Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Amplitude control
Reexamination Certificate
2000-01-04
2001-12-11
Zweizig, Jeffrey (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Amplitude control
C327S525000, C327S565000
Reexamination Certificate
active
06329863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to an input circuit for a semiconductor device having a fuse for selective activation/deactivation of circuits, for example protective circuits, therein, and a semiconductor device incorporating such an input circuit.
2. Description of the Related Art
Throughout the evolution of semiconductor devices, the level of integration has steadily and dramatically increased to the point where presently, 64 Megabyte (Mb) Dynamic Random Access Memories (DRAMs) are routinely fabricated. In general, as integration increases, so too does device complexity, and therefore, despite advancements in integration, device size can increase. As a consequence, this demand for larger device sizes, coupled with the demand for heightened integration, is often accompanied by the need for development of new technology in related fields, such as photolithography, which carries with it high cost and reduced device yield.
To address this issue, “stack-type” packages have recently been proposed, suitable for improving the integration of a semiconductor device by more than two fold. Here, the stack-type package refers to both a chip-stack package in which at least two integrated circuit chips are stacked within a single package, and a package-stack package in which at least two packages, each having a chip incorporated therein, are stacked. In this manner, the effective device capability is doubled, while maintaining the same footprint.
For example, in a chip-stack package, two 128 Mb memory chips may be mounted within a single package to provide a 256 Mb memory chip. Alternatively, in a package-stack package, two individually-packaged 128 Mb chip packages may be stacked, thereby likewise providing a 256 Mb memory chip. In this manner, with either form of stack-type package, the integration level can be doubled using conventional processing technology, without the need for advancement of the technology.
As a result of the stack-type package configuration, each external package pin is shared by circuits residing on two separate memory chips. Consequently, the input capacitance value as seen by the external pin increases. In the case of two stacked packages, for example, corresponding external pins are electrically connected to each other so that the load applied to the input circuit connected to the respective external pins is double that of the single individual packages. This results in a reduction in transmission speed for signals traversing the external pin.
SUMMARY OF THE INVENTION
To address the above limitations, it is an object of the present invention to provide an input circuit connected to an external pin adapted to minimize the input capacitance value as viewed by the pin.
It is another object of the present invention to provide a semiconductor device employing such an input circuit.
Accordingly, to achieve the above object, there is provided an input circuit for a semiconductor device including at least one bonding pad which externally receives an electrical input signal and an internal circuit connected to the bonding pad by a signal transmission line. The input circuit includes at least one protective element, electrically coupled to the signal transmission line, for protecting the internal circuit from excessive transmission characteristics (i.e. voltage, current, power, etc) in the input signal. A fuse is electrically coupled in series between the protective element and the signal transmission line, the fuse capable of being opened to electrically isolate the protective element from the bonding pad and the internal circuit.
The protective element preferably comprises a clamping circuit for clamping a voltage level of the input signal to within a predetermined operation voltage range.
To achieve the second object, the semiconductor device includes at least two bonding pads which receive external electrical input signals from a shared common external pin, and at least two internal circuits, each electrically coupled to a corresponding bonding pad by a signal transmission line. The semiconductor device further includes at least two protective elements, each electrically coupled to a corresponding signal transmission line, each for protecting the internal circuits from excessive electrical transmission characteristics in the input signal. At least two fuses are electrically coupled in series between the corresponding protective element and signal transmission line. The fuses are each capable of being opened to electrically insulate the protective elements from the bonding pads and the internal circuits.
The fuses are preferably formed of conductive layers which can be electrically cut or opened. The semiconductor device may be a chip-stack package in which at least two chips are stacked in a single package, or a package-stack package in which at least two packages, each having a chip incorporated therein, are stacked and pins corresponding to each package are externally connected.
By retaining only a single active fuse, and opening the balance of fuses from the other internal circuits, the overall system capacitance, as viewed by the common external pin, is greatly reduced. Therefore, signal transmission speed is greatly improved.
REFERENCES:
patent: 4296456 (1981-10-01), Reid
patent: 5731945 (1998-03-01), Bertin et al.
patent: 5807791 (1998-09-01), Bertin et al.
patent: 6141245 (2000-10-01), Bertin et al.
Jang Tae-seong
Lee Seung-Hoon
Mills&Onello LLP
Samsung Electronics Co,. Ltd.
Zweizig Jeffrey
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