JP2003031861A - Power supply line circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure and system for power supply line circuit that can reduce its power consumption, can secure the operating areas of logic circuits, can reduce the occupying areas of the logic circuits, and is suitable for the higher integration of a digital circuit. SOLUTION: The superconducting digital circuit is composed of logic circuits, such as an arithmetic circuit, a storage circuit, etc., which process digital signals and a power supply line 48 circuit which supplies a direct bias current or a bias DC voltage to the logic circuits. Each branch line 44 to the constituent element of each logic circuit is constituted of a resistor 43 and superconducting lines 401 and 402 . In addition, impedance discontinuity is imparted to the branch line 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field of a high-speed and high-frequency digital data processing device, and further, a superconducting digital data processing circuit that exhibits superconducting properties to exhibit unique performance. The present invention relates to the configuration and operation of a power supply circuit, which is an essential element of the data processing circuit.

[0002]

2. Description of the Related Art The performance required of a power supply circuit for driving a digital logic circuit is (1) supplying a voltage or current suitable for each operation to each gate or element element forming the logic circuit, (2) ) Even if a specific gate or element element is switched, the power supply current or voltage supplied to an adjacent gate or element element does not change due to a temporary change in element resistance due to switching, and (3) power line That is, to reduce power consumption in the circuit.

FIG. 2 shows an equivalent circuit of a conventional power supply line circuit. In FIG. 2, a logic circuit is composed of a plurality of element elements, and each element element has a resistor 12 for supplying a bias current for stabilizing the operation of each element element.
It is shown schematically that the power supply 10 is connected via 12 '. In order to satisfy the required performance (1), the resistors 12 and 12 'are connected to the wiring 8 that branches from the power supply line to each element element, the current of the power supply 10 is divided by the resistance value, and the desired value of current is supplied to each element. A method of distributing to elements is used.

In order to satisfy the required performance (2), a resistor 12 'which is sufficiently larger than the variation value of the resistance of each element element due to switching is connected to the wiring branched from the power supply line. For example, if the variation width of the resistance of the element element due to switching is 10 ohms, the redistribution ratio of the current associated with switching can be suppressed to 10% or less if the value of the resistance connected to the power supply line is 100 ohms. Such a method of constructing a power supply line circuit is usually often used especially in a superconducting circuit driven by an electric current. This power line circuit is constructed by Transactions on Appl by M. Currie et al.
ied Superconductivity, Vol. 9, No. 2, page 3531 (1999) and many other examples.

It goes without saying that in these examples of power supply line circuits, power supply line resistances which are generally sufficiently larger than the resistance values in the voltage states of the gates of logic circuits or element elements are used. Further, in order to satisfy the required performance (3), that is, in order to suppress the power consumption in the power supply line circuit, the resistance value of the wiring branched from the power supply line to each gate or the element element is lowered, and the element element is switched. In order to suppress the fluctuation of the supply current, a method has been proposed in which the ratio of the inductance and the resistance of the branch is made sufficiently large. The characteristics of this power line circuit are extended by N. Yoshikawa et al.
Abstract of the1999 International Superconductivit
y Electronics Conference, p. 339 (1999).

[0006]

As the performance required for the power supply line circuit of the digital circuit, in order to obtain a highly integrated and high performance digital circuit, in addition to satisfying the items described in the prior art, It is necessary to solve the problem described in.

That is, in order to realize a highly integrated circuit, not only the power consumption of the power supply line circuit is equal to or less than that of the logic circuit, but also the area ratio of the power supply line circuit to the entire circuit is required to be small. Is.

However, in order to reduce the power consumption of the power supply line circuit, it is necessary to lower the resistance value and to increase the inductance of the branch line in order to suppress the fluctuation of the supply current due to the switching of the element elements. It was necessary to extend the length of each branch line. As a result, the area occupied by the power supply line circuit is increased. For example, if the resistance value is 5 ohms and the inductance is 100 picohenries, the wiring length is about 100 microns even if the wiring has a width of 1 micron. Needless to say, if the wiring of 1 μm width is used, the size of the superconducting loop of the magnetic flux quantum circuit is within about 10 μm, so that the ratio of the power supply line circuit to the entire circuit is considerably increased.

Therefore, the problem to be solved by the present invention is as follows.
As mentioned earlier, a power supply circuit configuration of a digital circuit that can keep the power consumption sufficiently lower than the value in the logic circuit section, can secure the operation area of the logic circuit at a high value, and does not increase the occupied area ratio. To provide.

