Amplifier with amplifying stages which can be switched as a function of the amplitude of the input signal to be amplified

The amplifier 1 comprises a plurality of amplifying stages 11, 12, 13 whose outputs are connected in series by means of several diodes 35, 36, 37 mounted in cascade and placed respectively in parallel with the output terminals of each of the amplifiers, a transformer 4 comprising a primary winding 4a supplied by an AC voltage source 5 and several secondary windings 4b, 4c, 4d each connected to the input of an amplifying stage 11, 12, 13, each amplifying stage being formed by at least one current switch 29, 30, 31 placed between a secondary winding of the transformer and the diode placed in parallel with the output of the amplifying stage, each switch being operated by a control logic unit 2 whenever the signal to be amplified reaches a predetermined level. It also comprises at least n amplifying stages 6 each formed by a variable-width pulse generator controlled by the control logic unit 2, the width of each pulse being proportional to the amplitude of the signal measured between two successive switching levels. Application: high-power audiofrequency amplifier. L'AMPLIFICATEUR 1 COMPREND UNE PLURALITE D'ETAGES D'AMPLIFICATION 11, 12, 13 DONT LES SORTIES SONT RELIEES EN SERIE AU MOYEN DE PLUSIEURS DIODES 35, 36, 37 MONTEES EN CASCADE PLACEES RESPECTIVEMENT EN PARALLELE SUR LES BORNES DE SORTIE DE CHACUN DES AMPLIFICATEURS, UN TRANSFORMATEUR 4 COMPRENANT UN ENROULEMENT PRIMAIRE 4A ALIMENTE PAR UNE SOURCE DE TENSION ALTERNATIVE 5 ET PLUSIEURS ENROULEMENTS SECONDAIRES 4, 4, 4 RELIES CHACUN A L'ENTREE D'UN ETAGE D'AMPLIFICATION 11, 12, 13, CHAQUE ETAGE D'AMPLIFICATION ETANT FORME PAR AU MOINS UN INTERRUPTEUR DE COURANT 29, 30, 31 PLACE ENTRE UN ENROULEMENT SECONDAIRE DU TRANSFORMATEUR ET LA DIODE PLACEE EN PARALLELE SUR LA SORTIE DE L'ETAGE D'AMPLIFICATION, CHAQUE INTERRUPTEUR ETANT COMMANDE PAR UNE LOGIQUE DE COMMANDE 2 CHAQUE FOIS QUE LE SIGNAL A AMPLIFIER ATTEINT UN NIVEAU PREDETERMINE. IL COMPREND EGALEMENT AU MOINS N ETAGES D'AMPLIFICATION 6 FORMES CHACUN PAR UN GENERATEUR D'IMPULSIONS A LARGEUR VARIABLE COMMANDE PAR LA LOGIQUE DE COMMANDE 2, LA LARGEUR DE CHAQUE IMPULSION ETANT PROPORTIONNELLE A L'AMPLITUDE DU SIGNAL MESURE ENTRE DEUX NIVEAUX DE COMMUTATION SUCCESSIFS.APPLICATION: AMPLIFICATEUR AUDIOFREQUENCE DE FORTE PUISSANCE.