Clockless Time-Interval Conversion Using Successive Approximation
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Solution Overview
Problem
Current methods for converting time intervals to digital words in high-energy efficiency applications, such as biomedical equipment and mobile devices, face challenges in energy efficiency and require the use of clock signals, which are energy-intensive.
Innovation Solution
A clockless method using the Monotonic Successive Approximation (MSA) algorithm, where a time interval is converted by measuring the difference between reference and signal time periods using binary scaled capacitors, with a control module determining the start and end of the interval and assigning logical values to output bits based on charging processes, allowing for efficient energy use without a clock signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock signals are used for time interval conversion, then measurement precision is improved, but energy consumption increases
Solution Approach 1:
The patent extracts and eliminates the clock signal from the time interval conversion system. By using a clockless successive approximation method with binary-weighted capacitors, the invention removes the energy-intensive clocking mechanism while maintaining measurement functionality through direct charge comparison between reference and signal paths.
Solution Approach 2:
The patent replaces the mechanical/clock-based time measurement system with an electrical charge-based measurement system. Instead of using clock cycles to measure time intervals, the invention uses charge accumulation on capacitors proportional to time intervals, enabling clockless operation with reduced energy consumption.
2Measurement precision
If all binary scaled reference elements are used in the conversion process, then measurement precision is improved, but energy expenditure increases
Solution Approach 1:
The patent implements a successive approximation method that uses binary-weighted capacitors in a systematic charging sequence. By charging capacitors in order of their binary weights (from most significant bit to least significant bit) and using early termination conditions, the system achieves precise conversion while minimizing the total number of charging operations required, thus reducing energy expenditure.
3Measurement precision
If conversion time redundancy is increased to improve precision, then measurement accuracy is improved, but processing time increases
Solution Approach 1:
The patent employs a dynamic successive approximation algorithm that adapts the conversion process based on intermediate results. The method dynamically determines when the conversion can be terminated by comparing charge levels during the approximation process, allowing the system to achieve required precision with minimal processing time by avoiding unnecessary conversion steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method reduces energy consumption by eliminating the need for a clock signal and minimizing energy redundancy, achieving high energy efficiency and reducing processing time and capacitor requirements, while maintaining self-clocking capability.
Implementation Method 1
The reference time period is composed of reference intervals obtained as times of charging, by means of a reference current source, capacitors selected from of a set of n binary scaled capacitors
Data Source
Figure 1
Figure 2~3
AI summary
A method for clockless and direct conversion of a time interval to a digital word is characterized in that the converted time interval (T) is mapped in the form of a difference between a reference time period (RT) and a signal time period (ST), a sum of lengths of which is approximately proportional to the length of the converted time interval (T). The reference time period (RT) is first measured roughly using linear method, and next precisely by method of weight compensation.