[0010]

[Means for Solving the Problems] arithmetic circuit, memory circuit, etc.
In a digital circuit consisting of a logic circuit part that processes a digital signal and a power supply line circuit that supplies a DC bias current or a DC bias voltage to the logic circuit, the branch part of the power supply line circuit that reaches the element element of each logic circuit It is composed of a resistance and a superconducting line, and forms an impedance discontinuity at the branch. That is, in the present invention, the impedance equivalent to the apparent branch line inductance is increased by the impedance discontinuity formed in the branch portion of the power supply line circuit, and the same result as when the branch portion of the power supply line circuit is lengthened is obtained. Make it possible to get. The length of each branch of the power supply line circuit is one fourth or more of the length corresponding to the wavelength of the signal generated by the element element. This is necessary in each branch so that the signal generated by the element element can be regarded as an electromagnetic wave.

[0011]

FIG. 1 shows an equivalent circuit of a power supply line circuit according to the present invention. In FIG. 1, 5 and 6 are superconducting lines, 8 is a power supply branch line, 10 is a power supply, and 12 is a resistor.
Here, the main part of the wiring forming the power supply branch line 8 leading to each element element of the logic circuit is a series circuit of superconducting lines 5 and 6 having different impedances and a resistor 12 connected in series, and the resistance value of the resistor 12 is The value is equal to or smaller than the specific resistance of the element element of the logic circuit.
For example, in the case of a superconducting circuit, the specific resistance is a resistance value when the superconducting element is switched to a voltage state.

As a concrete method for changing the impedances of the superconducting lines 5 and 6, the capacitance per unit area of the wiring is discontinuously changed, or the width of the wiring is discontinuously changed. The circuit structure of is used. For example,
Capacitance value per unit area that is composed of the whole or a part of each branch line and the ground film by arranging the superconducting ground film through the insulating film in both the power line circuit and each element Is larger than the capacitance value per unit area formed between the wiring of the element element and the ground film. More specifically, the insulating film overlapping each branch line is replaced with an insulating film having a different relative permittivity in the middle of each branch line of the power line circuit or at the boundary with the element element. As a result, impedances are different on both sides of the insulating films having different relative permittivities in the middle of each branch line of the power supply line circuit.

Furthermore, in such a power line circuit,
Two or more types of insulating films having different relative dielectric constants are used. An insulator having a high relative dielectric constant is used for all or part of the insulating film that overlaps each branch line of the power supply line circuit. The insulating film that overlaps with the wiring of the element element, or the insulating film that overlaps with the wiring of the element element and a part of the branch line of the power line circuit has a layered structure of an insulating film with a high relative dielectric constant and an insulating film with a low relative dielectric constant. , Effectively realizing a low capacity per unit area. As an example of the insulating film forming the capacitor, an insulating material having a high dielectric constant such as strontium titanate is used.

In such a power supply line circuit, a logic circuit to be fed by the power supply line circuit comprises a superconducting wire and a superconducting element, that is, a superconducting junction and a superconducting inductor as main circuit elements, and a closed loop set of superconducting wires including the superconducting junction. It will be a superconducting circuit composed by combining. In the superconducting circuit, the superconducting junction serves as an element element. The carrier of the logic signal propagating in such a superconducting circuit is a magnetic flux quantum, and the signal is propagated by the movement of the magnetic flux quantum. That is, the logic signal propagating in the superconducting circuit is not a level signal that switches between two states,
The pulse signal is used to return the logic gate to the original state after the signal propagates.

The present invention will be described below based on the following embodiments. (Embodiment 1) A Josephson transmission line was constructed using the power supply line circuit having the construction shown in FIG. 3 and 4 schematically show the configuration of part of the Josephson transmission line including the power supply line circuit. FIG. 3 is a diagram schematically showing a plan view showing a portion corresponding to the Josephson transmission line of the flip-flop circuit shown in FIG. 7, which will be described later, and a portion of a power supply line for supplying a bias current thereto. FIG. 4 is a cross-sectional view of the cross section at the AA position in FIG. 3 as seen in the arrow direction.

