Dynamic focus system cascode amplifier

Claim 1

A dynamic focus amplifier system comprising: a cascode amplifier including first and second transistors, each having a control electrode and a pair of main current carrying electrodes forming a main current carrying path for each transistor, the main current carrying paths of each of said transistors connected in series and connected in series between first and second power supply terminals; an input terminal coupled to said control electrode of said first transistor, and an output terminal connected to one of said main current carrying electrodes of said second transistor, said first and second transistors forming a cascode amplifier means for together amplifying input signals having frequencies substantially above 16 KHz applied at said input terminal and providing said amplified input signals as high voltage peak-to-peak output signals at said output terminal; means directly coupling said output terminal and said output signals to a focus electrode of a cathode ray tube; wherein the improvement comprises signal coupling means for coupling AC signals corresponding to noninverting AC input signals provided at the control electrode of said first transistor to the control electrode of said second transistor, whereby a smaller phase shift for said cascode amplifier means is achieved.