An Amplitude-to-Time Conversion Technique Suitable for Multichannel Data Acquisition and Bioimpedance Imaging

作者：Baeg Jong Cheol^*; Wi Hun; Oh Tong In; McEwan Alistair Lee; Woo Eung Je

来源：IEEE Transactions on Biomedical Circuits and Systems, 2013, 7(3): 349-354.

DOI：10.1109/TBCAS.2012.2212437

• Amplitude-to-time conversion
• analog-to-digital converter (ADC)
• capture unit
• bioimpedance imaging
• microprocessors
• multichannel data acquisition

In this paper we exploit the high timing resolution offered by microprocessors to develop an amplitude measurement approach that is convenient for high channel count portable sinusoidal recording systems such as the bioimpedance measurements used in impedance imaging. This approach reduces the number of components required per channel, reducing cost, size and power consumption compared to the traditional approaches. The setup uses two high performance comparators to convert amplitude difference to a timing difference. This is captured by a high speed microprocessor. A straightforward algorithm removes DC and timing offsets. We suggest three modes of operation: fast: less than one period of the input, normal: exactly one input period and high precision: multiple input periods. The mean signal-to-noise ratio was 40, 81, and 112.4 dB in fast, normal, and high precision mode respectively for a range of resistive loads.

• 出版日期2013-6