In FIG. 3, reference numeral 40 ₁ is a superconducting wire,
A superconducting junction 42 is formed in the middle part thereof. One end of the superconducting wire 40 ₁ is connected to a superconducting ground film 52 via a superconducting connection 46. Reference numeral 41 is an inductor, which sequentially connects the other ends of the superconducting wires 40 ₁ . A series circuit of the superconducting wire 40 ₁ and the superconducting junction 42 is sequentially connected by the inductor 41 to form a Josephson transmission line. 40 ₂ is a superconducting wire, and a resistor 43 is formed on a part of it. The superconducting wire 40 ₂ on which the resistor 43 is formed functions as a power supply branch line 44, and one end of the superconducting wire 40 ₂ is connected to the superconducting wire 4 2.
0 ₁ and the inductor 41 are connected to each other, and the other end is connected to the power supply line 48. Here, reference numerals 53 and 54 denote regions of the high dielectric constant interlayer insulating film and the low dielectric constant interlayer insulating film. That is, the impedance of the power supply branch line 44 changes at the position where the region of the high dielectric constant interlayer insulating film 53 and the region of the low dielectric constant interlayer insulating film 54 intersect.

The circuit was manufactured using an oxide-based high temperature superconducting thin film. In the cross-sectional view shown in FIG.
2 is a superconducting ground film, 53 is a high dielectric constant interlayer insulating film, 5
4 is a low dielectric constant interlayer insulating film, 55 is a superconducting electrode film, 56 is an interlayer insulating film, 57 is a superconducting junction, 58 is a superconducting electrode film,
Reference numeral 59 is a resistance film. The relationship between the components shown in FIG. 4 and that in FIG. 3 is that the superconducting junction 57 is
In addition, the superconducting electrode film 55 is provided on the superconducting wire 40 ₁ , the superconducting electrode film 58 is provided on the power supply branch line 44 and the power supply line 48, and the resistance film 5 is formed.
9 corresponds to the resistor 43, respectively.

Two kinds of insulating materials having a high relative dielectric constant and a low relative dielectric constant are used for the interlayer insulating films 53 and 54. An interlayer insulating film having a low dielectric constant was used for the entire Josephson transmission line and the portion where the branch line 44 of the power supply line circuit is connected to the Josephson transmission line. Furthermore, a high dielectric constant interlayer insulating film is used for most of the branch lines of the power line circuit.

The substrate 51 has lanthanum, strontium, and
Aluminum tantalum oxide (LSAT) single crystal was used. An yttrium-barium-copper oxide (YBCO) film was used for the superconducting electrode, the wiring film, and the superconducting ground film. An Au film was used for the resistance. Cerium oxide (CeO) was used for the low dielectric constant interlayer insulating film, and strontium titanate (SrTiO) was used for the high dielectric constant interlayer insulating film.
In the superconducting junction, the edge of the lower electrode film is irradiated with an ion beam to damage it, and this is used as a barrier layer, and the upper electrode film is formed thereon. The YBCO film, Au film, CeO film, SrTiO film, etc. were formed by a laser deposition method in an oxygen atmosphere.

The film thickness of the interlayer insulating CeO film and the SrTiO film was 300 nm. According to the capacity measurement result, C
The relative dielectric constant of the eO film was 20, and the relative dielectric constant of the SrTiO film was approximately 500. The produced superconducting junction has a critical current of 0.2 mA at a temperature of 20 K, a resistance in a voltage state of 5 ohms, and a product of these values, which is an index of junction performance, is 1 m.
It was V. The resistance value of the branch line was 5 ohms. The line width of the Josephson transmission line and the branch line of the power supply line circuit was 1 micron. Also, the width of the wiring that connects one branch line is set to 1 micron. The length of each branch line to the Josephson transmission line was set to 15 microns. The length of this branch line is longer than ¼ times the wavelength when a high-frequency signal with a frequency of 200 GHz propagates.

The dependence of the magnetic flux quantum signal propagating through the Josephson transmission line having such a structure on the power supply current of the propagation time between superconducting junctions has resulted in the following result. That is, referring to FIG. 5, reference numeral 64 denotes a propagation delay time between superconducting junctions of a Josephson transmission line when the power supply line circuit according to the present invention is used, and the Josephson transmission using a conventional power supply branch line having only resistance. Reference numeral 6 for the propagation delay time of the path
5 shows the ratio of the power supply current to the critical current on the horizontal axis.

It was found that in the Josephson transmission line of this embodiment, the operating region for the power supply current also widens on the power supply current side near the critical current. Further, the frequency characteristic of the Josephson transmission line having the configuration of the present invention with respect to the power supply current was the same as that when the power supply branch lines 44 were made independent and the direct current was supplied individually. The power consumption of each power supply branch line 44 is 0.13 microwatts, which is almost the same as the power consumption when the superconducting junction is in the voltage state. The area occupied by the power supply branch line is 1 micron × 15 micron, and can be further reduced by miniaturizing the wiring.

