CA1138572A - Planar transmission line attenuator and switch - Google Patents
Planar transmission line attenuator and switchInfo
- Publication number
- CA1138572A CA1138572A CA000327246A CA327246A CA1138572A CA 1138572 A CA1138572 A CA 1138572A CA 000327246 A CA000327246 A CA 000327246A CA 327246 A CA327246 A CA 327246A CA 1138572 A CA1138572 A CA 1138572A
- Authority
- CA
- Canada
- Prior art keywords
- metallic conductors
- transmission line
- semiconductor layer
- schottky barrier
- semiconductor substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/10—Auxiliary devices for switching or interrupting
- H01P1/15—Auxiliary devices for switching or interrupting by semiconductor devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/22—Attenuating devices
- H01P1/227—Strip line attenuators
Abstract
Abstract The planar transmission line attenuator and switch is formed on a semiconductor substrate consisting of a high resistivity semiconductor material and a thin, conductive semiconductor layer. Transmission line metallic conductors are deposited on the conductive semiconductor layer, and at least one of the metallic conductors forms a Schottky barrier contact to the semiconductor substrate. The gap between the metallic conductors defines a shunt current path through the semiconductor layer. By applying a bias voltage to the metallic conductor forming the Schottky barrier contact, the conductivity of the shunt path can be controlled by changing the depletion layer width across the Schottky barrier. A
plurality of planar transmission line switches can be combined into multi-port networks, examples of which are cross-bar switching devices and .beta. element switching devices.
plurality of planar transmission line switches can be combined into multi-port networks, examples of which are cross-bar switching devices and .beta. element switching devices.
Description
~38572 Descr~tion PLANAR T~ANSMISSION I,INE ATTENUATOR AND SWITCH
_ The present invention generalli~ relates to r.f.
switching devices, and more particularly to r.f. switching devices formed by sections of transmission lines in which the attenuation can be switched from high values, such as 60dB, to low values, such as 5dB or OdB. The invention also relates to the use of such transmission line switches in multi-port networks such as microwave cross-bar switches and ~ switching d~-ices.
At the present time, microwave switching is accomplished mostly by means of PIN diodes which function by changing their capacitance in response to a change in bias voltage.
To act as a switch, PIN diodes must be combined with passive elements in a circuit attached in some way to a transmission line. The circuit must be carefully designed to provide the desired attenuation and VSWR in the off state and in the on state. The primary disadvantages of this type of switching element are its relatively high complexity and narrow band-width. The bandwidth is nherently limited because areactance change in the PIN diode is used to achieve the switching function.
The planar transmission line attenuator and switch according to this invention has certain similarities in con-struction to the device disclosed in United States PatentNo. 3,975,690, issued August 17, 197~ to Paul ~. Fleming, one of the co-inventors of the present invention. The Fleming patent discloses a planar transmission line comprising a Gunn effect semi-conductor on which transmission line conductors are deposited. This device can be used to either amplify or switch r.f. signals. When used as a switch, the device is operated under conditions so as not to exhibit gain. Near zero attenuation is achieved in either of two ways. The product of carrier concentration~ N, 3~ time the electric field length, L, between the conductors is made high enough so that at the on state bias, the field configuration is near the threshold 113~57Z
field. This is the field at which the differential mobility, ~d~ of slope of the velocity versus field curve (see Figure 2 of the patent) is zero. A short segment of the current path has a much higher field where ~d is also near zero. In the short transition between these two regions, ~d is negative and as a result the shunt conductivity per unit length, G, may be negative for some frequencies but will not have sufficiently large magnitude to overcome the series resistance losses in the metallic conductors. The product N t, where t is the thick-ness of the conductive semiconductor layer, must be kept below about 5 1011 to prevent small signal instability leading tospontaneous oscillation. The other way of using the Gunn effect is to allow a significant value of ~d over most of the current path but keeping the resulting negative conductivity small by making the thickness or carrier concentration of the conductive semiconductor layer small. The value of conductivity, G, could be adjusted to achieve exactly zero attenuation at a particular operating frequency.
While the device according to the Fleming patent can pro-vide excellent switching results in certain applications, it has the disadvantage of high d.c. power dissipation. This becomes a serious problem when a great many of these devices are arranged in a matrix to form a cross-bar switch, for example.
