| 摘要 |
Predistortion is obtained by a vectorial combination of a linear route and a nonlinear route, using attenuators, phase shifters, nonlinear elements, and delay lines, to have the same group propagation times along two routes in the given frequency range. The two routes are between two couplers, a power divider (23) and a power combiner (17). The linear route comprises an adjustable delay line (21), attenuators (13,31) formed by resistors, a phase shifter (19) containing the Lange coupler (33) and passive elements (37), for example capacitive, in the form of open sections of transmission lines, and resistors (38) with high-value resistances. The nonlinear route comprises a gain expander (25) as a function of input power which contains the Lange coupler (33), preferentially identical to that in the linear route, and active elements, in particular diodes (35), and a delay line (21). The diodes (35) connect the access points of the Lange coupler (33) to the ground. The delay lines (21), one adjustable, allow to adjust the non-constant frequency response of the linearizer in order to compensate that of power amplifier which require linearization. The relative phase between the two routes is adjusted to remain constant in all the frequency band.
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