or more complex filters, configured to combine the real component of the complex filtered and amplified mixed product signals to generate an RF transmission signal.