JPH09298323A - High-frequency power supply equipment for josephson integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high-frequency characteristics of an impedance conversion transformer which is required when high frequency electric power is supplied to Josephson integrated circuits in accordance with a balanced power supply method. SOLUTION: A neutral point is arranged on a primary winding of an impedance conversion transformer 20 and earthed to a ground plane. First phase power supply current ϕ1 from a high-frequency power supply 11 is supplied to one end of a primary winding, and a second phase power supply current ϕ2 whose phase is different by 180 deg. from the first phase power supply current ϕ1 is supplied to the other end. A DC bias current 1b from a DC bias current power supply 12 is supplied to the neutral point of a secondary winding. Secondary output currents iS-1, iS-2 are supplied to Josephson integrated circuits 41, 41 of a first set and a second set, respectively, as final power supply currents iP-1, iP-2 via voltage regulators 31, 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a device suitable for supplying power to a Josephson integrated circuit capable of high-speed operation of 1 GHz or higher.

[0002]

2. Description of the Related Art A Josephson integrated circuit composed of a group of Josephson logic gates constructed on a substrate chip is also
When actually incorporated into a Josephson computer system or the like to operate, it is naturally necessary to be supplied with power source power, like other active electronic circuits. However, characteristically, since the Josephson logic gate normally operates in the latching mode, the power supply current waveform is in principle a unipolar pulsating current waveform (however, when it falls, it may enter a slightly opposite polarity region. It is said that a pulsating flow waveform that covers a considerably high frequency, for example, a frequency of 1 GHz or more, is required so as not to impair the intrinsic high-speed operability of the gate. In principle, although a simple combinational circuit may be a single-phase pulsating current power supply, in a sequential circuit, the power supply current corresponds to the clock signal in the semiconductor logic circuit, so in order to perform signal transmission between clocks, the actual In an integrated circuit, multiphase pulsating current power supplies with different phases, basically two-phase pulsating current power supplies with 180 ° different phases are used.

Further, the potential reference of each integrated circuit, that is, the ground potential is generally the ground plane potential on the substrate chip on which the integrated circuit is constructed, but this type of Josephson integrated circuit that handles a relatively small voltage. However, even a slight fluctuation in the ground potential or ground plane potential poses a big problem, so a so-called balanced power supply method is adopted to prevent it from varying, and the phase is 180 ° different from the high-frequency power source provided outside the substrate chip. First and second phase power supply currents are supplied. On top of that, in order to achieve impedance matching between the power supply side and the driven integrated circuit side,
An impedance conversion transformer is required between the high frequency power source and each integrated circuit.

FIG. 3 shows a typical conventional configuration example of a high-frequency power supply portion in a Josephson integrated device constructed to satisfy such various conditions. The high-frequency power source 11 outputs first-phase and second-phase power supply currents φ1 and φ2 whose phases are different from each other by 180 ° for balanced feeding, and the superconducting integrated circuit is connected to the ground terminal E of the high-frequency power source 11. The ground plane (which is simply indicated by the ground symbol in this figure) for establishing the ground potential of the substrate chip 40 on which 41 is mounted is generally the power supply currents φ1, φ from the high frequency power source 11.
Connected via a shielded conductor that surrounds the 2 output line. It should be noted that the high-frequency power source 11 provided outside the substrate chip 40 and other external circuits (not shown) and the substrate chip 40 are not shown.
The board chip 40 is generally used for connection to the circuit mounted on the board.
Bonding pads provided along the peripheral edge of the
42 is used as appropriate.

On the substrate chip 40, impedance conversion transformers 50, 50 are provided which receive the power supply currents φ1, φ2 of the first phase and the second phase by the primary winding in response to the adoption of the balanced power feeding method. There is. As the waveforms of the power supply currents φ1 and φ2, the waveforms shown in FIG. 1, which will be described later in connection with the present invention, can be applied, and they are sine waveforms that are 180 ° out of phase with each other.

However, conventionally, the impedance conversion transformer 50 has a single input and a push-pull output. That is, the primary winding of each impedance conversion transformer 50, 50 is a single winding, the output line of the power supply current φ1, φ2 of each phase output from the high-frequency power source 11 is connected to one end, and the other end is a ground plane. Is connected to (grounded). On the other hand, the secondary winding is a series winding having a midpoint, which will also be described with reference to the waveforms shown in FIG. 1 together.
The secondary output currents iS-1 and iS-2, which are different by 180 °, are supplied to the midpoint of the secondary winding with a DC bias current Ib of a magnitude smaller than the one-side peak value Ia of the secondary output currents iS-1 and iS-2. iS-
Both 1 and iS-2 have waveforms that are shifted in the predetermined polarity direction (for example, the positive direction as shown in the figure) by the size Ib.

