KR20080041305A - Method of tunning a cryogenic receiver - Google Patents

Abstract

This invention relates generally to cryogenic devices and, more particularly, to cryogenic devices of very small size based on superconducting elements, low thermal transmission interconnects and low dissipated power semiconductor devices.

Description

How to tune a cryogenic receiver {METHOD OF TUNNING A CRYOGENIC RECEIVER}

FIELD OF THE INVENTION The present invention relates to cryogenic potential receivers, and more particularly to cryogenic potential receivers of minimum size based on superconducting elements, low heat transfer interconnects, self-resonating filters and low power dissipation profiles.

Until the late 1980s, superconductivity was virtually inapplicable due to the need to operate at temperatures within the range of liquid helium. In the late 1980s, ceramic metal oxide compounds containing rare earth core elements began to radically change this situation. Important examples of such materials are YBCO (yttrium-barium-copper oxide, see WO88 / 05029 and EP-A-0281753), TBCCO (tallium-barium-calcium-copper oxide, see US Pat. No. 4,962,083), and TPSCCO (tallium) Lead-strontium-calcium-copper oxide, see US Pat. No. 5,017,554). All of these documents are incorporated herein by reference in their entirety.

These compounds, called high temperature superconductor (HTS) materials, exhibit superconducting properties at temperatures high enough to allow the use of liquid nitrogen as a coolant. Since 77K (196 ° C./321° F.) of liquid nitrogen is 20 times more efficient and 10 times cheaper than liquid helium, economic feasibility prospects have begun to be offered for a wide variety of potential applications. For example, HTS materials have been used in applications ranging from diagnostic medical equipment to particle accelerators.

Because of the astronomical growth of the telecommunications industry and the increasing use of consumer electronics by the total population, one of the fastest growing superconducting applications today is the area of electronics and associated microwave engineering. However, despite recent developments in the field of superconductivity, size, cost and power requirements have limited the commercial use of this promising technology in all areas other than the most advanced fields such as space equipment and military applications.

In particular, a key component of many electronic devices in the communication field is the filter element. HTS filters have the important advantages of very low in-band insertion loss, high out-of-band rejection and steep skirts due to very low radio frequency (RF) losses of the HTS material.

However, conventional transmission line HTS filters having conventional HTS resonators (such as strip line resonators) as assembly blocks have a large practicality due to the area conditions where at least one dimension of the resonator must be approximately equal to half wavelength (ie, lambda / 2). Requires area See, for example, US Pat. No. 5,616,538, which is incorporated herein by reference in its entirety. Thus, the conventional low frequency HTS filter design has multiple poles and is combined with conventional semiconductor electronic components such as gallium arsenide (GaAs) amplifiers, which is required to cool the HTS material below its critical temperature T _c . Cryogenic chillers are relatively large and require an ambient temperature of 20 ° C. and at least 6 W of power at 80K.

1 is a perspective view of such a conventional cryogenic receiver. The whole package consists of several different elements. Connectors 110 are used to transfer power and RF signals into and out of cryogenic electronic portions consisting of a dewar assembly 120 comprising cryogenic components 130, such as RF filters and amplifiers. Dwarf assembly 120 is a vacuum cavity required to reduce convective heat transfer from molecules to cryogenic electronic components within dwarf assembly 120. In this case, the cryogenic source, which is the cooler 140, cools the cryogenic electronic portion. Enclosure 150 includes circuit board 160 that provides control functions for the cooler and other error or failure detection and alerts, the elements described above, and a fan 170 for cooling circuit board 160. External package.

As shown in Figure 1, the size of a conventional unit is typically on the order of at least about 15 inches wide by 20 inches long by 10 inches deep (about 38.1 x 50.8 x 25.4 cm). The large size and weight of these conventional units are mainly derived from the physical size of the cryogenic electronic portion, the power required by the amplifier, and from the RF transmission, which is a coaxial cable with a connector, usually into the Dwarf assembly 120 from the ambient environment. Due to the additional convective heat transfer. Thus, the physical size, weight and total operating power supplied to the unit is governed by the cooler 140 and the Dwarr assembly 120. In a conventional unit, the required cooling capacity per channel is about 1 W when operated at 20 ° C., thus the total operating power required for the cooler 140 itself exceeds 125 W.

Examples of conventional units include the trademark Superfilter ^TM Systems (see www.suptech.com for more information), available from Superconductor Technologies Inc., Santa Barbara, CA, USA. , Clearsite ^TM Systems (available at www.conductus.com for more information), available from Conductors Inc. of Sunnyvale, California.

The large size and weight of such conventional units substantially limit the application of this technique. One such application is a tower top device in which the receiver front end is mounted on the antenna of a mobile telephone or similar base station, as disclosed in US Pat. No. 6,104,934, which is incorporated herein by reference in its entirety. The size and cooling requirements of the disclosed receivers are such that the cooling unit must be located somewhere adjacent to the antenna and cannot be combined into a unit integrated with the electronic devices.

For the purpose of miniaturization, the components with the maximum required area are the cooler 140, the cryogenic electronic component 130 and the dwarf assembly 120.

One way to reduce the area requirement of cryogenic electron potential receivers is to employ an integrated element structure based on conventional HTS filters. While these filters can be made to operate at frequencies below 5 GHz with a somewhat smaller physical size, the filter performance of these conventional integrated element HTS filters is typically limited by inter-module product and insertion loss.

