Constant-Current Capacitor Timing for Low-Power Precision Measurement
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Solution Overview
Problem
Current time and capacitance measurement technologies require ultra-high frequency clocks and high power-consuming digital logic, leading to significant power consumption and circuit noise, making it difficult to achieve precise measurements without these constraints.
Innovation Solution
A system and method using a constant current source, current steering switch, capacitor, and analog-to-digital converter to measure time and capacitance with low clock speeds and low power consumption, allowing for high resolution measurements independent of the frequency accuracy of a time base reference and ADC resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultra-high frequency clocks (1-10 GHz) and high speed digital logic are used to precisely measure short time periods, then measurement precision is improved, but power consumption increases significantly
Solution Approach 1:
The patent replaces the mechanical/digital clock-based time measurement system with an analog measurement system. Instead of using ultra-high frequency digital clocks and counters, the invention uses a voltage ramp generator that creates a linearly increasing voltage over time, which is then converted to a digital value by an ADC. This analog approach eliminates the need for high-speed digital logic and ultra-high frequency clocks, dramatically reducing power consumption while maintaining picosecond-level measurement precision.
2Measurement precision
If ultra-high frequency clocks (1-10 GHz) are used to precisely measure short time periods, then measurement precision is improved, but circuit noise increases significantly
Solution Approach 1:
The patent eliminates the source of digital noise by replacing the digital clock and counter system with an analog voltage ramp generator and ADC. The analog voltage ramp creates no digital switching noise, and the ADC operates at low frequency, avoiding the generation of high-frequency digital noise that would interfere with the measurement signal. This results in a quiet measurement system with excellent signal-to-noise ratio.
3Measurement precision
If high resolution time measurement is achieved through ultra-high frequency clocks, then time resolution is improved, but device complexity increases
Solution Approach 1:
The patent simplifies the circuit architecture by replacing complex high-speed digital logic (clock generators, frequency dividers, counters, and timing logic) with simple analog circuitry (voltage ramp generator and ADC). The voltage ramp generator uses basic RC timing circuits, and the ADC is a standard low-speed converter. This analog approach dramatically reduces the number of components and interconnections, making the circuit simpler, more reliable, and easier to manufacture.
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
Enables precise time and capacitance measurements with picoseconds resolution and extended dynamic range, reducing power consumption and noise, while maintaining high accuracy and low power operation.
Implementation Method 1
a capacitor coupled to the current steering switch, the capacitor having a known value of capacitance, wherein a voltage on the capacitor increases substantially linearly in time when the current steering switch couples the constant current source to the capacitor
Data Source
AI summary
A time period of an event is determined by charging a known value capacitor from a constant current source during the event. The resultant voltage on the capacitor is proportional to the event time period and may be calculated from the resultant voltage and known capacitance value. Capacitance is measured by charging a capacitor from a constant current source during a known time period. The resultant voltage on the capacitor is proportional to the capacitance thereof and may be calculated from the resultant voltage and known time period. A long time period event may be measured by charging a first capacitor at the start of the event and a second capacitor at the end of the event, while counting clock times therebetween. Delay of an event is done by charging voltages on first and second capacitors at beginning and end of event, while comparing voltages thereon with a reference voltage.