A Low-Power Dual-Frequency RF Front-End Architecture for GNSS Receivers

With the availability in the years to come of several new Global Navigation Satellite Systems transmitting signals located in different frequency bands, the question of the feasibility of multi-frequency receivers aimed at the mass market is of major interest. Most solutions proposed today either use single-frequency receivers in parallel or directly sample the signals at the antenna, two solutions which are not applicable to the mass market. In this paper, a dual-frequency RF front-end architecture with a similar power-consumption and complexity as current state-of-the-art single-frequency front-ends is proposed. It is based on a super-heterodyne architecture and exploits the fact that the L1C/A and L2C signals only occupy 2 MHz of the 20 MHz L1 and L2 bands to allow the simultaneous acquisition and tracking of both the L1C/A and L2C signals

A ferrofluid micropump for lab-on-a-chip applications

A disposable micropump is presented that uses the piston actuation principle and relies on the magnetic properties of a ferrofluid, a colloidal suspension of nanosize ferromagnetic particles. The cost effective micropump consists of 7 bonded layers of polymethylmetacrylate (PMMA) that are either micromachined or structured by powder blasting. Two silicone check-valves are also integrated in the microchip. External dimensions of our prototype are 36 mm x 22 mm x 5 mm. The magnetic liquid plug is externally actuated by a motorized permanent magnet. Water has been successfully pumped at a flow rate of 30 µL/min without backpressure; pumping is demonstrated up to a backpressure of 25 mbar

A Versatile 1.4-mW 6-bits CMOS ADC for Pulse-Based UWB Communication Systems

An Analog to Digital Converter (ADC) using the low duty-cycle nature of pulse-based Ultra Wide-Band (UWB) communications to reduce its power consumption is proposed. Implemented in CMOS 180 nm technology, it can capture a 5 ns window at 4 GS/s each 100 ns, which corresponds to the acquisition of one UWB pulse at the pulse repetition rate of 10 mega pulses per second (Mpps). By using time-interleaved Redundant Signed Digit (RSD) ADCs, the complete ADC occupies only 0.15 mm2 and consumes only 1.4 mW from a 1.8 V power supply. The ADC can be operated in two modes using the same core circuits (operational transconductance amplifier, comparators, etc.). The first mode is the standard RSD doubling mode, while the second mode allows improving the signal-to-noise ratio by adding coherently the transmitted pulses of one symbol. For example, for audio applications, a 300 kbps data rate and processing gain up to 15 dB can be achieved at a clock frequency of 10 MHz

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed