GaAs video output amplifier for high definition CRT display

摘要

A GaAs video output amplifier for a high definition CRT display has been developed. If it is possible to use a GaAs HEMT which has superior high frequency performance on a video amplifier, wide band design may be realized without increasing power dissipation. As high withstand voltage is required for HEMT, the distance between gate and drain, and the recess length is designed to be long. The ohmic electrode is placed on the mesa. The frequency dispersion characteristic which is a disadvantage of GaAs can be overcome by using SiN{sub}x film as a passivation film of HEMT. Furthermore HEMT is used as a cascode connection circuit. The GaAs video output amplifier on which HEMT is used shows such an excellent high frequency characteristic as frequency band width of 210MHz for power supply voltage of 80V and output voltage amplitude of 40V. The developed amplifier is the most suitable for the high definition CRT display with large screen.