| 摘要 |
PROBLEM TO BE SOLVED: To increase the gain of an FET unit and to obtain the maximum output, by forming a slit widely which exposes the back surface of a source- electrode bus at a source-electrode-bus lower substrate, providing a state wherein the slit is filled in a through-hole or a conductor, and setting the grounding potential near each unit gate electrode. SOLUTION: A slit 46, having the opening slenderly extending in the expanding direction of a source electrode bus 45, is formed at a lower substrate 35 of a source electrode bus 45. The back surface of the source electrode bus 45 is exposed. A conductor layer 47 is provided at the inner wall of the slit 46. As a result, a unit source electrode 41 is electrically connected to a grounding layer 36 through the source electrode bus 45 and the conductor layer 47. The distance from the unit source electrode 41 at each unit cell 43 to the grounding layer 36 becomes approximately equal. The grounding distance of each unit cell 43 becomes short and approximately equal, and equal impedance is obtained. Therefore, the dispersion of the gains between the unit cells is decreased.
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