摘要:
An electrostatic discharge (ESD) protection circuit includes a first array of transistors, having source and drain doped with a first type of material, arranged in parallel in a first block, and a second array of transistors, having source and drain doped with the first type of material, arranged in parallel in a second block. The ESD protection circuit also includes an active region between the first and second array of transistors doped with a second type of material that is complementary to the first type of material.
摘要:
An ESD protection circuit is integrated into the core of an FPGA in a distributed fashion coupling the bodies of one or more transistors to the power supply pin and/or the ground pin of the FPGA. The ESD protection circuit includes one or more positive discharge paths and one or more negative discharge paths. In the case of a positive ESD event, the positive discharge paths are on and the negative discharge paths are off. In the case of a negative ESD event, the positive discharge paths are off and the negative discharge paths are on. In either event, the bodies of the transistors track the voltages at the power supply pin and/or the ground pin to protect the core from being by damaged by electrostatic discharge.
摘要:
In a conventional differential output circuit, the output terminals are connected to the drains of a differential pair of transistors and the sources of the transistors are connected together at a first node. The bodies of the transistors are connected to a second node having a potential different from that of the first node. In the event of a HBM ESD event, discharge may take place through the differential transistors, leading to destruction of one of them. To reduce the likelihood of such discharge, in a preferred embodiment, switches are provided to connect the body of each of the differential transistors to the first node when an ESD event is sensed. In an alternative embodiment, a switch is provided to connect the first node to the second node when an ESD event is sensed.
摘要:
A trigger circuit is provided for a pull-down device by connecting a diode between the I/O pad and the body of the pull-down device. In one embodiment, the pull-down device is formed as a plurality of discrete transistors in a single well. The drain of each transistor is connected through a ballast resistor to the I/O pad; and the source of each transistor is connected through a ballast resistor to ground. The trigger circuit is a diode formed in a different well from that of the transistors. The cathode of the diode is connected to the I/O pad and the anode is connected to the transistor well through a center tap located between the transistors. Preferably, the transistors are NMOS transistors formed in a P-well. Advantageously, the diode is an N+/PLDD diode. Alternatively, the diode is an N+/P diode where the P region is formed by an ESD implant. In other embodiments the diode is formed in the same well as the transistors. In these embodiments, either an N+/PLDD diode or an implanted diode is formed in place of one of the transistors.
摘要:
A conventional ESD protection circuit comprises an SCR and a first diode connected in series between ground and a node or pad to be protected and a second diode connected between ground and the node to be protected. An anode of the first diode and a cathode of the second diode are connected to the node to be protected. In one embodiment of the invention, the capacitance of the second diode is reduced by forming the second diode from a PN junction between a heavily doped region of one conductivity type and a substrate region instead of a well region of the opposite conductivity type. The reduction in the capacitance of the second diode makes it possible to increase the size of the first diode and SCR, thereby decreasing their resistance, while keeping the total capacitance of the ESD circuit at or below the capacitance of the prior art ESD circuit. A second embodiment of an ESD protection comprises an SCR and a first diode connected in series between ground and node to be protected and second and third diodes connected in series between ground and the node to be protected with the anode of the second diode connected to ground. Again, the capacitance of the second diode is reduced by forming the diode from a PN junction between a heavily doped region of one conductivity type and a substrate region of the other conductivity type.
摘要:
In a conventional differential output circuit, the output terminals are connected to the drains of a differential pair of transistors and the sources of the transistors are connected together at a first node. The bodies of the transistors are connected to a second node having a potential different from that of the first node. In the event of a HBM ESD event, discharge may take place through the differential transistors, leading to destruction of one of them. To reduce the likelihood of such discharge, in a preferred embodiment, switches are provided to connect the body of each of the differential transistors to the first node when an ESD event is sensed. In an alternative embodiment, a switch is provided to connect the first node to the second node when an ESD event is sensed.
摘要:
In a DIAC-like device that includes an n+ and a p+ region connected to the high voltage node, and an n+ and a p+ region connected to the low voltage node, at least two MOS devices are formed between the n+ and p+ region connected to the high voltage node, and the n+ and p+ region connected to the low voltage node.
摘要:
A trigger circuit is provided for a pull-down device by connecting a diode between the I/O pad and the body of the pull-down device. In one embodiment, the pull-down device is formed as a plurality of discrete transistors in a single well. The drain of each transistor is connected through a ballast resistor to the I/O pad; and the source of each transistor is connected through a ballast resistor to ground. The trigger circuit is a diode formed in a different well from that of the transistors. The cathode of the diode is connected to the I/O pad and the anode is connected to the transistor well through a center tap located between the transistors. Preferably, the transistors are NMOS transistors formed in a P-well. Advantageously, the diode is an N+/PLDD diode. Alternatively, the diode is an N+/P diode where the P region is formed by an ESD implant. In other embodiments the diode is formed in the same well as the transistors. In these embodiments, either an N+/PLDD diode or an implanted diode is formed in place of one of the transistors.
摘要:
A conventional ESD protection circuit connects a diode and main clamp between a pad or node to be protected and ground. To preserve high speed operation while improving charge device model (CDM) performance, the invention also connects between pad and ground a small diode in series with a secondary clamp and a small isolation resistance. The isolation resistance is approximately 20 ohms. The secondary clamp can be as small as 30 nm wide. Parallel diodes on the main clamp can be replaced with an N+/p-substrate (native) diode 290 to further reduce capacitance.
摘要:
An electrostatic discharge (ESD) protection circuit includes a first array of transistors, having source and drain doped with a first type of material, arranged in parallel in a first block, and a second array of transistors, having source and drain doped with the first type of material, arranged in parallel in a second block. The ESD protection circuit also includes an active region between the first and second array of transistors doped with a second type of material that is complementary to the first type of material.