Electrical resistors – With base extending along resistance element – Resistance element and/or terminals printed or marked on base
Reexamination Certificate
2000-07-20
2001-06-12
Gellner, Michael L. (Department: 2832)
Electrical resistors
With base extending along resistance element
Resistance element and/or terminals printed or marked on base
C338S320000, C338S325000
Reexamination Certificate
active
06246312
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention generally relates to resistors for impedance matching terminations in electronics. Specifically, the invention is a group of impedance matching or terminating resistors mounted in a high density network or array package using spherical solder connections and having low noise characteristics.
2. Description of the Related Art
Resistor networks are commonly used to terminate high speed digital signal lines to minimize unwanted reflections back through the transmission structure which is typically a printed circuit board. In most applications, the terminations are made by placing a resistor with a resistance matching the impedance of the transmission line, at the end of the transmission line. One end of the resistor is connected to a common termination voltage and the other end is connected to the signal line. For these applications, a bussed resistor network is a convenient solution, since at least one end of the termination is common to all signal lines.
The previous resistor network designs including surface mount, SIP and DIP versions have had resistors and conductor arrangements with individual conductor lines running for a length of some distance on the network before being tied to a common point. This is necessitated because all the external off resistor network connections are made at the periphery of the device and a conductor must be run from the periphery of the device to the individual resistor. The lengthy line length causes each resistor/conductor pair to have a higher mutual inductance between adjoining resistor/conductor pairs and leads to significant cross-talk noise being coupled between the resistor/conductor pairs when the resistor network is employed in its typical use as a terminating or impedance matching resistor for simultaneously switching transistors in an electronic device. As the transistor density and speed of semiconductor devices increase, the problem of cross-talk noise causing an erroneous signal becomes more of a problem in all areas of the electronic package and must be taken into consideration when designing electronic packaging. Further, at high frequencies, the high inductance of the common termination lines can cause a high impedance to appear at the end of the transmission line.
U.S. Pat. No. 5,977,863 provides a resistor network with lower inductance and noise for resistor networks that several inputs tied to a common termination voltage.
Certain circuit designs require specialized termination schemes. For example, in stub series terminated logic circuits two resistors are needed for termination of each data line. The signal is connected through one of the resistors and the termination voltage is connected through another resistor. In another example, emitter coupled logic circuits require two resistors for termination. The resistors are connected together and the data line is connected to the junction of the resistors. The other ends of the resistors are connected to two different termination voltages.
There is a current unmet need for a resistor terminator network for emitter coupled logic and stub series terminated logic with higher density, low cross-talk noise and improved signal integrity.
SUMMARY
It is a feature of the invention to provide a resistor network for terminating active electronic devices that has low noise and high density.
It is a feature of the invention to provide a resistor termination network for stub series terminated logic circuits. The network includes a substrate having a first and a second surface and a common via extending through the substrate. A plurality of resistor pairs are located on the first surface surrounding the common via. Each resistor pair has a first via that extends through the substrate and a second via that extends through the substrate. A first resistor is connected between the first and second vias. A second resistor is connected between the second and common vias. Several solder spheres are disposed on the second surface. Each of the solder spheres are electrically connected to one of the first, second or common vias.
Another feature of the invention is to provide a resistor termination network for terminating emitter coupled logic circuits. The network has a substrate with a first and a second surface. A common via extends through the substrate. The common via is connected to a first termination voltage.
A first group of resistors is located on the first surface surrounding the common via. Each resistor has a first end and a second end connected to the common via. A first group of vias extends through the substrate and is connected to the second ends. The first group of vias are connected to a data line. A second group of resistors are located on the first surface in proximity to the first group of vias, each having a third end and a fourth end. The third ends are connected to the first group of vias, respectively. A second group of vias extend through the substrate and are connected to the fourth ends. The second group of vias are connected to a second termination voltage. Several solder spheres are disposed on the second surface, each of the solder spheres are electrically connected to one of the first, or second group of vias or the common via.
The invention resides not in any one of these features per se, but rather in the particular combination of all of them herein disclosed and claimed and it is distinguished from the prior art in this combination of all of its structures for the functions specified.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the appended claims. Those skilled in the art will appreciate that the preferred embodiment may readily be used as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims are regarded as including such equivalent constructions in that they do not depart from the spirit and scope of the present invention.
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Cooper Richard O.
DeMars Richard S.
Poole David L.
Reinhard Robert L.
Borgman Mark W.
Bourgeois Mark P.
CTS Corporation
Gellner Michael L.
Lee Richard K.
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