A video amplifier having an on-screen display (OSD) capability uses one channel
of an OSD input video signal to generate a blanking signal for blocking output
of a video signal. When the blanking signal is asserted, the OSD channels provide
the on-screen display. The blanking signal is generated in a high speed mixer circuit
including an emitter-coupled differential pair for amplifying the OSD input signal
about an operating DC offset voltage and a pull down circuit for providing the
blanking signal.