The use of a device including HTS filters presents another design problem. For example, the interconnect commonly used to connect the cryogenic portion of a device (usually a Dwarr with an HTS filter under vacuum) to other electronic components is a long coaxial cable. Such long cables exhibit low heat transfer because of their length, which is highly desirable in cryogenic systems where it is important to keep components cold. However, these long cable lines also exhibit RF loss and thus cause degradation of RF performance (i.e., increase in signal-to-noise ratio). To further complicate the problems, long cables also require that the dewar of the cryogenic portion of the device increase in volume, which requires and achieves a design that can maintain the larger vacuum required over the life of the unit. Is even more difficult.

There has been a long need to reduce the size of filter elements composed of HTS materials and numerous attempts by those skilled in the art. US Pat. No. 6,108,569, which is incorporated herein by reference in its entirety, discloses the use of a self-resonant spiral resonator to reduce the size of the HTS material filter and currently solves crosstalk and connection problems. Despite the great potential for miniaturization enabled by recent significant technological advances, problems with vacuum degradation, high heat transfer and high power dissipation have resulted in less than optimal performance and increased cooling costs.

Moreover, conventional cryogenic potential receivers require a lot of time to manually adjust the filters, which contain the important functions of the unit. Since the resonant filters of the conventional filter structure do not each change in a fixed step manner, each pole of the filter must be rotated individually and the rotation of each pole affects all other poles in the filter array. The rotation process usually takes several days to be performed.

In addition, conventional cryogenic potential receivers suffer from the exhaust of molecules attached to the device walls during the manufacturing process. Typically, this problem is overcome by only slowly heating the device over a long period of time to exhaust gases such as residual oxygen, nitrogen, carbon dioxide, argon and water vapor. The process usually takes several days to complete, because the temperature required to evacuate the device walls in a short time damages the compressor motors that make up part of the cryogenic unit.

The prior art does not disclose a reduced size cryogenic potential receiver that may be employed adjacent to or integrated with the receiver and / or the transmitter.

The prior art also does not disclose a cryogenic potential receiver with interconnects exhibiting very low heat transfer between the dwwar and the cryogenic cooler to further insulate the dwwar.

The prior art also does not disclose a cryogenic potential receiver with interconnects employing a thermal barrier material and a self-regulating reduced length to reduce RF loss and improve degradation of RF performance.

Moreover, the prior art does not disclose cryogenic potential receivers with reduced power consumption capacity.

The prior art does not disclose a cryogenic potential receiver that is made of HTS material and employs a substantially reduced resonant filter that resonates at frequencies below 5 GHz.

The prior art does not disclose a method for evacuating a vacuum dwarf employing differential heating of the dwarf assembly.

The prior art does not disclose a cryogenic potential receiver that can be adjusted by changing the internal operating temperature of the potential receiver.

The present invention overcomes the drawbacks of the prior art as mentioned above and provides for the prior art in the area of interconnects of reduced length to reduce receiver size, power requirements, insulation, integration with the receiver or transmitter, and RF loss. It is to provide technical advantages.

The present invention has been made in view of the foregoing facts and, in one aspect, has a cryogenic potential receiver.

Another aspect of the invention can be characterized as a cryogenic device, the device comprising a cryogenic electronic portion and a non cryogenic electronic portion further comprising a thermal barrier portion.

In order to achieve these and other advantages in accordance with the object of the invention as embodied and outlined, the invention can be characterized as a cryogenic potential unit comprising a cryogenic electronic unit according to one aspect, the cryogenic unit being input It includes a signal interface and an output signal interface. The cryogenic cooler is in thermal communication with the cryogenic electronic unit. The cryogenic unit further includes an input signal interconnect coupled to the input signal interface and an output signal interconnect coupled to the output signal interface.

Another aspect of the invention may be characterized as a cryogenic device comprising a cryogenic electronic portion, a non cryogenic electronic portion, and an interconnect connecting the cryogenic and non cryogenic electronic portions, the interconnect being cryogenic and non cryogenic electronic portions. It includes a heat shield in between.

Another aspect of the invention can be characterized as a cryogenic device comprising a cryogenic electronic portion contained within a vacuum dwarf assembly, wherein the cryogenic electronic portion has an input end and an output end and is cryogenic from ambient having a peripheral end The input connector of is passed through a vacuum dwarf assembly to a cryogenic end connected to the input end of the cryogenic electronic portion. A cryogenic to ambient output connector having a cryogenic end connected to the output end of the cryogenic electronic portion passes through the vacuum dwarf assembly to the peripheral end. The cryogenic source is connected to the vacuum dwarf assembly in intimate contact with the cryogenic electronic portion having an input end and an output end. The cryogenic electronic portion includes at least one of a high temperature superconductor filter element and a cryogenic active semiconductor circuit (such as a low noise amplifier). The input end of the cryogenic electronic portion is connected to the cryogenic end of the input connector, and the output end of the cryogenic electronic portion is connected to the cryogenic end of the output connector. If an active semiconductor circuit is used, such an active semiconductor circuit must produce less than about 850 mW of total power dissipated into the cryogenic electronic portion. The cryogenic device has an ambient temperature of 20 ° C. and a maximum cooler capacity of less than about 3 W at 80K.

