Wearable Signal Acquisition Circuit With Negative Capacitance Compensation
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Solution Overview
Problem
Existing bioelectric signal acquisition circuits face challenges due to parasitic capacitance, which reduces input impedance and exacerbates power frequency interference, limiting the effectiveness of signal acquisition.
Innovation Solution
The implementation of negative capacitance circuits connected to the leads of the signal acquisition circuit, which cancel out parasitic capacitance to ground, thereby increasing the input impedance and reducing power frequency interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a higher input impedance is required to reduce power frequency interference, then power frequency interference is reduced, but parasitic capacitance causes a decrease in input impedance, exacerbating the problem
Solution Approach 1:
The patent applies preliminary anti-action by introducing negative capacitance circuits before the signal is affected by parasitic capacitance. The negative capacitance circuits are configured to produce a capacitive effect that opposes and cancels the parasitic capacitance in the leads, thereby preventing the reduction of input impedance before it occurs. This proactive compensation ensures that the input impedance remains high enough to reject power frequency interference effectively.
Solution Approach 2:
The patent converts the harmful effect of parasitic capacitance into a benefit by using negative capacitance circuits that generate an opposing capacitive effect. The negative capacitance circuits are designed to produce a capacitance value that is equal in magnitude but opposite in sign to the parasitic capacitance, thereby transforming the harmful parasitic effect into a useful compensation mechanism that actually improves the input impedance and reduces power frequency interference.
2Reliability
If negative capacitance circuits are added to cancel parasitic capacitance, then input impedance increases and power frequency interference reduces, but circuit complexity increases
Solution Approach 1:
The patent uses operational amplifiers as intermediary components to implement the negative capacitance effect without requiring direct complex circuitry. The operational amplifiers are configured with feedback networks that include capacitors and resistors, creating an equivalent negative capacitance effect through controlled impedance transformation. This intermediary approach allows the complex negative capacitance function to be achieved using standard, readily available components in a systematic and manageable way.
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 significantly enhances the signal acquisition circuit's performance by increasing input impedance and minimizing the impact of parasitic capacitance, leading to improved signal-to-noise ratio and reduced risk of circuit saturation.
Implementation Method 1
Both the first negative capacitance circuit and the second negative capacitance circuit may exhibit a negative capacitance effect
Data Source
AI summary
Embodiments of the present disclosure provide a signal acquisition circuit. The signal acquisition circuit includes a differential amplifier, a first electrode, a second electrode, a first negative capacitance circuit, and a second negative capacitance circuit. The first electrode is connected to a first input terminal of the differential amplifier through a first lead, and the second electrode is connected to a second input terminal of the differential amplifier through a second lead. The first negative capacitance circuit is electrically connected to the first lead and ground, and the second negative capacitance circuit is electrically connected to the second lead and the ground. Both the first negative capacitance circuit and the second negative capacitance circuit exhibit a negative capacitance effect.