Abstract: A semiconductor circuit for protecting an I/O pad against ESD events comprising a pMOS transistor (510) in a first n-well (511) having its source connected to Vdd and the first n-well, and its drain connected to the I/O pad; the transistor has a finger-shaped contact (513) to the first n-well. Further a finger-shaped diode (520) with its cathode (521) located in a second n-well and connected to the I/O pad, and its anode connected to ground. The anode is positioned between the cathode and the first n-well, whereby the finger-shaped anode and cathode are oriented approximately perpendicular to the finger-shaped transistor n-well contact. Further a third finger-shaped n-well (551) positioned between the first n-well and the diode, the third n-well connected to ground and approximately perpendicular to the first n-well contact, acting as a guard wall (550).

Abstract: A semiconductor circuit for protecting an I/O pad against ESD events comprising a pMOS transistor (510) in a first n-well (511) having its source connected to Vdd and the first n-well, and its drain connected to the I/O pad; the transistor has a finger-shaped contact (513) to the first n-well. Further a finger-shaped diode (520) with its cathode (521) located in a second n-well and connected to the I/O pad, and its anode connected to ground. The anode is positioned between the cathode and the first n-well, whereby the finger-shaped anode and cathode are oriented approximately perpendicular to the finger-shaped transistor n-well contact. Further a third finger-shaped n-well (551) positioned between the first n-well and the diode, the third n-well connected to ground and approximately perpendicular to the first n-well contact, acting as a guard wall (550).

Abstract: A semiconductor circuit for protecting an I/O pad against ESD events comprising a pMOS transistor (510) in a first n-well (511) having its source connected to Vdd and the first n-well, and its drain connected to the I/O pad; the transistor has a finger-shaped contact (513) to the first n-well, which touches source junction 512c. Source 512 has further an ohmic (silicided) connection to contact 513. A finger-shaped diode (520) with its cathode (521) is located in a second n-well and connected to the I/O pad, and its anode connected to ground. The anode is positioned between the cathode and the first n-well, whereby the finger-shaped anode and cathode are oriented approximately perpendicular to the finger-shaped transistor n-well contact. Further a third finger-shaped n-well (551) positioned between the first n-well and the diode, the third n-well connected to power (Vdd) and approximately perpendicular to the first n-well contact, acting as a guard wall (550).

Abstract: A protection circuit for protecting an integrated circuit pad 201 against an ESD pulse, which comprises a discharge circuit having an elongated MOS transistor 202 (preferably PMOS) in a substrate 205 (preferably n-type), said discharge circuit operable to discharge the ESD pulse to the pad, to ground 203. The embodiment further contains a pump circuit connected to the pad for receiving a portion of the pulse's current; the pump circuit comprises a component 221 determining the size of this current portion (for example, another transistor, a string of forward diodes, or a reverse Zener diode), wherein the component is connected to ground. A discrete resistor 222 (for example about 40 to 60 ?) is connected between the pad and the component and is operable to generate a voltage drop (about 0.5 to 1.0 V) by the current portion.

Abstract: A semiconductor device for locally protecting an integrated circuit input/output (I/O) pad (301) against ESD events, when the I/O pad is located between a power pad (303) and a ground potential pad (305a). A first diode (311) and a second diode (312) are connected in series, the anode (311b) of the series connected to the I/O pad and the cathode (312a) connected to the power pad. A third diode (304) has its anode (304b) tied to the ground pad and its cathode (304a) tied to the I/O pad. A string (320) of at least one diode has its anode (321b) connected to the series between the first and second diode (node 313), isolated from the I/O pad, and its cathode (323a) connected to the ground pad. The string (320) may comprise three or more diodes.

Abstract: A pMOS transistor (601) is located in an n-well (602) and has at least one gate (603). Transistor (601) is connected between power pad Vdd or I/O pad (604) and ground potential Vss (605). Gate (603) is connected to power pad (604). The n-well (602) is capacitively (620) coupled to ground (605), decoupled from the transistor source (606) and floating under normal operating conditions. Under an ESD event, the diode formed by the source (606) and the n-well (602) is forward biased (n-well negatively biased) to turn on the lateral pnp transistor to discharge the ESD current. The well voltage keeps increasing up to the value that triggers the lateral bipolar pnp transistor. The ESD protection is scalable with the width of gate (603), improving with shrinking gate width.

Abstract: A pMOS transistor (601) is located in an n-well (602) and has at least one gate (603). Transistor (601) is connected between power pad Vdd or I/O pad (604) and ground potential Vss (605). Gate (603) is connected to power pad (604). The n-well (602) is capacitively (620) coupled to ground (605), decoupled from the transistor source (606) and floating under normal operating conditions. Under an ESD event, the diode formed by the source (606) and the n-well (602) is forward biased (n-well negatively biased) to turn on the lateral pnp transistor to discharge the ESD current. The well voltage keeps increasing up to the value that triggers the lateral bipolar pnp transistor. The ESD protection is scalable with the width of gate (603), improving with shrinking gate width.

Abstract: A PMOS ESD protection device is disclosed in which gate and substrate coupling techniques are implemented to afford protection during positive ESD events. A snapback leg in curves capable of being produced in accordance with one or more aspects of the present invention is removed, and a trigger voltage at which the device turns on is thereby reduced so as to be less than a second voltage corresponding to a second breakdown region.