Reconfigurable multiport amplifier (MPA) with optimal calibration and reliability enhancement

Abstract

Various approaches have been applied to increase system operation flexibility and power allocation efficiency within satellite communication coverage. Among many techniques used to adaptively control communication traffic during the lifetime of a satellite, the use of multi-port amplifier (MPA) has been studied as an effective approach in multi-beam systems. Compared with the classical power amplification architectures, MPA shows more flexible use of power amplifiers (PAs) having low saturation power and consumes less DC power. However, good isolation characteristics among the output ports of MPA should be achieved to ensure the successful operation in multi-beam systems. Thus, for good port-to-port isolations in a practical application, an automatic calibration circuitry is generally included in MPA to compensate the possible variations in electrical performances of PAs that are sensitive to operation environments. Especially for satellite-based MPAs, it is necessary to minimize the number of calibration tests and reduce the complexity of on-board hardware dedicated to the MPA calibration block. According to the previously proposed MPA calibration schemes, the errors in MPA were only detected through output power measurements after output hybrid matrix (OHM). The previously reported calibration techniques were based on finding the point where the powers of the desired output port and the other ports were the maximum and minima, respectively. However, since the amplified signals in each RF array path were all recombined after OHM, the source of errors could not be distinguished whether the errors arose from an amplitude mismatch and/or a phase mismatch. In addition, the signal path causing the errors could not be found among the array of signal paths and thus the calibration uncertainty increased. That is, an optimal calibration technique to eliminate the drawbacks of currently used calibration schemes must be considered for practical applications. Moreover, t...