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

Abstract

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 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 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 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.Index Terms-Efficiency, helix-on-pad, integrated passive device, power amplifier (PA), small size, WCDMA.

Ultra-small Form-Factor Helix on Pad-Type Stage-Bypass WCDMA Tx Power Amplifier Using a Chip-Stacking Technique and a Multilayer Substrate

“…The measured results show that it incurred almost the same loss as a typical transmission line over the whole band-5 frequency range (less than 0.07 dB difference) [3]. The measured results show that it incurred almost the same loss as a typical transmission line over the whole band-5 frequency range (less than 0.07 dB difference) [3].…”

“…The HoP in the OMN consists of solenoid-type wires with a height of 1.5 mm and a diameter of about 30 μm (1.2 mil) on a substrate. The measured results show that it incurred almost the same loss as a typical transmission line over the whole band-5 frequency range (less than 0.07 dB difference) [3]. The on-chip iPD was fabricated using a low-loss Si 3 N 4 dielectric (ε r of about 6.8 and tanδ = 0.001) on the same GaAs process with the HBT PA MMIC to replace the capacitors in the OMN.…”

“…To reduce the area of the output matching network (OMN), which occupies the largest area inside a PA module, we recently proposed a new type of OMN [2], [3]. It consists of a helix-on-pad (HoP) and an integrated passive device (iPD).…”

“…It consists of a helix-on-pad (HoP) and an integrated passive device (iPD). However, because the work in [2] and [3] was focused on introducing the idea of a HoP-iPD OMN, there was no consideration for practical use, such as a control IC and the commercial bottom dimension. 1.…”

“…Moreover, to ensure control logic compatibility between the baseband chipset and the PA, the use of an additional control IC has been necessary to implement the PA module, which has been another obstacle to reducing the size of the PA module. Manuscript To reduce the area of the output matching network (OMN), which occupies the largest area inside a PA module, we recently proposed a new type of OMN [2], [3]. It consists of a helix-on-pad (HoP) and an integrated passive device (iPD).…”