–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...

A project to build a GPS receiver using an FPGA for base-band processing began in 2004. The new receiver platform uses a commonly available RF front end ASIC to convert the GPS signals to a suitable IF. The digital design for baseband processing is normally a reasonably straight forward task. However, because the received GPS signals are at such low levels this presents some challenges. One of ...

Most communication system contains an RF front end which performs signal processing with RF filters. Micro strip filters are a low cost means of doing this. This paper describes the design of low cost and low insertion loss microstrip stepped impedance Fractal low pass filter (LPF) by using microstrip layout which works at 0.4 GHz for permittivity 4.7 value with a substrate thickness 1.6 mm wit...

In RF power device design, much of the analysis is based on measurements. Complete analysis by simulation is often avoided because the high-frequency, largesignal operation makes device simulation unsuitable, and the difficulties in obtaining a good physical compact model make circuit simulation inaccurate. This work presents a methodology that overcomes these limitations by utilizing a combina...

Heavy beam loading in the PEP-II B Factory along with large ring circumferences places unique requirements upon the low-level RF (LLRF) system. RF feedback loops must reduce the impedance observed by the beam while ignoring the cavity transients caused by the ion clearing gap. Special attention must be placed on the cavity tuner loops to allow matching the ion clearing gap transients in the hig...

Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio prop...

RF-ID systems are susceptible to frequency interference from other communciation systems particularly when the RF-ID tags transmit on a fixed carrier frequency. The RF-ID systems are less vunerable to frequency interference when frequency diversity is used by the RF-ID system. This paper proposes an architecture for an RF-ID receiver which allows a number of active RF-ID tags with oscillators o...