Fernando Rangel de Sousa

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Most of the new generation compact models for the MOSFET have many commonalities since they are based on the same main approximations: gradual channel, charge-sheet, and depletion charge linearization. In this study we show that if we include some additional physics-consistent conditions for the MOSFET equations we obtain a very compact model that we call(More)
—Human body communication (HBC) is a communication technology that uses the body of a person as a channel to propagate signals. Many characteristics of HBC present advantages over the most common radiation-based methods, which makes it an interesting alternative to implement the emergent body area networks. The characterization of the HBC channel presented(More)
—In this paper, we present a MOSFET-based Colpitts oscillator based on a " zero-threshold " transistor operating at a supply voltage below 20 mV. The circuit was carefully analyzed and expressions relating the start-up conditions and the voltage supply, as well as the oscillation frequency were developed. Measurement results obtained on a discrete prototype(More)
—In this paper we present the design of a wireless power receiver fully integrated. The circuit was constrained to occupy a silicon area of 1.5 mm × 1.5 mm in a 0.18 µm RF-CMOS process. The main target was to optimize the part of the power transfer efficiency concerning only the receiver side. In that way, we optimized the quality factor of the integrated(More)
— Increasing interest in wireless body area networks has created the need for alternative communication schemes. One example of such schemes is the use of the human body as a communication medium. This technology is called human body communication (HBC) and it offers advantages over the most common radiation-based methods, which makes it an interesting(More)
This paper presents the design of a power amplifier integrated in a CMOS 180 nm technology, which is intended to drive an inductive link operating at 990 MHz. A class-D topology is employed to avoid the use of inductors. A design methodology is proposed to find the optimal transistor width, solving the trade-off between the ON-resistance and gate(More)
— This paper presents an oscillator design technique for low-power applications. The circuit is based on the common-gate Colpitts oscillator with additional positive feedback provided by an inductive gate degeneration. This technique decreases the required transconductance to start-up oscillations, which makes possible to reduce the power consumption. Two(More)
Continuous patient monitoring enables early detection and treatment of diseases. Small and wireless devices are more comfortable to the patient and simplify the implantation procedure. This paper presents the design and partial testing of an integrated RF-powered temperature sensor suitable for the human body temperature range, from 35 to 42 o C. The device(More)