In other words, this aspect of the invention,

(1) a cryogenic electronic portion contained within a vacuum dwarf assembly having an input end and an output end,

(2) an input connector from ambient to cryogenic having a peripheral end through a vacuum dwarf assembly leading to a cryogenic end connected to the input end of the cryogenic electronic portion;

(3) an output connector from cryogenic to ambient through a vacuum dwarf assembly leading to a peripheral end and having a cryogenic end connected to the output end of the cryogenic electronic portion;

(4) a cryogenic source coupled to the vacuum dwarf assembly in intimate contact with the cryogenic electronic portion,

(Iii) the cryogenic electronic portion comprises at least one of a high temperature superconductor filter element and a cryogenic active semiconductor circuit,

(Ii) if an active semiconductor circuit is present, it produces less than about 850 mW of total power dissipated into the cryogenic electronic portion,

(Iii) The cryogenic device relates to a cryogenic device characterized by having an ambient temperature of 20 ° C. and a maximum cooler capacity of less than about 3 W at 80K.

Another aspect of the invention may be characterized as a cryogenic receiver wherein the cryogenic electronic portion of the cryogenic device described above comprises a high temperature superconductor filter element having an input end and an output end, and an active semiconductor circuit having an input end and an output end, The input end of the active semiconductor circuit is connected to the cryogenic end of the input connector via a high temperature superconductor filter element. The input end of the filter element is connected to the cryogenic end of the input connector and the output end of the filter element is connected to the input end of the active semiconductor circuit.

In other words, these other suns,

The cryogenic electronic portion of the cryogenic device described above comprises a high temperature superconductor filter element having an input end and an output end, and an active semiconductor circuit having an input end and an output end,

The input end of the active semiconductor circuit is connected to the cryogenic end of the input connector through a high temperature superconductor filter element,

The input end of the filter element is connected to the cryogenic end of the input connector,

The output end of the filter element relates to a cryogenic receiver characterized in that it is connected to an input end of an active semiconductor circuit.

Another aspect of the invention can be characterized as a cryogenic receiver that is contained within a vacuum dwarf assembly and includes a cryogenic electronic portion having an input end and an output end. Cryogenic to cryogenic input connector passes through a vacuum dwarf assembly to a cryogenic end connected to the input end of the cryogenic electronic portion and to a cryogenic to ambient around cryogenic end connected to the output end of the cryogenic electronic portion. The output connector passes through the vacuum dwarf assembly to the peripheral end. The cryogenic receiver further includes a cryogenic source coupled to the vacuum dwarf assembly in intimate contact with the cryogenic electronic portion. The cryogenic electronic portion further comprises a high temperature superconductor filter element having an input end and an output end, and an active semiconductor circuit having an input end and an output end. The input end of the filter element is connected to the cryogenic end of the input connector and the output end of the filter element is connected to the input end of the active semiconductor circuit. The output end of the active semiconductor circuit is connected to the cryogenic end of the output connector, and the active semiconductor circuit produces less than about 850 mW of total power dissipated into the cryogenic electronic portion. The cryogenic receiver has an ambient temperature of 20 ° C. and a maximum cooler capacity of less than about 3 W at 80K.

In other words, another aspect of the present invention,

(1) a cryogenic electronic portion contained within a vacuum dwarf assembly having an input end and an output end,

(2) an input connector from ambient to cryogenic having a peripheral end through a vacuum dwarf assembly leading to a cryogenic end connected to the input end of the cryogenic electronic portion;

(3) an output connector from cryogenic to ambient, having a cryogenic end connected to the output end of the cryogenic electronic portion and passing through the vacuum dwarf assembly to the peripheral end;

(4) a cryogenic source coupled to the vacuum dwarf assembly in intimate contact with the cryogenic electronic portion,

(Iii) the cryogenic electron part,

    (a) a high temperature superconductor filter element having an input end and an output end,

    (b) an active semiconductor circuit having an input end and an output end,

(Ii) the input end of the filter element is connected to the cryogenic end of the input connector,

(Iii) the output end of the filter element is connected to the input end of the active semiconductor circuit,

(Iii) the output end of the active semiconductor circuit is connected to the cryogenic end of the output connector,

(Iii) the active semiconductor circuit produces less than about 850 mW of total power dissipated into the cryogenic electronic portion,

(Iii) The cryogenic receiver relates to a cryogenic receiver characterized by having an ambient temperature of 20 ° C. and a maximum cooler capacity of less than about 3 W at 80K.

The reader should be aware that when one "component" is connected to another "component" only the order is included and thus other components may be connected between them. For example, the input connector-filter element-active semiconductor circuit-output connector is an order that can be interposed by other components. Keeping the number of components in the vacuum dewar assembly to a minimum (e.g., reducing cooling requirements) is a commonly accepted practice, and therefore from the input connector to the filter element as discussed in more detail below. It is desirable to make a direct connection from the filter element to the active semiconductor circuit and from the active semiconductor circuit to the output connector.

The combination of HTS filters (especially based on self-resonant spiral resonators), low power dissipation semiconductor devices (which work effectively under the required cryogenic conditions) and interconnects as described above, results in much smaller (such as low noise receivers) Cryogenic devices are constructed that require less than about 3 W, preferably less than about 2 W, more preferably less than about 1 W, to cool the cryogenic electronic portion at 20 ° C. and 80 K. Can be cooled by a small cryogenic cooler. In other words, the present invention provides a compact cryogenic device that provides optimum performance with minimal size and cooling cost.

A further advantage of miniaturization possible by the present invention is a significant reduction in the heat gain of the operating unit, which is directly related to improved cryogenic cooler efficiency, increased system operating life and reliability, and reduced energy consumption and operating costs.

The invention also provides a method of adjusting a cryogenic receiver that includes a high temperature superconductor filter element and is programmed to operate at a specific operating frequency and at a specific temperature, the method altering the specific operating temperature to induce displacement of the operating frequency of the cryogenic receiver. It includes a step.

