Method of automatic adjustment of a tunable impedance matching circuit, and automatic tuning system using this method

An automatic tuning system having a user port and a target port, the automatic tuning system allowing, at a given frequency, a transfer of power from the user port to the target port, the automatic tuning system comprising:

• a sensing unit, the sensing unit delivering one or more sensing unit output signals, each of the one or more sensing unit output signals being mainly determined by one or more electrical variables sensed at the target port while an excitation is applied to the user port;
• a single-input-port and single-output-port tunable matching circuit, the single-input-port and single-output-port tunable matching circuit comprising one or more adjustable impedance devices, the one or more adjustable impedance devices being referred to as the adjustable impedance devices of the tunable matching circuit and being such that, at said given frequency, each of the adjustable impedance devices of the tunable matching circuit has a reactance, the reactance of any one of the adjustable impedance devices of the tunable matching circuit being adjustable by electrical means;
• a signal processing unit, the signal processing unit delivering tuning instructions, at least one of the tuning instructions being an initial tuning instruction, each of the one or more initial tuning instructions being determined as a function of one or more real quantities depending on an impedance seen by the target port, said one or more real quantities depending on an impedance seen by the target port being estimated as a function of one or more of the one or more sensing unit output signals, at least one of the tuning instructions being a subsequent tuning instruction, the signal processing unit performing an extremum-seeking control algorithm to determine each of the one or more subsequent tuning instructions, the extremum-seeking control algorithm seeking to maximize or to minimize a performance variable, the performance variable being estimated as a function of one or more of the one or more sensing unit output signals;
• and
• a tuning control unit, the tuning control unit receiving the tuning instructions from the signal processing unit, the tuning control unit delivering one or more tuning control signals to the single-input-port and single-output-port tunable matching circuit, the tuning control unit generating, for each of the one or more tuning control signals, one or more values of said each of the one or more tuning control signals, said one or more values of said each of the one or more tuning control signals being determined as a function of at least one of the tuning instructions, the reactance of each of the adjustable impedance devices of the tunable matching circuit being mainly determined by at least one of the one or more tuning control signals.