Patent ID: 7286183

Claim:
A device for producing a sharpness improvement signal for a video image while providing black level clipping of an associated video signal, said device comprising: a first differential transconductance stage having: a voltage input for receiving the video signal, said video signal having a determined fixed component which corresponds to the black level and a variable active component; a differential pair with a first transistor having a control terminal coupled to the voltage input, and a second transistor having a control terminal coupled to the voltage input via an integrator; a first controlled current source coupled to a first main terminal of the first transistor and a second controlled current source coupled to a first main terminal of the second transistor, said first current source and said second current source each delivering one and the same variable bias current a resistor connected between said first respective main terminals of the first and of the second transistor; a first current output coupled to a second main terminal of the first transistor and a second current output coupled to a second main terminal of the second transistor, the sharpness improvement signal being the differential current signal between said first and second current outputs; and means for producing a control signal for the first and for the second current source, in such a way that the bias currents are directly proportional to the active component of the video signal.