A Ka‐Band GaN low‐noise amplifier monolithic microwave integrated circuit using external source interconnect for gate‐side parasitic suppression

Abstract This paper presents a Ka‐band low‐noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) using a GaN high‐electron‐mobility transistor (HEMT) structure designed to minimize gate–source parasitic capacitance ( C gs ). In conventional multigate GaN HEMTs, internal source interconnects tie split sources, increasing parasitic coupling near the gate and degrading the minimum noise figure (NF min ) at millimeter‐wave frequencies. To overcome this limitation, an external source interconnect is routed outside the active region, effectively suppressing gate‐side parasitics and reducing C gs , without compromising circuit integrity or layout compactness. The proposed five‐stage common‐source LNA MMIC, fabricated using ETRI's 0.15 μm GaN‐on‐SiC process, achieves a gain of 23–28 dB and a noise figure of 2.1–2.3 dB across 26–30 GHz. Compared with recently reported Ka‐band GaN LNA MMICs, the design attains figures of merit: FoM 1 = 724 GHz/mm 2 and FoM 2 = 0.72 GHz/mW·mm 2 . These improvements result from the reduced C gs enabled by the external source interconnect and compact layout, confirming the suitability of the proposed HEMT structure for high‐performance millimeter‐wave front‐end receivers requiring low‐noise and efficient integration.