RF DAC Time-Interleaving With Return-to-Zero Nyquist Control
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Solution Overview
Problem
Radio-frequency digital-to-analog converter systems face challenges in generating accurate analog signals across multiple Nyquist zones with minimal interleaving error and maintaining high spurious free dynamic range, particularly when operating at full digital rates.
Innovation Solution
The system employs first and second digital-to-analog converters operating in a return-to-zero configuration, with a digital controller generating codes that are synchronized and delayed to ensure simultaneous signal generation in both Nyquist zones, using a common output circuit to combine analog signals while avoiding interleaving errors and maintaining high spurious free dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple digital-to-analog converters operate simultaneously at full digital rates, then productivity is improved, but manufacturing precision deteriorates due to interleaving errors
Solution Approach 1:
The patent implements a return-to-zero configuration where each DAC operates in periodic cycles: during the first half of each digital period, the first DAC is enabled and the second DAC is reset; during the second half, the second DAC is enabled and the first DAC is reset. This periodic switching eliminates simultaneous operation and interleaving errors while maintaining full digital rate operation.
2Adaptability or versatility
If signals from multiple Nyquist zones are generated simultaneously, then adaptability is improved, but object-generated harmful factors worsen due to interference between zones
Solution Approach 1:
The patent uses periodic time-division multiplexing where the first DAC generates signals for the first Nyquist zone during the first half of each period, and the second DAC generates signals for the second Nyquist zone during the second half. This periodic separation eliminates simultaneous interference between zones while enabling multi-band operation through code manipulation.
Solution Approach 2:
The patent applies preliminary code manipulation before DAC conversion: the first code is formed by adding the first and second components of the input code, while the second code is formed by subtracting the second component from the first component. This preliminary processing prepares the signals to be generated in different Nyquist zones without interference.
Data Source
AI summary
A digital-to-analog converter system has digital-to-analog converters, a common output, and a digital controller for transmitting first codes to one of the converters at a radio-frequency digital rate, and for transmitting second codes to another one of the converters at the same rate. The digital controller includes a timing system for operating each converter at the digital rate in a return-to-zero configuration, such that a signal from the first converter is transmitted to the common output while the second converter is reset, and vice versa. The digital-to-analog converter system can generate a radio-frequency analog signal having signals in first and second Nyquist zones simultaneously.