The transmission line attenuator and switch according to the present invention exhibits a wide range of attenuation over a very broad bandwidth, and this is accomplished with a very simple structure. Thus, the transmission line attenuator and switch according to this invention has neither the complexity or narrow bandwidth which are inherent in microwave switches us-ing PIN diodes. ~t the same time, the transmission line attenu-ator and switch according to the present invention is to be distinguished from the device disposed in the Fleming patent in that this device is characterized by making one or more of the metallic conductors to form a Schottky barrier contact to the semiconductor substrate. Use is made of the change in the depletion layer width with bias voltage across the Schottky barrier to vary the conductivity in the conductive semiconductor layer. More specifically, the depletion layer is defined as a layer in the semiconductor adjacent the metal contact, and this layer contains no free electrons and is therefore said to be depleted. If the bias voltage across the depletion layer is -- 113~S~2 zero, then the width of the depletion layer is small. A positive bias reduces the depletion layer width, and a negative bias in-creases it. The carrier concentration and the length of the shunt current path is chosen such that at zero biasl most of the shunt current path is through the undepleted semiconductor, while at an appropriate negative bias, most of this path is through the depletion layer. This results in high attenuation at a small forward bias and much lower attenuation at the negative bias.
In one aspect the invention pertains to a planar trans-mission line attenuator and switch including a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming the planar surface, the resistivity of the semiconductor material being very high com-pared to that of the semiconductor layer so that electric cur-rents flow only in the semiconductor layer. At least two metal-lic conductors are deposited on the planar surface and spaced to form a uniform gap therebetween, the gap defining a shunt current path between the conductors through the semiconductor layer. At least one of the metallic conductors forms a Schottky barrier contact to the semiconductor substrate, the at least two metallic conductors forming an r.f. transmission line having input and output ports. Means provide for applying an r.f. sig-nal to the input port of the transmission line to cause the r.f.
signal to propagate along the gap toward the output port of the transmission line, and bias means is connected to the at least one of the metallic conductors forming a Schottky barrier for controlling the conductivity of the shunt current path.
The invention also pertains to a cross-bar switching device of the type having a plurality of switches arranged in a matrix such that the selective operation of the switches per-mits the connection of any one of a plurality of input lines to any one of a plurality of output lines, each of the switches being of the type referred to above.
Further the invention comprehends a beta element switching device comprising a semiconductor substrate of the above type with five metallic conductors deposited on the planar surface and spaced to form uniform gaps therebetween. One of the metal-lic conductors has a generally square geometry and the otherfour of the metallic conductors has a generally trapezoidal geometry and is symmetrically arranged about the one metallic conductor~ The gaps between adjacent ones of the conductors defines shunt current paths between the adjacent conductors through the semiconductor layer, the one metallic conductor forming an ohmic contact to the semiconductor substrate while the other four metallic conductors form Schottky barrier con-tacts to the semiconductor substrate. Adjacent ends of theother four metallic conductors define input or output ports of r.f. transmission lines formed by the five metallic con-ductors. Means provide for applying an r.f. si~nal to at least one input port to cause the r.f. signal to propagate along the gap toward one of at least two ouput ports, and bias means is connected to each of the other four of the metallic con-ductors for selectively controlling the conductivity of the shunt current paths.
In the drawings:
Figure 1 is a perspective view illustrating a planar transmission line attenuator and switch according to the present invention;
Figures 2 to 6 are schematic plan views illustrating several alternative embodiments of the transmission line at-tenuator and switch according to the invention; and Figure 7 is a schematic plan view illustrating theconstruction of a ~ switching element using the transmission line attenuator and switch according to the invention.
As shown in Figure 1, the transmission line attenuator and switch comprises a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material 10 over which is formed a thin, conductive semiconductor layer 12. The semiconductor layer 12 has a carrier concentra-tion, N, and mobility, ~, and a thickness t. The semiconductor material 10 has a resistivity which is very high compared to that of the semiconductor layer 12 so that electric currents flow only in the semiconductor layer. Gallium arsenide is a preferred semiconductor material, but in addition to the semi-conductor materials mentioned in the Fleming patent, silicon may also be used. The semiconductor layer 12 is preferably formed by epitaxial growth on the base substrate material 10.
