J. Low Power Electron. Appl., Volume 3, Issue 1 (March 2013) – 3 articles , Pages 1-53

Usually Wide Dynamic Range (WDR) sensors that autonomously adjust their integration time to fit intra-scene illumination levels use a separate digital memory unit. This memory contains the data needed for the dynamic range. Motivated by the demands for low power and chip area reduction, we propose a different implementation of the aforementioned WDR algorithm by replacing the external digital memory with an analog in-pixel memory. This memory holds the effective integration time represented by analog encoding voltage (AEV). In addition, we present a “ranging” scheme of configuring the pixel integration time in which the effective integration time is configured at the first half of the frame. This enables a substantial simplification of the pixel control during the rest of the frame and thus allows for a significantly more remarkable DR extension. Furthermore, we present the implementation of “ranging” and AEV concepts on two different designs, which are targeted to reach five and eight decades of DR, respectively. We describe in detail the operation of both systems and provide the post-layout simulation results for the second solution. The simulations show that the second design reaches DR up to 170 dBs. We also provide a comparative analysis in terms of the number of operations per pixel required by our solution and by other widespread WDR algorithms. Based on the calculated results, we conclude that the proposed two designs, using “ranging” and AEV concepts, are attractive, since they obtain a wide dynamic range at high operation speed and low power consumption. Full article

This paper presents an energy-efficient solar energy harvesting and sensing microsystem that harvests solar energy from a micro-power photovoltaic module for autonomous operation of a gas sensor. A fully integrated solar energy harvester stores the harvested energy in a rechargeable NiMH microbattery. Hydrogen concentration and temperature are measured and converted to a digital value with 12-bit resolution using a fully integrated sensor interface circuit, and a wireless transceiver is used to transmit the measurement results to a base station. As the harvested solar energy varies considerably in different lighting conditions, in order to guarantee autonomous operation of the sensor, the proposed area- and energy-efficient circuit scales the power consumption and performance of the sensor. The power management circuit dynamically decreases the operating frequency of digital circuits and bias currents of analog circuits in the sensor interface circuit and increases the idle time of the transceiver under reduced light intensity. The proposed microsystem has been implemented in a 0.18 µm complementary metal-oxide-semiconductor (CMOS) process and occupies a core area of only 0.25 mm². This circuit features a low power consumption of 2.1 µW when operating at its highest performance. It operates with low power supply voltage in the 0.8V to 1.6 V range. Full article

Loop control is an essential area of electronics engineering that today’s professionals need to master. Rather than delving into extensive theory, this practical book focuses on what you really need to know for compensating or stabilizing a given control system. You can turn instantly to practical sections with numerous design examples and ready-made formulas to help you with your projects in the field. You also find coverage of the underpinnings and principles of control loops so you can gain a more complete understanding of the material. This authoritative volume explains how to conduct analysis of control systems and provides extensive details on practical compensators. It helps you measure your system, showing how to verify if a prototype is stable and features enough design margin. Moreover, you learn how to secure high-volume production by bench-verified safety margins. Full article