These and other features and advantages of the present invention will be more readily understood by those skilled in the art from the following detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and do not limit the claimed invention. For example, it is to be understood that the features of the invention described below in the context of separate embodiments for purposes of clarity may be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may be provided separately or in any subcombination.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the invention and, together with the description, explain the principles of the invention.

According to the present invention, in the area of interconnects of reduced length to overcome the drawbacks of the prior art as mentioned above and to reduce receiver size, power requirements, insulation, integration with a receiver or transmitter, and RF loss. It can provide technical advantages over the technology.

Embodiments of the present invention will now be described in detail, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used to indicate the same or similar parts (elements) throughout the drawings.

The present invention overcomes the drawbacks of the prior art as mentioned above and provides for the prior art in the area of interconnects of reduced length to reduce receiver size, power requirements, insulation, integration with the receiver or transmitter, and RF loss. Provide technical advantages.

As used herein, the term "periphery" refers to a condition that exists outside the surrounding environment, ie, the Dwar assembly. For example, the surroundings may refer to elevated temperature conditions present as a result of normal room conditions, warm weather and / or heat generated during operation of the equipment, or low temperature conditions present in the outer space. This is in contrast to “cold temperature” intentionally cooled (by cryogenic sources) to indicate the state inside the Dwarr assembly, ie to maintain the low temperature required for optimal operation of the cryogenic electronic portion.

An improvement of the present state of the art according to the invention is shown in FIGS. 2 and 3. For illustration purposes a cryogenic receiver is shown in which the cryogenic electronic portion is a combination of HTS filter elements 205 connected to the active semiconductor circuit 210 and contained within the vacuum dewar assembly 215. The vacuum dewar assembly 215 includes a body 220 and a cold plate 225 in close contact or very close to both the cryogenic electronic portion and the cryogenic source as a base. In this embodiment, the cryogenic source is a small cryogenic cooler 230. Vacuum dwarf assembly 215 is a self-contained unit that includes a housing or shell. Dewar 215 includes a cover 520 as shown in FIGS. 5A-5E. Typically, the vacuum dwarf assembly 215 and the cryogenic cooler 230 are in close proximity to each other. In another embodiment, the dewar 215 and cryogenic cooler 230 are either in close proximity to each other or are formed as an integrated unit or assembly (interlocked) as shown in FIG.

The vacuum dwarf assembly 215 may also include a heat / infrared heat shield 235 covering at least the HTS filter element 205, for example to further reduce the cooling and power requirements of the cryogenic device.

In another embodiment, the size of the cryogenic device is at least superconducting (not shown) on the bottom of the heat / infrared heat shield 235 facing the HTS filter element 205 and in intimate contact with the cooling plate 225. It can be further reduced by positioning the plate. The use of superconducting plates in this embodiment helps to provide a reduced surface area for cryogenic device elements, thus further reducing the cooling and power requirements of the device.

For example, the superconducting plate may comprise a disk having a film of HTS material on at least the side of the disk facing the HTS filter element 205. The disk is typically not in physical contact with the HTS filter element 205, but may be close to it without contacting the HTS filter element 205, as the structure of the dwarf assembly permits. The disk may include one or more spacer legs or edges to contact the cold plate 225 but not the HTS filter element 205. Typically, the disc covers as many cryogenic electronic parts as the Dwarf assembly allows.

In addition, superconducting plates can be used for adjustment purposes, for example as disclosed in WO01 / 41251, which is incorporated herein by reference in its entirety.

A method that can be used for adjustment is to change the temperature at which the unit is programmed to operate. For example, a unit operating at 79.5K or 80.0K may introduce a displacement of less than 200 KHz within the operating frequency of the HTS filter element 205, depending on the filter design. Such temperature control may be achieved by changing the set temperature of the temperature controller for the cryogenic cooler 230. Another way to control this temperature is to change the temperature voltage curve of the temperature-measuring silicon diode or resistive temperature device (RTD) in the controller, or add an additional resistor in series with the RTD or silicon diode to adjust the voltage curve. Keep it fixed.

In another embodiment, the operating temperature of the cryogenic unit can be varied such that the unit can operate at a second center frequency for emergency or backup purposes in narrow band applications. For example, if the unit is designed to operate at a center frequency of 1950 MHz with a bandwidth of 2 MHz, the operating range would be 1949 to 1951 MHz. By varying the operating temperature, the unit can be made to operate at a center frequency of 1949 MHz with a band width of 1948 to 1950 MHz. The temperature can also be changed in smaller increments to fine tune the cryogenic units, which operate slightly off the center of the intended center frequency due to deviations in the manufacturing process.

The cryogenic electronic portion connects each of the input and output connectors 240, 245 from the cryogenic state inside the vacuum dwarf assembly 215 to the ambient state outside the vacuum dwarf assembly 215 as shown in FIG. 5A. Through the input source and output components 260 and 265.

As mentioned above, the total cooling power required by the cryogenic electronic portion directly affects the size, weight and total operating power of the cryogenic cooler functioning as a cryogenic source. The larger the total cooling power required, the larger the size, weight and total operating power of the cooler. The total cooling power required is infrared heating of the cold surface, conduction heat transfer from the warm surface of the gas molecules to the cold surface, power dissipated into the vacuum dwarf assembly 215 by the active semiconductor circuit 210, and the connector 240. , 245) is a function of a plurality of factors, including but not limited to conduction heat leakage. Infrared heating of the cold surface can be reduced by varying the size of the cold surface and the temperature at which the cold surface is maintained relative to the environment. Filter size and packaging tend to influence the size of cold surfaces.

