Temperature sensor integrated on CMOS image sensor and control method thereof

Abstract

The invention discloses a temperature sensor integrated on a CMOS image sensor and a control method thereof. The temperature sensor comprises a temperature-to-voltage module and a single-integral ADCmodule. The temperature-to-voltage conversion module comprises a proportional current generation circuit; the proportional current generation circuit converts a current source into two paths of bias currents with a fixed proportion; the bias currents are iput into collectors of two NPN-type bipolar transistors in the core temperature sensing module, base-emitter voltages of the two NPN-type bipolar transistors are respectively input into the single-integral ADC module after being sampled by the switched capacitor amplifier, and the single-integral ADC module quantizes and outputs sampled nd amplified analog voltage values. According to the control method of the temperature sensor, a method of twice sampling and twice conversion is adopted, and the precision of the on-chip temperature sensor is improved on the premise of not increasing the complexity of a circuit.

Description

technical field [0001] The invention belongs to the field of sensors, and relates to a temperature sensor integrated in a CMOS image sensor and a control method thereof. Background technique [0002] Temperature is an important parameter affecting the performance of integrated circuits, especially analog integrated circuits. In a CMOS image sensor, changes in ambient temperature will affect ambient noise, dark current of devices, and thermal noise. In order to monitor the influence of the temperature on the dark current in the chip and improve the reliability of the system, an integrated temperature sensor is mostly used at present. At present, the main implementation methods of CMOS on-chip temperature sensors can be divided into three categories: voltage temperature sensors, which convert temperature signals into digital values ​​using voltage power sources and voltage ADCs that vary with temperature; frequency temperature sensors, where the output frequency of the sensor...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of insufficient detection accuracy of the temperature sensor integrated in the CMOS image sensor in the prior art, to provide a temperature sensor integrated in the CMOS image sensor and its control method, and to sample twice at the output end of the temperature sensing module Output voltage value, convert the voltage value sampled for the first time into a digital code and then take the complement code, and set the obtained complement code as the initial value of the digital code in the second analog-to-digital conversion process, eliminating the offset voltage of the operational amplifier , circuit noise and the influence of the offset voltage of the analog-to-digital converter, and improve the accuracy of the on-chip temperature sensor without increasing the complexity of the circuit

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