Enhancement-mode Pseudomorphic High Electron Research Articles

A PHEMT based wideband LNA for wireless applications

This work is about the development of a super low noise amplifier with minimum power consumption and high gain for several wireless applications. The amplifier operates at frequency bands of 0.9–2.4 GHz and can be used in many applications like Wireless local area network (WLAN), WiFi, Bluetooth, ZigBee and Global System for mobile communications (GSM). This new design can be employed for the IEEE 802.15.4 standard in industrial, scientific and medical (ISM) Band. The enhancement mode pseudomorphic high electron mobility transistor PHEMT is used here due to its high linearity, better performance and less noisy operation. The common source inductive degeneration method is employed here to enhance the gain of amplifier. The amplifier produces a gain of more than 17 dB and noise figure of about 0.5 dB. The lower values of S11 and S22 reflect the accuracy of impedance matching network placed at the input and output sides of amplifier. Agilent Advance Design System (ADS) is used for the design and simulation purpose. Further the layout of design is developed on the FR4 substrate.

Performances of CYTOP TM low- k dielectric layer bridged GaAs-based enhancement mode pHEMT for wireless power application

Cyclized-perfluoropolymer, which is commercialized under the trade name CYTOP TM, possesses the desirable properties of low dielectric constant ( ε r = 2.1) and low dissipation factor (tan δ = 0.0007). We have developed a method to integrate CYTOP TM dielectric interlayer with state-of-the-art power GaAs-based enhancement mode pseudomorphic high electron mobility transistor. CYTOP TM thin films with approximately 3.5 μm in thickness was spin-coated and patterned on wafers with completed transistor and nitride passivation processes. Au-based interconnect metal was then fabricated using sputtering and plating processes over the CYTOP TM dielectric layer. The whole integrated structure was found to be stable at annealing temperatures up to 200 °C. Moreover, output power, gain, and power added efficiency of the CYTOP TM-integrated 0.5 μm gate transistor was measured and compared with standard air-bridged devices. The studies show that the CYTOP TM low- k dielectric layer has negligible effect on the device performances as compared with the air-bridged devices.