Parallel Delta-Sigma Modulator Architecture for Efficient RF Power Amplifiers
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Solution Overview
Problem
Current power amplifier architectures face challenges in achieving high power conversion efficiency, particularly for RF applications, due to limitations in switching speeds and noise shaping filter constraints, which hinder efficient operation at multi-GHz frequencies and result in significant heat dissipation and complexity.
Innovation Solution
The implementation of a parallel delta sigma modulator architecture that demultiplexes input signals into multiple streams, processes them using un-constrained delta sigma modulators, and multiplexes the outputs into a pulse train, allowing for higher oversampling ratios and un-constrained noise shaping filters, enabling efficient power conversion and reducing peak-to-average power ratio (PAPR) without degrading signal linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional single delta sigma modulator architecture is used, then circuit complexity is reduced, but power conversion efficiency deteriorates and operating frequency is limited to below 10 GHz
Solution Approach 1:
The patent divides the single modulator into multiple parallel delta sigma modulators, each operating at lower frequencies with relaxed bandwidth requirements. This segmentation allows each unit to achieve high efficiency while the combined system operates at multi-GHz frequencies, resolving the contradiction between circuit simplicity and power conversion efficiency.
Solution Approach 2:
The patent transitions from a single-modulator time-domain approach to a multi-modulator parallel architecture, adding spatial dimensionality to the system. This dimensional change enables frequency division where each modulator handles a portion of the spectrum, achieving both simplicity and high efficiency simultaneously.
2Loss of energy
If higher oversampling ratios are used to improve power conversion efficiency, then noise shaping filter bandwidth requirements increase, but this increases device complexity and limits operating frequency
Solution Approach 1:
The patent segments the high-bandwidth filter requirement into multiple lower-bandwidth filters operating in parallel. Each delta sigma modulator uses a filter with relaxed bandwidth constraints, eliminating the need for complex wideband filters while maintaining high oversampling ratios for improved power conversion efficiency.
Solution Approach 2:
Each parallel modulator operates with excessive oversampling relative to the final output rate, allowing individual filters to have narrow bandwidths. The combined output of multiple modulators achieves the required overall sampling rate, resolving the contradiction between efficiency and filter complexity.
3Loss of energy
If switch-mode power amplifiers operate at multi-GHz frequencies, then power conversion efficiency can be improved, but switching speed limitations and heat dissipation increase complexity
Solution Approach 1:
The patent segments the high-frequency switching task across multiple parallel modulators, each operating at lower frequencies with manageable switching speeds. This distribution reduces individual device stress and heat generation while maintaining overall multi-GHz operation, resolving the contradiction between efficiency and thermal management complexity.
Data Source
AI summary
A parallel delta sigma modulator architecture is disclosed. The parallel delta sigma modulator architecture includes a signal demultiplexer configured to receive an input signal and to demultiplex the input signal to output a plurality of streams, a plurality of delta sigma modulators executing in parallel, each delta sigma modulator configured to receive a stream from the plurality of streams and to generate a delta sigma modulated output, and a signal multiplexer configured to receive a plurality of delta sigma modulated outputs from the plurality of delta sigma modulators and to multiplex together the plurality of delta sigma modulated outputs into a pulse train.