ECG Multiplexer DPDT Switching for Low-Noise ASIC Sampling
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Solution Overview
Problem
Existing ECG systems face issues with switching noise when multiplexing analog signals, which can distort bioelectric signal outputs.
Innovation Solution
Incorporating a double pole double throw (DPDT) switch in the multiplexer that first connects to a reference signal and then to the incoming ECG signal, reducing noise by minimizing charge injection during switching events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a multiplexer is used to transfer multiple analog ECG signals through a single A/D converter, then device complexity is reduced, but switching noise is introduced into the signal output
Solution Approach 1:
The DPDT switch connects to a reference signal before connecting to the incoming ECG signal at each switching event. This preliminary connection to a known reference voltage prepares the switching circuitry and minimizes charge injection artifacts, reducing switching noise in the multiplexed signal output
2Productivity
If switching speed is increased to improve productivity, then signal acquisition rate increases, but switching noise and artifacts increase
Solution Approach 1:
By pre-connecting the DPDT switch to a reference signal before the actual ECG signal switching occurs, the circuit is prepared in advance with a known voltage state. This reduces the magnitude of voltage transitions and associated noise when switching to the ECG signal, allowing faster switching rates with reduced artifacts
Solution Approach 2:
The reference signal acts as an intermediary state between switching events. The DPDT switch transitions through this reference voltage level rather than directly between different ECG signal levels, reducing charge injection and switching transients that would otherwise contaminate the bioelectric signals
Data Source
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 consist of 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.