Ahmed A. Helmy

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In this paper, a CMOS on-chip sensor is presented to detect dielectric constant of organic chemicals. The dielectric constant of these chemicals is measured using the oscillation frequency shift of an LC voltage-controlled oscillator (VCO) upon the change of the tank capacitance when exposed to the liquid. To make the system self-sustained, the VCO is(More)
A highly sensitive CMOS-based sensing system is proposed for permittivity detection and mixture characterization of organic chemicals at microwave frequencies. The system determines permittivity by measuring the frequency difference between two voltage-controlled oscillators (VCOs); a sensor oscillator with an operating frequency that shifts with the change(More)
This paper presents a state-of-the-art distributed amplifier with coupled inductors in the gate line. The proposed coupled inductors, in conjunction with series-peaking inductors in cascode gain stages, provide bandwidth extension with flat gain response for the amplifier without any additional power consumption. On the other hand, gate-inductor coupling(More)
A wideband low-noise amplifier (LNA), which is a key block in the design of broadband receivers for multiband wireless communication standards, is presented in this paper. The LNA is a fully differential common-gate structure. It uses multiple feedback paths, which add degrees of freedom in the choice of the LNA transconductance to reduce the noise figure(More)
In this paper, a miniaturized broadband dielectric spectroscopy system is presented for permittivity detection, chemical sensing, and mixture characterization for 1-8-GHz frequency range. A sensing capacitor exposed to the material under test (MUT) is part of a true time-delay (TTD) cell excited by a microwave signal at the sensing frequency of interest.(More)
A new broadband low-noise amplifier (LNA) is proposed in this paper. The LNA utilizes a composite NMOS/PMOS cross-coupled transistor pair to increase the amplification while reducing the noise figure. The introduced approach provides partial cancellation of noise generated by the input transistors, hence, lowering the overall noise figure. Theory,(More)
This paper presents an integrated sensing system for complex dielectric spectroscopy in the 0.62-10 GHz frequency range. A capacitive sensor exposed to the material under test (MUT) shows variations in its admittance according to the complex permittivity of MUT. The sensing capacitor along with a fixed capacitor forms a voltage divider circuit and is(More)
This paper presents two novel ultra-wideband (UWB) true-time-delay beam-forming receiver architectures to reduce the size of the receiver compared to the reported beam-forming receivers. Size reduction is due to lowering the total amount of delay by half and employing a negative feedback loop in the receiver. The proposed systems are analyzed to investigate(More)
In this paper, a miniaturized broadband dielectric spectroscopy system is presented for complex permittivity detection of organic chemicals in the 0.5-3-GHz frequency range. A sensing capacitor exposed to a material under test exhibits changes in its capacitance and resistance according to the complex permittivity. The sensing capacitor is embedded inside a(More)
The past few years have witnessed unprecedented growth of the Internet. Several new service models have been introduced since. In particular, the advent of the IP multicast technology has contributed to the success of the Internet as a medium for wide-area group communication. Multicast protocols support an important class of applications ranging from(More)