The secondary output currents iS-1, iS-2 thus configured
Then a pair of voltage regulators (current clampers) 3
1 and 31, and as a result, the waveform heads are clamped to a certain size, that is, two-phase pulsating current waveforms iP-1 and iP-2 with a phase difference of 180 ° from each other. Power is supplied as a final power supply current to each of the pair of Josephson integrated circuits 41, 41 formed on the chip 40.

As described above, the Josephson integrated circuits 41, 41 are themselves an assembly of at least one or more known Josephson logic gates, but the present invention relates to the circuit contents. Therefore, illustration and description thereof are omitted. However, in general, the equivalent impedances Zc, Zc of at least a pair of Josephson integrated circuits 41, 41 of the first set and the second set driven by the pulsating currents iP-1 and iP-2 of the first phase and the second phase, respectively. Are in principle equalized. Even if you do not do so, you can cope by changing the impedance ratio sandwiching the middle point of the secondary winding of the impedance conversion transformer 50, but the same value is easier to design and manufacture, and the operation symmetry can be maintained, so the circuit Reliability also increases. By the way, since the equivalent impedance Zc of each Josephson integrated circuit 41 is quite low, the impedance conversion transformer 50 is a so-called down converter in terms of input / output impedance. For example, the winding ratio of the primary winding to the secondary winding is chosen to be 4: 1 and so on, so that the impedance ratio is 16: 1.

Further, the voltage regulators 31 and 31 which are respectively inserted in parallel with the winding portions between the ends of the secondary winding of the impedance conversion transformer 50 and the midpoint are generally composed of a plurality of n Joseph's. It is configured by connecting Sonson junctions in series, thereby stabilizing the voltage across the junction to a voltage n · Vg that is n times the gap voltage Vg of one Josephson junction. However, as described above, the secondary output currents iS-1 and iS- of the impedance conversion transformers 50 and 50 shown in FIG.
2 or, as can be seen in the pulsating current output currents iP-1 and iP-2 from the voltage regulators 31 and 31 as the final power supply currents supplied to the Josephson integrated circuits 41 and 41, their falling edges. Sometimes it is necessary to put each voltage regulator 31, 31 into the reverse polarity region (negative region in the figure) by a little dI.
Even if the current flowing in the Josephson junction used in the above becomes zero, the rotation of the phase does not immediately become zero, and if nothing is done, the so-called punch-through phenomenon easily occurs, so the phase is forced and promptly changed. This is to avoid this inconvenience by returning to zero. The magnitude of the current component dI in this case is selected within a value range smaller than the critical current value Ic of the Josephson junction used in each voltage regulator 31, 31.

FIG. 4 shows an example of a conventional plane structure for one transformer that can be used as the impedance conversion transformers 50, 50 shown in FIG. However, the insulating layer provided between the superconductor or the superconducting line forming each of the ground plane 53, the secondary winding 52, and the primary winding 51 is omitted in order to simplify the drawing, Only those superconductors or lines are taken out and shown. As is well known, in the Josephson integrated circuit, a so-called microstrip line structure using the ground plane 53 as a ground conductor is adopted for the superconducting line in order to transmit a high frequency power source current and a high frequency signal current. However, since the magnetic coupling circuit is not completed if this structure is provided where the impedance conversion transformer 50 should be provided, an opening 54 is opened in the ground plane 53 and the secondary surface is passed over the opening 54. The primary windings 52 and 51 are patterned. In this case, the secondary winding 52 is the primary winding
It is provided under 51 and is formed in a winding shape for one turn, and a terminal portion to which the DC bias current Ib is supplied is provided at a midpoint portion thereof.

The primary winding 51 is located on the secondary winding 52 and has one end supplied from the high frequency power source 11 (not shown in the figure: see FIG. 3) with the first phase power supply current φ1 or the second phase. Power supply current φ
It is a terminal part that receives the supply of 2 and has a spiral pattern which is wound inward from the terminal appropriately, and is grounded by connecting it to the ground plane 53 via the ground contact 55 at the innermost end of the spiral. It It should be noted that, in the case shown, for the sake of complete explanation, the number of turns of the primary winding 51 is about three turns, and therefore the impedance conversion ratio is also about 9:
It is about 1, but it may actually be set lower. On the other hand, it is often difficult to raise the ratio to 16: 1 or more with the current technology due to deterioration of frequency characteristics and the like for the reason described later.

