| 摘要 |
A stacked high-voltage ESD protection clamp is provided that realizes the desired triggering characteristics of a BJT or BSCR stacked snapback clamp. The operational principle of the new circuit is based upon introduction of a middle node capacitor into the stacked (cascoded) clamp. The capacitor (or driver) provides conditions for a two-stage turn-on. At the beginning of an ESD pulse, the capacitor is discharged. With the ESD voltage increase, part of the current is used to charge the capacitor, thus shunting one of the BJTs (BSCRs). As a result, the other BJT (BSCR) will experience fast turn-on. After turn-on, the current provides a fast charge of the capacitor and the turn-on of the second device. Thus, the middle node capacitor allows the triggering characteristics of the clamp to be controlled.
|
