Switched Capacitor Charge Pump Sensing for Low-Battery Medical Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing medical devices with sensing circuitry for low frequency signals, such as cardiac pacing devices, face issues with high battery drain due to the use of active preamplifiers that require constant bias current, leading to shorter battery life and increased noise interference.
Innovation Solution
Implementing a switched capacitor charge pump (SCCP) with a Fibonacci series topology that uses passive devices and switches, eliminating the need for a fixed bias current, thereby reducing current consumption and noise contribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an active preamplifier is used in sensing circuitry, then signal amplification is achieved, but battery drain increases due to constant bias current requirement
Solution Approach 1:
The patent employs a switched capacitor charge pump that operates in periodic cycles, using capacitors to store and transfer charge in discrete steps rather than continuous current flow. This periodic switching action replaces the continuous bias current of traditional active preamplifiers, significantly reducing average power consumption while maintaining signal amplification capability through cumulative charge transfer over multiple cycles.
Solution Approach 2:
The patent substitutes traditional active electronic amplification (requiring continuous power) with a passive capacitor-based charge pumping mechanism. By using capacitors to store electrical energy and switches to redirect charge flow, the system achieves signal amplification through electrostatic charge transfer rather than active device conduction, eliminating the need for constant bias current and reducing battery drain.
2Power
If an active preamplifier is used in sensing circuitry, then signal amplification is achieved, but noise interference increases
Solution Approach 1:
The patent replaces active preamplifier circuits with a passive switched capacitor charge pump architecture. This substitution eliminates noise sources inherent in active devices (such as thermal noise from bias currents and shot noise from junctions), using only passive capacitors and switches that generate minimal noise. The charge pumping mechanism amplifies signals through charge transfer rather than current amplification, inherently reducing noise interference.
Solution Approach 2:
The patent uses simple, low-cost passive components (capacitors and switches) instead of complex active preamplifier circuits. These passive components are inherently more reliable and generate less noise, trading the continuous operation requirement of active devices for periodic charge transfer cycles that accumulate signal amplification over time with minimal noise contribution.
3Use of energy by moving object
If a Fibonacci series charge pump is used, then current consumption is reduced to passive switching currents, but circuit complexity increases
Solution Approach 1:
The patent implements the charge pump using multiple discrete capacitor stages arranged in a Fibonacci series configuration. Each stage consists of separate capacitors and switches that operate independently in sequence, breaking down the overall charge pumping function into manageable segments. This segmentation allows for reduced current consumption at each stage while maintaining the cumulative amplification effect, and facilitates modular implementation that manages circuit complexity through systematic decomposition.
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
The SCCP reduces battery drain and noise, enhancing the reliability and longevity of medical devices by limiting current consumption to passive switching currents, allowing for more efficient sensing of low frequency signals.
Implementation Method 1
The switched capacitor charge pump may include a plurality of passive devices and a plurality of passive switches
Implementation Method 2
a switched capacitor charge pump configured to amplify sensed signals to generate amplified signals
Data Source
AI summary
An example device includes a memory configured to store representations of sensed signals. The example device includes processing circuitry coupled to the memory, the processing circuitry being configured to read or write the representations of the sensed signals in the memory. The example device includes sensing circuitry coupled to the processing circuitry, the sensing circuitry being configured to sense signals indicative of a physiological condition of a patient via a plurality of electrodes and to output to the processor circuitry the representations of the sensed signals. The sensing circuitry includes a switched capacitor charge pump configured to amplify the sensed signals to generate amplified signals.