Flash-Assisted Parallel SAR ADC for High-Speed Low-Power Conversion
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Solution Overview
Problem
Conventional analog-to-digital conversion systems are inadequate in terms of speed, accuracy, and power efficiency, as they either require excessive power due to numerous comparators or are slow due to serial data comparison.
Innovation Solution
A hybrid system combining flash ADC and SAR (Successive Approximation Register) architectures, where flash ADC performs coarse conversion and SAR performs fine conversion with error correction, utilizing a special offset for error correction and parallel processing to achieve high speed and low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If flash ADC uses numerous comparators to achieve high-speed conversion, then conversion speed is improved, but power consumption increases
Solution Approach 1:
The ADC is divided into two functional segments: a flash ADC portion that converts k MSBs in a single cycle using comparators, and a SAR portion that converts n-k LSBs using fewer comparators. This segmentation allows the system to achieve high-speed conversion for the most significant bits while reducing overall power consumption by using a lower-comparator-count architecture for the remaining bits.
Solution Approach 2:
Different parts of the conversion process use different architectures optimized for their specific requirements. The flash portion uses high-speed comparator-based conversion for MSBs where speed is critical, while the SAR portion uses energy-efficient sequential comparison for LSBs where power consumption is the primary concern.
2Use of energy by moving object
If SAR ADC uses serial data comparison to reduce power consumption, then power efficiency is improved, but conversion speed decreases
Solution Approach 1:
The conversion process is segmented into two phases: the flash ADC handles the time-critical MSB conversion in a single cycle, while the SAR ADC handles the less time-sensitive LSB conversion with lower power consumption. This segmentation allows each portion to operate in its optimal performance regime.
Solution Approach 2:
The flash ADC performs preliminary conversion of the MSBs first, establishing a coarse digital representation. This preliminary action reduces the burden on the SAR portion, allowing it to focus on refining the LSBs with fewer comparison cycles and lower power consumption.
3Device complexity
If conventional ADC systems use single architecture to simplify design, then device complexity is reduced, but they cannot achieve both high speed and low power consumption
Solution Approach 1:
The system merges two different ADC architectures (flash and SAR) into a unified hybrid structure. The flash ADC portion and SAR portion are combined such that they share common components like the comparator array and control logic, reducing overall device complexity while achieving both high speed and low power consumption through the complementary strengths of each architecture.
Data Source
AI summary
The present invention is directed to signal processing systems and methods thereof. In various embodiments, the present invention provides an analog-to-digital conversion (ADC) system that includes a flash ADC portion and a time-interleaved parallel SAR portion. For an n-bit ADC process, the flash ADC portion converts k MSBs of the n bits during a single cycle, and the SAR portion converts n−k LSBs in m number of cycles. The SAR portion includes a number of SAR channels that perform A/D conversion in parallel, and the k MSB from the course flash converter is verified for errors by the SAR portion and allows a net saving of the power consumption by reducing the number of fine resolution SARs. There are other embodiments as well.