Two-Wire Measurement Interface With Regulated Feedback Compensation
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Solution Overview
Problem
The existing two-wire interface architecture for measuring devices, such as piezoelectric accelerometers, faces limitations due to the direct integration of a zener diode with the amplification stage, which restricts signal excursion and introduces noise that cannot be corrected by feedback loops, making it incompatible with transducers requiring constant voltage and low impedance for conditioning.
Innovation Solution
An electronic measuring device with a two-wire interface that includes a processing stage with a feedback loop connected to a regulator, allowing for robust compensation of the regulator's influence, and featuring a series regulator or voltage lift regulator with a power storage device to maintain a constant voltage supply for the transducer and amplification stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Zener diode is integrated in series with the amplification stage to provide constant voltage, then the transducer and amplification stage can be powered, but the voltage excursion of the output signal is limited and noise cannot be corrected by feedback
Solution Approach 1:
The patent divides the power supply function into two separate circuits: a first power supply circuit (Zener diode) dedicated to powering the amplification stage, and a second power supply circuit (voltage regulator) dedicated to powering the transducer. This segmentation allows each circuit to operate independently without interfering with the signal path, thereby maintaining both power stability and signal dynamic range.
Solution Approach 2:
The patent extracts the transducer power supply function from the amplification stage power supply. By using a separate voltage regulator circuit specifically for the transducer, the design removes the constraint that previously limited voltage excursion. This extraction allows the signal to utilize the full dynamic range while the amplification stage receives stable power from the Zener diode circuit.
2Reliability
If a fixed voltage power supply is used for the transducer and amplification stage, then the components can operate reliably, but the architecture becomes incompatible with two-wire IEPE interfaces that provide constant current
Solution Approach 1:
The patent introduces voltage regulator circuits as intermediary components between the two-wire IEPE interface and the transducer/amplification stage. These regulators convert the constant current from the interface into the fixed voltage required by the components, serving as a mediator that reconciles the incompatibility between the current-based interface and voltage-based component requirements.
Solution Approach 2:
The patent changes the electrical parameter form from constant current (provided by the two-wire interface) to fixed voltage (required by the transducer and amplification stage) through the use of voltage regulator circuits. This parameter transformation enables compatibility between the interface and the components while maintaining reliable operation.
3Ease of manufacture
If the constant voltage across the Zener diode is directly used in the signal path, then the circuit is simple to implement, but disturbances from diode characteristic discrepancies cannot be corrected
Solution Approach 1:
The patent segments the power supply function from the signal path by using a separate voltage regulator circuit for transducer power supply. This separation allows the Zener diode circuit to remain simple for amplification stage power, while the independent regulator circuit provides accurate, stable power to the transducer without introducing disturbances into the signal path.
Solution Approach 2:
The patent extracts the voltage regulation function for the transducer from the Zener diode circuit. By implementing a dedicated voltage regulator circuit specifically for the transducer power supply, the design removes the source of disturbances (Zener diode characteristic variations) from the signal path while maintaining the simplicity of the Zener diode circuit for the amplification stage.
Data Source
Figure 1~3d
Figure 3a~3c
Figure 4a~4b
AI summary
The invention relates to an electronic device for measuring a specific quantity. The device has a two-wire interface with two connection terminals for connecting to a conductive pair that supplies power to the measuring device and carries back an electrical signal representative of the measured quantity. The device comprises a transducer providing a raw measurement of the specified quantity, a processing stage for conditioning the raw measurement, the processing stage comprising an input connected to the transducer and an output, and a regulator electrically connected to the processing stage. The regulator includes an input port electrically connected to the two connection terminals of the two-wire interface and an output port supplying a regulated voltage to the transducer and/or the processing stage. The device also includes a feedback circuit electrically connected to the input port of the regulator and to the processing stage.