DE10313156B3 - Switch for HF electrical signal has current supply with which current density can be produced in switching section respectively above and below critical current density for superconducting properties - Google Patents

Abstract

The device has a signal path (12b) for the HF signal and a control path (14b) for a switching current for activating a switching process in the signal path with a switching element. The switch element is a switching section consisting of a superconductor that simultaneously forms part of the signal path and the control path and is connected via the control path to a current supply (18b) with which a current density can be produced in the switching section respectively above and below the critical current density for the superconducting properties of the switching section. An independent claim is included for a method of switching a high frequency electrical signal.

Description

The invention relates to a switch for an electrical high-frequency signal with a signal path for the high-frequency signal and with a control path for a switching current for activating a switching process in the signal path by means of a switching element. Such a switch is, for example, from the publication "Performance and Dynamics of a RF MEMS Switch" by Florian roach and other part of the "11 ^th International Conference on Solid-State Sensors and actuator" from 10 to 14 June 2001 in Munich, Germany known. From this publication, a microrelay is known as a switch for an electrical high-frequency signal, which has a relay plate produced in etching technology as a switching element with which two signal paths for the high-frequency signal can be switched. The etched relay plate is deliberately deformed in a capacitor field in order to close a contact in the signal paths. The capacitor field is generated between capacitor plates produced in layer technology, which can be connected to a power supply via a control path. The capacitor field can be changed via the control paths in such a way that a switching process is generated with the relay plate. The switching times that can be achieved during the switching process are on the one hand of. the electrical properties of the capacitor and on the other hand depending on the mechanical properties of the relay plate.

From the DE 38 44 053 C2 and the DE 41 32 707 A1 Superconducting switching elements are also known, which are used, for example, in electrical networks as current limiters for the event of a short circuit. The activation of the switching element is brought about by an impermissibly high short-circuit current, which leads to quenching of the superconducting switching elements and thus causes a sudden increase in the electrical resistance of these switching elements. Due to the increase in resistance, the current is limited in the superconducting switching elements, the electrical power in the switching element being converted into heat. The limited current flowing through the switching element that has passed into the normal conductive state can be completely switched off by a conventional switching element.

The The object of the invention is to provide a switch for an electrical To specify high-frequency signal with which there are comparatively short switching times let it be realized.

This object is achieved in that the switching element is a switching path consisting of a superconductor, which simultaneously forms part of the signal path and the control path and is connected via the control path to a power supply with which a current density in the switching path is above and below that critical current density I _{C can be} generated for the superconducting properties of the switching path.

With equipped the switching element according to the invention Switches can for high frequency signals are used whose frequencies are at least in the kHz range. It is particularly advantageous to use such switches in the MHz and GHz range, in which, for example, the transmission frequencies of mobile radio networks lie. The control current generated by the power supply, the can be fed into the control path, a direct current or be an alternating current, in the case of an alternating current the frequency must be at least 100 times lower than the frequency of the to be switched high-frequency signal, so that the control current and do not undesirably influence the high-frequency signal.

The mode of operation of the switching element according to the invention is based on the property of the superconductor to change to the normal conducting state when the critical current density I _{C is} exceeded, this transition being achieved by feeding a sufficiently high current into the control path. Since the superconductor also forms part of the signal path, a transition from the superconducting to the normally conducting state leads to the power of the high-frequency signal to be transmitted being converted into heat due to the now high resistance. This means that the switch is switched on when the superconductor is in the superconducting state and is switched off when it is loaded with a current density greater than I _C. Since the transition between the normally conductive and superconducting state of the superconductor takes place suddenly, the switching principle described advantageously makes it possible to achieve a short switching time. In addition, the losses at the switch in the switched-on state can advantageously be kept extremely low, since the resistance of superconductors in the superconducting state is extremely low.

According to an alternative solution to the problem, it is provided that the switching element consists of a capacitor, one capacitor plate of which is a signal line section of the signal path and the other capacitor plate of which is a control line section consisting of a superconductor, which forms a part of the control path which overlaps with the signal line section and above the control path is connected to a power supply with which in the control line section a current density can be generated in each case above and below the current density I _C critical for the superconducting properties of the control line section. The statements made above apply to the frequencies of the high-frequency signal and control current with which the switch can be operated.

The Switching principle of the switching element designed as a capacitor exists in that the capacitor plates of the capacitor each consist of parts of the signal path and the control path are formed. As soon as builds up a field in the capacitor thus formed, the high-frequency signal from the signal path into the control path and is thus via the Control route removed. The In this case, the control section itself can also advantageously be used as Signal path can be used when the high-frequency signal over the control path to a location suitable for processing the high-frequency signal is forwarded. The line of the high-frequency signal in the signal path is interrupted, however, so that the switch is in the "Off" position. In this Position, the impedance of the signal path is greatly increased, whereby the increase in impedance in the respective application must be sufficient, to transfer the Effectively suppress high-frequency signal.

