A BJT-Based Temperature Sensor with an Inaccuracy of $\pm 0.5$ °C by Segwise Fitting and 2-Point Calibration

In this paper, a high-precision CMOS temperature sensor with wide range and fast response is presented for electronic systems. Substrate p-n-p bipolar junction transistors (BJTs) are used as temperature sensitive devices. In order to obtain high-precision temperature sensing front-end, a no-opamp negative feedback bias structure and dynamic element matching (DEM) techniques are employed. The readout circuit consists of a first-order one-bit delta-sigma <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathbf{\Delta}\mathbf{\Sigma})$</tex> analog-to-digital converter (ADC), providing a numerical representation of the temperature values. The temperature sensor is implemented using a standard <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0.18}\ \boldsymbol{\mu} \mathbf{m}$</tex> CMOS process, with a layout area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0.06}\ \mathbf{mm}^{\mathbf{2}}$</tex>. After segwise linear fitting and 2-point temperature calibration, a resolution of 0.1 °C and an inaccuracy of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm \mathbf{0.5}$</tex> °C are achieved from -40 °C to 125 °C. With a 3.3 V power supply voltage, the total power consumption is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{75.8}\ \boldsymbol{\mu} \mathbf{W}$</tex>. And each temperature conversion time is 2 ms.