Pipelined ADC Flash Stage Layout for Comparator Regeneration Time
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Solution Overview
Problem
In pipelined analog-to-digital converters (ADCs), the regeneration time of comparators can shorten the gain time, leading to reduced performance, especially at high frequencies where clock cycles are short, affecting the overall operation of the ADCs.
Innovation Solution
The implementation of two or more flash ADCs connected in parallel, alternately generating digital signals, allows for increased regeneration time while maintaining or extending the gain time by using separate capacitor blocks or dual latch flash ADCs, which can substitute multiple flash ADCs, thereby avoiding the shortening of gain periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comparators are used in pipelined ADCs, then analog-to-digital conversion can be performed, but the regeneration time of comparators shortens the gain time, reducing performance at high frequencies
Solution Approach 1:
The patent divides the single comparator function into two separate entities: a flash ADC for rapid analog-to-digital conversion and a separate comparator for regeneration operations. This segmentation allows the gain time and regeneration time to occur in parallel rather than sequentially, eliminating the trade-off between them. The flash ADC processes the analog signal during the gain phase while the comparator operates independently during regeneration.
Solution Approach 2:
The patent implements alternating operation between two parallel paths: one path performs flash ADC conversion while the other performs comparator regeneration, and they alternate in subsequent cycles. This periodic action ensures that regeneration occurs without encroaching on gain time, as each path operates during its designated phase while the other path remains active.
2Productivity
If clock frequency is increased to improve productivity, then conversion speed increases, but the short clock cycles leave insufficient time for both gain and regeneration operations
Solution Approach 1:
The patent ensures continuous useful action by overlapping the gain and regeneration operations in time. While the flash ADC performs conversion during the gain phase, the comparator simultaneously performs regeneration in parallel. This continuity eliminates idle time and allows the system to maintain high conversion speeds without sacrificing the necessary regeneration time, even at increased clock frequencies.
3Duration of action of stationary object
If separate capacitor blocks are used for flash ADC and comparator, then regeneration time can be increased without reducing gain time, but device complexity increases
Solution Approach 1:
The patent segments the capacitor resources into separate blocks: one capacitor block dedicated to the flash ADC and another dedicated to the comparator. This segmentation isolates the charge storage functions, allowing each block to operate independently without interfering with the other. The separate capacitor blocks enable the comparator to have sufficient regeneration time while the flash ADC maintains its gain time, resolving the time trade-off despite increased component count.
Data Source
AI summary
Apparatus and methods for pipelined analog-to-digital conversion are disclosed. In some embodiments, a pipeline analog-to-digital converter includes a plurality of multiplying digital-to-analog converter (MDAC) stages coupled in cascade. At least one of the MDAC stages includes two or more flash ADCs connected in parallel, operating alternately to generate digital signals from an analog input voltage. In one embodiment, the flash ADCs provide the digital signals in an alternating manner to a capacitor block that receives a delayed analog input voltage. In another embodiment, the at least one MDAC may include two or more capacitor blocks, each of which is associated with a respective one of the flash ADCs, forming two or more sets of a flash ADC and a capacitor block. In yet another embodiment, the at least one MDAC also include three or more capacitor blocks, each of which can be randomly selected for one of the flash ADCs.