Multipath D/A Converter Phase Alignment for Wideband Low Distortion
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Solution Overview
Problem
Existing multipath D/A converters face challenges in achieving optimal phase alignment and signal processing across multiple digital-to-analog conversion paths, leading to suboptimal performance in terms of bandwidth and distortion minimization.
Innovation Solution
A multipath D/A converter device with input terminals for multiple digital signal paths, where each path includes means for inverting every second sample and multiplying with a cosine shape function, all operating at the same phase, with integrated D/A converters, analog combining units, and digital filters whose coefficients adjust based on these operations, ensuring synchronized operation and efficient signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple D/A converters operate in parallel with different phase responses to increase bandwidth, then bandwidth is improved, but phase alignment and signal distortion worsen
Solution Approach 1:
The system divides the signal processing into multiple parallel D/A converter paths, each handling a portion of the spectral content. By segmenting the bandwidth allocation and using different sampling rates in each path, the system achieves overall bandwidth expansion while maintaining phase coherence through careful design of each segment's phase response.
Solution Approach 2:
The patent employs different sampling rates (e.g., 2.4 GHz and 4.8 GHz) in different signal paths, and applies phase rotation operations to adjust the phase response of each path. This parameter variation allows each converter to operate optimally while contributing to the overall phase-aligned output when combined.
2Speed
If multiple D/A converters operate in parallel to enhance bandwidth, then bandwidth is improved, but signal distortion products increase
Solution Approach 1:
The patent introduces digital signal processing operations (phase rotation, amplitude adjustment, and cosine function multiplication) as intermediary steps between the parallel D/A converters and their combination. These intermediary operations pre-compensate for potential distortion and ensure that when the signals are combined, distortion products are minimized rather than amplified.
Solution Approach 2:
The system deliberately introduces controlled phase variations and sampling rate differences that would normally create distortion, but then uses digital processing to convert these variations into beneficial effects. The different sampling rates create aliasing that is intentionally used to fold higher frequency content into the desired bandwidth, converting potential distortion into useful signal content.
3Speed
If different sampling rates are used in parallel D/A converter paths to increase bandwidth, then bandwidth is improved, but system complexity increases
Solution Approach 1:
The patent uses a unified digital processing architecture that handles multiple sampling rates through the same basic operations (phase rotation, amplitude scaling, and cosine multiplication). This multi-functional approach allows the system to process different sampling rates using identical hardware blocks, reducing overall complexity despite handling multiple rates.
Solution Approach 2:
The system employs periodic phase rotation and cosine function multiplication with periods related to the sampling rate ratios. This periodic structure allows the use of efficient, pre-computed lookup tables and simplifies the timing control logic, reducing the complexity of managing multiple sampling rates.
Data Source
AI summary
A Multipath D/A converter device is proposed having input terminals for a least a first and a second digital signal path, in at least one of the at least one first and second signal path, means for inverting every second sample of the digital signal, and each signal path comprising a D/A converter. The D/A converter of all signal paths are designed to operate at the same phase. The multipath converter device includes an analog combining unit designed for combining the analog signals output by each of the D/A converter.