Analog Front-End CMOS Temperature Sensor Interface for Optogenetic Devices

This work presents a CMOS temperature sensor interface based on a second-generation current conveyor (CCII) and a transimpedance amplifier (TIA) with a high linear and temperature-independent pseudo-resistor. Since the LED in optogenetic implantable devices generates heat, a temperature sensor is required to monitor the temperature. Thus, the reverse current of the LED can be employed as its own sensing element. This paper will utilize the LED reverse current as a temperature-sensitive parameter (TSP) to sense the junction temperature. The sensor interface operates under a supply voltage of ±0.6 V. The reverse current driving capability is ±1.7 µA. The total power consumption of the CMOS sensor interface is 192 µW. The circuit provides an operational frequency of up to 2.08 MHz. The transimpedance gain of the proposed temperature sensor interface is equal to 300×103 V/A. The proposed circuit is designed using 90 nm CMOS technology and simulated using LTspice.