*Article* **A Highly Accurate, Polynomial-BasedTemperature Compensation for**

 **in 180 nm** 

**Sensor**

#### **Imran Ali, Muhammad Asif, Khuram Shehzad, Muhammad Riaz Ur Rehman, Dong Gyu Kim, BehnamSamadpoorRikan,YoungGunPu,Sang SunYooandKang-YoonLee\***

College of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Korea; imran.ali@skku.edu (I.A.); m.asif@skku.edu (M.A.); khuram1698@skku.edu (K.S.); riaz@skku.edu (M.R.U.R.); rlarlarbrb@skku.edu (D.G.K.); behnam@skku.edu (B.S.R.); hara1015@skku.edu (Y.P.); rapter@kaist.ac.kr (S.S.Y.)

**CMOS**

**\*** Correspondence: klee@skku.edu; Tel.: +82-31-299-4954

Received: 14 August 2020; Accepted: 11 September 2020; Published: 14 September 2020

**Abstract:** Recently, piezoresistive-type (PRT) pressure sensors have been gaining attention in variety of applications due to their simplicity, low cost, miniature size and ruggedness. The electrical behavior of a pressure sensor is highly dependent on the temperature gradient which seriously degrades its reliability and reduces measurement accuracy. In this paper, polynomial-based adaptive digital temperature compensation is presented for automotive piezoresistive pressure sensor applications. The non-linear temperature dependency of a pressure sensor is accurately compensated for by incorporating opposite characteristics of the pressure sensor as a function of temperature. The compensation polynomial is fully implemented in a digital system and a scaling technique is introduced to enhance its accuracy. The resource sharing technique is adopted for minimizing controller area and power consumption. The negative temperature coe fficient (NTC) instead of proportional to absolute temperature (PTAT) or complementary to absolute temperature (CTAT) is used as the temperature-sensing element since it o ffers the best temperature characteristics for grade 0 ambient temperature operating range according to the automotive electronics council (AEC) test qualification ACE-Q100. The shared structure approach uses an existing analog signal conditioning path, composed of a programmable gain amplifier (PGA) and an analog-to-digital converter (ADC). For improving the accuracy over wide range of temperature, a high-resolution sigma-delta ADC is integrated. The measured temperature compensation accuracy is within ±0.068% with full scale when temperature varies from −40 ◦C to 150 ◦C according to ACE-Q100. It takes 37 μs to compute the temperature compensation with a clock frequency of 10 MHz. The proposed technique is integrated in an automotive pressure sensor signal conditioning chip using a 180 nm complementary metal–oxide–semiconductor (CMOS) process.

**Keywords:** temperature compensation; digital controller; piezoresistive; pressure sensor; negative temperature coe fficient; ACE-Q100; CMOS