The reason why the operation area of the Josephson transmission line according to the present invention is widened and the frequency performance is improved is as follows. In the superconducting circuit using the magnetic flux quantum as a signal carrier in the present embodiment, the reason for narrowing the operation region is that the magnetic flux quantum passes through the superconducting junction.
This is because the current pulse generated from the superconducting junction does not necessarily propagate only in the Josephson transmission line.

That is, along with the propagation of the magnetic flux quantum, not only the current pulse is transmitted through the Josephson transmission line, but also a part of the current pulse is transmitted to the power supply branch line 44. This current pulse propagates through the adjacent power supply branch line 44 and is added to the power supply current of the adjacent superconducting junction. Therefore, the upper limit of the operable power supply current is reduced as compared with the case where such a phenomenon does not exist.

The magnetic flux quantum signal is a high frequency pulse signal of several hundred gigahertz. This frequency component is proportional to the product of the critical current of the superconducting junction and the resistance in the voltage state, and when the product is 1 mV, it reaches 300 to 500 GHz. It is possible to control the propagation of such a high frequency pulse by designing a power supply line circuit as a distributed constant circuit. That is, if the length of the power supply branch line 44 is equal to or longer than the wavelength of the magnetic flux quantum pulse signal, the design is not based on the mere resistance size or the lumped constant that attenuates the signal amplitude by the ratio of the inductance and the resistance. , It is necessary to process the magnetic flux quantum pulse signal as a wave.

That is, in the power supply branch line 44 of this embodiment,
The interlayer insulating film between the ground plane and the CeO film having a relative permittivity of 20 changes discontinuously to the SrTiO film having a relative permittivity of 500. Here, the impedance and the propagation velocity of the magnetic flux quantum pulse signal are deviated five times or more. Therefore, the magnetic flux quantum pulse signal component leaked to the power supply branch line 44 is reflected at this discontinuous portion and returns to the original state. It does not propagate through the power supply branch line 44, propagate through the adjacent power supply branch line 44, and reach the superconducting junction which is about to transit due to the flux quantum.

Such a situation is apparent from the frequency dependence of the S parameter shown in FIG. Figure 6
(A) is the circuit configuration of FIG. 3, except for the Josephson transmission line, leaving only the power supply line circuit, focusing on one power supply branch line, propagating this, and reaching the adjacent power supply branch line. The S-parameters of the signal are shown. Here, the reflected signal strength at the power supply branch line according to the present invention is shown at 62, and the propagation signal strength at the power supply branch line according to the present invention is shown at 63. As is clear from the figure, in the frequency region of 50 GHz or higher, the signal components reaching the adjacent power supply branch lines are 10% or less, and most of them return to the power supply branch line which generated the signal. In addition,
The characteristics shown in the figure depend on the calculated circuit structure, and are not common characteristics of this type of circuit. However, as in the present invention, the power supply branch line has impedance discontinuity. As a result, it is shown that signal propagation through the power supply branch line can be effectively suppressed. Although not shown in the figure, the frequency dependence of the current distribution revealed that the current density flowing into the low dielectric constant side of the adjacent power supply branch line was sufficiently low in the frequency region of 50 GHz or higher. Such a phenomenon is due to reflection at a portion where the permittivity of the high frequency signal changes discontinuously, that is, a portion where the impedance changes discontinuously. Using an insulating material having a high dielectric constant such as SrTiO has the effects of causing impedance discontinuity and shortening the line length of the power supply branch line.

For comparison, the S parameter of the power supply branch line in the case where the power supply line circuit is formed by using only CeO oxide as the interlayer insulating film, that is, in the state where there is no impedance discontinuity in the power supply branch line, is shown in FIG. It is shown in B). The reflected signal strength at the power supply branch line is shown at 62 ', and the propagation signal strength at the power supply branch line is shown at 63'. The signal strength propagating to the adjacent power supply branch line is stronger up to the frequency of 100 GHz. At frequencies higher than this, the signal strength returning to the branch line that has generated the signal is stronger, but the difference from the signal strength propagating to the adjacent power supply branch line is small.

