Output Offset Cancellation Circuit for Sensor Signal Amplification
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Solution Overview
Problem
Existing electronic components, particularly sensors, generate unwanted offset voltages at their output terminals, complicating circuit analysis and accuracy, which existing methods fail to address efficiently without altering the input circuit.
Innovation Solution
A circuit comprising multiple resistors, including a variable resistor and transistors, is connected to the output terminal to cancel offset voltages, utilizing a Wheatstone bridge configuration to control the voltage difference between output terminals to zero, employing a junction gate field-effect transistor (JFET) for amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circuit is changed at the input terminal to cancel offset voltage, then the offset voltage can be cancelled, but the circuit complexity increases and the input circuit must be modified
Solution Approach 1:
Instead of modifying the input circuit to cancel offset voltage, the patent applies the cancellation circuit at the output terminal. This inverted approach maintains the original input circuit simplicity while achieving the same offset cancellation effect through a dedicated output-stage circuit comprising operational amplifiers and resistors.
Solution Approach 2:
The patent separates the offset cancellation function from the main signal processing path by creating a dedicated cancellation circuit at the output terminal. This segmentation allows the input circuit to remain simple while the output circuit handles the offset correction independently through separate operational amplifier stages.
2Power
If the output voltage is amplified directly without offset cancellation, then the signal amplification is achieved, but the offset voltage is also amplified causing measurement errors
Solution Approach 1:
The patent performs offset voltage cancellation before the signal amplification process. The first operational amplifier stage cancels the offset voltage from the sensor output, and only then does the second operational amplifier stage amplify the corrected signal. This preliminary offset removal prevents the offset from being amplified along with the signal.
Solution Approach 2:
The patent introduces an intermediate offset cancellation stage between the sensor output and the final amplification stage. This intermediary circuit, comprising the first operational amplifier and associated resistors, acts as a mediator that removes the offset component before the signal proceeds to the amplification stage, preventing error propagation.
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
Effectively cancels offset voltages at the output terminals, allowing accurate sensor measurements by eliminating unwanted voltage components and providing signal amplification, thereby enhancing measurement precision and reliability.
Implementation Method 1
utilizing a Wheatstone bridge configuration to control the voltage difference between output terminals to zero
Implementation Method 2
employing a junction gate field-effect transistor (JFET) for amplification
Data Source
AI summary
According to the present disclosure, a circuit for cancelling an off-set voltage included in an output voltage of an electronic component includes: a first resistor having one end connected to a bias voltage terminal; a second resistor connected to the first resistor, and having one end connected to the bias voltage terminal; a third resistor having one end connected to the first resistor and the other end connected to a ground terminal; and a transistor having one end connected to the second resistor and the other end connected to the ground terminal, and applied with an output voltage including an off-set voltage from a sensor.