An Integrated Circuit Solution to Johnson Noise Thermometry Using Low-Cost and Fast CMOS Technology

An integrated circuit solution to Johnson noise thermometry (ICJNT) using a low-cost and fast complementary metal-oxide-semiconductor (CMOS) technology is investigated in this paper. Benefits from both noise thermometry and integrated circuits (ICs) can be maintained in ICJNTs, which cost significantly less, work orders of magnitude faster than discrete-device JNTs, and can be applied to various applications. As a first attempt at an ICJNT, this paper presents the relevant analysis and design techniques, demonstrates the potential benefits of ICJNTs, and discusses the challenges unique to integrated circuit solutions. A prototype IC chip is fabricated using the 0.13-μm CMOS technology with fully on-chip circuits, including sensing resistors, a pre-amplifier, and a flash analog-to-digital converter. To demonstrate the efficacy, a test PCB for the ICJNT was developed and measured in a standard industrial thermal chamber with a laboratory grade platinum resistance thermometer as a comparison reference. The test results show that this first ICJNT prototype is able to provide temperature measurement from 0 °C to 70 °C. The maximum deviation with two-point calibration is 1.2 °C at a measurement of 40 °C due to systematic error, and the standard deviation is approximately 2 °C. The measurement time is only 10 ms due to the fast IC technology. These results established the feasibility of the ICJNT concept. Since the ICJNT is a complete solution without discrete devices and the sensing resistors are not limited to specific IC materials, the ICJNT can be applied to various emerging applications, such as electric vehicles and microelectromechanical systems.