ECG Multiplexer Reference Switching to Reduce Channel Noise
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Solution Overview
Problem
Existing ECG measurement systems face issues with switching noise when multiplexing multiple analog signals, which can distort bioelectric signal outputs.
Innovation Solution
Incorporating a double pole double throw (DPDT) switch in the multiplexer to connect and disconnect the ECG signals in a controlled manner, first to a reference signal and then to the incoming bioelectric signal, to minimize noise during switching events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple analog ECG signals are multiplexed using a standard multiplexer, then the number of channels being monitored is increased, but switching noise is introduced into the signal output
Solution Approach 1:
The DPDT switch performs a preliminary connection to the reference voltage before connecting to the ECG signal channel. This preliminary action allows the circuit to settle and eliminates switching noise by establishing a stable reference state before signal acquisition begins.
Solution Approach 2:
The reference voltage serves as an intermediary element between the multiplexer switching mechanism and the ECG signal. By connecting to the reference voltage first, the circuit creates a stable intermediate state that prevents direct coupling of switching transients to the signal path.
2Object-generated harmful factors
If a DPDT switch is used to connect to reference signal first, then switching noise is reduced, but the complexity of the multiplexer increases
Solution Approach 1:
The DPDT switch combines multiple functions into a single component: channel selection and reference voltage connection. This merging of functions reduces the overall system complexity compared to using separate switches for each function.
Solution Approach 2:
The DPDT switch performs multiple functions simultaneously - it acts as both a channel selector and a reference voltage connector. This multi-functionality eliminates the need for additional dedicated reference connection components, thereby reducing overall circuit complexity.
Data Source
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AI summary
Medical catheterization is carried out by receiving a plurality of analog bioelectric signals in respective channels and multiplexing the bioelectric signals in respective selection events. The selection events comprise making a first connection with a reference voltage, thereafter breaking the first connection and making a second connection with one of the bioelectric signals. The method is further carried out by outputting the multiplexed bioelectric signals to an analog-to-digital converter.