| 摘要 |
<p>A transistor provides a substantially noise-immune hard clamp circuit for the video signal in a television receiver. Such a clamp circuit is rendered increasingly immune to noise in proportion to an increase in frequency above the sync frequency of the video signal by bypassing the emitter-base clamp diode with a capacitor. The effects of the base circuit impedance on the clamp impedance are reduced by employing a high beta transistor. In this manner impedance means can be employed to limit loading of the video signal by the capacitor. Means are also provided to prevent any voltage supply irregularities from affecting the DC-restored vido signal, so that substantially 100% DC restoration is achieved.</p> |