If the current density in the control path is increased above the critical current density I _C , the superconductor in the control path changes to the normally conductive state, as a result of which the electrical resistance increases drastically. As a result, the electrical field in the capacitor breaks down, so that the high-frequency signal can be transmitted unhindered in the signal path. Since the transition of the superconductor to the normal conducting state (as well as the transition to the superconducting state) takes place suddenly, a very short switching time of the switch can advantageously be achieved by means of the switching element according to the invention. In addition, the switch advantageously enables very low-loss transmission of the high-frequency signal when switched on.

According to one execution of the invention is between the signal line section and the control line section a dielectric is provided. This strengthens the electric field in the Capacitor, whereby the blocking or

damping effect of the control line section forming the capacitor plate leaves.

Another embodiment provides that a switchable magnet is arranged in such a way that the control line section is in its magnetic field. This can advantageously be achieved that the critical current density I _{C is} reduced by switching on the magnet, so that lower current densities in the control path are sufficient to bring about a transition of the superconductor into the normally conductive state.

Another alternative solution to the problem provides that the switching element is a switching bridge consisting of a superconductor and spanning the signal path, which forms part of the control path and is connected via the control path to a power supply with which a current density in the switching bridge is above each and can be generated below the current density I _C critical for the superconducting properties of the switching bridge, the switching bridge being arranged to be movable in the direction of the signal path in a magnetic field, the field strength of which is decreasing in the direction of the signal path. The statements made above apply to the frequencies of switching current and high-frequency signal with which the switch can be operated.

The The movable arrangement of the switching bridge in a magnetic field enables the Exploitation of the so-called Meissner effect. This effect is caused by the property of superconducting materials, to displace a magnetic field from within. So the jumper is located in the superconducting state, so urges the magnetic field from within. Since this is regarding the field strength reduced towards the signal path results from this Repression one Force that moves the movable switching bridge towards the signal path. This initiates a switching process.

If the current density in the switching bridge is increased above the critical current density I _C , the switching bridge enters the normally conductive state. In this state, the switching bridge is flowed through by the magnetic field, so that this can no longer exert a static influence on the switching bridge in the direction of the signal path. Therefore, the switching bridge moves back to its initial position, which represents its idle state, while the deflection towards the signal path can be achieved, for example, by an elastic deformation.

It is advantageous if the switching bridge is arranged so movable is that a touch between the switching bridge and the signal path possible is. That touch is then caused by deflection of the superconductivity located signal bridge achieved by mechanical contact between control path and signal path mechanical contacting is advantageously achieved.

Another switching mechanism can advantageously be achieved if there is a dielectric between the switching bridge and the signal path. This can, for example, on the signal path be applied so that the switching bridge can be placed on the dielectric in the superconducting state. This creates a configuration in which the overlap areas of the control and signal paths form a capacitor. The operation of this capacitor as a switching element has already been explained. As an alternative to the provision of a dielectric, the mobility of the switching bridge can also be limited in such a way that this can only be deflected to such an extent that a gap remains between the signal path and the control path. Instead of the dielectric, spacers can then be used to ensure a defined distance between the switching bridge and the signal path.

Independent of the explained Switching principles can be changed due to the sudden change the switching bridge between normal conducting and superconducting state depending the current density advantageous very short switching times for the switch realize. Moreover is the transfer of the Radio frequency signals in the signal path with the switch turned on advantageously very low loss.

Farther The invention relates to a method for switching a high frequency electrical signal.

On Such procedure is initially based on the publication listed there already detailed explained Service.

The The object of the invention is to provide a method for switching specify an electrical high-frequency signal with which it can be compared let short switching times be realized.

This object is achieved according to the invention by a method for switching an electrical high-frequency signal, in which a superconductor forms a switching path in a signal path transmitting the high-frequency signal and at the same time forms part of a control path, and by means of a power supply a current density above the current density I critical for the superconducting properties of the switching path _C he is generated, whereby a blocking effect is generated in the signal path for the electrical high-frequency signal. As already explained above, the switching principle is based on the change between a superconducting and a normally conducting state of the switching path, the switching path in the normally conducting state producing a blocking effect for the high-frequency signal due to its suddenly increasing resistance. The change between normally conducting and superconducting properties of the switching path takes place suddenly, so that extremely short switching times can advantageously be achieved.

