At EDI CON China 2016 Thomas W. Crowe, President of Virginia Diodes Inc. gave Microwave Journal an insight into the company’s background, its focus on very high frequencies, its current activities in China and future technology developments.
This paper explains the pulsed RF operation of Microsemi pulsed GaN HEMT RF power transistors using as an example the 1011GN-700ELM 1030 MHz Mode-S Enhanced Message Length (ELM) avionics device. General descriptions are presented detailing both the pulsed gate bias operation and the bias sequencing operation of the pulser circuit used on the Microsemi evaluation test fixtures.
This paper explains the pulsed RF operation of Microsemi pulsed GaN HEMT RF power transistors using as an example the 1011GN-700ELM 1030 MHz Mode-S Enhanced Message Length (ELM) avionics device. General descriptions are presented detailing both the pulsed gate bias operation and the bias sequencing operation of the “pulser” circuit used on the Microsemi evaluation test fixtures.
Dual-polarity supplies are commonly needed to operate
electronics such as op amps, drivers, or sensors,
but there is rarely a dual-polarity supply available at
the point of load. The LTCÃÂ®3260 is an inverting charge
pump (inductorless) DC/DC converter with dual low
noise LDO regulators that can produce positive and
negative supplies from a single wide input (4.5V to
32V) power source. It can switch between high efficiency
Burst ModeÃÂ® operation and low noise constant
frequency mode, making it attractive for both portable
and noise-sensitive applications.
Ever-increasing demands for faster product launch times, higher performance, lower part counts and reduced costs create RF system design challenges. This paper focuses on how the latest gallium nitride (GaN) products, specifically discrete transistors, amplifiers and switches, offer design engineers enhanced flexibility and performance options by reducing RF board space and system prime power requirements.
A system that utilizes OFDM/OFDMA, such as the E-UTRA (LTE) downlink or the IEEE 802.11a/g and the IEEE 802.16 physical
layers, transmits OFDM symbols, each comprising a number of modulated sub-carriers carrying data or pilot symbols, with
inter-subcarrier spacing being equal to or an integer multiple of a fixed frequency. The channel bandwidth (B) is determined by
the number of 'occupied' (modulated) subcarriers and the subcarrier spacing.
There are several options for the architecture of the transmit signal path. The factors that impact transmit signal elements are introduced, followed by a discussion of the different architectures. Figure 1 shows a direct conversion architecture for an initial point of reference only. Section 6 of 3GPP TS 25.105 describes the transmit signal requirements used throughout this discussion.
The next frequency frontier is the millimeter wave (mm-wave) band, which occupies the 30 GHz to 300 GHz spectrum (wavelengths from 10 to 1 mm). Emerging applications now span radio astronomy, communication, imaging, space research, and homeland security, and are starting to seriously populate this vast spectrum resourse. Market forecast and limited available spectrum suggest that attractive growth is just over the horizon so explorers are naturally migrating to stake their claim in this next frontier.
The small-signal nonlinear distortion of a system can be described with sufficient accuracy using a third order Volterra expansion
of the output in terms of the input. This simple model assumes a memoryless, frequency independent amplifier system, whereby the amplifier characteristics remain constant over the operation bandwidth or, stated equivalently, the operation bandwidth is small compared with the available amplifier system bandwidth....