The transmission line illustrated in Figure 1 is a three conductor transmission line comprising ground planes 14 and a center conductor 16. These metallic conductors are deposited on the planar surface of the semiconductor sub-strate so as to form a uniform gap 18 between the ground plane conductors 14 and the center conductor 16. The gap 18 defines an electric field length L between the center conductor 16 and the ground plane conductors 14. The semi-conductor 12 has ~ shunt conductivity per unit length, G, which is proportional to the sheet conductance, ~et, divided by the distance, L (across which drift current flows between the conductors). This shunt conductivity causes an attenuation per unit length which can be large compared to that due to the series resistance of the metallic conductors.
In order to bring the value of G to zero or close to zero and thus greatly reduce the attenuation per unit length, one or more of the metallic conductors 14 and 16 are made to form a Schottky barrier contact to the semiconductor sub-strate. As shown in Figure 2, the center conductor 16 can be made to form the Schottky barrier, while the ground plane conductors 14 may be made to make an ohmic contact with the semiconductor substrate. Alternatively, the center conductor 16 may make an ohmic contact and the ground plane conductors made to form Schottky barriers as illustrated in Figure 3. It is also possible to make all three conductors form a Schottky barrier contact as shown in Figure 4. Moreover, the invention is not limited to three conductor transmission lines but may also be realized with a slot line configuration. Such a configuration is schematically illustrated in Figures 5 and 6. In these figures, metallic conductors 20 and 22 are deposited on the semiconductor substrate to define a single g~p 18. In Figure 5, the metallic conductor 20 is made to form a Schottkv barrier, while the metallic ccnductoi- 22 foLm~
an ohmic contact with the semiconductor. On the other hand in Figure 6, both of the metallic conductors 20 and 22 are made to form Schottky barriers with the semiconductor substrate.
The mechanism by which the prescnt invention operates is the change in the depletion layer width with bias volta~e across the Schottky barrier. The depletion layer is a layer in the semiconductor adjacent the metal contact, and this layer contains no free carriers and is therefore said to be depleted. Because the depletion layer contains no free carriers, an increase in the size of the depletion layer results in a decrease in attenuation of an r.f. signal propagated by the transmission line. In other words, minimum attenuation occurs when a negative bias is applied to the Schottky barrier contact, because there are no free carriers to absorb the r.f. signal being propagated by the transmission line. In contrast, when the bias voltage is slightly positive, the depletion layer no longer exists resulting in high atten-uation because of the r.f. signal absorption due to the high shunt conductivity in the semiconductor layer 12.
In an experimental model with L = 5~m and Q = 1550~m, the attenuation was switched from a high value, such as 18dB, at a forward bias voltage of 0.6 to a low value, such as 4dB, for a reverse bias voltage of -20 volts. Because the width of the depletion layer can be controlled by the application of the bias voltage to the Schottky barrier contact, the transmission line according to this invention allows a control of the attenuation of an r.f. signal over a very wide range.
The lower power consumption of the transmission line switches according to the present invention make them partic-ularly attractive when combined into multi-port networks.
One important application is a microwave cross-bar switch which can be used, for example, onboard a communications satellite. Such a cross-bar switch is made by providing a matrix of transmission line switches of the type shown in Figure 1. Each of these transmission line switches would be switchable by selective application of bias voltages to con-nect corresponding row and column lines of the cross-bar switch.
Another multi-port network which can be realized using the advantage of the present invention is a ~ switching element. Such an element is generally illustrated in Figure 7 and comprises five metallic conductors deposited on a semiconductor substrate. The cer.tral conductor 24 has a generally s~uare geometry and forms an ohmic contact with the substrate. Typically, this conductor is ~Jrounded. The other 113~57Z
four conductors 26, 28, 30 and 32 are symmetrically arranged about the central conductor 24. Each of these conductors has a generally trapezoidal shape and are sp~ced from one another and the central conductor 24 to provide a uniform gap width. Each of the conductor~ 26, 28, 30 and 32 is made to form a Schottky barrier contact with the semiconductor substrate. The gaps between adjacent ends of the conductors 26, 28, 30 and 32 define input or output ports of the r.f.
transmission lines formed by the five metallic conductors.
