A BJT/Resistor Hybrid CMOS Temperature Sensor With Low 3<i>σ</i>-Inaccuracy at 0-pt Trim

Conventional temperature sensors can achieve low inaccuracy at the expense of multipoint trimming due to the nonlinear temperature dependency. However, a multipoint trimming technique cannot avoid complex and high-cost digital processing. This article proposes a bipolar junction transistor (BJT)/resistor-based hybrid complementary metal–oxide–semiconductor (CMOS) temperature sensor that achieves 0-pt trimming by reducing the high-order temperature dependency from −40 °C to 125 °C. Compliment-to-absolute-temperature (CTAT) current is generated by using a BJT while minimizing the second-order temperature dependency. A poly resistor with a feedback circuit accurately characterizes proportional-to-absolute-temperature (PTAT) current out of CTAT even if a mismatch in the resistor is present. The CTAT current is subtracted from the PTAT current to cancel the high-order characteristic of both CTAT and PTAT currents, resulting in a linearity error of less than ±0.19%. As a result, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\sigma $ </tex-math></inline-formula>-inaccuracy and a figure of merit (FoM) of the proposed sensor without trimming are +0.60, −0.44 °C, and 0.84 pJ°C2.