As described above, according to the power supply line circuit of the present invention, the operating area of the logic circuit is expanded, the power consumption of the power supply line circuit is reduced, and the area occupied by the logic gate centering on the power supply line circuit is reduced. With this, it is possible to increase the density of the logic circuit, and to achieve high integration and high functionality of the digital circuit. (Example 2) Set / reset by using this power line circuit
A flip-flop circuit (abbreviated as flip-flop) was manufactured. An equivalent circuit of the produced flip-flop is shown in FIG. In FIG. 7, 100 is a flip-flop. Reference numeral 31 ₁ is a set signal generation circuit, and 31 ₂ is a reset signal generation circuit. These signal generating circuits consist of a signal source 14, a series circuit of a resistor 15 and an inductor 16 and a superconducting junction 17, and are circuits for converting the level signal of the signal source 14 into a magnetic flux quantum signal and outputting it. Set signal generation circuit 3
1 ₁ , the signal generated from the reset signal generation circuit 31 ₂ is the inductor 16 and the superconducting junction 1 described in the first embodiment.
And a reset terminal 10 of the flip-flop 100 via a Josephson transmission line 32 composed of
Added to 2. Flip-flop 100 of this embodiment
Then, when a set signal is applied to the set terminal 101,
This is stored in the form of a circulating current in the inductor 16. When a reset signal is applied to the reset terminal 102 when the inductor 16 has a circulating current, the output terminal 104
The output signal is output to. Even if a reset signal is applied to the reset terminal 102 when the inductor 16 has no circulating current, no output signal is output to the output terminal 104. The output signal of the output terminal 104 is transmitted to the conversion circuit 33 for converting a magnetic flux quantum signal into a level signal, which is an output interface, through the Josephson transmission line 32 including the inductor 16 and the superconducting junction 17.

The flip-flop 100 and the Josephson transmission line 32 require a power supply for supplying a bias current as described above. Also in this embodiment,
A bias current is supplied using the power supply line circuit having the configuration shown in FIG. Reference numeral 10 is a power source, and 11 is a superconducting line. Here, the superconducting line 11 has the same configuration as the series circuit of the superconducting lines 5 and 6 in FIG. 1, but the display is as shown in the figure in order to simplify the figure. The element element in the superconducting circuit of this embodiment is a superconducting junction. A superconducting circuit is constructed based on a superconducting closed loop including a superconducting junction, and a circuit operation method is used in which magnetic flux quantum is used as a signal carrier.

As shown in the figure, one power supply branch line was connected to the superconducting junction as each element element. The power supply branch line was a series connection of a resistor 12 and a superconducting wire 11. Each power supply branch line was bundled into one and connected to the power supply 10 outside the chip.

An example of a sectional structure of a part of such a superconducting flip-flop circuit is shown in FIG. FIG. 8 is a sectional view of a portion corresponding to the position AA shown in FIG. In FIG. 8, 51 is a substrate, 52 is a ground plane, 53 is a high dielectric constant interlayer insulating film, 54 is a low dielectric constant interlayer insulating film, 55 is a superconducting electrode film, 56 is an interlayer insulating film, 57 is a superconducting junction, and 58 is The superconducting electrode film and 59 are resistance films. The substrate 51 was an LSAT single crystal. The superconducting junction 57 was a lamp edge type, and the damaged layer formed by irradiating the end face of the lower electrode with argon ions was used as the barrier layer, and the YBCO film was used as the electrodes 55 and 58. The ground film 52 is a YBCO film, and STO is used for insulation between the ground film and the electrodes of the superconducting junction or between the ground film and the wiring film.
A membrane was used. In the flip-flop circuit body, the interlayer insulating film covering the ground film is a laminated structure of STO film and CeO film 5
In the power supply line circuit portion including the power supply branch line, the interlayer insulating film covering the ground film is a single layer 53 of the STO film. The resistance value of the superconducting junction in the voltage state is 5 ohms to 1
It was in the 0 ohm range. A gold film was used for the resistor 59.

There is no essential difference between the structure illustrated in FIG. 8 and the above-described FIG.
High dielectric constant interlayer insulating film 53 and low dielectric constant interlayer insulating film 54
The only difference is the laminated structure of.

The optimum value of the current to be supplied to each superconducting junction was calculated in advance by numerical simulation. As a value inversely proportional to these currents, the power supply branch line 4
The resistance value of 4 was calculated. The average value of the resistance 12 was 3 ohms. On the other hand, the wiring length of the power supply branch line 44 is 20
Micron was used.

FIG. 9 shows operation waveforms of the flip-flop circuit according to the second embodiment. As described above, when the reset signal 22 is input while the set signal 21 is input, an output signal is obtained, and the output signal 23 is detected by the conversion circuit 33 from the magnetic flux quantum signal to the level signal. To be done. On the other hand, if the reset signal 22 is input without the input of the set signal 21, no output signal is obtained, and the output signal is not detected by the conversion circuit from the magnetic flux quantum signal to the level signal. When the operation waveform of the circuit according to Example 2 was measured, the operation as a flip-flop was confirmed.