More specifically, the gap 34 between conductors 26 and 32 can be defined as an input port as can the gap 36 between the conductors 28 and 30. The output ports may be defined as the gaps 38 and 40 between the conductors 30, 32 and 26, 28, respectively. Negative bias voltages are selectively applied to the conductors 26, 28, 30 and 32 to control the coupling of of input r.f. signals at input ports 34 and 36 to the output ports 38 and 40. For example, if negative bias voltages are applied to the conductors 26 and 30 while a slight forward bias is applied to conductors 28 and 32, an r.f. signal coupled to input port 34 will propagate to output port 40, while an r.f. signal coupled to input port 36 will propagate to output port 3~. On the other hand, if negative bias voltages are applied to conductors 28 and 32 while a slight forward bias voltage is applied to conductors 26 and 30, an r.f. signal coupled to input port 34 will propagate to output port 38, while an r.f. signal coupled to input port 36 will propagate to output port 40.
_ The present invention generalli~ relates to r.f.
switching devices, and more particularly to r.f. switching devices formed by sections of transmission lines in which the attenuation can be switched from high values, such as 60dB, to low values, such as 5dB or OdB. The invention also relates to the use of such transmission line switches in multi-port networks such as microwave cross-bar switches and ~ switching d~-ices.
At the present time, microwave switching is accomplished mostly by means of PIN diodes which function by changing their capacitance in response to a change in bias voltage.
To act as a switch, PIN diodes must be combined with passive elements in a circuit attached in some way to a transmission line. The circuit must be carefully designed to provide the desired attenuation and VSWR in the off state and in the on state. The primary disadvantages of this type of switching element are its relatively high complexity and narrow band-width. The bandwidth is nherently limited because areactance change in the PIN diode is used to achieve the switching function.
The planar transmission line attenuator and switch according to this invention has certain similarities in con-struction to the device disclosed in United States PatentNo. 3,975,690, issued August 17, 197~ to Paul ~. Fleming, one of the co-inventors of the present invention. The Fleming patent discloses a planar transmission line comprising a Gunn effect semi-conductor on which transmission line conductors are deposited. This device can be used to either amplify or switch r.f. signals. When used as a switch, the device is operated under conditions so as not to exhibit gain. Near zero attenuation is achieved in either of two ways. The product of carrier concentration~ N, 3~ time the electric field length, L, between the conductors is made high enough so that at the on state bias, the field configuration is near the threshold 113~57Z
field. This is the field at which the differential mobility, ~d~ of slope of the velocity versus field curve (see Figure 2 of the patent) is zero. A short segment of the current path has a much higher field where ~d is also near zero. In the short transition between these two regions, ~d is negative and as a result the shunt conductivity per unit length, G, may be negative for some frequencies but will not have sufficiently large magnitude to overcome the series resistance losses in the metallic conductors. The product N t, where t is the thick-ness of the conductive semiconductor layer, must be kept below about 5 1011 to prevent small signal instability leading tospontaneous oscillation. The other way of using the Gunn effect is to allow a significant value of ~d over most of the current path but keeping the resulting negative conductivity small by making the thickness or carrier concentration of the conductive semiconductor layer small. The value of conductivity, G, could be adjusted to achieve exactly zero attenuation at a particular operating frequency.
While the device according to the Fleming patent can pro-vide excellent switching results in certain applications, it has the disadvantage of high d.c. power dissipation. This becomes a serious problem when a great many of these devices are arranged in a matrix to form a cross-bar switch, for example.
The transmission line attenuator and switch according to the present invention exhibits a wide range of attenuation over a very broad bandwidth, and this is accomplished with a very simple structure. Thus, the transmission line attenuator and switch according to this invention has neither the complexity or narrow bandwidth which are inherent in microwave switches us-ing PIN diodes. ~t the same time, the transmission line attenu-ator and switch according to the present invention is to be distinguished from the device disposed in the Fleming patent in that this device is characterized by making one or more of the metallic conductors to form a Schottky barrier contact to the semiconductor substrate. Use is made of the change in the depletion layer width with bias voltage across the Schottky barrier to vary the conductivity in the conductive semiconductor layer. More specifically, the depletion layer is defined as a layer in the semiconductor adjacent the metal contact, and this layer contains no free electrons and is therefore said to be depleted. If the bias voltage across the depletion layer is -- 113~S~2 zero, then the width of the depletion layer is small. A positive bias reduces the depletion layer width, and a negative bias in-creases it. The carrier concentration and the length of the shunt current path is chosen such that at zero biasl most of the shunt current path is through the undepleted semiconductor, while at an appropriate negative bias, most of this path is through the depletion layer. This results in high attenuation at a small forward bias and much lower attenuation at the negative bias.
