Non-Binary SAR ADC Mode Switching for Noise-Resilient Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-performance Analog to Digital (A/D) converters face challenges in modern telecommunication receiver architectures due to increasing resolution and sampling frequency requirements, particularly in SAR converters, where thermal noise and limited bandwidth lead to comparison errors and reduced signal-to-noise ratio (SNR), exacerbated by reduced voltage supply and device degradation in scaled CMOS technologies.
Innovation Solution
A non-binary successive approximation ADC converter with dynamically adjustable noise levels, utilizing switchable capacitors and a clock divider to operate in different modes with varying noise properties, allowing for redundancy in conversion steps to compensate for thermal noise and reduce loop noise impact, thereby enhancing SNR without significant power consumption or silicon area increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution and high sampling frequency are implemented in SAR ADC converters, then conversion performance is improved, but thermal noise and loop noise increase causing comparison errors
Solution Approach 1:
The patent implements dynamic switching between two operational modes (first mode with longer conversion time and lower noise, second mode with shorter conversion time and higher noise) based on the conversion step. The mode selection is controlled dynamically during the conversion process to optimize the balance between noise performance and conversion speed, directly addressing the contradiction between high resolution and noise-induced comparison errors
Solution Approach 2:
The patent changes the operational parameters of the ADC by switching between different conversion modes with different noise characteristics and conversion times. The first mode uses a longer conversion time to reduce noise impact, while the second mode uses a shorter conversion time for faster operation. This parameter switching allows the system to adapt to different noise conditions and maintain comparison accuracy throughout the conversion process
2Productivity
If conversion speed is increased to meet high sampling frequency requirements, then productivity is improved, but thermal noise and loop noise cause more comparison errors
Solution Approach 1:
The patent dynamically adjusts the conversion mode based on the current conversion step and noise conditions. Early conversion steps use the first mode with longer conversion time to establish accurate initial comparisons, while later steps may use the second mode with shorter conversion time. This dynamic adjustment allows the system to maintain high overall conversion speed while ensuring comparison accuracy at critical stages
Solution Approach 2:
The patent performs preliminary comparisons using the first mode with longer conversion time and lower noise in the initial steps. This preliminary action establishes a reliable foundation for the conversion process, allowing subsequent faster steps to proceed with confidence that the initial comparison decisions are accurate, thereby preventing error propagation
3Measurement precision
If redundant conversion steps are added to compensate for noise, then measurement precision is improved, but conversion time increases
Solution Approach 1:
The patent applies partial redundancy by adding extra conversion steps only when noise compensation is needed, rather than using full redundancy throughout the entire conversion process. The mode switching mechanism allows the system to use the first mode (with inherent noise compensation capabilities) for a portion of the conversion steps, providing just enough redundancy to correct noise-induced errors without unnecessarily extending the total conversion time
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A non-binary successive approximation analogue to digital converter, for converting using successive conversion steps, is operable in first and second modes. The first and second modes have different noise properties and the converter is switched between the modes during the conversion process.