Development of GaN based High Electron Mobility Transistors for L to C Band Amplifier by Mitsubishi Electric
The most commonly used power amplifier today are based on gallium arsenide (GaAs) used in microwave transmitters, however gallium nitride (GaN) based amplifiers are gaining market attention due to their high breakthrough voltage and high saturated electron speed, resulting in building High Electron Mobility Transistors (HEMT) that are higher in power density contributing to energy saving, while making the transmitter more compact in size and lightweight with an expanded operating life cycle. Based on this Mitsubishi Electric has made an announcement on development of new GaN based HEMT with 10W, 20W and 40W outputs ideal for L and C band (0.5 -6 GHz) amplifiers. Read more
Development of High Electron Mobility Transistor for Millimeter Band Receivers by FUJITSU
Millimeter-wave signals are ideal for transmitting large volumes of data which can exceeds several gigabits per second, where high-capacity millimeter-band transmission equipment can alternatively be used in place of trunk lines in places where is difficult to lay fiber-optic cables. Furthermore, the permeable characteristic of radio waves in the millimeter-band frequency range extending from 30 GHz to 300 GHz can greatly boost the image capture capability of image sensors, where they can travel through thin walls and fabric. However, to make a millimeter-band transceiver highly sensitive in the high electron mobility transistor (HEMT) which is used in the transceiver’s amplifier, it would be necessary to control the noise that is generated along the side of high signal amplification rates. Read more
Development of World’s First Gallium-Nitrate HEMT for power supply by Fujitsu
Power loss as heat in current power supplies used in today’s electronic hardware accounts for 30% or more of the total power consumed by the device. Furthermore, wasted heat creates the need for additional cooling equipment resulting in a ripple effect of increased power consumption.
The power supplies take the alternating-current (AC) power from a wall outlet and convert it to the stabilized direct-current (DC) power that electronics require. The AC power from the public utility companies features an erratic behavior making it necessary to first stabilize and then reduce the voltage before converting it to DC power. The devices that are responsible for this voltage reduction are transistors which are capable of switching between a state that passes current and one that blocks the current using the resulting high-frequency AC power. The power supply typically use silicon transistors but such transistors suffer from some power loss which is known as “on-state loss” when passing current as well as considerable amount of power loss during switching between ON and OFF states known as “switching loss” contributing to 30% of total power loss in a power supply. Normally, “on-state loss” caused when a transistor is ON and the “switching loss” occurs when switching from an ON state to an OFF state contributing to a power loss which increases when switching speed is slow. One effective solution to over come the “on-state loss” is use of transistors which are made of high breakdown-voltages such as Gallium-Nitrate HEMT (High electron mobility transistor). GaN HEMTs transistors have less than one-fifth the on-state loss of silicon transistors plus an excellent high-speed characteristic resulting in switching losses of less than 1% of those of silicon transistors. Current power supplies used in products such as PCs, home appliances and automobiles demand a complete current-interruption in stand-by mode, in which no voltage is being applied to the gate electrodes. Read more
