Television display apparatus having a video amplifier

Claim 1

A video output stage for a television display tube having a control electrode, said stage comprising a video amplifier comprising a pair of active elements including output electrodes having a high output impedance and control electrodes, said output electrodes being coupled to one another and adapted to be coupled to said control electrode of said picture display tube, a first capacitor means for applying a signal of high video frequencies only to one of said element control electrodes, the elements comprising a complementary pair of transistors which are coupled in series and have emitter, base, and collector electrodes, said last two recited electrodes being said control and output electrodes respectively, said collectors being adapted to be coupled to the control electrode of the picture display tube, the base of one of the transistors being controlled by said capacitor, a first diode means coupled to said capacitor controlled base and to a potential source for providing that in the absence of a signal substantially no direct current flows through this transistor, the polarity of the diode being that after a possible change in the charge of the capacitor due to a signal jump which has rendered the base-emitter junction of the transistor conductive the said change in charge can be cancelled by an opposite signal jump which renders the diode conductive, the quiescent state of the other transistor being also substantially currentless, and a voltage feedback means from an output of the amplifier to an input.