Multi-objective optimization of a low-noise antenna amplifier for multi-constellation satellite-navigation receivers

Although the major parts of function blocks for the satellite navigation receivers are fully integrated in a CMOS chip in most cases, it is convenient to create an antenna preamplifier as a separate circuit based on a low-noise pHEMT. Such an RF front end can be strongly optimized to attain a trade-off between the noise figure and transducer power gain. Furthermore, as all the principal navigation systems (GPS, GLONASS, Galileo, and Compass) work in similar frequency band (roughly from 1.1 to 1.7 GHz), it is reasonable to create this low-noise preamplifier for all of them. In the paper, a sophisticated method of the amplifier design is suggested based on multi-objective optimization. First, an extraction of pHEMT model parameters was performed, including comparisons among several models. The extraction was carried out by our original three-step robust identification procedure based on a combination of meta-heuristic and direct optimization methods. Second, a substantial improvement of a standard method for the multi-objective optimization is outlined. Third, the equations of passive elements of the circuit (including transmission lines and T splitters) were carefully defined using frequency dispersion of their parameters as Q, ESR, etc. Fourth, an optimal selection of the amplifier operating point and essential passive elements was performed using the previously improved goal attainment method. Finally, the s-parameters and noise figure of the proposed preamplifier were measured, and the third-order intermodulation products were also checked.