A Low Power Front-end for Biomedical Fluorescence Sensing Applications

This paper presents a CMOS optical analog frontend for an implantable fluorescence biosensor for single-cell measurements. The front-end is configurable by a set of switches and consists of three integrated photodiodes (PD), three transimpedance amplifiers (TIA) for detecting a current range between 1 pA up to 10 mA. Also, ambient light and dark current canceling technique is proposed to make the sensor operate at different environmental conditions. The proposed front-end could be configured for ultra-low light detection or ultra-low power consumption. The circuit is simulated at the post-layout level. The minimum integrated input-referred current noise is obtained as 546 fA at the average power consumption of 1 μW for bandwidth (BW) of 1.4 kHz. For ultra-low-power configuration, the front-end has an average power consumption of 24 nW and input integrated current noise of 210 pA with 50 kHz BW.