| 摘要 |
<p>A burst gate pulse generator circuit generates a burst gate pulse signal representative of a time period during which a burst signal is present within a composite video signal without requiring external components. Each period of the composite video signal includes a horizontal synchronization signal pulse, a burst signal and a video information signal. A pair of integrated capacitors (C1 and C2) are discharged during the horizontal synchronization pulse. The capacitors (C1 and C2) are charged at different rates by two current sources after the horizontal synchronization pulse. A first amount of charge across a first capacitor (C2) rises above a predetermined threshold level in a first time period. The burst gate pulse signal is activated when the first amount of charge rises above the predetermined threshold level. This occurs before the burst signal is present within the composite video signal. A second amount of charge across a second capacitor (C1) rises above the predetermined threshold level in a second time period. The burst gate pulse signal is deactivated when the second amount of charge rises above the predetermined threshold level. This occurs after the burst signal is complete within the composite video signal.</p> |