In addition to the features described above, the present invention employs a plurality of other features to reduce the size and total cooling power required to maintain the cryogenic electronic portion at the optimum operating temperature as shown in FIGS. 2 and 2A.

As can be seen in Figures 2 and 2A, the connectors 240, 245 are made integral to the vacuum dwarf assembly 215 as opposed to the detachable module 110 shown in the prior art of Figure 1. Connectors 240 and 245 include jumpers 250 and 255 connected to input and output hermetic connectors 260 and 265, respectively. Hermetic connectors 260 and 265 provide electrical connection from vacuum dwarf assembly 215 and include, for example, "O" -rings, to maintain a vacuum seal inside vacuum dwarf assembly 215. Direct glass is used for the solder seals and / or metal seals. Direct glass for metal seals typically provides a suspension seal. The part outside the dwarf assembly of the hermetic connector 260, 265 may be formed of, for example, an optical fiber (conversion of an RF signal to an encrypted optical signal in order to use an optical fiber connection) and a twisted pair according to the type of connection required. It may be in the form of the same coaxial or other known connector.

Jumpers 250 and 255 are connected from the cryogenic temperature at the connection to the cryogenic component to the ambient temperature at the connection to the hermetic connector 260 and 265. Jumpers 250 and 255 may be of conventional construction, depending on the end use, for example, microstrip transmission lines for low frequency signals or waveguides for high frequency signals. In other embodiments, interconnects (ie jumpers 250, 255) are formed on the thermal barrier material to reduce heat gain from the environment. For example, jumpers 250 and 255 may be formed as microstrip transmission lines on a substrate such as alumina, glass (fused silica, quartz and MACOR, etc.), fiber optic epoxy, or aerogels greater than 0.002 inches (0.051 mm) thick. Can be. Substrates used in the present invention may be formed of fused silica (thermal conductivity (K) of about 1.5 W / mK) or silica-based aerogel (about 0.02 W / mK (300K, 1 atmosphere) to 0.004 W / mK (300K, vacuum) K), which is composed of a very low thermally conductive material that serves as an effective thermal barrier. In another embodiment, a high thermally conductive substrate is also contemplated that also includes some type of thermal barrier material. Those skilled in the art will appreciate that various thermal shields may be employed and do not depart from the disclosure of the present invention.

An example of this embodiment is shown in FIG. 3, where the interconnect includes an inserted thermal barrier. Substrate material 320 includes an insert 330 of low thermally conductive material (such as an aerogel) between the cold end 310 and the warm end 340 of the conductive strip on the micro strip line. In a similar context, the waveguide cavity may consist of a low thermally conductive material, such as a metallized aerogel on at least an inner surface, or may consist of a standard material, such as a metal with an inserted thermal barrier. An embodiment of the inserted thermal barrier material is shown in FIG. 4, wherein the substrate material 410 is metallized (aerogel) on at least the inner surface 430 between the cold end 440 and the warm end 450 of the waveguide cavity. Insert 420 of a low thermally conductive material, such as;

It should be noted that although the thermal barrier further reduces thermal conduction from the surroundings, low thermally conductive materials should first be used to avoid as much of the conductive heat gain as possible in the cryogenic electronic portion. The application of heat shields in combination and design of low thermally conductive materials is usually the best at the expense of increased size, and thus may not be practical in all applications. Since conductive heat transfer is inversely proportional to the length of the conductive material, jumpers 250 and 255 (see FIG. 5D) can be lengthened, but this can lead to increased signal loss and an increase in the size of the vacuum dwarf assembly. However, the balance between RF loss and low heat gain can be optimized by those skilled in the art based on the material and structural dimensions of jumpers 250 and 255.

The cryogenic receiver will be described in detail with reference to FIGS. 5A-5E.

Fig. 5A shows a front perspective view of the hermetically sealed cryogenic receiver of the present invention, and Fig. 5B shows a front exploded perspective view of Fig. 5A. Cryogenic receivers will be assembled with reference to FIGS. 5A-5E, respectively.

The lid 520 of the vacuum dwarf assembly 215 may be attached to the dwarf body 220 by welding, soldering, or mechanical connection. As shown in FIG. 5B, a screw 522 is inserted through a hole in the lid 520 to engage the body 220 through the screw hole 523. An “O-ring” seal 530 is positioned in the groove 222 to form a seal when the lid 520 is engaged with the body 520 by screws 522.

The o-ring seal 530 may be made of, but is not limited to, a rubber, synthetic material, or metal required to maintain a vacuum. In another embodiment, attachment of the lid 520 is accomplished by an O-ring seal 530, typically made of solder and metal. In another embodiment of the present invention, where some of the components are heat sensitive, making it difficult to use conventional welding or soldering techniques, malleable metal O-rings (such as those composed of indium) may include a lid 520 and a Dwarf body. A “cold” welding technique may be employed that is positioned between the 220 and the seal is adjusted by applying pressure to the lid 520 to compress the O-ring 530 in the groove 222.

A getter 525 that absorbs the remaining impurities after the housing / body 220 is evacuated through the vacuum tube 266 is in place by a fastener 526 with a bolt 527. maintain. In the present embodiment, four getters 525 are shown, but as long as the getters have sufficient capacity to absorb the expected inhibitory impurities over the lifetime of the cryogenic unit.

