Counter based CMOS temperature sensor for low frequency applications

A simple temperature sensor in Bi-CMOS technology is proposed for applications with low frequency temperature variations in addition to a complete analysis of each block in the system. Most CMOS temperature sensors are based on the temperature characteristics of parasitic bipolar transistors. Two important factors need to be met in the design of the sensor: the first is the accuracy of the sensor, and the second is the power consumption of the temperature sensor that needs to be reduced. A simplified counter approach is used here instead of the commonly used complex decimation filter techniques. This approach is appropriate for applications that have low sampling rate of the temperature. The design achieves one degree accuracy over the range 0°C to 85°C which is suitable for most applications. Using such approach saves power and area due to the simplicity of the counter design compared to the decimation filter.