Current Sensing Circuit with Adjustable Capacitor Sets for Dynamic Precision
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Solution Overview
Problem
Current current sensing circuits for ambient-light sensors require varying precision across different light intensity ranges, from as low as 1 Lux in dark conditions to 20-30 Lux in bright conditions, necessitating a solution that adjusts precision dynamically to match the sensed light source intensity.
Innovation Solution
A current sensing circuit comprising a current sensing unit with adjustable precision using first and second capacitor sets, a feedback control unit, and a digital output unit, which selects capacitors and adjusts voltage to produce a pulse signal and digital output, allowing for different precisions based on current values without a conventional ADC, enabling direct digital conversion of sensed current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional ADC with over 16-bits is used to meet the broad sensing range, then the sensing range is covered, but the precision cannot be dynamically adjusted to match different light intensity requirements
Solution Approach 1:
The patent applies dynamics by making the capacitor configuration adjustable based on light intensity levels. The sensing circuit dynamically switches between different capacitor combinations (first capacitor set for low light, second capacitor set for bright light) to adapt the precision characteristics to the current measurement range, resolving the contradiction between fixed ADC precision and variable precision requirements across different lighting conditions
Solution Approach 2:
The patent changes the electrical parameters (capacitance values) of the sensing circuit based on the measured light intensity. By selecting different capacitor sets or combinations, the circuit parameters are adjusted to provide appropriate precision for each lighting condition - higher precision capacitors for dark conditions and lower precision capacitors for bright conditions - thereby achieving both broad range coverage and adaptive precision
2Measurement precision
If high precision is maintained across all sensing ranges, then precision is improved, but power consumption increases and device complexity increases
Solution Approach 1:
The patent applies local quality by providing different precision levels in different operating ranges. Instead of uniformly high precision across all ranges, the circuit uses high-precision capacitor configurations only when needed (low light conditions below 1000 Lux), and switches to lower-precision configurations for bright conditions (above 10000 Lux), thereby reducing overall power consumption while maintaining necessary precision where required
Solution Approach 2:
The circuit dynamically adjusts its precision characteristics by switching between different capacitor sets based on the measured light level. This dynamic adaptation allows the system to consume less power by using lower-precision configurations during bright conditions when high precision is not required, while still providing high precision when needed in dark conditions
3Measurement precision
If high precision is maintained across all sensing ranges, then measurement precision is improved, but device complexity increases due to requiring over 16-bits ADC
Solution Approach 1:
The patent segments the sensing range into different zones (low light, medium light, bright light) and assigns different capacitor configurations to each zone. This segmentation allows the use of simpler, lower-bit ADC configurations for each segment rather than requiring a single high-precision 16-bit ADC for the entire range, thereby reducing overall device complexity while maintaining appropriate precision for each segment
Solution Approach 2:
The patent changes the capacitance parameters of the sensing circuit based on the measured range, allowing the use of different effective resolution levels for different light intensity ranges. This parameter adjustment enables the system to achieve high precision when needed through capacitor selection rather than requiring a permanently high-bit-depth ADC, thus reducing device complexity
4Device complexity
If fixed precision is used for the entire sensing range, then device complexity is reduced, but the precision does not match the varying requirements of different light intensities
Solution Approach 1:
The patent introduces dynamic adjustment capability through switchable capacitor sets. The circuit can change its precision characteristics in response to different light intensity levels, matching the precision to the requirements of each range (higher precision for dark conditions, lower precision for bright conditions) without requiring a permanently complex high-precision ADC architecture
Solution Approach 2:
The patent applies different precision characteristics to different operating ranges. By using different capacitor sets for different light intensity zones, the circuit achieves locally optimized precision - high precision where needed (dark conditions) and lower precision where acceptable (bright conditions) - thereby matching precision to requirements while keeping the overall device complexity manageable
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 solution allows for efficient and precise current sensing across a broad range, reducing power consumption and enhancing image quality by dynamically adjusting precision according to light intensity, enabling faster digital conversion and broader sensing ranges with lower precision where needed.
Implementation Method 1
Nearly all of ambient-light sensors take a photodiode architecture, which requires a voltage power for operation. A photo sensor produces different currents according to different sensed light intensities
Implementation Method 2
The current sensing unit includes a first capacitor set and a second capacitor set. The current sensing unit selects at least one capacitor in the first capacitor set and at least one capacitor in the second capacitor set according to the current value so as to adjust the precision of the current sensing circuit
Data Source
AI summary
A current sensing circuit includes a current sensing unit, a feedback control unit and a digital output unit. The current sensing unit senses a current and produces a pulse signal according to at least one reference signal and at least one feedback signal. The current sensing unit includes a first capacitor set and a second capacitor set. The current sensing unit selects at least one capacitor in the first capacitor set and at least one capacitor in the second capacitor set according to the current value so as to adjust the precision of the current sensing circuit. The feedback control unit is coupled to the current sensing unit and produces the feedback signals according to a clock signal and the pulse signal. The digital output unit is coupled to the current sensing unit and outputs a digital signal according to the pulse signal.