The cooling plate 225 is housed inside the body 220 having an internal cavity area 555 formed therein. An alignment tool 510 is used to align the cold plate 225 with the body 220 of the unit. The tool 510 is removed when the cooling plate 225 is properly secured inside the cavity 555. The filter 205 and the amplifier 210 are located on the cold plate 225 or very close to the cold plate 225. The RF shield 235 is positioned to communicate with the cold plate 225, the shield filter 205, and the amplifier 210. Brackets 535, 539, 541 are used to keep the cold plate 225, filter 205 and amplifier 210 (ie, potential receiver) in their respective positions inside cavity 555. All cryogenic and non-cryogenic surfaces inside the cavity 555 are preferably plated with a highly reflective material such as, for example, gold, platinum, silver or a similar type of metal (ie, a highly conductive metal with low reactivity to the environment). do. Jumpers 250 and 255 are in communication with filter 205 and amplifier 210.

Various inputs and outputs are accessible to the receiver through ports 260 (Rf _in ), 265 (Rf _out ), and 270 (DC _in ). The temperature indication inside the unit is provided via port 564.

Cooling fingers 572 extend through the central opening 554 of the cavity 555 and are in thermal communication with the cooling plate 225. The cooling finger 572 extends from the top 280 of the dwarf assembly 215 (ie, the heat dissipation zone). O-ring 570 forms a seal with area 282 when bottom plate 565 is secured to a bolt or screw hole 290 formed in dwarf top 280 by bolts or screws.

As an example of considering a plurality of thermal resin factors, the size of the HTS filter element is kept smaller than 40 cm ² , the divergence power of the active semiconductor circuit is kept smaller than 350 mW, and jumpers (5 cm in length, 0.005 in thickness) By maintaining the heat leakage produced by an inch (0.127 mm), microstrip transmission line on a 5 mm wide fused silica substrate) of less than 100 mW, the required cooling capacity per channel is 600 at ambient temperatures of 20 ° C. and 80 K. can be reduced to less than mW.

As mentioned above, jumpers 250 and 255 are preferably evacuated materials that can degrade the vacuum over time and increase the heat load to the cooler due to thermal conduction by the evacuated material. It is a microstrip transmission line formed on fused silica or silica aerogel substrates which can be effectively used in a long time vacuum environment due to the absence of a very low thermal conductivity substrate. In addition, an additional advantage of the airgel substrate is that the material is essentially a large surface area silica material. Silica surfaces tend to absorb water vapor and thus improve the quality of the vacuum. Silica materials, such as fused silica or silica aerogels, function as "getters" that are optimal electrical and thermal interfaces and help to maintain the required vacuum in the Dwar, thus improving vacuum reliability.

In other embodiments, jumpers 250 and 255 are typically laminated on one side of a fused silica substrate (5 m in length, 5 cm long, 2.5 to 5 mm wide and 0.005 inch (0.127 mm) thick) A microstrip transmission line (such as gold wire), and the other side of the substrate has a ground layer (eg, a conductive metal such as gold) thereon.

Conventional waveguide cavities made entirely of conductive metals tend to produce too large heat leakage for cryogenic electronic portions used in the frequency range lower than approximately 2 GHz. Thus, the waveguide cavity may be constructed from a metal coated substrate (eg, airgel) with low thermal conductivity (if waveguide is applied), or at least by inserting a "heat shield" of the metal coated airgel material into the waveguide cavity structure. It is recommended to reduce conduction heat transfer.

The HTS filter element can be one or more small filters that can meet the size constraints imposed by the structure of the vacuum dwarf assembly. Preferred miniature filters are disclosed in US Pat. No. 6,108,569, referenced above, and are based on various types of self-resonant spiral resonators, including but not limited to squares, squares with rounded corners, polygons, hairpins, ovals, and circles. . The size of the self resonant spiral resonator is reduced by reducing the width of the gap between adjacent lines and reducing the central open area within the spiral resonator. The resonant frequency f of the self-resonant spiral resonator is varied by varying the length of the helix λ; f = λ / 2, varying the gap width between adjacent lines of the helix and placing the conductive adjustment pad in the center of the helix. Can be changed. The last method can be used as fine frequency adjustment. Frequency adjustment can also be achieved through the use of an HTS plate located above the filter element and operating temperature variations as discussed above.

The design of the HTS filter element also depends on a number of factors such as, for example, the purpose of the filter element (eg band pass or band rejection), operating frequency, sensitivity, and other factors recognizable by those skilled in the art. Based on these factors, those skilled in the art will appreciate the instructions provided in US Pat. No. 6,108,569, referenced above, and Sonnet EM Suite, available from commercially available software packages (eg, Sonnet Software, Inc.). (Sonnet EM Suite) can be used to design the appropriate filter elements.

In various embodiments, the superconducting material of the HTS filter element (and other components including the superconducting material) has a transition temperature T _c greater than about 77K. In addition, the substrate for the HTS filter element must have a lossy tangent of less than about 0.0001 and have a dielectric material lattice matched to the HTS film deposited thereon. Particularly good materials include, but are not limited to:

HTS material-YBa ₂ Cu ₃ O ₇ , Tl ₂ Ba ₂ CaCu ₂ O ₈ , TlBa ₂ Ca ₂ Cu ₃ O ₉ , (TlPb) Sr ₂ CaCu ₂ O ₇ and (TlPb) Sr ₂ Ca ₂ Cu ₃ O ₉ One or more, and

Substrate material-at least one of LaAlO ₃ , MgO, LiNbO ₃ , sapphire and quartz.

