Electronic digital logic circuitry – Interface – Current driving
Reexamination Certificate
2001-12-26
2003-04-01
Tokar, Michael (Department: 2819)
Electronic digital logic circuitry
Interface
Current driving
C326S022000
Reexamination Certificate
active
06542003
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a configuration for the direct electrical isolation of systems with broadband transmission, and to a method for the direct electrical isolation of systems with broadband transmission.
Since there is an unceasing rise in the required speed of data transmission in the age of merging information and communication networks, interference-free transmission of data presents a challenge for the developers active in this field, since the susceptibility of the transmitted data to interference also increases with the speed.
One source of errors in data transmission is the direct electrical interfering influence caused by common current paths, which becomes apparent through voltage drops relative to the common ground connection that are superposed on the data signals. These voltage drops are caused by contact resistances at connections or plug connections.
One possibility for avoiding the direct electrical interfering influencing is to use direct electrical decoupling. The decoupling is effected by avoiding common reference conductors and by providing potential isolation of the electric circuits and is realized by using optocouplers in data transmission.
High-speed optocouplers are required for fast data transmission, as is customary nowadays in computer technology, for example, in the case of a “universal serial bus” USB.
One disadvantage of high-speed optocouplers is the high purchase price. Many competing companies are simultaneously active in this field, and the level of production costs and hence of the purchase costs are therefore crucial for selection by the purchaser and for the success of the companies.
A further disadvantage of the optocouplers is the relatively long temperature- and voltage-dependent signal propagation times. These propagation times cause difficulties primarily in transmitting a plurality of data signals in parallel, since the individual propagation times of the optocouplers may, in the extreme case, differ to such an extent that the transmitted data signals are no longer synchronous.
Published German Patent Application DE 196 10 248 A1 discloses a method and a circuit configuration for directly electrically isolating a signal path, in which at least one signal input and at least one signal output assigned to this signal input have a direct electrical isolation between the input and output. A circuit configuration is provided for the direct electrical isolation of the signal path.
Summary of the Invention
It is accordingly an object of the invention to provide a simple, cost-effective circuit configuration and a method for performing a directly electrically isolated broadband transmission which overcome the above-mentioned disadvantages of the prior art apparatus and methods of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a circuit configuration for performing directly electrically isolated broadband transmission. The circuit configuration has an input stage including at least one logic signal combination device, a first line for transmitting a clock signal, a second line for transmitting a data signal, and a connection to a first ground potential. The circuit configuration also has an output stage including at least one second logic signal combination device, a filter connected downstream of the second logic signal combination device, and a connection to a second ground potential. The circuit configuration also has a decoupling device.
The first logic signal combination device has a first signal input that receives the data signal and a second signal input that receives the clock signal. The first logic signal combination device includes a first signal output outputting a first output signal to the decoupling device. The first output signal consists of the data signal superposed on the clock signal. The decoupling device decouples the input stage from the output stage by generating a decoupled clock signal from the clock signal and by generating a decoupled first output signal from the first output signal. The second logic signal combination device includes a third signal input that receives the decoupled first output signal from the decoupling device. The second logic signal combination device includes a fourth signal input that receives the decoupled clock signal from the decoupling device. The second logic signal combination device includes a second signal output outputting a second output signal consisting of a decoupled data signal that is separated from the decoupled clock signal. The second signal output always outputs defined and/or stable signals. The filter is configured to filter out interference pulses contained in the second output signal to generate a third output signal that is a filtered decoupled data signal. The decoupling device decouples the input stage from the output stage such that the first ground potential is directly electrically isolated from the second ground potential and such that the clock signal and the first output signal are transmitted in a directly electrically isolated manner from the input stage to the output stage.
The number of first logic signal combination devices is determined by the number of data signals in such a way that each data signal is associated with a first logic signal combination device. The number of second logic signal combination devices and filters is determined by the number of data signals such that each data signal is associated with a second logic signal combination device and a filter connected downstream of the respective second logic signal combination device. The first logic signal combination device has a first signal input, at which a data signal is present, and a second signal input, at which the clock signal is present, and is configured in such a way that a first output signal is output as a data signal superposed on the clock signal at a first signal output.
The second logic signal combination device has a third signal input, at which a decoupled first output signal is present, and a fourth signal input, at which a decoupled clock signal is present. The second logic signal combination device is configured such that a second output signal is output as a decoupled data signal that is freed from the decoupled clock signal at a second signal output. In each case, a filter is connected downstream of the second logic signal combination device, which filter filters out interference pulses contained in the second output signal so that a third output signal is generated as a decoupled data signal freed from interference pulses.
The input stage and the output stage are decoupled such that the first ground potential is directly electrically isolated from the second ground potential and the clock signal and the respective first output signal are transmitted in a directly electrically isolated manner.
The essential advantage of circuit configuration for performing directly electrically isolated broadband transmission is the short signal propagation times which, moreover, can be calculated since they essentially depend on the logic signal combination device used and also on the frequency of the clock signal. Low costs are also achieved, since standard mass produced components are used which can be procured at favorable prices. Since the propagation times can be calculated, this circuit configuration can be used, in particular, for implementing parallel data transmission.
In accordance with an added feature of the invention, the output stage includes at least one third logic signal combination device connected downstream from the filter. The third logic signal combination device has a fifth signal input receiving the third output signal and a sixth signal input receiving the second ground potential. The third logic signal combination device is configured such that pulses of the third output signal are converted back into a rectangular form for generating a recovered data signal. The third logic signal combination device has a third signal output that outpu
Cho James H.
Greenberg Laurence A.
Locher Ralph E.
Siemens Aktiengesellschaft
Stemer Werner H.
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