ECG Front End Circuitry with Shared Protection Resistor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
ECG monitoring systems face challenges in protecting electronics from high voltage defibrillator pulses while maintaining effective detection of pacemaker spikes and filtering out noise from electrosurgery units, leading to increased complexity, space requirements, and cost due to the high number of protection resistors needed.
Innovation Solution
The use of a filtering capacitor connected to a virtual ground of the amplifier in ECG front end circuitry allows sharing of protection resistors between ECG and high frequency signals, reducing the total number of protection resistors and simplifying the circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel protection resistors are used for ECG and high frequency signals, then the electronics are protected from high voltage defibrillator pulses, but the total number of protection resistors increases leading to high space requirement, cumbersome circuitry, and high cost
Solution Approach 1:
The patent merges the protection function for both ECG and high frequency signals into a single shared protection resistor. The capacitor connected to virtual ground creates signal path separation while allowing both signal types to pass through the same protection resistor, thereby reducing the total number of protection resistors from multiple parallel units to a single shared unit.
Solution Approach 2:
The single protection resistor is designed to serve multiple functions: protecting both ECG signals and high frequency signals (pacemaker spikes, respiratory signals, electrosurgery noise) from high voltage defibrillator pulses. This multi-functional approach eliminates the need for separate dedicated protection resistors for each signal type.
2Adaptability or versatility
If multiple parallel input branches are used for different signals, then detection of various signals is enabled, but input impedance imbalance increases which reduces common mode noise rejection
Solution Approach 1:
By merging the input paths for ECG and high frequency signals through a single protection resistor, the patent reduces input impedance imbalance. This single shared input path improves common mode noise rejection while still enabling detection of multiple signal types through the capacitor-based frequency separation at the virtual ground node.
3Object-generated harmful factors
If filtering capacitor is used to filter electrosurgery noise, then noise is reduced, but high frequency signals such as pacemaker spikes and excitation signals are attenuated
Solution Approach 1:
The capacitor connected to virtual ground acts as an intermediary element that selectively filters noise while preserving high frequency signals. The virtual ground node serves as a mediator that allows the capacitor to create frequency-dependent signal paths, enabling noise filtering for ECG signals while maintaining signal integrity for high frequency components through the amplifier's differential input configuration.
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 reduces the number of protection resistors, minimizing bulkiness and cost, while improving input impedance balance and noise rejection, making the ECG monitoring system more efficient and practical.
Implementation Method 1
a capacitor (17) connected to a virtual ground (P2) of a second input amplifier (19)
Implementation Method 2
the protection resistor drops the defibrillator output voltage, which is of the order of 5 kV, to a level of about 5 volts or below
Implementation Method 3
the capacitor needed as a filtering element is connected to a virtual ground of the amplifier that serves as an input amplifier for the high frequency signals
Data Source
AI summary
An ECG front end and a method for acquiring ECG signals are disclosed. The front end comprises a plurality of parallel measurement branches, each measurement branch comprising a protection resistor having a first terminal and a second terminal, wherein the first terminal is connectable to a respective ECG electrode. Each measurement branch comprises a first input amplifier operatively connected to the second terminal of the protection resistor and a capacitor having a first and a second terminal, wherein the first terminal of the capacitor is operatively connected to a point between the first input amplifier and the second terminal of the protection resistor and the second terminal of the capacitor is connected to a virtual ground of a second input amplifier. Each first input amplifier serves as a source of an ECG channel signal and each second input amplifier as a source of high frequency signal components.