The AP2406 is a 1.5Mhz constant frequency, slope compensated current mode PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. It is ideal for powering portable equipment that runs from a single cell lithium-Ion (Li+) battery. The AP2406 can supply 600mA of load current from a 2.5V to 5.5V input voltage. The output voltage can be regulated as low as 0.6V. The AP2406 can also run at 100% duty cycle for low dropout operation, extending battery life in portable system. Idle mode operation at light loads provides very low output ripple voltage for noise sensitive applications.
The AP2406 is offered in a low profile (1mm) 5-pin, thin SOT package, and is available in an adjustable version and fixed output voltage of 1.2V, 1.5V and 1.8V
The SP2526A device is a dual +3.0V to +5.5V USB Supervisory Power Control Switch ideal
for self-powered and bus-powered Universal Serial Bus (USB) applications. Each switch has
low on-resistance (110mΩ typical) and can supply 500mA minimum. The fault currents are
limited to 1.0A typical and the flag output pin for each switch is available to indicate fault
conditions to the USB controller. The thermal shutdown feature will prevent damage to the
device when subjected to excessive current loads. The undervoltage lockout feature will
ensure that the device will remain off unless there is a valid input voltage present.
High-Speed, Low-Power
Dual Operational Amplifier
The AD826 features high output current drive capability of
50 mA min per amp, and is able to drive unlimited capacitive
loads. With a low power supply current of 15 mA max for both
amplifiers, the AD826 is a true general purpose operational
amplifier.
The AD826 is ideal for power sensitive applications such as video
cameras and portable instrumentation. The AD826 can operate
from a single +5 V supply, while still achieving 25 MHz of band
width. Furthermore the AD826 is fully specified from a single
+5 V to ±15 V power supplies.
The AD826 excels as an ADC/DAC buffer or active filter in
data acquisition systems and achieves a settling time of 70 ns
to 0.01%, with a low input offset voltage of 2 mV max. The
AD826 is available in small 8-lead plastic mini-DIP and SO
packages.
This book gives a comprehensive overview of the technologies for the advances of
mobile radio access networks. The topics covered include linear transmitters,
superconducting filters and cryogenic radio frequency (RF) front head, radio over
fiber, software radio base stations, mobile terminal positioning, high speed
downlink packet access (HSDPA), multiple antenna systems such as smart
antennas and multiple input and multiple output (MIMO) systems, orthogonal
frequency division multiplexing (OFDM) systems, IP-based radio access networks
(RAN), autonomic networks, and ubiquitous networks.
Employing multiple transmit and receive antennas, namely using multi-input multi-output
(MIMO) systems, has proven to be a major breakthrough in providing reliable wireless
communication links. Since their invention in the mid-1990s, transmit diversity, achieved
through space-time coding, and spatial multiplexing schemes have been the focus of much
research in the area of wireless communications.
Multiple-Input Multiple-Output (MIMO) systems have recently been the
subject of intensive consideration in modem wireless communications as they
offer the potential of providing high capacity, thus unleashing a wide range of
applications in the wireless domain. The main feature of MIMO systems is the
use of space-time processing and Space-Time Codes (STCs). Among a variety
of STCs, orthogonal Space-Time Block Codes (STBCs) have a much simpler
decoding method, compared to other STCs
Multiuser multiple-input-multiple-output (MU-
MIMO) systems are known to be hindered by dimensionality
loss due to channel state information (CSI) acquisition overhead.
In this paper, we investigate user-scheduling in MU-MIMO
systems on account of CSI acquisition overhead, where a base
station dynamically acquires user channels to avoid choking the
system with CSI overhead.
The writing of this book was prompted by two main developments in wireless
communications in the past decade. First is the huge surge of research activities in
physical-layer wireless communication theory. While this has been a subject of study
since the 60’s, recent developments in the field, such as opportunistic and multi-input
multi-output (MIMO) communication techniques, have brought completely new per-
spectives on how to communicate over wireless channels.
To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation
(5G) mobile communication systems has been undertaken in recent years. It is expected that the spectral and energy
efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation
(4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing
of multiple antennas. In the last twenty years, multiple-input multiple-output (MIMO) antenna techniques have been
considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale
antenna array (which is also called massive MIMO) is equipped in a base-station, or a large number of distributed
antennas (which is also called large-scale distributed MIMO) are deployed, the spectral and energy efficiencies can
be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO
and large-scale distributed MIMO systems, including spectral efficiency analysis, channel state information (CSI)
acquisition, wireless transmission technology, and resource allocation.
