RF DAC Return-to-Zero Timing for Multi-Nyquist Signal Output
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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 rate.
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 and timing system to avoid interleaving errors and achieve high spurious free dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple digital-to-analog converters operate simultaneously at full digital rate, then productivity is improved, but interleaving error increases
Solution Approach 1:
The patent implements a time-division multiplexing scheme where multiple digital-to-analog converters operate in periodic alternating cycles. During each period, one converter is active while others are reset, creating a periodic action pattern that allows simultaneous operation without continuous interference. This resolves the contradiction by maintaining high productivity through rapid cycling while eliminating interleaving errors through temporal separation.
Solution Approach 2:
The patent applies preliminary action by resetting converters during their inactive periods before they become active again. This preliminary reset action ensures that each converter starts fresh in each cycle, preventing accumulation of errors and eliminating interleaving effects. The reset operation is performed in advance during the periodic cycle when other converters are active, maintaining both high productivity and precision.
2Productivity
If converters operate in overlapping cycles, then productivity is improved, but spurious free dynamic range deteriorates
Solution Approach 1:
The patent uses periodic action with precisely timed non-overlapping cycles for each digital-to-analog converter. Each converter operates during its designated time slot and remains reset during other converters' active periods. This periodic timing arrangement maintains high operational efficiency by ensuring continuous output from the system while preventing spurious signals that would degrade the spurious free dynamic range by eliminating overlap interference.
3Measurement precision
If converters are reset continuously, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent implements periodic resetting where each digital-to-analog converter is reset only during the time slots when other converters are active. This creates an efficient periodic pattern where resetting and signal generation are interleaved in time. The approach maintains high signal accuracy through regular resetting while minimizing time loss by ensuring that reset operations do not create idle periods in the overall system output, as other converters maintain productivity during reset phases.
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.