M.M. Mojarradi

Bio: M.M. Mojarradi is an academic researcher from California Institute of Technology. The author has contributed to research in topics: Transistor & CMOS. The author has an hindex of 13, co-authored 49 publications receiving 500 citations.

Investigation of the four-gate action in G/sup 4/-FETs

Abstract: The four-gate silicon-on-insulator transistor (G/sup 4/-FET) combines MOS and JFET actions in a single transistor to control the drain current. The various operation modes of the G/sup 4/-FET are analyzed, based on the measured current-voltage, transconductance and threshold characteristics. The main parameters (threshold voltage, swing, mobility) are extracted and shown to be optimized for particular combinations of gate biasing. Numerical simulations are used to clarify the role of volume or interface conduction mechanisms. Besides excellent performance (such as subthreshold swing and transconductance) and unchallenged flexibility, the new device has the unique feature to allow independent switching by its four separate gates, which inspires many innovative applications.

Low-frequency noise in SOI four-gate transistors

Abstract: Low-frequency noise characteristics of the silicon-on-insulator four-gate transistor [G/sup 4/-field-effect transistor] are reported. The noise power spectral density as a function of biasing conditions is presented and compared for surface and volume conduction modes. It is shown that, for the same drain current, the volume of the transistor generates less noise than its surface. The possible transition from carrier-number fluctuations to mobility fluctuations as the conducting channel is moved away from the surface toward the volume is also discussed.

The Four-Gate Transistor

Abstract: The four-gate transistor or G4-FET combines MOSFET and JFET principles in a single SOI device. Experimental results reveal that each gate can modulate the drain current. Numerical simulations are presented to clarify the mechanisms of operation. The new device shows enhanced functionality, due to the combinatorial action of the four gates, and opens rather revolutionary applications.

Four-Gate Transistor Voltage-Controlled Negative Differential Resistance Device and Related Circuit Applications

Abstract: A novel voltage-controlled negative differential resistance device, using complementary SOI Four-Gate Transistors (G4-FETs) is presented Innovative LC oscillator and Schmitt trigger circuits based on the G4-FET NDR device are experimentally demonstrated

Powering MEMS portable devices—a review of non-regenerative and regenerative power supply systems with special emphasis on piezoelectric energy harvesting systems

Abstract: Power consumption is forecast by the International Technology Roadmap of Semiconductors (ITRS) to pose long-term technical challenges for the semiconductor industry. The purpose of this paper is threefold: (1) to provide an overview of strategies for powering MEMS via non-regenerative and regenerative power supplies; (2) to review the fundamentals of piezoelectric energy harvesting, along with recent advancements, and (3) to discuss future trends and applications for piezoelectric energy harvesting technology. The paper concludes with a discussion of research needs that are critical for the enhancement of piezoelectric energy harvesting devices.

Prognostics and health management of electronics

Abstract: There has been a growing interest in monitoring the ongoing "health" of products and systems in order to predict failures and provide warning to avoid catastrophic failure. Here, health is defined as the extent of degradation or deviation from an expected normal condition. While the application of health monitoring, also referred to as prognostics, is well established for assessment of mechanical systems, this is not the case for electronic systems. However, electronic systems are integral to the functionality of most systems today, and their reliability is often critical for system reliability. This paper presents the state-of-practice and the current state-of-research in the area of electronics prognostics and health management. Four current approaches include built-in-test (BIT), use of fuses and canary devices, monitoring and reasoning of failure precursors, and modeling accumulated damage based on measured life-cycle loads. Examples are provided for these different approaches, and the implementation challenges are discussed.

Wireless Charging Technologies: Fundamentals, Standards, and Network Applications

Abstract: Wireless charging is a technology of transmitting power through an air gap to electrical devices for the purpose of energy replenishment. The recent progress in wireless charging techniques and development of commercial products have provided a promising alternative way to address the energy bottleneck of conventionally portable battery-powered devices. However, the incorporation of wireless charging into the existing wireless communication systems also brings along a series of challenging issues with regard to implementation, scheduling, and power management. In this paper, we present a comprehensive overview of wireless charging techniques, the developments in technical standards, and their recent advances in network applications. In particular, with regard to network applications, we review the static charger scheduling strategies, mobile charger dispatch strategies and wireless charger deployment strategies. Additionally, we discuss open issues and challenges in implementing wireless charging technologies. Finally, we envision some practical future network applications of wireless charging.

Prognostics and Health Management of Electronics

Abstract: Reliability is the ability of a product or system to perform as intended (i.e., without failure and within specified performance limits) for a specified time, in its life-cycle environment. Commonly used electronics reliability prediction methods (e.g., Mil-HDBK-217, 217-PLUS, PRISM, Telcordia, FIDES) based on handbook methods have been shown to be misleading and provide erroneous life predictions. The use of stress and damage models permits a far superior accounting of the reliability and the physics of failure (PoF); however, sufficient knowledge of the actual operating and environmental application conditions of the product is still required. This article presents a PoF-based prognostics and health management approach for effective reliability prediction. PoF is an approach that utilizes knowledge of a product's life-cycle loading and failure mechanisms to perform reliability modeling, design, and assessment. This method permits the assessment of the reliability of a system under its actual application conditions. It integrates sensor data with models that enable in situ assessment of the deviation or degradation of a product from an expected normal operating condition and the prediction of the future state of reliability. This article presents a formal implementation procedure, which includes failure modes, mechanisms, and effects analysis, data reduction and feature extraction from the life-cycle loads, damage accumulation, and assessment of uncertainty. Applications of PoF-based prognostics and health management are also discussed. Keywords: reliability; prognostics; physics of failure; design-for-reliability; reliability prediction

1/f Noise Sources

Abstract: This survey deals with 1/f noise in homogeneous semiconductor samples. A distinction is made between mobility noise and number noise. It is shown that there always is mobility noise with an /spl alpha/ value with a magnitude in the order of 10/sup -4/. Damaging the crystal has a strong influence on /spl alpha/, /spl alpha/ may increase by orders of magnitude. Some theoretical models are briefly discussed none of them can explain all experimental results. The /spl alpha/ values of several semiconductors are given. These values can be used in calculations of 1/f noise in devices. >