In one aspect the invention pertains to a planar trans-mission line attenuator and switch including a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming the planar surface, the resistivity of the semiconductor material being very high com-pared to that of the semiconductor layer so that electric cur-rents flow only in the semiconductor layer. At least two metal-lic conductors are deposited on the planar surface and spaced to form a uniform gap therebetween, the gap defining a shunt current path between the conductors through the semiconductor layer. At least one of the metallic conductors forms a Schottky barrier contact to the semiconductor substrate, the at least two metallic conductors forming an r.f. transmission line having input and output ports. Means provide for applying an r.f. sig-nal to the input port of the transmission line to cause the r.f.
signal to propagate along the gap toward the output port of the transmission line, and bias means is connected to the at least one of the metallic conductors forming a Schottky barrier for controlling the conductivity of the shunt current path.
The invention also pertains to a cross-bar switching device of the type having a plurality of switches arranged in a matrix such that the selective operation of the switches per-mits the connection of any one of a plurality of input lines to any one of a plurality of output lines, each of the switches being of the type referred to above.
Further the invention comprehends a beta element switching device comprising a semiconductor substrate of the above type with five metallic conductors deposited on the planar surface and spaced to form uniform gaps therebetween. One of the metal-lic conductors has a generally square geometry and the otherfour of the metallic conductors has a generally trapezoidal geometry and is symmetrically arranged about the one metallic conductor~ The gaps between adjacent ones of the conductors defines shunt current paths between the adjacent conductors through the semiconductor layer, the one metallic conductor forming an ohmic contact to the semiconductor substrate while the other four metallic conductors form Schottky barrier con-tacts to the semiconductor substrate. Adjacent ends of theother four metallic conductors define input or output ports of r.f. transmission lines formed by the five metallic con-ductors. Means provide for applying an r.f. si~nal to at least one input port to cause the r.f. signal to propagate along the gap toward one of at least two ouput ports, and bias means is connected to each of the other four of the metallic con-ductors for selectively controlling the conductivity of the shunt current paths.
In the drawings:
Figure 1 is a perspective view illustrating a planar transmission line attenuator and switch according to the present invention;
Figures 2 to 6 are schematic plan views illustrating several alternative embodiments of the transmission line at-tenuator and switch according to the invention; and Figure 7 is a schematic plan view illustrating theconstruction of a ~ switching element using the transmission line attenuator and switch according to the invention.
As shown in Figure 1, the transmission line attenuator and switch comprises a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material 10 over which is formed a thin, conductive semiconductor layer 12. The semiconductor layer 12 has a carrier concentra-tion, N, and mobility, ~, and a thickness t. The semiconductor material 10 has a resistivity which is very high compared to that of the semiconductor layer 12 so that electric currents flow only in the semiconductor layer. Gallium arsenide is a preferred semiconductor material, but in addition to the semi-conductor materials mentioned in the Fleming patent, silicon may also be used. The semiconductor layer 12 is preferably formed by epitaxial growth on the base substrate material 10.
The transmission line illustrated in Figure 1 is a three conductor transmission line comprising ground planes 14 and a center conductor 16. These metallic conductors are deposited on the planar surface of the semiconductor sub-strate so as to form a uniform gap 18 between the ground plane conductors 14 and the center conductor 16. The gap 18 defines an electric field length L between the center conductor 16 and the ground plane conductors 14. The semi-conductor 12 has ~ shunt conductivity per unit length, G, which is proportional to the sheet conductance, ~et, divided by the distance, L (across which drift current flows between the conductors). This shunt conductivity causes an attenuation per unit length which can be large compared to that due to the series resistance of the metallic conductors.
