High speed magnetic deflection amplifier having low-power dissipation

Claim 1

A deflection amplifier responsive to signals applied thereto from a source of signals for controlling the current through an inductor for operating in a character writing mode and a slewing mode, said deflection amplifier including: a voltage amplifier stage having an input voltage amplifier section coupled to said source of signals and an output push-pull current source section; an impedance matching stage responsive to the output signals from said push-pull current source section and having output circuits coupled to said inductor so as to control the current therethrough; feedback means for applying a voltage representative of the current through the inductor, to the input of said input voltage amplifier section; positive voltage supply means responsive to the voltage across said inductor, for applying an output voltage of a first positive value when the voltage across the inductor is less than a preselected positive value in character writing mode and for applying an output voltage of a second positive value when the voltage across the inductor is greater than the preselected positive value in slewing mode; negative voltage supply means responsive to the voltage across said inductor, for applying an output voltage of a first negative value when the voltage across the inductor is less negative than a preselected value in character writing mode and for applying an output voltage of a second negative value when the voltage across the inductor is more negative than said preselected negative value in slewing mode; means for coupling the output signals from said positive and negative voltage supply means to said impedance matching stage; and wherein said impedance matching stage includes means for deriving the current applied to said inductor from said output signals from said supply means; and wherein the improvement comprises: means for applying the output signals from said positive and negative voltage supply means to said output push-pull current source section of said voltage amplifier stage so that a first current source section thereof is coupled between the output of said positive voltage supply means and a potential substantially equal to the voltage across said inductor, and so that a second current source section of said output push-pull section is coupled between the output of said negative voltage supply means and the potential substantially equal to the voltage across said inductor; said means for applying an output signal from said positive and negative supply means being also coupled to said impedance matching stage so that a first stage thereof is coupled between said positive voltage supply means of a potential substantially equal to the voltage across said inductor, and so that a second stage of said impedance matching stage is coupled between the output of said negative supply means and the potential substantially equal to the voltage across said inductor; said first positive supply voltage being applied during the character writing mode and said second positive supply voltage being applied during the slewing mode; said first negative supply voltage being applied during the character writing mode and said second negative supply voltage being applied during the slewing mode; and feedback means coupling the output of said push-pull current source section to the input voltage amplifier section of said voltage amplifier stage for providing a feedback signal for improving the small signal bandwidth thereof.