In this paper, a 10-bit 40-MS/s analog-to-digital converter (ADC) is presented. A power consumption of 12 mW was achieved by using a time-interleaved and pipelined architecture with shared operational amplifiers. This circuit was fabricated in a 2.5-V 0.25-/spl mu/m technology with metal-oxide-metal capacitors. Experimental results are within design ranges and are in good agreement with simulation data. It turns out that the proposed Nyquist-rate ADC provides a potential solution for low-power high-speed applications, e.g., wireless LANs.

We have developed a simple model for the carrier capture and escape processes in quantum-well (QW) lasers, which yields an analytical expression for the ratio of the carrier capture and escape times. It predicts a decrease in the escape time with injected carrier density due to the state filling effect. It also shows an exponential dependence of the escape time on the effective barrier height and on the inverse of the temperature. A comparison between experimental and calculated values for InGaAs/GaAs QW lasers is presented showing a good agreement.

An efficient binary collision approximation (BCA) ion implant code with good prediction capabilities for semiconductor materials (Si, GaAs, SiC) with only one fitting parameter for low implantation doses is presented. It includes specific interatomic potentials and recent improvements in physical models for inelastic stopping. A periodic ab initio full bond electron density for the target is used. Damage accumulation is supported using a modified Kinchin–Pease model [G. H. Kinchin and R. S. Pease, Rep. Prog. Phys. 18, 1 (1955)]. Also, some of the BCA integration algorithms and target selection procedure have been refined. An algorithm commonly used for statistical noise reduction has been modified to also improve the noise reduction in the lateral and shallow zones. The agreement with experiments is good, even under channeling conditions and for different target materials. A comparison with experimental secondary ion mass spectroscopy results for several projectiles and targets is presented.

This work introduces a microwave-based system able to detect tumours in breast phantoms in a non-invasive way. The data acquisition system is composed of a hardware system which involves high-frequency components (antennas, switches and cables), a microcontroller, a vector network analyser used as measurement instrument and a computer devoted to the control and automation of the operation of the system. Concerning the software system, the computer runs a Python script which is in charge of mastering and automatising all the required stages for the data acquisition, from initialisation of the hardware system to performing and saving the measurements. We also report on the design of the high-performance broadband antenna used to carry out the measurements, as well as on the algorithm employed to build the final medical images, based on an adapted version of the so-called Improved Delay-and-Sum (IDAS) algorithm improved by a Hamming window filter and averaging preprocessing. The calibration and start-up of the system are also described. The experimental validation includes the use of different tumour models with different dielectric properties inside the breast phantom. The results show promising tumour detection capabilities, even when there is low dielectric contrast between the tumoural and healthy tissues, as is the usual case for dense breasts in young women.

We demonstrate superluminal and negative group velocity regimes in a linear passive Mach–Zehnder interferometer. This phenomenon occurs in a narrow frequency region around the interferometer’s transmission minima. Experiments are performed in the radio frequency range by using coaxial cables and $1\times 2$ wave splitters. Group velocities of $2c$ and tunneling with a maximum fractional advancement of 0.12 were measured for electromagnetic sinusoidal wave packets of $2\mu \text{s}$ width. These results agree with theoretical predictions using the interferometer’s transmission phase function. This system is proposed as a simpler alternative to photonic crystals and active or microstructured multiple-beam interferometers for sustaining anomalous group velocities.