Flash ADC Dynamic Comparator Activation for Lower Power
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Solution Overview
Problem
Flash ADCs consume high power due to the large number of comparators required for precise conversions, which is a limitation in applications requiring low power consumption while maintaining performance.
Innovation Solution
The proposed solution involves a Flash ADC architecture that includes a coarse-measurement circuit, a fine-measurement circuit with dynamic comparators activated by a clock signal, and an activation circuit that processes coarse measurements to generate activation signals, allowing only one subset of dynamic comparators to perform fine measurements, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Flash ADC uses a large number of comparators to achieve high precision conversion, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent divides the ADC into two distinct stages: a coarse-measurement circuit that performs initial conversion with fewer comparators, and a fine-measurement circuit that performs precision conversion with additional comparators only when needed. This segmentation allows the system to achieve high precision when required while consuming less power during operations that don't demand maximum precision.
Solution Approach 2:
The patent implements dynamic comparator activation where the fine-measurement comparators are enabled only when the coarse measurement indicates they are needed for achieving the desired precision. The comparators are dynamically controlled through enable signals that activate them based on the coarse measurement results, allowing the system to adapt power consumption to actual measurement requirements.
2Speed
If a Flash ADC activates all comparators continuously to maintain readiness for fine measurements, then measurement speed is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic activation of the fine-measurement comparators based on the results of coarse measurements. Rather than keeping all comparators continuously active, the system periodically enables the fine-measurement circuit only when the coarse measurement indicates that higher precision is required, thus maintaining conversion speed when needed while reducing power consumption during routine operations.
Solution Approach 2:
The patent performs a preliminary coarse measurement before activating the fine-measurement comparators. This preliminary action allows the system to determine in advance whether the fine-measurement circuit needs to be activated, avoiding unnecessary power consumption while ensuring that comparators are ready when actually needed for high-precision conversions.
3Measurement precision
If a Flash ADC uses 2^n-1 comparators for n-bit conversion to achieve high precision, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the comparator circuitry into a coarse-measurement section with fewer comparators and a fine-measurement section with additional comparators. This segmentation allows the system to achieve n-bit precision when needed while using significantly fewer than 2^n-1 comparators in the normal operating state, thereby reducing device complexity while maintaining measurement precision capability.
Solution Approach 2:
The patent implements dynamic control of comparator activation where the full set of comparators required for n-bit precision are not permanently instantiated or activated simultaneously. Instead, the system dynamically enables additional comparators only when the coarse measurement indicates they are needed, effectively reducing the average device complexity while maintaining the capability for high-precision conversion when required.
Data Source
AI summary
An analog-to-digital converter comprises a first set of comparators configured for generating a coarse digital measurement of an analog input signal, and a second set of comparators for performing a fine digital measurement of the analog input signal. The second set comprises a plurality of dynamic comparators, wherein each dynamic comparator is configurable for being activated by a clock signal. An activation circuit processes the coarse measurement and an input clock signal for generating a set of activation signals, which activate a subset of the dynamic comparators to generate the fine digital measurement.