In order to bring the value of G to zero or close to zero and thus greatly reduce the attenuation per unit length, one or more of the metallic conductors 14 and 16 are made to form a Schottky barrier contact to the semiconductor sub-strate. As shown in Figure 2, the center conductor 16 can be made to form the Schottky barrier, while the ground plane conductors 14 may be made to make an ohmic contact with the semiconductor substrate. Alternatively, the center conductor 16 may make an ohmic contact and the ground plane conductors made to form Schottky barriers as illustrated in Figure 3. It is also possible to make all three conductors form a Schottky barrier contact as shown in Figure 4. Moreover, the invention is not limited to three conductor transmission lines but may also be realized with a slot line configuration. Such a configuration is schematically illustrated in Figures 5 and 6. In these figures, metallic conductors 20 and 22 are deposited on the semiconductor substrate to define a single g~p 18. In Figure 5, the metallic conductor 20 is made to form a Schottkv barrier, while the metallic ccnductoi- 22 foLm~
an ohmic contact with the semiconductor. On the other hand in Figure 6, both of the metallic conductors 20 and 22 are made to form Schottky barriers with the semiconductor substrate.
The mechanism by which the prescnt invention operates is the change in the depletion layer width with bias volta~e across the Schottky barrier. The depletion layer is a layer in the semiconductor adjacent the metal contact, and this layer contains no free carriers and is therefore said to be depleted. Because the depletion layer contains no free carriers, an increase in the size of the depletion layer results in a decrease in attenuation of an r.f. signal propagated by the transmission line. In other words, minimum attenuation occurs when a negative bias is applied to the Schottky barrier contact, because there are no free carriers to absorb the r.f. signal being propagated by the transmission line. In contrast, when the bias voltage is slightly positive, the depletion layer no longer exists resulting in high atten-uation because of the r.f. signal absorption due to the high shunt conductivity in the semiconductor layer 12.
In an experimental model with L = 5~m and Q = 1550~m, the attenuation was switched from a high value, such as 18dB, at a forward bias voltage of 0.6 to a low value, such as 4dB, for a reverse bias voltage of -20 volts. Because the width of the depletion layer can be controlled by the application of the bias voltage to the Schottky barrier contact, the transmission line according to this invention allows a control of the attenuation of an r.f. signal over a very wide range.
The lower power consumption of the transmission line switches according to the present invention make them partic-ularly attractive when combined into multi-port networks.
One important application is a microwave cross-bar switch which can be used, for example, onboard a communications satellite. Such a cross-bar switch is made by providing a matrix of transmission line switches of the type shown in Figure 1. Each of these transmission line switches would be switchable by selective application of bias voltages to con-nect corresponding row and column lines of the cross-bar switch.
Another multi-port network which can be realized using the advantage of the present invention is a ~ switching element. Such an element is generally illustrated in Figure 7 and comprises five metallic conductors deposited on a semiconductor substrate. The cer.tral conductor 24 has a generally s~uare geometry and forms an ohmic contact with the substrate. Typically, this conductor is ~Jrounded. The other 113~57Z
four conductors 26, 28, 30 and 32 are symmetrically arranged about the central conductor 24. Each of these conductors has a generally trapezoidal shape and are sp~ced from one another and the central conductor 24 to provide a uniform gap width. Each of the conductor~ 26, 28, 30 and 32 is made to form a Schottky barrier contact with the semiconductor substrate. The gaps between adjacent ends of the conductors 26, 28, 30 and 32 define input or output ports of the r.f.
transmission lines formed by the five metallic conductors.
More specifically, the gap 34 between conductors 26 and 32 can be defined as an input port as can the gap 36 between the conductors 28 and 30. The output ports may be defined as the gaps 38 and 40 between the conductors 30, 32 and 26, 28, respectively. Negative bias voltages are selectively applied to the conductors 26, 28, 30 and 32 to control the coupling of of input r.f. signals at input ports 34 and 36 to the output ports 38 and 40. For example, if negative bias voltages are applied to the conductors 26 and 30 while a slight forward bias is applied to conductors 28 and 32, an r.f. signal coupled to input port 34 will propagate to output port 40, while an r.f. signal coupled to input port 36 will propagate to output port 3~. On the other hand, if negative bias voltages are applied to conductors 28 and 32 while a slight forward bias voltage is applied to conductors 26 and 30, an r.f. signal coupled to input port 34 will propagate to output port 38, while an r.f. signal coupled to input port 36 will propagate to output port 40.
