Fully Differential Receiver for Polarity-Independent IMD Communication
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Solution Overview
Problem
Existing implantable medical devices (IMDs) face challenges in effectively communicating with each other due to limitations of single-ended receivers, including sensitivity to signal polarity, noise immunity, electrode connectivity requirements, and complexity, especially in multi-electrode systems like S-ICDs.
Innovation Solution
A fully-differential receiver with a differential pair of inputs and outputs, comprising a preamplifier, buffer, AC coupling network, and comparators, operates in two modes to enhance signal reception, reducing noise sensitivity and electrode connectivity constraints while supporting multi-electrode systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-ended receiver is used in IMDs, then the device complexity is reduced, but the noise immunity and sensitivity to signal polarity deteriorate
Solution Approach 1:
The receiver is segmented into fully-differential components including a differential preamplifier, differential buffer, and differential comparators. This segmentation allows each component to process differential signals independently, improving noise immunity while maintaining manageable complexity through modular design.
Solution Approach 2:
The receiver transitions from single-ended (one-dimensional) signal processing to fully-differential (two-dimensional) signal processing. By processing both positive and negative differential signals simultaneously through matched pairs of components, the system achieves superior noise rejection and polarity independence.
2Ease of operation
If a single-ended receiver is used, then the electrode connectivity requirements are simplified, but the adaptability to multi-electrode systems deteriorates
Solution Approach 1:
The fully-differential receiver is designed with universal applicability to multi-electrode systems such as S-ICDs. The differential architecture can accommodate multiple electrode configurations and orientations, allowing the same receiver design to work across various implantable device architectures without requiring simplification of connectivity requirements.
3Measurement precision
If a fully-differential receiver is implemented, then the signal reception independence from polarity is improved, but the device complexity increases
Solution Approach 1:
Each stage of the receiver (preamplifier, buffer, comparators) is designed with local differential symmetry, where matched transistor pairs and balanced signal paths ensure that polarity variations are handled uniformly throughout the signal chain. This local quality control maintains polarity independence while preventing complexity from compounding across stages.
4Use of energy by moving object
If conventional receivers are used in IMDs, then the power consumption is lower, but the communication effectiveness between IMDs deteriorates
Solution Approach 1:
The receiver employs periodic switching between low-power sleep mode and active reception mode. During normal operation, the receiver remains in a low-power state and activates fully-differential signal processing only when communication signals are detected or expected, thereby maintaining communication effectiveness while minimizing overall power consumption.
Data Source
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AI summary
Described herein is a fully-differential receiver (102) for use with an implantable medical device (IMD) (402) and configured to receive conducted communication signals that are transmitted by another IMD or an external device. The fully-differential receiver (102) includes a fully-differential preamplifier (112), a fully-differential buffer (122), a first comparator (142), a second comparator (152), and an AC coupling network (132) coupled between differential outputs of the fully-differential buffer (122) and a coupled together differential pair of inputs of the first and second comparators (142, 152). A differential pair of inputs of the fully-differential receiver (102) comprise the differential pair of inputs of the fully-differential preamplifier (112), and a differential pair of outputs of the fully-differential receiver (102) comprise a first output of the first comparator (142) and a second output of the second comparator (152). In order to conserve power, the fully-differential receiver (102) is selectively changed from operating in a first mode to operating in a second mode, and vice versa.