Flash ADC Window Control for High-Speed Low-Power Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high-speed analog-to-digital converters (ADCs) used in SERDES receivers consume high power due to the need for all comparators to be active during sampling, which is inefficient, especially when only a fraction of the dynamic range is used.
Innovation Solution
A flash ADC with a window controller that selectively activates and deactivates comparators based on the rate of change of the analog signal, using a profiler, look-up tables, and a selective activation block to determine the optimal window size and position, reducing power consumption by only activating a subset of comparators during each sampling cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a flash ADC with a bank of comparators is used for high-speed analog-to-digital conversion, then gigahertz sampling rates are achieved, but power dissipation and input capacitance increase significantly
Solution Approach 1:
The patent implements dynamic comparator activation where the window controller selectively enables or disables comparators based on the actual signal activity and rate of change. This dynamic reconfiguration allows the ADC to operate at high speeds when needed while reducing power consumption during periods of lower signal activity, directly resolving the contradiction between speed and power dissipation
Solution Approach 2:
The patent changes the operational parameters of the comparator bank by adjusting the number of active comparators based on signal characteristics. The window controller modifies the activation state of comparators in response to detected signal rate of change, enabling the system to adapt between high-performance mode (all comparators active) and low-power mode (subset active), thus resolving the speed-power tradeoff
2Measurement precision
If all comparators in the bank are activated for each sampling cycle, then full dynamic range conversion is achieved, but power consumption increases
Solution Approach 1:
The patent applies partial action by activating only a subset of comparators rather than the full bank. The window controller determines the minimum necessary number of comparators based on signal rate of change, enabling accurate conversion for the actual signal range while leaving excess comparators inactive, thus reducing power consumption without sacrificing measurement precision for the relevant signal portion
Solution Approach 2:
The patent segments the comparator bank into multiple groups that can be independently controlled. The window controller selectively activates specific segments (groups of comparators) based on signal characteristics, allowing the system to maintain precision for the active signal range while powering down other segments, thereby resolving the contradiction between full precision and power consumption
3Measurement precision
If a large number of comparators are used to cover the full voltage range, then resolution is maintained, but input capacitance increases
Solution Approach 1:
The patent dynamically adjusts the number of active comparators based on signal rate of change detected by the window controller. When signal changes are slow, fewer comparators are activated, reducing input capacitance. When fast transitions are detected, more comparators are activated to maintain resolution, thus dynamically resolving the contradiction between resolution and input capacitance
Data Source
AI summary
An analog-to-digital converter (“ADC”). The ADC includes a bank of comparators and a window controller. The window controller is coupled to the bank of comparators to selectively activate first comparators of the bank of comparators associated with a window size and to selectively inactivate second comparators of the bank of comparators.