A compact high directivity coupler with ±0.15dB error under VSWR 2.5∶1 for 3×3mm2 UMTS power amplifier modules

This paper presents an approach to design high directivity couplers on compact multilayer power amplifier module (PAM). Coplanar and bilevel coupled lines structures are analyzed and compared. The effects of layout are investigated. A bilevel coupled line coupler is developed and integrated into 700 MHz UMTS 3 × 3 mm
²
PAM. It achieves more than 28 dB directivity and the coupling factor variation of PAM is within ±0.15 dB under VSWR 2.5:1.