A low power integrated temperature sensor with digital outputsfor on-chip temperature monitoring applications

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: ÖZGE TURAN

Danışman: TAYFUN AKIN

Özet:

This thesis presents the design and implementation of a low power temperature sensor with digital outputs for on-chip temperature monitoring applications. The temperature sensor is based on the substrate bipolar transistor which generates the bandgap reference voltage and proportional to absolute temperature (PTAT) voltage. The bandgap reference voltage is temperature and supply independent thus it is used to generate the reference signals for Analog to Digital Converter (ADC), while the PTAT voltage generated by the temperature sensor is connected to the input of the ADC. The ADC is implemented with a Successive Approximation Register (SAR) ADC, which converts the analog temperature signal to a 12-bit digital data. The SAR ADC with a split capacitive array Digital to Analog Converter (DAC) is chosen for low power and low area advantages for medium resolution applications. All the bias voltages and bias currents are generated with respect to the reference currents that are generated from the bandgap voltage. The configuration of the bias signals and operation specifications are all configurable through the Serial Programming Interface (SPI). The digital controller provides the communication with external electronics through SPI, controlling the process parameters via configuration memory and on-chip calibration. The on-chip calibration is designed to compensate the errors coming from predominantly small temperature variations of the ADC bias voltages generated in the bias generator, ADC noise, comparator offset voltage, and nonlinearity of PTAT voltage. The output data format is a serial 12-bit data generated by the output serializer block. The number of output pads decreased by a serializer block, reducing the required power and area. The external pins include only power and SPI communication pins. The operation region of the temperature sensor is between -55 ºC to 125 ºC. A resolution of 0.08 ºC is achieved by the 12-bit SAR ADC. The total power consumption of the full chip is at most 2 mW with a 3.3 V power supply. The full chip is designed and implemented using a 0.35 μm CMOS process in an area of the 2 mm × 2 mm, and it is submitted to a multi-project wafer (MPW) run for fabrication.