A Power Adaptive, 1.22-pW/Hz, 10-MHz Read-Out Front-End for Bio-Impedance Measurement.

Area of Science:

• Biomedical Engineering
• Integrated Circuit Design
• Electrical Engineering

Background:

• Accurate tissue impedance measurement is vital for various diagnostic and therapeutic applications.
• Existing front-end circuits often face limitations in power consumption, frequency range, and signal-to-noise ratio.

Purpose of the Study:

• To design and validate a low-power, high-performance read-out front-end application-specific integrated circuit (ASIC) for tissue impedance measurement.
• To achieve a wide operational frequency range with superior signal integrity and power efficiency.

Main Methods:

• Fabrication of a 2-channel front-end ASIC using 0.18 μm CMOS technology.
• Implementation of adaptive gain control in the instrumentation amplifier for wide dynamic range.
• Integration of a dual digital-to-analog converter (DAC) hybrid SAR analog-to-digital converter (ADC) for reduced power consumption.

Main Results:

• The ASIC operates effectively from 100 Hz to 10 MHz.
• Achieved power performance of 1.22 pW/Hz.
• Signal-to-noise ratio (SNR) exceeds 72 dB for frequencies ≤ 1 MHz and 65 dB for frequencies ≥ 1 MHz.
• Total power consumption ranges from 2.1 to 21.7 mW.
• ADC driver power consumption reduced sevenfold for frequencies between 4 kHz and 1 MHz.

Conclusions:

• The developed ASIC provides a robust and efficient solution for tissue impedance measurement.
• Its wide frequency range, high SNR, and low power consumption make it suitable for advanced biomedical instrumentation.
• The adaptive gain control and optimized ADC design contribute significantly to its performance and power efficiency.