TRANSLATING CIRCUIT FOR TELEVISION RECEIVER ON-SCREEN GRAPHICS DISPLAY SIGNALS

摘要

A DC coupled signal translating circuit for supplying auxiliary graphics information switching signals to a video signal processor. The switching signal comprises plural switching levels including a quiescent level. The translating circuit includes first and second complementary conductivity input transistors with interconnected emitter signal inputs for receiving switching currents representative of the graphics switching signals via a conductor which undesirably exhibits a parasitic capacitance. The transistors are biased to conduct a nominal quiescent current and develop collector output currents which are proportional to the input switching currents, and which are respectively coupled via current repeating networks to control inputs of the video processor. Switching delays attributable to the parasitic capacitances of the input coupling conductor are significantly reduced due to the emitter voltage clamping action of the input transistors for all conditions of the input switching signals.