Automated Large-Signal Load-Pull Characterization of Adjacent-Channel Power Ratio for Digital Wireless Communication Systems

Large-signal adjacent-channel power ratio load-pull contours of a GaAs MESFET and a GaAs HEMT excited by ¿4-DQPSK modulation are demonstrated for the first time using an automated load-pull system. It is shown that in general there is only a weak relationship between two-tone third-order intermodulation and adjacent-channel power ratio for the (Japanese) Personal Digital Cellular standard. The relationship is both load impedance and device technology dependent insofar as two-tone linearity characterization cannot generally be used to optimize adjacent-channel power. The load-pull system presented here is modulation and device technology independent.