In addition to substrates and HTS materials, various buffers and alignment layers may be used where appropriate as disclosed in, for example, US Pat. No. 5,508,255 and US Pat. No. 5,262,394, which are incorporated herein by reference in their entirety.

The input and output coupling of a small filter based on a spiral resonator has two commonly accepted structures. One is a parallel structure comprising a transmission line having one end connected to a connector of a small filter through a normal metal contact pad on the top of the line, and the other end of the line to provide an input or output coupling for the filter (input circuit For the first resonator or the final resonator (for the output circuit) to extend close to or parallel to the helix. The other is an insertion line structure comprising a transmission line having one end connected to a connector of a small filter through a normal metal contact pad on the top of the line, the other end of the line being provided to provide an input or output coupling for the filter ( Extending into the divided helix of the first resonator (for the input circuit) or the final resonator (for the input circuit). Other details can be found with reference to US Pat. No. 6,108,569, referenced above.

Resonant period coupling between adjacent spiral resonators in a small filter is provided by superposing an electromagnetic field at the edges of adjacent resonators. Coupling strength can be adjusted by changing the longitudinal distance between adjacent spiral resonators, changing the orientation of the spiral resonators and displacing the position of the spiral resonator along the transverse direction. The last method can be used for fine control of the coupling strength. Further details can also be found with reference to US Pat. No. 6,108,569, referenced above.

The small filter is preferably in intimate contact with the cold plate 225 of the vacuum dwarf assembly 215 via a metallized ground plane on the "rear" side of the small filter substrate, see above for further details. US Patent No. 6,108,569, which is incorporated by reference. The small filter and active semiconductor circuit may be, for example, by using a conductive epoxy or solder between the metalized ground plane and the cold plate 225, or by resistance welding the metalized ground plane to the cold plate 225, or It may be attached to the cold plate 225 by simply mechanical means such as screws.

The active semiconductor circuit 210 can be connected to the filter element 205 by any conventional means, such as soldering, wire bonding or parallel gap welding, but typically the active semiconductor circuit 210 by soldering, thermal compression bonding or resistance welding. It is connected by a short metal wire that is attached from a contact pad (not shown) on the top to a contact pad (not shown) on the filter element 205.

The active semiconductor circuit 210 may be, for example, one or a combination of amplifiers, mixers, analog-to-digital converters, and digital processors. For a typical receiver, the active semiconductor circuit 210 may, but is not limited to, an InP or GaAs HEMT, HBT, pHEMT, nHEMT, III-V heterostructure, or a monolithic microwave integrated circuit (MMIC) amplifier. It includes an amplifier that is not limited. Such amplifiers are known. InP or GaAs pHEMT or nHEMT amplifiers are usually preferred. Commercially available examples include, for example, Miteq Inc., Hauperg, New York, USA, Model No. SAFS1-01500200-08-CR-S and Microwave Technology Inc .; Fremont, California, USA, model number SG0-7446, part number 01-50-660).

The cryogenic source of the cryogenic device cools the cryogenic electronic components. The cryogenic source may be in an ambient external space state when the device is placed in an external space, but the cryogenic source is typically a small cryogenic cooler unit 230 that requires adequate size and power. Such compact cryogenic coolers are typically Stirling cycle machines as disclosed in US Pat. Nos. 4,397,155, EP-A-0028144, WO90 / 12961 and WO90 / 13710 (all incorporated herein by reference in their entirety).

The cryogenic devices described above can be used in band pass and band rejection filter devices in many fields, particularly in the field of wireless communications. One such area is the front end of a wireless communication base station receiver in a terrestrial tower tower device. Universal details of such uses can be found in the above referenced documents. In such applications, the cryogenic potential receiver of the present invention is in some general aspects in that it includes a cryogenic electronic unit and control circuitry within a single enclosure that can be electrically connected directly or remotely to other components of a base station (shown in FIG. 1). May be an integrated package similar to a conventional unit). However, due to the advanced features of the cryogenic electronic units described herein, the size, weight and power requirements of the potential receiver according to the invention are in several cases more than several times while maintaining equivalent or even better performance than such conventional units. Can be significantly reduced.

Significant reductions in size, weight and power requirements make the cryogenic device according to the invention ideal for integration into antenna assemblies, satellite base stations, radar arrays and RF receivers, for example.

Specific examples of the above include an integrated antenna assembly in which the cryogenic device and at least one antenna of the wireless base station are assembled as an integrated unit. In contrast to the system shown in the previously referenced US Pat. No. 6,104,934, in which the cryogenic electronic portion of the unit can be very close to the antenna, the present invention provides a unit integrated with an antenna that further reduces noise contamination for the system. Make it possible.

6A-6F illustrate various embodiments of a wireless communication base station and a self-regulating cryogenic potential receiver. 6A shows a schematic diagram of a wireless base station cryogenic unit structure that includes a diversity antenna 605 and a primary receiver 610. Diversity antenna 605 provides approximately 3 db of additional gain relative to the gain of the signal received via main receiver 610. The diversity receiver only receives the signal, but the main receiver 610 simultaneously receives and transmits. Corresponding signals are transmitted directly to the cryogenic unit 630 in the case of the diversity antenna 605 and to the diplexer 615 before being sent to the cryogenic unit 630 for the main receiver 610.