FIG. 10 shows a region of the power supply current in which the flip-flop circuit according to the second embodiment can change the power supply current and perform the flip-flop operation. In the entire circuit, including the case where the CeO film is used as the interlayer insulating layer on the ground plane, 60 indicates the operating region of the power supply current by the power supply branch line according to the present invention, and 61 is the conventional power supply branch line with only resistance. Shows the operating region of the power supply current by. As is clear from the figure, the operating region of the power supply current is expanded in this embodiment. By expanding the operating region in this way, it is possible to increase the degree of integration and operate the circuit even when the nonuniformity of the element element characteristics such as the superconducting critical current is expanded.

The average energizing current per superconducting junction in this example is 0.15 mA. Therefore, the average power consumption of the current supply line per superconducting junction is 75 nanowatts. On the other hand, when the power supply branch line having the conventional structure is used, the average power consumption increases in proportion to the resistance value.
When the resistance value is set to 10 times the superconducting junction resistance in order to stabilize the flip-flop operation, the power consumption becomes 1.1 microwatt. As described above, the power supply line circuit structure according to the present invention exhibits not only a wide operating area but also low power consumption performance as compared with the conventional structure.

As shown in this embodiment, by using the power supply line circuit according to the present invention, the operating region is expanded,
The power consumption can be reduced and the circuit area can be reduced. Therefore, higher density and higher integration of the circuit are possible. (Example 3) A four-stage shift register circuit was manufactured using the power supply line circuit having the configuration shown in FIG. An equivalent circuit of the manufactured shift register is shown in FIG. 4 of this embodiment
The stage shift register circuit includes a clock signal line circuit 34 in which a superconducting junction line JTL and a branch circuit SP are connected in a cascade, and a data signal line in which a superconducting junction line JTL and a set / reset flip-flop rs-FF are connected in a cascade. Circuit 36 and branch circuits SP and set / reset flip-flops r that form a pair
The s-FF and the s-FF are connected by a superconducting junction line JTL to form a branch circuit 35. There is no branch circuit SP at the final stage. A magnetic flux quantum signal is applied to the first-stage superconducting junction line 121 of the clock signal line circuit 34 similarly to the set or reset signal generation circuit 31 described with reference to FIG.
The magnetic flux quantum signal output from the superconducting junction line 121 is divided into two magnetic flux quantum signals by the branch circuit 122 and added to the superconducting junction lines 123 and 124 provided in the subsequent stages. A set / reset flip-flop rs-FF 126 is provided at the output stage of the superconducting junction line 124. Set / reset flip-flop rs-F
The output of another superconducting junction line 125 is applied to F126. A data input signal is applied to the superconducting junction line 125. The set / reset flip-flop rs-FF 126 holds the data input signal applied via the superconducting junction line 125. To the set / reset flip-flop rs-FF128. Such a branch circuit SP and a set / reset flip-flop rs-
This is a 4-bit shift register in which four FFs are arranged in a cascade.

The 4-bit shift register of this embodiment is also
Each element element naturally needs a power supply, and the power supply line circuit configured as shown in FIG. 1 is used to supply a power supply current. Reference numeral 10 is a power source, 11 is a superconducting line, and 12 is a resistor. In the figure, the set / reset flip-flop rs-FF, the superconducting junction line JTL, and the branch circuit SP are shown to be supplied with power by a single power supply branch line. As described above, it goes without saying that when the superconducting junction line JTL is composed of a plurality of element elements, it is necessary to provide a power supply branch line for each of them to supply power. Power is supplied to each superconducting junction by a power branch line formed by a series connection of a resistor 11 and a superconducting wire 12 branched from a power source 10. The power branch line to each element of the shift register is 1
It was put together in a book and connected to a power source 10 outside the chip. Resistance 12
The value of was 2 ohms.

FIG. 1 is a structural diagram of a part of the shift register circuit.
Shown in 2. In FIG. 12, 40 is a superconducting wire, 41 is an inductor, 42 is a superconducting junction, 43 is a resistance, 44 is a power supply branch line, 54 is a ground plane, 46 is a superconducting connection, and 48 is a power supply line. Unlike the power line circuit in the first embodiment,
The line width of the wiring 48 that bundles the power supply branch lines is set to 5 times the width of the power supply branch lines. Except that the line width of the wiring 48 for collecting the power supply branch lines is five times, there is essentially no difference from the structural diagram described in FIG. The shift register circuit was manufactured using a YBCO superconducting thin film. The substrate was LSAT single crystal. The superconducting junction is a lamp edge type, and the damage layer formed by irradiating the lower electrode end face with argon ions is used as a barrier layer.
The BCO film was used as an electrode. The ground film was a YBCO film, and the STO film was used for insulation between the ground film and the electrodes of the superconducting junction or between the ground film and the wiring film. In the flip-flop circuit body, the interlayer insulating film covering the ground film has a laminated structure of STO film and CeO film, and in the power line circuit section including the power supply branch line, the interlayer insulating film covering the ground film is a single layer of the STO film. did. The resistance value of the superconducting junction in the voltage state was in the range of 5 to 10 ohms. A gold film was used for the resistance.

