A Low-Power Low-Offset DAC-Less LC-ADC for Biomedical Signal Acquisition

F. Modarresi (Mahabad, Iran), A. Amini (UNIPV, Italy)

This paper presents a low-power DAC-less level-crossing analog-to-digital converter (LC-ADC) designed for biomedical signal acquisition. In contrast to conventional uniform-sampling ADCs, level-crossing converters generate samples only when the input signal crosses predefined amplitude levels, making them particularly suitable for sparse biomedical signals and enabling significant power reduction. The proposed architecture eliminates the conventional n-bit digital-to-analog converter (DAC), thereby reducing circuit complexity and power consumption compared to traditional LC-ADC implementations. Furthermore, an offset-cancellation mechanism is incorporated to suppress comparator offset and improve conversion accuracy. The proposed 8-bit LC-ADC is designed and simulated in a standard 0.18 μm CMOS technology using HSPICE. Simulation results show that the converter operates from a 5 V supply while consuming approximately 30 μW of power. For input bandwidths ranging from 50 Hz to 3 kHz, the converter achieves an effective number of bits (ENOB) of 7.6 bits and a figure-of-merit (FoM) of 15.9 pJ/conv, demonstrating its suitability for low-power biomedical sensing applications