资 源 简 介
The AD9200ARS and AD9200KST parts feature an opTIonalclamp circuit for dc restoraTIon of video or ac coupled signals.Figure 24 shows the internal clamp circuitry and the externalcontrol signals needed for clamp operaTIon. To enable theclamp, apply a logic high to the CLAMP pin. This will closethe switch SW1. The clamp amplifier will then servo the voltageat the AIN pin to be equal to the clamp voltage applied atthe CLAMPIN pin. After the desired clamp level is attained,SW1 is opened by taking CLAMP back to a logic low. Ignoringthe droop caused by the input bias current, the input capacitorCIN will hold the dc voltage at AIN constant unTIl the nextclamp interval. The input resistor RIN has a minimum recommendedvalue of 10 W, to maintain the closed-loop stability ofthe clamp amplifier.
