Helix on Pad-Type Ultra Small-Size Power Amplifiers for WCDMA Handset Applications

Ultra small-size power amplifier (PA) modules were developed for WCDMA handset applications. To reduce the size of the PA modules, the bulky transmission lines and lumped surface mountable chip elements of the conventional output matching network (OMN) were replaced with the proposed helix-on-pad (HoP) and an integrated passive device (iPD), respectively. Three 2 mm times 2 mm single-band PA modules were developed using the proposed OMNs for UMTS Band-5, Band-1, and Band-2 applications. No RF performance degradation was observed from the size-reduced PA modules. For the demonstration of ultimate size reduction, a dual-band PA for UMTS Band-2/ Band-5 application was developed in a 3 mm X 3 mm form-factor. The PAs exhibited adjacent channel leakage ratios (ACLRs) better than -38 dBc over the entire output power range together with power-added efficiencies (PAEs) in excess of 39 % at 28.5 dBm. Besides, the PAs showed good low-power efficiency of 16% at P_out = 16 dBm due to the stage-bypass architecture. The proposed method can be applied in a variety of wireless Tx applications requiring small form-factors and high efficiencies.