CMOS RMS Detector Analog Circuit Noise Filtering
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Solution Overview
Problem
Existing RMS detectors face challenges in directly computing signal RMS values from analog circuits efficiently, particularly in high-speed applications and in environments with noise, which can lead to circuit breaker malfunctions.
Innovation Solution
A CMOS-integrated RMS detector is designed with voltage/current sensing units, square circuit units, a summing circuit, and a root circuit to directly compute RMS values without digital signal processing, using a configuration that includes transistors and current sources to perform square and root functions, and a comparator to prevent malfunctions due to noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital signal processing is used to compute RMS values, then measurement precision is improved, but processing speed decreases and device complexity increases
Solution Approach 1:
The patent replaces digital signal processing (mechanical/computational system) with an analog circuit system that directly computes RMS values. The analog circuit includes squaring circuits, integrating circuits, and square root circuits that perform RMS computation through continuous analog operations rather than discrete digital processing steps, thereby achieving both high precision and high speed.
Solution Approach 2:
The patent changes the operational parameters from digital domain to analog domain. By using continuous voltage signals and analog mathematical operations (squaring, integrating, square rooting) instead of digital sampling and computation, the system achieves real-time RMS measurement with high speed while maintaining precision through proper analog circuit design.
2Measurement precision
If digital signal processing is used to compute RMS values, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex digital signal processing systems with a streamlined analog circuit architecture. The analog implementation uses fundamental circuit elements (operational amplifiers, resistors, capacitors) to perform mathematical operations, eliminating the need for microprocessors, ADCs, and complex digital algorithms, thereby reducing overall device complexity while maintaining measurement precision.
3Reliability
If noise filtering is applied to detected signals, then reliability is improved, but processing time increases
Solution Approach 1:
The patent performs noise filtering through the analog integrating circuit as part of the RMS computation process itself, rather than as a separate subsequent step. The integration operation naturally averages out noise components while computing the RMS value, achieving reliability improvement without additional processing time loss.
Data Source
AI summary
The present disclosure relates to a RMS detector for directly computing a signal detected through an analog circuit to measure its RMS value, and a circuit breaker using the same. For this purpose, a RMS detector according to the present disclosure may include a plurality of voltage/current sensing units configured to detect a voltage or current shaped analog signal for an arbitrary load; a plurality of square circuit units configured to compute square function units, respectively, based on a voltage output from the plurality of voltage/current sensing units; a summing circuit unit configured to sum a plurality of output voltages output from the plurality of square circuit units, respectively; and a root circuit unit configured to compute a RMS value based on a voltage output from the summing circuit unit.