Sökning: "low noise amplifier"
Visar resultat 21 - 25 av 70 avhandlingar innehållade orden low noise amplifier.
Sammanfattning : This thesis describes the development, fabrication, performance and applications of liquid nitrogen cooled voltage amplifiers based on high temperature superconducting quantum interference devices (SQUIDs). The SQUID based voltage amplifier is intended for characterization of electrical and noise properties of devices with resistance around and below 1 Ohm. LÄS MER
Sammanfattning : In recent years all-digital or digitally-intensive RF transmitters (TX) have attracted great attention in both literature and industry. The motivation is to implement RF circuits in a manner suiting advanced nanometer CMOS processes. To achieve that, information is encoded in the time-domain rather than voltage amplitude. LÄS MER
Sammanfattning : Today’s data rates in wired networks can reach 100 Gbit/s using optical fiber while data rates in wireless networks are much lower - tens of Mbit/s for 3G mobile communication and 480 Mbit/s for ultra-wideband (UWB) short range wireless communications. This difference in data rates can mainly be explained by the limited allowed frequency spectrum, the nature of the radio signal and the high requirements imposed on all hardware designed for high speed and wideband wireless communications. LÄS MER
Sammanfattning : The modern small devices of today require cheap low power radio frequency (RF) transceivers that can provide reliable connectivity at all times. In an RF transceiver, the analog-to-digital converter (ADC) is one of the most important parts and it is also one of the main power consumers. LÄS MER
25. Radio Frequency Systems for NMR Imaging: Coil Development and Studies of Non-Thermal Biological Effects
Sammanfattning : This thesis concerns both design and optimization of NMR imaging systems and studies on non-thermal biological effects of electromagnetic fields. These two research fields are linked together by the fact that humans are subject to static and pulsed magnetic fields as well as to magnetic radio frequency fields (RF) during an NMR imaging investigation. LÄS MER