[0012]

However, in the impedance conversion transformer 50, as shown in FIG. 3 in a lumped constant manner, the so-called hot side is generally connected to one end of the primary winding connected to the ground. An equivalent inductance Lp is expected up to the other end, and similarly, a stray capacitance Cs exists with respect to the ground on the other end side as shown by a virtual line. Therefore, the resonance system is configured by the inductance Lp and the capacitance Cs, and the resonance frequency fr is fr = 1 / {2π (LpCs) ^1/2 } according to a well-known formula. Therefore, the impedance conversion transformer 50 is restricted in its high frequency characteristics by the resonance frequency fr, and can be practically used only in the frequency range below the resonance frequency fr.

Nevertheless, as described above, since the conventional impedance conversion transformer uses a single input, its equivalent inductance Lp is considerably large. As a result, as is clear from the above equation, the resonance frequency fr
However, there is a problem that the original high-speed performance of the Josephson integrated circuit that can potentially operate at a high frequency cannot be fully exerted because of a low value.

The present invention has been made in view of this point,
In order to realize the high speed operation of the Josephson integrated circuit, the resonance frequency fr in the impedance conversion transformer is increased,
It is intended to suppress deterioration of high frequency characteristics of the transformer.

[0015]

In the present invention, in order to achieve the above object, (a) a middle point is provided in the primary winding of an impedance conversion transformer, and (b) the middle point of the primary winding is a Josephson integrated circuit. (C) Connect the output line of the first-phase power supply current output by the high-frequency power source according to the balanced feeding method to one end of the primary winding, and connect it to the ground plane provided on the board chip Then, connect the output line of the second-phase power supply current, which is 180 ° out of phase with the first-phase power supply current.

In view of the basic object of the present invention, the present invention can be applied even if the secondary side of the impedance conversion transformer actually drives only a single-phase driven Josephson integrated circuit. It is possible. However, in general, it is necessary to construct a sequential circuit as described at the beginning, so in such a case, a middle point is also provided in the secondary winding of the impedance conversion transformer, and DC bias current is supplied to the point, and the voltage regulator is connected in parallel to the winding part between the one end side of the secondary winding and the midpoint and the winding part between the other end side and the midpoint. The Josephson integrated circuit is provided as at least a first set and a second set, from one end of the secondary winding to the Josephson integrated circuit of the first set, and from the other end of the secondary winding to the second set of Josephson The power supply current may be supplied to each Son integrated circuit.

The impedance conversion transformer may be mounted on the same substrate chip as the substrate chip on which the Josephson integrated circuit is provided, or a chip carrier that supports the substrate chip on which the Josephson integrated circuit is provided. It may be provided above.

[0018]

FIG. 1 shows a preferred embodiment of the present invention in which the conventional device shown in FIG. 3 is improved. Therefore, the same reference numerals as those in FIG. 3 indicate the same or the same components, and some may avoid reiteration in this section, and conversely, the above description can be applied to such components.

The improvement according to the invention is found in the impedance transformation transformer 20, and in particular in its primary winding side construction. The primary winding is a series winding having a midpoint, and the midpoint is connected to a ground plane (indicated by a ground symbol in this figure) provided on the substrate chip 40. One of both ends of the primary winding is connected to the output line of the first-phase power supply current φ1 of the external high-frequency power source 11, and the other end of the second-phase is 180 ° out of phase with the first-phase power supply current φ1. It is connected to the output line of power supply current φ2. The ground terminal E of the high-frequency power source 11 is connected to the ground plane of the substrate chip 40 via a shield coating conductor that shields the power supply current line, thereby realizing the balanced power feeding method.

In this way, the impedance conversion transformer
Configure the primary winding of 20 in the so-called push-pull input type,
When currents with 180 ° phase difference are supplied to both ends, the midpoint potential does not change. Therefore, the potential of the ground plane, and thus the ground potential, which is the reference potential of the Josephson integrated circuits 41, 41 mounted on the substrate chip, does not change, and unlike the conventional example, basically, a single impedance conversion transformer is used. A balanced feeding system can be adopted by using only 20. In the past, at least two impedance conversion transformers 50, 50 were required due to the principle configuration, but the space factor is improved, or the degree of freedom in design is greatly increased.

