Sensor Compensation Circuit for Offset and Interference Detection
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Solution Overview
Problem
Existing bridge sensors face accuracy issues due to leakage currents and offsets in low noise amplifiers and analog-to-digital converters, which are not effectively compensated by existing detection circuits.
Innovation Solution
A sensor with a compensation circuit comprising four switches and an amplifier, operating in two modes to cancel amplifier offsets and compensate leakage currents, with an analog-to-digital converter and calculation circuit to generate corrected output data, and a noise threshold to detect interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing detection circuits are used, then the sensor can detect output voltage, but the accuracy is degraded due to uncompensated leakage currents and amplifier offsets
Solution Approach 1:
The patent applies preliminary action by performing offset compensation measurements before the actual sensor measurement. The system first measures the offset voltage with switches in a known state, then subtracts this offset from subsequent measurements. This preliminary characterization of the amplifier offset and leakage current effects allows accurate compensation during normal operation, improving measurement precision without adding complexity to the core sensing function.
Solution Approach 2:
The patent utilizes parameter changes by switching the state of switches S1-S4 to different configurations. By changing the switch states between measurement phases, the system can isolate and measure offset components separately from the actual sensor signal. The amplifier gain and switching timing are also controlled parameters that enable precise separation of offset and signal components for accurate compensation.
2Measurement precision
If compensation circuits are added to improve accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent achieves multi-functionality by using the same amplifier and switching network for both offset compensation and normal sensing operations. The switches S1-S4 serve dual purposes: they enable offset measurement during calibration phases and perform normal signal routing during measurement phases. This universal use of components avoids adding separate dedicated compensation hardware, thereby improving accuracy while minimizing increased circuit complexity.
Solution Approach 2:
The system performs self-service by automatically measuring and compensating for its own offset and leakage current effects without requiring external calibration equipment or additional compensation circuits. The amplifier and switching network measure their own non-ideal characteristics and use this information to correct subsequent measurements, eliminating the need for separate compensation hardware that would increase device complexity.
3Measurement precision
If multiple switches are added for compensation, then leakage current compensation improves, but the number of components increases
Solution Approach 1:
The four switches S1-S4 perform multiple functions: they route power sources to sensor inputs during offset measurement, enable normal sensor operation during measurement phases, and facilitate leakage current path control. This multi-functional use of the switches compensates for leakage currents without requiring additional dedicated compensation switches, as the same switches serve both normal operation and compensation functions.
Solution Approach 2:
The patent applies dynamics by using time-varying switch configurations to achieve compensation. The switches dynamically change their state between different measurement phases, enabling the system to adapt the circuit topology for offset measurement, leakage compensation, and normal operation. This dynamic switching approach provides effective leakage current compensation without requiring additional static compensation components.
Data Source
AI summary
Disclosed is a sensor with compensation circuit for compensating offset by use of a switching circuit. The sensor has two operation modes for generating two output voltages, respectively. Offset is compensated by adding the two output voltages, and magnitude of the offset is calculated by subtracting the two output voltages. A noise threshold is set for checking if the circuit is affected by interference. When the circuit is affected by interference, the adding result of the two output voltages will be larger than the noise threshold, the output data will be hold and not updated, then a reminding signal will be issued to show that the circuit is affected by interference, and the output data flickers on a display unit when the adding result of the two output voltages is larger than the noise threshold for showing the circuit is affected by interference.