An alternative solution to this object according to the invention is a method for switching an electrical high-frequency signal, in which a control path that overlaps with a signal path carrying the high-frequency signal to form a capacitor and is designed as a superconductor at least in the overlap region formed in this way, by means of a power supply a current density above the current density I _C which is critical for the superconducting properties of the overlap region is generated, as a result of which a blocking effect of the capacitor for the electrical high-frequency signal in the signal path is eliminated.

The Blocking effect of the capacitor and thus the switching principle of this switching method according to the invention are already explained Service. The formation of one of the capacitor plates of the capacitor as a superconductor, which by varying the current density in the superconducting and normal conducting area is advantageously enabled due to of the sudden transition between the two states of the superconductor very short switching times.

Further Details of the invention are described below with reference to the drawing explains show here

1a and b an embodiment of the switch according to the invention with a superconducting switching path as a switching element in the switched off and on state as a schematic section,

2a and b an embodiment of the switch according to the invention with a capacitor as switching elements with and without a switchable solenoid as a schematic section and

3a and b an embodiment of the switch according to the invention with a superconducting switching bridge in a magnetic field in the switched off and on state as a schematic section.

A switch according to 1 is in layer technology on a substrate 11a manufactured. On this substrate 11a is a signal path 12a applied as a structured layer. On the signal path 12a there is an insulation layer 13a , Even the substrate 11a is an electrical insulator.

A control path 14a is made of vias 15 in the substrate 11a and a switching path 16 educated. The switching path 16 is identical to that part of the signal path 12a , which is between points of contact 17 the via conclusions 15 with the signal path 12a extends.

To the vias 15 for example, a power supply 18a connect, with this in the switching path 16 that like the signal path 12a consists of a superconducting material, a current density greater than the critical current density I _{C can be} generated, so that the switching path changes from the superconducting to the normal conducting state. In 1a is the superconducting state of the switching path 16 shown in which a radio frequency signal in the signal path 12a can be transferred; in 1b is the switching distance 16 in the normally conductive state, so that this has a blocking effect on the signal path 12a exercises and the high-frequency signal can not be transmitted.

The order after 1 is also conceivable as a purely planar structure. The signal path and control path are then superimposed and structured in layer technology (not shown).

To manufacture a switch according to 2 is first on a substrate 11b an insulation layer 13b applied. On this is a signal path 12b (runs in 2 perpendicular to the plane of the drawing) by structuring a superconducting layer. The signal path 12b comes with a dielectric 19b coated. Then a control path 14b such on the insulation layer 13b applied that this with the dielectric 19b provided signal path 12b crosses. This creates a capacitor at the crossing point 20b whose capacitor plates through the intersecting sections of signal line 12b and control line 14b are formed, these capacitor plates the dielectric 19b lock in.

As in 2a can be shown by applying the control path 14b for example with a direct current by means of a power supply 18b a transition of the control path 14b forming superconductor in the normal conducting state (exceeding the critical current density I _C in the control path). The capacitor field of the capacitor breaks 20b together, which triggers the switching process. The switching element thus forms the capacitor 20b ,

As in 2 B illustrates a switchable magnet 21 be arranged such that the part of the control path forming the capacitor plate 14b is in its magnetic field when the magnet is switched on. The magnetic field reduces the critical current density I _{C of} the superconducting material, so that with a suitably selected current density I the capacitor field in the capacitor 20b breaks down, which triggers the switching process.

With a switch according to 3 is on a substrate 11c an insulation layer 13c applied, on which a signal path is produced by structuring a superconducting layer (runs in the exemplary embodiment according to FIG 3 perpendicular to the plane of the drawing). The signal path 12c is with a dielectric 19c coated.

On both sides of the signal path 12c are spacers 22 on the insulation layer 13c put on, which with another insulation layer 23 are provided. These spacers serve as bridge pillars for a switching bridge 24 that are part of the control path 14c is formed and between the spacers 22 unsupported above the signal path 12c and its course is crossed ( 3a ). Above the switching bridge 24 is a magnet 25 arranged in the magnetic field of the switching bridge 24 located. Will the switching bridge 24 by means of a power supply 18c loaded with a current density above the critical current density I _C , this jumper is located 24 in the normal conductive state and is caused by the magnetic field of the magnet 25 unaffected. The magnetic field passes through the normally conductive switching bridge 24 rather, unhindered, so that these are reflected in their 3a shown, undeformed starting position.

