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

초록

Conventional temperature sensors can achieve low inaccuracy at the expense of multi-point trimming due to the nonlinear temperature dependency. However, a multi-point trimming technique cannot avoid complex and high-cost digital processing. This paper proposes a bipolar junction transistor (BJT)/resistor-based hybrid CMOS temperature sensor that achieves 0-pt trimming by reducing the high-order temperature dependency from -40 to 125 degrees 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 mismatch in the resistor presents. The CTAT current is subtracted from the PTAT current to cancel the high-order characteristic of both CTAT and PTAT currents, resulting in linearity error less than +/- 0.19%. As a result, the 3 sigma-inaccuracy and a figure of merit (FoM) of the proposed sensor without trimming are +0.60, -0.44 degrees C and 0.84 pJ degrees C-2.

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