Highly Area Efficient Component Sharing Extended Counting ADC for Multi-Channel Sensing

• Published in: IEEE transactions on circuits and systems. II, Express briefs Vol. 70; no. 3; p. 1
• Main Authors: Asgari, Mohammadreza, Lee, Kye-Shin, Chung, Hae
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitors; Circuits; Clocks; Component sharing; Discharges (electric); extended counting ADC; Generators; highly area efficient; Impedance; Power consumption; Sensors; Sigma-delta modulation; time-mode ADC
• ISSN: 1549-7747; 1558-3791
• DOI: 10.1109/TCSII.2022.3219768

This brief describes a highly area efficient 10-bit, 40kS/s extended counting ADC for multi-channel cell impedance sensing applications. The proposed ADC shares major circuit components including the amplifier, comparator, and feedback capacitors between the 6-bit incremental sigma-delta ADC and the 4-bit time-mode ADC that both operates with the same clock frequency. Furthermore, the MSB of the time-mode ADC is generated by processing the integrator output voltage after the counting operation of the incremental sigma-delta ADC without using additional circuit components, which simplifies the time-mode ADC operation. As a result, this leads to significant area and power reduction compared to other ADCs with similar resolution and bandwidth. The prototype ADC is implemented using CMOS 0.18μm technology, where the measurement results show max. DNL and INL of 0.40 LSB and 0.88 LSB, 58.9 dB SNDR, and 1.15 μW power consumption, with core area of 75 μm × 45 μm (0.00375 mm2).