A Low-Power CT Incremental 3rd Order <formula formulatype="inline"> <tex Notation="TeX">$\Sigma\Delta$</tex></formula> ADC for Biosensor Applications

Abstract

Abstract-This paper proposes a 3 rd order single-loop continuous-time incremental sigma-delta analogue-to-digital converter (ADC) for time-multiplexed signals. Incremental sigmadelta modulation is used to address medium to high resolution requirements of multi-channel applications, while a 3 rd order continuous-time implementation is investigated as an alternative for low-power solutions. A prototype of the proposed modulator, running at 320 kHz, has been fabricated in a 0.15-µm CMOS technology, while the synchronization circuitry to allow incremental operation was built on-board. Measurement results show that the ADC achieves 65.3 dB peak SNR, 64 dB peak SNDR and 68.2 dB dynamic range over a 2 kHz bandwidth. The modulator's power dissipation is 96 µW from a 1.6 V power supply. This translates into the best figure-of-merit when compared to recently published continuous-time alternatives, while being competitive with respect to state-of-the-art discrete-time counterparts.