Capacitive Voltage Scaling Circuit for High-Impedance Node Measurement
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Solution Overview
Problem
Integrated circuits face challenges in accurately measuring high voltage nodes due to the influence of high impedance nodes on voltage divider circuits, leading to significant voltage drops and measurement inaccuracies, especially when the impedance of the voltage source is high, which existing techniques struggle to account for effectively.
Innovation Solution
A voltage scaling circuit using on-chip capacitors and switches is employed to scale down high voltage levels to a lower voltage domain, utilizing a charge phase and charge sharing phase to generate a scaled voltage that is proportional to the original voltage, while minimizing the impact of leakage currents and temperature-related errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage divider circuit is used to measure high voltage nodes, then the measurement circuit can operate at lower voltage levels, but high impedance nodes cause significant voltage drops and measurement inaccuracies
Solution Approach 1:
The patent introduces an intermediary circuit between the high voltage node and the measurement ADC that actively compensates for voltage drops caused by high impedance. This intermediary circuit measures the actual voltage at the ADC input and uses it to calculate corrections, thereby eliminating the harmful effect of impedance-induced voltage drops while allowing the measurement circuit to operate at safe lower voltage levels
Solution Approach 2:
The patent implements feedback by measuring the actual voltage at the ADC input terminal and using this information to correct the final measurement result. The system continuously monitors the voltage division ratio and adjusts calculations accordingly, ensuring accurate measurements even when impedance conditions change, thus resolving the contradiction between safety and measurement accuracy
2Measurement precision
If existing measurement techniques are used, then the measurement circuit can be simple, but they fail to account for leakage currents and temperature-related errors effectively
Solution Approach 1:
The patent uses feedback by measuring the actual voltage at the ADC input and using this information to correct for leakage currents and temperature effects. The system monitors environmental conditions and measurement results, then applies corrections based on pre-characterized behavior of the voltage divider circuit under various conditions, achieving high precision without requiring complex compensation hardware
Solution Approach 2:
The measurement system performs self-characterization by measuring its own behavior under known conditions and storing correction factors. The voltage divider circuit is automatically calibrated by measuring its division ratio using the same ADC it will use for actual measurements, eliminating the need for external calibration equipment or complex manual adjustment mechanisms
3Measurement precision
If voltage scaling is performed using traditional methods, then high voltage levels can be reduced, but leakage currents and temperature effects significantly impact measurement accuracy
Solution Approach 1:
The patent applies feedback by continuously monitoring the actual voltage at the ADC input and using this information to correct for leakage and temperature effects. The system measures the voltage division ratio under actual operating conditions and adjusts calculations accordingly, eliminating the need for complex real-time compensation circuits while maintaining high measurement precision across varying temperature and leakage conditions
Solution Approach 2:
The patent changes the approach from trying to physically eliminate leakage and temperature effects to changing how the measurement is interpreted. By measuring the actual voltage at the ADC input and using this parameter to correct the final result, the system accounts for leakage and temperature effects without requiring the measurement circuit to be immune to these phenomena
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 approach allows for accurate measurement of high voltage nodes by reducing the influence of high impedance and leakage currents, improving measurement accuracy across a wide temperature range and maintaining a compact chip layout.
Implementation Method 1
A voltage scaling circuit using on-chip capacitors and switches is employed to scale down high voltage levels to a lower voltage domain, utilizing a charge phase and charge sharing phase
Data Source
AI summary
One or more examples relate to methods and apparatuses for measuring a voltage node. An example method may include providing, between an input of a measurement circuit and a voltage node associated with a higher voltage domain than the measurement circuit, a circuit including decoupled capacitors, the decoupled capacitors including at least a first capacitor and a second capacitor; generating, by the measurement circuit, a first digital value representing a voltage level related to a voltage level at the voltage node at least partially responsive to performing a measurement process utilizing the circuit; and generating, by a processor, a second digital value representing the voltage level at the voltage node at least partially responsive to the first digital value and a scaling factor, the scaling factor representing a pre-specified relationship between the voltage level represented by the first digital value and the voltage level at the voltage node.