Capacitive Voltage Sampling for High-Voltage CMOS Measurement
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Solution Overview
Problem
Standard CMOS digital circuits are limited to processing voltages of 5 V or 1.5 V, making it challenging to accurately measure high input voltages in automotive applications without significant area consumption using resistive dividers.
Innovation Solution
A measurement apparatus using switchable capacitances and switches to periodically alternate between high input voltages and reference potentials, allowing a measurement circuit adapted for lower voltages to process the input voltage, incorporating a comparator and successive approximation register for analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resistive dividers are used to reduce high input voltage to a voltage range suitable for standard CMOS circuits, then high input voltage can be processed, but significant area is consumed on the semiconductor chip
Solution Approach 1:
The patent applies periodic action by using switches that alternately connect the capacitor to the high-voltage input signal and to reference voltages at different time intervals. This periodic switching enables the measurement circuit to process high voltages indirectly through time-multiplexed operations, avoiding the need for large resistive dividers while maintaining voltage measurement capability.
2Adaptability or versatility
If resistive dividers are used to reduce high input voltage, then voltage scaling is achieved, but measurement accuracy deteriorates
Solution Approach 1:
The patent changes the operating parameters by using a capacitor-based voltage sampling approach with periodic switching instead of continuous resistive division. This parameter change enables accurate voltage measurement through time-domain sampling and digital processing, avoiding the accuracy losses inherent in resistive divider approaches.
3Ease of manufacture
If standard CMOS circuits are used for voltage measurement, then manufacturing compatibility is maintained, but voltage processing capability is limited to low voltages
Solution Approach 1:
The patent introduces a capacitor as an intermediary element that temporarily stores the high-voltage signal. This capacitor acts as a mediator between the high-voltage input and the low-voltage standard CMOS measurement circuit, enabling the CMOS circuit to process high-voltage information indirectly without being directly exposed to high voltage stress.
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 accurate measurement of high input voltages while minimizing area consumption on semiconductor chips, allowing for efficient processing of voltages up to 50 V using standard CMOS technology.
Implementation Method 1
A capacitor input is alternately switched between a high input voltage and reference potentials such that a measurement circuit adapted for processing lower voltages is able to process the input voltage
Data Source
AI summary
Measurement apparatuses and methods are described. A measurement input is coupled with a first terminal of a capacitance via a first switch, and a reference voltage is coupled with the first terminal of the capacitance via a second switch. A measurement circuit is coupled to a second terminal of said capacitance.