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A 1.9-GHz CMOS differential power amplifier for polar transmitter applications is designed using a 0.25-μm RF CMOS process. The input transformer and output transformer are fully integrated on the chip. The transmission line transformer is used as an output power combiner and an output matching component. To increase the coupling factor of the transformer, an interdigitated transmission line transformer is used and it achieves a drain efficiency of 28% at the maximum output power. The maximum output power is 28.2 dBm with a 1.8-V supply voltage. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3162–3166, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22957

In situ compatibilized melt blends of polyamide 6 (PA-6) with polyester elastomer (PEL) were prepared in a corotating twin-screw extruder using two types of coupling agent (CA): diglycidyl ether of bisphenol A (DGEBA) and 1,4-phenylene bis(2-oxazoline) (PBO). The notched impact strength of PA-6 and PA-6/PEL blends increased with the addition of coupling agent, especially DGEBA, and the maximum impact toughening of the blend was obtained with 0.6 mol % DGEBA, the composition of minimum domain size observed from SEM. Viscosities of the untreated blends increased over those of the base resins at low frequencies. Viscosities of both the base resins and the blends increased with the addition of CA, and the effect was much more pronounced with DGEBA, especially for PA-6 and PA-6–rich blends. The crystallization temperature (Tc) of PEL increased over 10°C, whereas the Tc of PA-6 decreased by 2–3°C in the blends. With the addition of coupling agents, the crystallization melting temperature (Tm) and Tc of PA-6 decreased by up to 5°C with DGEBA, implying that the crystallization of PA-6 is disturbed by the in situ formed PA-6–CA–PEL or PA-6–CA–PA-6 type copolymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3966–3973, 2004

A fully integrated CMOS power amplifier for 5 GHz WLAN applications is implemented using 0.18 μm CMOS technology. An on-chip transmission-line transformer is used for output matching and voltage combining. An input balun, interstage matching components, an output transmission-line transformer, and RF chokes are fully integrated in the amplifier, and thus no external components are required. The power amplifier occupies a total area of 1.7 mm × 1.2 mm. At a 3.3 V supply voltage, the amplifier exhibits a 22.6 dBm output 1 dB compression point, 23.8 dBm saturated output power, and 25 dB power gain. The power added efficiency (PAE) is 21% at maximum, 19% at P1dB. When a 54 Mbps/64 QAM OFDM signal is applied, the PA delivers an average power of 12 dBm at an EVM of −25 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2551–2553, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24683