AMPLIFICATEUR DE PUISSANCE FONCTIONNANT A GRANDE VITESSE ET UTILISABLE POUR LA COMMANDE DE CHARGES INDUCTIVES

L'INVENTION CONCERNE UN AMPLIFICATEUR DE PUISSANCE FONCTIONNANT A GRANDE VITESSE ET UTILISABLE POUR LA COMMANDE DE CHARGES INDUCTIVES.CET AMPLIFICATEUR SERVANT A COMMANDER UNE CHARGE INDUCTIVE364 COMPREND UN OSCILLATEUR DELIVRANT UN SIGNAL EN ONDE CONTINUE, DES MOYENS DE COMMUTATION334, 336, 344 REPONDANT A CE SIGNAL POUR ENVOYER UN SIGNAL DE COMMUTATION A LADITE CHARGE, ET DES MOYENS D'ADAPTATION D'IMPEDANCE PERMETTANT D'ADAPTER L'IMPEDANCE DE SORTIE DE L'OSCILLATEUR A L'IMPEDANCE D'ENTREE DES MOYENS DE COMMUTATION ET INCLUANT UN TRANSFORMATEUR DE PUISSANCE A FIL BOBINE DONT LES CARACTERISTIQUES DU TEMPS DE REPONSE NE MODIFIENT PAS DE FACON SUBSTANTIELLE LES CARACTERISTIQUES DU TEMPS DE TRANSITION DU SIGNAL EN ONDE CONTINUE.APPLICATION NOTAMMENT A LA COMMANDE DU BLOC DEFLECTEUR DANS UN TUBE CATHODIQUE. A high-speed power amplifier for driving inductive loads is capable of operating at frequencies of at least 270 kHz. The drive amplifier includes an oscillator that develops a continuous square-wave signal having relatively short transition times and a regulated 50% duty cycle. The oscillator output signal is applied to a filar-wound impedance transformer whose response time characteristics do not change substantially the transition time characteristics of the oscillator output signal. The impedance transformer circuit includes a pair of transistors operating in a push-pull configuration simultaneously to maintain the relatively short transition times of the oscillator output signal and to develop the high-current transformer output signal needed to drive a power transistor switch. The power amplifier is designed to provide a base current signal that promotes better dissipation of the power generated in the power transistor as it operates at high switching speeds. An exemplary embodiment of the power amplifier drives the yoke mechanism of the horizontal deflection circuitry of a display system employing a cathode ray tube. Operating the power amplifier at higher frequencies increases the degree of resolution of an image formed by such a display system.