2 research outputs found

    A 250mV sub-threshold asynchronous 8051microcontroller with a novel 16T SRAM cell for improved reliability in 40nm CMOS

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    Asynchronous approach for digital systems is a way to resolve increased timing uncertainty with technology scaling since timing issue is eliminated in asynchronous systems. This paper presents a sub-threshold operating asynchronous 8051 microcontroller (A8051) with a novel 16T SRAM cell for improved reliability in asynchronous systems. This A8051, adopting a 4-phase dual-rail protocol, can operate up to 250 mV. A8051 has 67.53 μs as a critical path delay with 91.6 nW power consumption at 250 mV, which is equivalent to 12.88 kHz in synchronous systems. At 1.0 V, the delay of a critical path of A8051 microcontroller is 5.74 ns, which is equivalent to 151.55 MHz, with 8.98 mW power consumption. The proposed 16T SRAM cell is applied in memory blocks. The 16T SRAM structure eliminates charge contentions between devices during read and write operations so that SRAM can be operated fully in static mode, bringing about improved write margin (WM). The WM of this 16T SRAM cell is 1.81 times greater than the conventional 6T SRAM cell and 1.58 times better than 8T SRAM cell. At 250 mV, the SNM of SRAM cell is 12.5 mV under process and mismatch variations. Write delay of the asynchronous SRAM block is 4.02 μs (equivalent to 248.5 kHz) with 5.44 pJ energy dissipation, while read delay is 12.61 μs (equivalent to 79.3 kHz) with 9.08 pJ energy dissipation

    Ultra Low-power Wireless Sensor Node Design for ECG Sensing Applications

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    Ubiquitous computing, such as smart homes, smart cars, and smart grid, connects our world closely so that we can easily access to the world through such virtual infrastructural systems. The ultimate vision of this is Internet of Things (IoT) through which intelligent monitoring and management is feasible via networked sensors and actuators. In this system, devices transmit sensed information, and execute instructions distributed via sensor networks. A wireless sensor network (WSN) is such a network where many sensor nodes are interconnected such that a sensor node can transmit information via its adjacent sensor nodes when physical phenomenon is detected. Accordingly, the information can be delivered to the destination through this process. The concept of WSN is also applicable to biomedical applications, especially ECG sensing applications, in a form of a sensor network, so-called body sensor network (BSN), where affixed or implanted biosignal sensors gather bio-signals and transmit them to medical providers. The main challenge of BSN is energy constraint since implanted sensor nodes cannot be replaced easily, so they should prolong with a limited amount of battery energy or by energy harvesting. Thus, we will discuss several power saving techniques in this thesis.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137081/1/hesed_1.pd
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