Design of a Low-Power LNIA-ADC Interface Circuit in 22nm FDSOI for a Thermopile Sensor in Biomedical Application

This paper presents a design of a low-noise instrumentation amplifier (LNIA) and analog-to-digital converter (ADC) interface in 22 nm FDSOI for infrared (IR) sensingin biomedical applications. The LNIA is used as a signal conditioning block for a thermopile sensor input and utilizes a capacitively-coupled chopper instrumentation amplifier (CCIA) topology with a ripple reduction loop (RRL). The ADC adopts a successive approximation register (SAR) topology to digitize the signal from the LNIA with a power-gated counter D flip-flop array and a split binary weighted (SBW) capacitive digital-toanalog converter (CDAC). Schematic simulation shows that the interface circuitconsumes $1.65 \mu \mathrm{~W}$ of power and can output a digital signal that represents a data set from a temperature range of $25^{\circ} \mathbf{C}$ to $45^{\circ} \mathbf{C}$ with a step of 200 mK.