A cmos temperature sensor

Abstract

The invention relates to a CMOS temperature sensor which comprises a bipolar transistor, an over-sampling analog-digital conversion module, a correction module and at least two unit current sources. The output end of each unit current source is coupled to the collector electrode of the bipolar transistor through a switching module. The collector electrode and the base electrode of the bipolar transistor are connected with a reference ground and then connected to the analog-digital conversion module; the analog-digital conversion module is connected with a reference voltage; the switching module switches all the unit current sources to the bipolar transistor; the analog-digital conversion module outputs a first conversion result; then the unit current sources are switched to the bipolar transistor within a collecting cycle of the analog-digital conversion module in sequence, only one unit current source can be connected each time, and the analog-digital conversion module outputs a second conversion result; the correction module combines the first conversion result and the second conversion result to obtain a final correction value. The CMOS temperature sensor can improve correcting efficiency.

Description

technical field [0001] The invention relates to the field of sensors, in particular to a CMOS temperature sensor. Background technique [0002] With the portability and miniaturization of various electronic products, temperature sensors based on modern CMOS technology that can be integrated with data acquisition circuits, calibration modules and even system chips are widely used due to their small size and low cost. This type of CMOS integrated temperature sensor is mainly based on the bandgap reference voltage source circuit, that is, a PTAT voltage proportional to the absolute temperature and a CTAT voltage with a negative temperature coefficient are combined to form a voltage without bipolar transistors and some current bias circuits. The temperature coefficient voltage is used as a reference voltage, and the temperature is detected by measuring the ratio of the PTAT voltage or CTAT voltage to the reference voltage. In this process, due to many unideal factors in the chi...

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Problems solved by technology

[0008] The above analysis ignores various error factors caused by the mismatch of various components and parameter deviations in the actual production process of the chip, such as the input offset voltage of the op amp, the proportional imbalance of the resistors R1, R2, and R3, and the deviation of the parameters of the bipolar transistor itself. The shift makes Vbe drift, ADC input offset voltage, gain error and other factors will bring drift to the final temperature output, sensitivity error and even nonlinear error

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