Switching amplifier for driving a load through an alternating-current path with a constant-amplitude, varying duty cycle signal

A driver circuit for a horizontal output transistor which promotes the flow of a deflection current in a television apparatus in which the recurrence rate of the deflection is controlled by fixed rate synchronization signals and in which the duty cycle of said horizontal output transistor drive signal is varied, said driver circuit comprising:

• first and second controllable switch means, each including a controlled main current conducting path and a control electrode, said main current conducting paths being coupled at a juncture to form a first series path and controlled for conduction during alternate first and second time intervals;
• a source of energizing potential;
• inductance means serially coupled with said first series path across said source of energizing potential for establishing an operating potential at said juncture during said first interval which is less than the full potential of said source of energizing potential;
• alternating-current coupling means coupled to said juncture and to said horizontal output transistor for coupling an AC drive voltage to said horizontal output transistor;
• a source of reference potential related to said source of energizing potential;
• and
• clamp means coupled to said inductance means and to said source of reference potential for establishing a voltage across said inductance means during said second interval that causes peak-to-peak voltage variations to be developed across said inductance means with variations in duty cycle.

A driver circuit for a horizontal output transistor which promotes the flow of a deflection current in a television apparatus in which the recurrence rate of the deflection is controlled by fixed rate synchronization signals and in which the turn-off of said horizontal output transistor is controlled by a duty cycle controlling feedback loop to maintain the retrace pulses in synchronism with said synchronization signals, said driver circuit comprising:

• first and second controllable switch means, each including a controlled main current conducting path and a control electrode, said main current conducting paths being coupled at a juncture to form a first series path and controlled for conduction during alternate first and second time intervals;
• a source of energizing potential;
• inductance means serially coupled with said first series path across said source of energizing potential for establishing an operating potential across said inductance means during said first interval of a magnitude which is less than the full potential of said source of energizing potential;
• alternating-current coupling means coupled to said juncture and to said horizontal output transistor for applying an AC drive to said horizontal output transistor, varying said duty cycle resulting in variation of the peak-to-peak magnitude of said AC drive;
• and
• clamp means coupled across said inductance means for establishing a fixed voltage across said inductance means during said second interval to vary said operating potential such that duty cycle variation results in peak-to-peak magnitude variation of said AC drive of a sense opposite that of the peak-to-peak variation of the voltage across said inductance means.

An amplifier for driving a load through an alternating-current path with a signal having duty cycle variations, comprising:

• first and second controllable switch means, each including a controlled main current conducting path and a control electrode, said main current conducting paths being coupled at a juncture to form a first series path for the flow of charge and controlled for conduction during alternate first and second time intervals;
• a source of energizing potential;
• inductance means serially coupled with said first series path across said source of energizing potential for establishing an operating potential across said inductance means during said first interval which is less in magnitude than the full potential of said source of energizing potential, said duty cycle variations causing peak-to-peak voltage variations across said inductance means;
• alternating-current coupling means coupled to said juncture and to the load for developing an alternating current voltage across the load;
• and
• means coupled to said inductance means for establishing a voltage across said inductance means during said second interval of a magnitude that results in peak-to-peak voltage variations of said alternating current voltage of a sense opposite that of the peak-to-peak voltage variations across said inductance means.

A drive circuit for driving the base of a switching transistor with an alternating-current signal of varying duty cycle, comprising:

• an inductor;
• a source of voltage;
• first switch means coupling said inductor with said base and said source for storing energy in said inductor and for applying a forward drive switching voltage to said base during a first portion of the drive cycle;
• second switch means for applying to said inductor a reference voltage during a second portion of said drive cycle to establish by average-value considerations the voltage across said inductor during said first portion of the drive cycle, duty cycle variations causing variations in the voltage across said inductor during said first portion resulting in magnitude variations of said forward drive switching voltage, said reference voltage selected such that the variations of said forward drive switching voltage are in an opposite sense to the variations in the voltage across said inductor during said first portion.