Claims (9)
1. A planar transmission line attenuator and switch comprising:
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that electric currents flow only in said semiconductor layer, at least two metallic conductors deposited on said planar surface and spaced to form a uniform gap therebetween, said gap defining a shunt current path between said conduc-tors through said semiconductor layer, at least one of said metallic conductors forming a Schottky barrier contact to said semiconductor substrate, said at least two metallic conductors forming an r.f. transmission line having input and output ports, means for applying an r.f. signal to the input port of said transmission line to cause said r.f. signal to propagate along the gap toward the output port of said transmission line, and bias means connected to said at least one of said metallic conductors forming a Schottky barrier for controlling the conductivity of said shunt current path.
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that electric currents flow only in said semiconductor layer, at least two metallic conductors deposited on said planar surface and spaced to form a uniform gap therebetween, said gap defining a shunt current path between said conduc-tors through said semiconductor layer, at least one of said metallic conductors forming a Schottky barrier contact to said semiconductor substrate, said at least two metallic conductors forming an r.f. transmission line having input and output ports, means for applying an r.f. signal to the input port of said transmission line to cause said r.f. signal to propagate along the gap toward the output port of said transmission line, and bias means connected to said at least one of said metallic conductors forming a Schottky barrier for controlling the conductivity of said shunt current path.
2. A planar transmission line attenuator and switch as recited in claim 1, wherein both of said metallic conductors form a Schottky barrier contact to said semiconductor substrate.
3. A planar transmission line attenuator and switch as recited in claim 1, wherein three metallic conductors are deposited on said planar surface to form an r.f. transmission line having a center conductor uniformly positioned between two ground planes.
4. A planar transmission line attenuator and switch as recited in claim 3, wherein said center conductor forms a Schottky barrier contact to said semiconductor substrate
5. A planar transmission line attenuator and switch as recited in claim 3, wherein the metallic conductors forming said ground planes form Schottky barrier contacts to said semiconductor substrate.
6. A planar transmission line attenuator and switch as recited in claim 3, wherein each of said three metallic conductors forms a Schottky barrier contact to said semi-conductor substrate.
7. In a cross-bar switching device of the type having a plurality of switches arranged in a matrix such that the selective operation of said switches permits the connection of any one of a plurality of input lines to any one of a plurality of output lines, the improvement wherein each of said switches comprise:
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that the electric currents flow only in said semiconductor layer, at least two metallic conductors deposited on said planar surface and spaced to form a uniform gap therebetween, said gap defining a shunt current path between said con-ductors through said semiconductor layer, at least one of said metallic conductors forming a Schottky barrier contact to said semiconductor substrate, said at least two metallic conductors forming an r.f. transmission line having input and output ports, means for applying an r.f. signal to the input port of said transmission line to cause said r.f. signal to propagate along the gap toward the output port of said transmission line, and bias means connected to said at least one of said metallic conductors forming a Schottky barrier for controlling the conductivity of said shunt current path.
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that the electric currents flow only in said semiconductor layer, at least two metallic conductors deposited on said planar surface and spaced to form a uniform gap therebetween, said gap defining a shunt current path between said con-ductors through said semiconductor layer, at least one of said metallic conductors forming a Schottky barrier contact to said semiconductor substrate, said at least two metallic conductors forming an r.f. transmission line having input and output ports, means for applying an r.f. signal to the input port of said transmission line to cause said r.f. signal to propagate along the gap toward the output port of said transmission line, and bias means connected to said at least one of said metallic conductors forming a Schottky barrier for controlling the conductivity of said shunt current path.
8. The cross-bar switching device as recited in claim 7, wherein each of said switches have three metallic conductors deposited on said planar surface of said semiconductor sub-strate to form an r.f. transmission line having a center conductor uniformly positioned between two ground planes.
