Switch-Mode Amplifier Shaping Distortion Above the Signal Band
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Solution Overview
Problem
Current amplifiers for bandpass-signals in wireless communication suffer from low power efficiency and non-linearity, especially when dealing with signals having high peak-to-average power ratios, leading to unwanted distortions and emissions. Existing solutions, such as adaptive digital predistortion and switch-mode techniques, increase hardware complexity and instability at high frequencies.
Innovation Solution
A switch-mode amplifier system that generates a binary input-signal by combining a binary continuous-time signal with a rectangular wave signal, ensuring distortions occur at frequencies higher than the desired bandpass frequency, allowing for high power-efficiency amplification and low-pass filtering to maintain signal linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switch-mode amplifier is used to amplify bandpass-signals, then power efficiency is improved, but linearity deteriorates due to strong nonlinearity and amplitude information loss
Solution Approach 1:
The amplification process is segmented into two independent stages: first, a switch-mode amplifier processes only the phase information of the signal (which is linear), and second, an envelope amplifier processes the amplitude information separately. This segmentation allows each stage to operate in its optimal mode without the trade-off between efficiency and linearity that plagues conventional single-stage amplifiers.
Solution Approach 2:
The signal representation is transformed from the conventional amplitude-phase domain to a phase-envelope domain. By separating the signal into a phase component (processed by the switch-mode amplifier for high efficiency) and an envelope component (processed by the envelope amplifier for linearity), the invention operates in a different dimensional space that resolves the efficiency-linearity contradiction.
2Manufacturing precision
If adaptive digital predistortion is applied to improve linearity, then signal linearity is improved, but device complexity increases
Solution Approach 1:
The invention replaces complex digital signal processing systems (adaptive predistortion algorithms, feedback loops, and control electronics) with a simpler analog signal decomposition and parallel amplification architecture. The linearity improvement is achieved through the fundamental signal separation approach rather than through complex digital correction mechanisms.
3Productivity
If the input signal amplitude is increased to improve productivity, then amplification output is improved, but nonlinearity increases causing distortions
Solution Approach 1:
By segmenting the signal into phase and envelope components, the system can process the phase component through the switch-mode amplifier at high power levels without distortion (since phase information is preserved in the switching operation), while the envelope component is processed separately to maintain amplitude linearity. This allows high productivity without the strong nonlinearity that would normally cause distortions.
Data Source
AI summary
Embodiments of the present invention provide an apparatus for amplifying an input-signal. The apparatus includes a switch-mode amplifier for amplifying a digital input-signal. The apparatus is characterized by a generator for generating the digital input-signal based on the input-signal, wherein the generator is configured to generate the digital input-signal such that the digital input-signal is located at a predefined frequency band and such that distortions are located at a frequency higher than the predefined frequency band.