System and method for multi-level gain control

摘要

An analog to digital converter circuit having sync control is constructed to monitor the sync condition of the digital output. When sync is lost, for example due to a low input signal level or due to an out of phase situation, the gain of the output increased to relatively high level so as to enhance the possibility of detecting the sync condition. As soon as sync is reestablished the gain is immediately turned down to a level lower than the blanking level and then gradually increased to the blanking level. The gain levels at startup and during the sync reestablishment intervals are fixed but under selective control.