As shown in FIG. 13, the clock signal 2
It was found that an output signal train 26 of a bit train similar to the signal train 25 of the input data was obtained in synchronism with 4 and the operation as the shift register was realized. The operable area for the power supply current is plus or minus 25%
Met. This value was plus or minus 3% wider than the operable area when the resistance value of the power supply branch line was set to 16 ohms and was made sufficiently higher than the resistance value in the voltage state of the superconducting junction.

As described above, when the shift register is used by using the power supply line circuit according to the present invention, the operation area is widened due to the contribution of the power supply line circuit, and its mechanism is as described in the first embodiment. Is. Further, the average power consumption of the current supply line per superconducting junction in this example was 50 nanowatts, which was about ⅛ that when the current supply line having the conventional structure was used.

The expansion of the operating region, the reduction of the power consumption of the power supply line circuit, and the reduction of the occupied area by using this power supply line circuit are not limited to the flip-flops and shift registers, but also confluence buffers, AND, OR, and inverter gates. The same applies to other circuits. Furthermore, even with a functional circuit configured by combining these circuits, the operating area of the entire circuit can be expanded, and the power consumption and occupied area of the power supply line circuit can be reduced.

[0044]

As described above in the embodiments of the invention, the power supply line circuit according to the present invention has the following effects. (1) The operation area of the logic circuit which supplies the current from the power supply line circuit is expanded to facilitate the execution of the logic operation. (2) The power consumption of the power supply line circuit can be reduced, and the power consumption of the entire circuit can be reduced to the level of power consumption that is inevitably involved in signal propagation. (3) The area occupied by the power supply line circuit can be reduced, and high density can be achieved. (4) It enables high integration and high functionality of digital circuits.

[Brief description of drawings]

FIG. 1 is an equivalent circuit of a power supply line circuit according to the present invention.

FIG. 2 is an equivalent circuit of a conventional power supply line circuit.

FIG. 3 is a diagram schematically showing a partial configuration example of a Josephson transmission line including a power supply line circuit according to the present invention.

FIG. 4 is a diagram showing a partial cross section of the Josephson transmission line of FIG. 3;

FIG. 5 is a diagram showing the dependence of the propagation delay time of the Josephson transmission line on the bias current ratio.

FIG. 6 is a diagram showing the frequency dependence of the S parameter of the power supply branch line having the impedance discontinuity of the Josephson transmission line according to the present invention.

FIG. 7 is a diagram showing an equivalent circuit of a superconducting flip-flop adopting the power supply line circuit according to the present invention.

FIG. 8: 1 of a superconducting flip-flop circuit according to the present invention
The figure which shows the cross-section example of a part as a cross-sectional view of the part corresponding to the AA position shown in FIG.

9 is a diagram showing operation waveforms of the superconducting flip-flop shown in FIG.

10 is a diagram showing an operable power supply current region of the superconducting flip-flop shown in FIG.

FIG. 11 is a diagram showing an equivalent circuit of a superconducting shift register circuit according to the present invention.

FIG. 12 is a diagram showing a structure of a superconducting shift register circuit adopting a power supply line circuit according to the present invention.

13 is a diagram showing operation waveforms of the superconducting shift register circuit shown in FIG.

[Explanation of symbols]

