Radio frequency (rf) apparatus

A radio frequency (RF) apparatus that amplifies an RF signal, comprising:

• a semiconductor chip;
• and
• an assembly base that mounts the semiconductor chip thereon in upside down arrangement of a ball grid array,
• wherein the semiconductor chip includes,
• a semiconductor substrate that provides a semiconductor active device therein,
• first to third metal layers stacked on the semiconductor substrate in this order and electrically isolated to each other by an insulating layer,
• a top metal layer provided on a top surface of the insulating layer, the top metal layer including a top ground layer and a pad electrically isolated from the top ground layer by a gap, the pad being connected to the assembly base through a solder ball of the ball grid array,
• a signal line that carries the RF signal to the semiconductor active device or extracts the RF signal from the semiconductor active device,
• a stub line connected to the pad, the stub line has a length shorter than λ/4, where λ is a wavelength subject to the RF signal, and
• an inner ground layer overlapping with the gap between the pad and the top ground layer.