It's like in 3b shown, the current density in the switching bridge is less than I _C , it is superconducting and displaces the magnetic field from the cross section of the switching bridge (Meissner effect). As a result, the magnetic field, which leads to the signal path 12c decreases towards the switching bridge 24 a force, which is why it deforms towards the signal path and forms a capacitor 20c on the dielectric 19c stores. The section of the switching bridge crossing the signal path forms 24 one capacitor plate and the crossed portion of the signal path the other capacitor plate. The function of the capacitor 20c as a switching element is analogous to that 2a and 2 B described mode of action.

Alternatively (not shown), the dielectric 19c also be omitted. Under this condition, the switching bridge is laid 24 forming an electrical contact directly on the signal path 12c , which is short-circuited. This enables a mechanical switch to be implemented.

In the embodiments according to the 1 to 3 the signal path is formed by a superconductor. This is a particularly advantageous embodiment for high-frequency signals, since they can be transmitted almost without loss as long the signal path is in the superconducting state. This is particularly advantageous if the high-frequency signals to be transmitted are to be used simultaneously for the transmission of electrical power, since the losses occurring in the signal path (for example heat development) are advantageously kept very low. For the functioning of the switches according to the 1 to 3 however, these superconducting properties of the signal path are not a requirement. The switching process is achieved by a change between superconducting and normally conducting properties of the control path. This effect can also be used if the signal path is made of a normally conductive material such as. B. copper is made.

Claims (9)

Switch for an electrical high-frequency signal with a signal path ( 12a ) for the high frequency signal and with a control path ( 14a ) for a switching current for activating a switching process in the signal path by means of a switching element, characterized in that the switching element comprises a switching path consisting of a superconductor ( 16 ) which is - at the same time part of the signal path ( 12a ) and the control path ( 14a ) forms and - via the control path ( 14a ) with a power supply ( 18a ) is connected to that in the switching path ( 16 ) a current density above and below that for the superconducting properties of the switching path ( 16 ) critical current density I _{C can be} generated. Switch for an electrical high-frequency signal with a signal path ( 12b ) for the high frequency signal and with a control path ( 14b ) for a switching current to activate a switching process in the signal path by means of a switching element, characterized in that the switching element consists of a capacitor ( 20b ), whose one capacitor plate is a signal line section of the signal path ( 12b ) and the other capacitor plate of which is a control line section consisting of a superconductor which - a part of the control path overlapping with the signal line section ( 14b ) forms and - via the control path ( 14b ) with a power supply ( 18b ) is connected, with which a current density can be generated in the control line section in each case above and below the current density I _C critical for the superconducting properties of the control line section. Switch according to claim 2, characterized in that between the signal line section and the control line section a dielectric ( 19b ) is provided. Switch according to one of claims 2 or 3, characterized in that a switchable magnet ( 21 ) is arranged such that the control line section is in its magnetic field. Switch for an electrical high-frequency signal with a signal path ( 12c ) for the high frequency signal and with a control path ( 14c ) for a switching current for activating a switching process in the signal path by means of a switching element, characterized in that the switching element comprises a switching bridge consisting of a superconductor and cantilevering over the signal path ( 24 ) which is - part of the control path ( 14c ) forms and - via the control path ( 14c ) with a power supply ( 18c ) is connected to that in the switching bridge ( 24 ) a current density above and below that for the superconducting properties of the switching bridge ( 24 ) critical current density I _{C can be} generated, the switching bridge ( 24 ) towards the signal path ( 12c ) is movably arranged in a magnetic field, the field strength of which is directed towards the signal path ( 12c ) reduced. Switch according to claim 5, characterized in that the switching bridge ( 24 ) is movably arranged so that contact between the switching bridge ( 24 ) and the signal path ( 12c ) is possible. Switch according to claim 5, characterized in that between the switching bridge ( 24 ) and the signal path ( 12c ) there is a dielectric. Method for switching an electrical high-frequency signal, in which a signal conductor covers a switching path ( 16 ) in a signal path transmitting the high-frequency signal ( 12a ) and at the same time part of a control path ( 14a ) forms and by means of a power supply ( 18a ) a current density above that for the superconducting properties of the switching path ( 16 ) critical current density I _{C is} generated, whereby a blocking effect is generated in the signal path for the electrical high-frequency signal. Method for switching an electrical high-frequency signal, in which a control path ( 14b ) which is connected to a signal path carrying the high-frequency signal ( 12b ) forming a capacitor ( 20b ) overlaps and is designed as a superconductor, at least in the overlap region formed in this way, by means of a power supply ( 18b ) a current density is generated above the current density I _C which is critical for the superconducting properties of the overlap region, as a result of which a blocking effect of the capacitor ( 20b ) for the electrical high-frequency signal in the signal path ( 12b ) will be annulled.