TRANSLATING CIRCUIT FOR TELEVISION RECEIVER ON-SCREEN GRAPHICS DISPLAY SIGNALS

摘要

Abstract of the DisclosureA DC coupled signal translating circuit forsupplying auxiliary graphics information switching signalsto a video signal processor. The switching signal comprisesplural switching levels including a quiescent level. Thetranslating circuit includes first and second complementaryconductivity input transistors with interconnected emittersignal inputs for receiving switching currents representa-tive of the graphics switching signals via a conductorwhich undesirably exhibits a parasitic capacitance. Thetransistors are biased to conduct a nominal quiescentcurrent and develop collector output currents which areproportional to the input switching currents, and which arerespectively coupled via current repeating networks tocontrol inputs of the video processor. Switching delaysattributable to the parasitic capacitances of the inputcoupling conductor are significantly reduced due to theemitter voltage clamping action of the input transistorsfor all conditions of the input switching signals.