5: superconducting line, 6: superconducting line, 8: power supply branch line, 1
0: power supply, 11: superconducting line, 12: resistor, 13: superconducting junction, 14: signal source, 15: resistor, 16: inductor, 17: superconducting junction, 21: set signal, 22: reset signal, 23: magnetic flux quantum -Level signal converter output signal, 24: clock signal, 25: input data signal string,
26: output signal, 31: set, reset signal generation circuit, 32: Josephson transmission line, 33: magnetic flux quantum signal to level signal conversion circuit, 34: clock signal line, 3
5: branch, 36: data signal line, 40: superconducting line, 4
1: inductor, 42: superconducting junction, 43: resistance, 4
4: Power supply branch line, 46: Superconducting connection, 48: Power supply line, 5
1: substrate, 52: ground plane, 53: high dielectric constant interlayer insulating film,
54: low dielectric constant interlayer insulating film, 55: superconducting electrode film, 5
6: Interlayer insulating film, 57: Superconducting junction, 58: Superconducting electrode film, 59: Resistor, 60: Operable power supply current region of the flip-flop circuit using the power supply branch line according to the present invention, 6
1: Power supply current region in which a flip-flop circuit using a power supply branch line having only a resistor is operable, 62: Reflected signal strength in the power supply branch line according to the present invention, 63: Propagation signal strength in the power supply branch line according to the present invention, 64: Propagation delay time of Josephson transmission line using power supply branch line according to the present invention, 6
5: Propagation delay time of Josephson transmission line using power supply branch line with only resistance, 100: Flip-flop circuit, 10
1: Set terminal of flip-flop circuit, 102: Reset terminal of flip-flop circuit, JTL, 121, 1
23, 125, 127: superconducting junction line, rs-FF,
126 and 128: set / reset flip-flops, SP and 122: branch circuits.

Continued front page    (72) Inventor Keiichi Tanabe             1-14-3 Shinonome, Koto-ku, Tokyo Foundation               International Superconductivity Industrial Technology Research Center F term (reference) 4M113 AA06 AA16 AA25 AC33 AD23                       AD36 AD42 AD67 AD68 BB07                       BC08 CA34                 5J042 AA01                 5J056 AA00 BB17 BB57 DD53 KK02

Claims (10)

[Claims] 1. A digital circuit including a logic circuit portion for processing a digital signal, such as an arithmetic circuit and a memory circuit, and a power supply line circuit for supplying a DC bias current or a DC bias voltage to the logic circuit. A power line circuit, wherein a branch line of the power line circuit reaching an element element of a logic circuit is composed of a resistance and a superconducting line, and the branch line has impedance discontinuity. 2. The power supply line circuit according to claim 1, wherein the length of each branch line of the power supply line circuit is not less than ¼ of the length corresponding to the wavelength of a signal generated by an element element. 3. A main portion of wiring constituting each branch line of the power supply line circuit is obtained by connecting a superconducting line and a resistor in series, and a resistance value of a resistance film is equal to a specific resistance of an element element of a logic circuit. The power supply line circuit according to claim 1, wherein the power supply line circuit has a value which is smaller than or equal to the specific resistance. 4. The inside of the wiring forming each branch line of the power supply line circuit, or the connection portion between the wiring forming each branch line and the wiring that bundles these branch lines, or the wiring and the elements forming each branch line. The power supply line circuit according to claim 1, wherein impedances are different at a connection portion between wirings forming the element. 5. A unit area formed by arranging a superconducting ground film through an insulating film in both the power line circuit and the element element, and forming the entire branch line or a part of the branch line and the ground film. The power supply line circuit according to claim 1 or 4, wherein the capacitance value of is larger than the capacitance value per unit area formed between the wiring of the element element and the ground film. 6. The insulating film which overlaps with each branch line of the power supply line circuit is replaced with an insulating film having a different relative dielectric constant at an end or in the middle of the wiring.
The power line circuit according to any one of 1. 7. An element element, wherein two types of insulating films having different relative dielectric constants are used, and an insulating film having a high relative dielectric constant is used for all or part of an insulating film overlapping with each branch line of the power line circuit. The insulating film that overlaps with the wiring, or the insulating film that overlaps with the wiring of the element element and a part of the branch line of the power supply line circuit has a layered structure of an insulating film having a high relative dielectric constant and an insulating film having a low relative dielectric constant. The power supply line circuit according to claim 1, claim 4, or claim 5. 8. An insulating material having a high dielectric constant, such as strontium titanate, is used as a part of an insulating film constituting a capacitor, claim 5, claim 6, and claim 7.
The power line circuit according to any one of 1. 9. The logic circuit to be fed by the power line circuit is a superconducting circuit composed of superconducting wiring and a superconducting element, and a carrier of a logic signal propagating through the superconducting circuit is a flux quantum. Power line circuit. 10. A digital circuit comprising a logic circuit portion for processing a digital signal, such as an arithmetic circuit and a memory circuit, and a power supply line circuit for supplying a DC bias current or a DC bias voltage to the element elements of the logic circuit. A digital circuit characterized in that a branch line of the power supply line circuit reaching the element element of each logic circuit is constituted by a resistance and a superconducting line, and the branch line has impedance discontinuity.