9. A beta element switching device comprising:
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that electric currents flow only in said semiconductor layer, five metallic conductors deposited on said planar surface and spaced to form uniform gaps therebetween, one of said metallic conductors having a generally square geometry and the other four of said metallic conductors having a generally trapezoidal geometry and being symmetrically arranged about said one of said metallic conductors, the gaps between adjacent ones of said conductors defining shunt current paths between the adjacent conductors through said semiconductor layer, said one of said metallic conductors forming an ohmic contact to said semiconductor substrate while said other four of said metallic conductors forming Schottky barrier contacts to said semiconductor substrate, adjacent ends of said other four of said metallic conductors defining input or output ports of r.f. transmission lines formed by said five metallic conductors, means for applying an r.f. signal to at least one input port to cause said r.f. signal to propagate along the gap toward one of at least two output ports, and bias means connected to each of said other four of said metallic conductors for selectively controlling the conductivity of said shunt current paths.
a semiconductor substrate having a planar surface and consisting of a high resistivity semiconductor material over which is formed a thin, conductive semiconductor layer forming said planar surface, the resistivity of said semi-conductor material being very high compared to that of said semiconductor layer so that electric currents flow only in said semiconductor layer, five metallic conductors deposited on said planar surface and spaced to form uniform gaps therebetween, one of said metallic conductors having a generally square geometry and the other four of said metallic conductors having a generally trapezoidal geometry and being symmetrically arranged about said one of said metallic conductors, the gaps between adjacent ones of said conductors defining shunt current paths between the adjacent conductors through said semiconductor layer, said one of said metallic conductors forming an ohmic contact to said semiconductor substrate while said other four of said metallic conductors forming Schottky barrier contacts to said semiconductor substrate, adjacent ends of said other four of said metallic conductors defining input or output ports of r.f. transmission lines formed by said five metallic conductors, means for applying an r.f. signal to at least one input port to cause said r.f. signal to propagate along the gap toward one of at least two output ports, and bias means connected to each of said other four of said metallic conductors for selectively controlling the conductivity of said shunt current paths.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90496678A | 1978-05-11 | 1978-05-11 | |
| US904,966 | 1992-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1138572A true CA1138572A (en) | 1982-12-28 |
Family
ID=25420057
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000327246A Expired CA1138572A (en) | 1978-05-11 | 1979-05-09 | Planar transmission line attenuator and switch |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS54149448A (en) |
| CA (1) | CA1138572A (en) |
| DE (1) | DE2918921A1 (en) |
| FR (1) | FR2425734A1 (en) |
| GB (1) | GB2020899B (en) |
| NL (1) | NL7903689A (en) |
| SE (1) | SE7904141L (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2472269A1 (en) * | 1979-12-19 | 1981-06-26 | Labo Electronique Physique | HIGH FREQUENCY SEMICONDUCTOR POWER LIMITER |
| DE3210028A1 (en) * | 1982-03-19 | 1984-02-02 | ANT Nachrichtentechnik GmbH, 7150 Backnang | SWITCH FOR HIGH FREQUENCY ENERGY |
| GB2149208B (en) * | 1983-10-28 | 1987-02-25 | Gen Electric Co Plc | Solid-state bloch-type electronic oscillators |
| JP4547992B2 (en) | 2003-07-24 | 2010-09-22 | 株式会社村田製作所 | High frequency switch and electronic device using the same |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2226094A5 (en) * | 1972-08-07 | 1974-11-08 | Labo Cent Telecommunicat | |
| GB1495527A (en) * | 1974-06-14 | 1977-12-21 | Marconi Co Ltd | Switching arrangements |
| US4090155A (en) * | 1975-05-12 | 1978-05-16 | Agency Of Industrial Science & Technology | Transmission line for electromagnetic wave |
-
1979
- 1979-05-09 CA CA000327246A patent/CA1138572A/en not_active Expired
- 1979-05-10 SE SE7904141A patent/SE7904141L/en not_active Application Discontinuation
- 1979-05-10 NL NL7903689A patent/NL7903689A/en not_active Application Discontinuation
- 1979-05-10 FR FR7911889A patent/FR2425734A1/en not_active Withdrawn
- 1979-05-10 GB GB7916233A patent/GB2020899B/en not_active Expired
- 1979-05-10 DE DE19792918921 patent/DE2918921A1/en not_active Withdrawn
- 1979-05-11 JP JP5718779A patent/JPS54149448A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2918921A1 (en) | 1979-11-22 |
| GB2020899A (en) | 1979-11-21 |
| SE7904141L (en) | 1979-11-12 |
| NL7903689A (en) | 1979-11-13 |
| FR2425734A1 (en) | 1979-12-07 |
| GB2020899B (en) | 1982-07-28 |
| JPS54149448A (en) | 1979-11-22 |
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| MKEX | Expiry |