This paper describes a highly linear Low Noise Amplifier (LNA) exhibiting a flexible linearity profile intended as a way to meet future flexible mobile communications standards. This has the potential of inclusion in Ad-hoc Software Defined Radio (SDR) networks where a frequency hand and modulation scheme can be chosen based on the characteristics of the frequency spectrum and user requirements...

–High power efficiency is an important requirement in cellular transmitter radios. OFDM systems require very linear transmission because of high peak-to-average-power-ratio (PAPR). However, linear power amplifiers (PA) have very low efficiency. To enhance the power efficiency, non-linear PAs are applied and even forced to work near the saturation point. This generates inevitably huge non-linear...

All transistor circuits introduce distortion. In Radio Frequency (RF) circuits, the third-order distortion components are the most important. The quest for more linear circuits has become more important with complex-modulation as used in modern cellular phone systems. Quinn’s Cascomp Amplifier, first reported in the 1970s, promises ideal linearity and can deliver close to that promise. We revie...

Linear behaviour of bootstrap switches is of critical importance in low-voltage analogue circuits and understanding the major factors affecting the linearity helps design a better switch. This study presents a theoretical approach for evaluating the distortion of bootstrap switches in the frequency domain based on the Volterra series. Five major factors affecting the linearity of the bootstrap ...

Non-linearity in the human ear can cause audible distortion not present in the original signal. Such distortion is generated within the ear by inter-modulation of a spectral complex, itself containing possible masked components. When psychoacoustic codecs remove these supposedly masked components, the in-ear-generated distortion is also removed, and so our listening experience is modified. In t...

As an extension of previous work on computer-generated phantoms, more accurate, realistic phantoms are generated by integrating image distortion and signal loss caused by susceptibility variations. With the addition of real motions and activations determined from actual functional MRI studies, these phantoms can be used by the fMRI community to assess with higher fidelity pre-processing algorit...

Practical laser speckle contrast analysis systems face a problem of spatial averaging of speckles, due to the pixel size in the cameras used. Existing practice is to use a system factor in speckle contrast analysis to account for spatial averaging. The linearity of the system factor correction has not previously been confirmed. The problem of spatial averaging is illustrated using computer simu...

In echo-planar imaging (EPI), such as commonly used for functional MRI (fMRI) and diffusion-tensor imaging (DTI), compressed distortion is a more difficult challenge than local stretching as spatial information can be lost in strongly compressed areas. In addition, the effects are more severe at ultra-high field (UHF) such as 7T due to increased field inhomogeneity. To resolve this problem, two...

In the field of computer aided celiac disease diagnosis, wide-angle endoscopy lenses are employed which introduce significant barrel type distortions. Although the images can be rectified using distortion correction methods, computer based diagnosis suffers from missing information in highly distorted image regions. First, we investigate the impact of simple and advanced interpolation technique...

The topographic mapping products of airborne light detection and ranging (LiDAR) are usually required in the national coordinates (i.e., using the national datum and a conformal map projection). Since the spatial scale of the national datum is usually slightly different from the World Geodetic System 1984 (WGS 84) datum, and the map projection frame is not Cartesian, the georeferencing process ...