Nobuyuki Kasai

High-Efficiency and Highly Reliable 20 W GaAs Power Field-Effect Transistor in C Band

This paper describes a high-performance and highly reliable GaAs field-effect transistor (FET) with a new gate structure employing the stepped gate recess combined with a multirefractory metal gate. This gate structure allows the simultaneous increase of maximum channel current and gate-drain breakdown voltage (Vgdo) of the FET and thus improves significantly its output power (Po) and power-added efficiency (ηadd). The resultant high Vgdo with highly stable gate Schottky characteristics and a novel surface stabilization prior to plasma-SiN passivation effectively suppress both catastrophic and gradual failures. The four-chip internally matched device (4×12.6 mm) has delivered Po of 20 W at 1 dB gain compression with 39% ηadd over 3.5 to 4.2 GHz. Sufficient reliability of the 20 W device available for satellite use has been assured by comprehensive reliability tests.

New pseudomorphic N/sup -//N/sup +/ GaAs/InGaAs/GaAs power HEMT with high breakdown voltages

A pseudomorphic N/sup -//N/sup +/GaAs/InGaAs/GaAs power HEMT (high electron mobility transistor) with high breakdown voltages (VB) of more than 20 V and full channel current of 460 mA/mm is described. This power HEMT allows the simultaneous improvement of output power (P/sub out/), linear gain (G/sub L/), and power-added efficiency (N/sub add/) over GaAs FETs. A record maximum output power of 4.7 W at 14.25 GHz was achieved by a large 10.5-mm-wide HEMT chip with G/sub L/ of 8 dB and N/sub add/ of 25%.<<ETX>>