Diplexer 615 consists of filters 620 and 625 for separating the signal into its transmit and receive signal elements. The received signal element is then transmitted to the cryogenic unit 630. In a typical case, the transmission signal is not processed through the cryogenic unit because of the heating capacity limitation, but can be processed by the cryogenic unit 630 without the heating capacity limitation. In this embodiment, the cryogenic unit 630 is composed of HTS filters 635, 645 with amplifiers 640, 650, respectively. Typically, the amplifier is a low-noise-amplification (LNA) amplifier. The received signal is then sent to amplifiers 655 and 660, respectively, and diplexed by the diplexer 665 to the transmitting element of the signal in the case of the main receiver 610 electrical path, and then the rest of the base station. Is sent.

6B shows a second embodiment of a wireless base station and cryogenic unit structure of the present invention. FIG. 6B differs from the embodiment shown in FIG. 6A in that the cryogenic units 630 and 680 are dedicated to the primary receiver 610 signal and the diversity antenna 605 signal, respectively. This structure provides increased reliability and also includes bypass circuits 642 and 692 respectively to ensure that the base station continues to receive and transmit RF signals even if one or both of the units 630 and 680 fail. .

6C shows a third embodiment of the radio base station and the cryogenic unit structure of the present invention, where only the diversity antenna 605 signal is the signal processed by the cryogenic unit 630. In addition, the bypass circuit 642 further includes a filter 644 to provide increased reliability and filtering along this path that is not provided in the embodiment shown in FIGS. 6A and 6B.

6D shows a fourth embodiment of a wireless base station and cryogenic unit structure of the present invention. FIG. 6D does not include the diversity antenna of the embodiment shown in FIGS. 6A-6C. This embodiment includes bypass 642 without filter 644, but in all other respects functions like the previous embodiments.

Figure 6e shows a fifth embodiment of the radio base station and the cryogenic unit structure of the present invention. 6E differs from the fourth embodiment in that it includes a diplexer 665 in the circuit before the signal is sent to the remaining portion of the base station.

Figure 6f shows a sixth embodiment of a wireless base station and cryogenic unit structure of the present invention. 6F illustrates a structure in which only the diversity antenna 605 signal is processed by the cryogenic unit 630. This embodiment further includes a bypass circuit 642 and a diplexer 665 with a bypass filter 644 prior to transmitting the processed signal to the rest of the base station.

The reader should appreciate that the above embodiments are exemplary and are not intended to limit the scope of the invention. The invention can be applied in any environment where RF signals (and especially microwaves) are received and transmitted, such as, but not limited to, radar arrays, satellite facilities (home or commercial), and wireless and mobile telephone base stations. In such a case, the cryogenic device according to the present invention may provide 1, 2, 3 or significantly higher db gains in the output signal to noise ratio, depending on the application and component configuration.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention and the configuration of the present invention without departing from the scope of the present invention. Other embodiments of the invention will be apparent to those skilled in the art upon consideration of the specification and embodiments of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being defined by the following claims.

Other embodiments of the invention will be apparent to those skilled in the art upon consideration of the specification and examples of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being defined by the following claims.

1 shows a perspective view of a conventional integrated cryogenic receiver.

Figure 2 shows a front perspective view of an embodiment of the cryogenic receiver according to the present invention.

2A shows a top perspective view of an embodiment of a cryogenic receiver in accordance with the present invention.

3 is a schematic diagram of a microstrip transmission line with a thermal shield that can be used as part of a connector from ambient to cryogenic (or vice versa).

4 is a schematic diagram of a waveguide structure with a thermal barrier that can be used as part of a connector from ambient to cryogenic (or vice versa).

5A shows a front perspective view of an hermetically sealed cryogenic receiver of an embodiment of the present invention.

Fig. 5B shows a front exploded perspective view of the embodiment shown in Fig. 5A of the present invention.

5C is an exploded front perspective view of the embodiment shown in FIG. 5B of elements on cut line AA of the present invention.

5D is an exploded front perspective view of the embodiment shown in FIG. 5B of elements on cut line BB of the present invention.

5E is an exploded front perspective view of the embodiment shown in FIG. 5B of elements on cut line BB of the present invention.

6A shows a schematic circuit diagram of a cryogenic receiver that includes a mobile telephone base station and a primary receiver antenna and diversity receiver antenna input structure of an embodiment of the present invention.

FIG. 6B shows a schematic circuit diagram of a receiver including a primary receiver antenna and a diversity receiver antenna input structure including a mobile telephone base station and a multiple receiver input and bypass circuit structure of another embodiment of the present invention.

6C shows a schematic circuit of a receiver including a primary receiver antenna and a diversity receiver antenna input including a mobile telephone base station and a bypass circuit and filter structure of another embodiment of the present invention.

Fig. 6D shows a schematic circuit diagram of a receiver including a mobile telephone base station and a main receiver antenna input and bypass circuit structure of another embodiment of the present invention.

Figure 6e illustrates a schematic circuit of a receiver including a mobile telephone base station and a primary receiver antenna input cryogenic receiver having a multiple diplexer and bypass circuit structure of another embodiment of the present invention.

Figure 6f shows a sixth embodiment of a wireless base station and cryogenic unit structure of the present invention.

<Explanation of symbols for the main parts of the drawings>

205: HTS Filter Element

210: active semiconductor circuit

215: Vacuum Dwarf Assembly

220: body

225: cold plate

230: Compact Cryogenic Cooler

Claims (2)

A method of tuning a cryogenic receiver comprising a high temperature superconductor filter element and having an operating frequency at operating temperature, The method includes varying the operating temperature to displace the operating frequency of the cryogenic receiver. A method of tuning a cryogenic receiver having a high temperature superconductor filter element and having an operating center point frequency at operating temperature, The method includes varying the operating temperature to displace the operating frequency of the cryogenic receiver.

Images