Bio-impedance Measurement Compensation for Low Power Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bio-impedance measurement devices introduce errors that degrade accuracy, especially at higher frequencies, necessitating novel architectural solutions for high accuracy with low power consumption.
Innovation Solution
The bio-impedance measurement device employs multiple detection channels with compensation parameters to correct for relative time quantization errors, scaling, and phase adjustments, as well as common mode voltage compensation, to enhance measurement accuracy while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional bio-impedance measurement devices are used, then power consumption is reduced, but measurement accuracy is degraded
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual bio-impedance measurements to determine compensation parameters. These parameters are stored and applied during operation to correct errors without requiring additional real-time power consumption for recalibration, thus improving accuracy while maintaining low power consumption.
Solution Approach 2:
The patent implements feedback by using the measured detection signals to calculate compensation parameters that are then applied to correct subsequent measurements. The system continuously compensates for errors introduced by demodulators and amplifiers by feeding back correction factors derived from calibration data, thereby improving measurement accuracy without increasing power consumption.
2Speed
If working frequency is increased, then measurement speed is improved, but measurement accuracy is degraded
Solution Approach 1:
The patent replaces mechanical/time-based error sources with electronic compensation. By substituting the effect of time quantization errors (caused by clock granularity at high frequencies) with electronic compensation parameters applied in the signal processing domain, the system maintains accuracy at higher measurement speeds without being constrained by temporal sampling limitations.
Solution Approach 2:
The patent changes parameters by applying frequency-dependent compensation parameters that are determined during calibration at specific frequencies. These parameters are stored and applied when operating at different frequencies, allowing the system to maintain measurement accuracy across a range of operating frequencies including higher frequencies where faster measurements are possible.
3Measurement precision
If compensation parameters are applied to correct errors, then measurement accuracy is improved, but device complexity is increased
Solution Approach 1:
The patent uses copying by creating a digital model of the error characteristics through calibration measurements. Instead of physically characterizing and compensating for each error source, the system copies the net error effect into compensation parameters stored in memory, which are then applied to correct measurements. This approach improves accuracy while avoiding the complexity of individually characterizing and correcting each error source.
Solution Approach 2:
The patent applies universality by using a single set of compensation parameters to correct multiple error sources simultaneously. The calibration process determines parameters that account for errors from demodulators, amplifiers, and time quantization effects all at once, rather than requiring separate compensation mechanisms for each error source, thereby improving accuracy without proportionally increasing device complexity.
Data Source
AI summary
A method and apparatus for compensating and calibrating a bio-impedance measurement device are provided. In the method and apparatus, a memory stores a plurality of compensation parameters and a first detection channel receives a first detection signal, compensates the first detection signal using a first compensation parameter of the plurality of compensation parameters. In the method and apparatus, a second detection channel receives a second detection signal and a third detection signal and compensates the second and third detection signals using second and third compensation parameters of the plurality of compensation parameters and the compensated first detection signal. The impedance measurement device generates a first output signal representative of a first impedance measurement and a second output signal representative of a second impedance measurement based on the compensated first, second and third detection signals.