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An integrated CMOS-compatible Pirani vacuum sensor system has been developed in this paper, which consists of a tungsten microhotplate array with four same microhotplates in series, a constant current circuit, an 8-b A/D converter, and a digital interface. With a tiny amount of the external components, a gas pressure between 10-1 and 105 Pa can be sampled, digitized, and real-time displayed by a LED. It can also be transferred to an external process unit, which makes it suitable for application in a gas pressure control system. The sensor system is implemented in a 0.5-μm CMOS process. When the sensor system works at 5-V voltage and 2.5-MHz clock input, the total power consumption is 350 mW, and the temperature increase of each microhotplate is 35°C.