Further, in comparison with the conventional impedance conversion transformer 50 on the same scale, in the case of the impedance conversion transformer 20 used in the present invention, as shown schematically in FIG. 1, the equivalent inductance of the primary winding is Since half of the conventional one is Lp / 2 and the stray capacitance is also half of Cs / 2,
The resonance frequency fr due to them is doubled. In other words, the high frequency characteristic of the impedance conversion transformer 20 used in the present invention is greatly improved, and a power supply current having a higher frequency than before can be supplied to the Josephson integrated circuit 41, and the essence of the Josephson integrated circuit 41 is High speed performance can be fully exerted.

The circuit configuration on the secondary side of the impedance conversion transformer 20 used in the present invention is
There is no particular need for modification. Speaking in the illustrated case, the secondary winding of the impedance conversion transformer 20 is also configured as a push-pull output type having a midpoint, and the DC bias current Ib from the DC bias current source 12 is flown into the midpoint. In this case, the one-sided amplitude Ia of the secondary side output currents iS-1 and iS-2 is used because the punch-through phenomenon described above is prevented.
DC bias current to a value slightly smaller than the current value dI
The size of Ib should be chosen so that it is 180
The secondary output currents iS-1 and iS-2, which have a phase difference of °, are designed to enter the negative region only slightly when they fall.

Voltage regulators 31, 31 are connected in parallel between the midpoint of the secondary winding and each end, but there is no particular need for modification in itself, and for example, the gap voltage is
For example, four unit Josephson junctions with a 2.8 mV Nb / AlOx / Nb junction are connected in series, so that the clamp voltage value is 11.2 mV. DC bias current
The above-mentioned current value dI described for Ib is preferably selected to be a value slightly smaller than the critical current value Ic of the Josephson junction used.

The current waveforms iP-1 and iP-2 thus voltage-clamped and consequently current-clamped to the Josephson integrated circuit 41 of the first set and the Josephson integrated circuit 41 of the second set. Each is supplied as a final power supply current, which satisfies the two-phase pulsating current power supply drive. As described above, it is preferable that the impedances Zc of the pair of Josephson integrated circuits 41, 41 viewed from the power supply side are equal, but the impedance is not limited to this. Further, the primary / secondary winding ratio in the impedance conversion transformer 20 is generally about 4: 1 or less (impedance ratio is about 16: 1 or less), but according to the present invention, the high frequency characteristics are improved, There is room for commercializing a transformer with a large winding ratio.

FIG. 2 shows a planar configuration example of the impedance conversion transformer 20 used in the present invention. However, the illustration of the superconductor layers or the insulating layer between the superconductor lines is omitted for the sake of simplicity. The secondary and primary windings 22 and 21 are provided so as to pass over the opening 24 opened in the ground plane 23 provided on the substrate chip 40 (FIG. 1), thereby constructing a magnetic coupling circuit, that is, a transformer portion. This is the same as the previous configuration example described with reference to FIG. 4, and the same applies to the fact that the input terminal for the DC bias current Ib is provided at the midpoint of the secondary winding 22. The difference is that the ground contact 25 is provided at the midpoint of the primary winding 21 and is grounded here, while the first-phase power supply current φ1 from the high-frequency power source 11 is at the beginning of the winding and the maximum at the end of the winding. The second end is the point at which the second-phase power supply current φ 2 is supplied to the inner end portion via the base contact 26 and the line portion under the primary winding 25. However, of course, the number of windings shown is merely an example for the purpose of explanation, and is a design problem that is changed according to individual needs.

Although the preferred embodiment of the present invention has been described above, any modification is free as long as it complies with the gist of the present invention. Since the present invention basically discloses a device for improving the high frequency characteristics of the impedance conversion transformer, as described above, in principle, the secondary side is a two-phase pulsating current power source-driven Josephson power source. It is applicable even if it is not an integrated circuit. This is because even in such a case, it is often desirable to feed power from the high-frequency power source 11 provided outside, according to the balanced feeding method at least on the primary side.

Further, since the impedance conversion transformer according to the present invention can be manufactured in a small size, it can be formed on the same substrate chip 40 as the substrate chip 40 on which the Josephson integrated circuit 41 is mounted. In fact, it is preferable. There are many. However, this is not limiting and in some cases the substrate chip 40 may be physically supported and provided on a chip carrier (not shown) that is often used in this type of field.

[0028]

According to the present invention, as a high-frequency power supply device for a Josephson integrated circuit, a balanced impedance feeding system can be realized by a single impedance conversion transformer, and in addition, the driven Josephson integrated circuit has excellent high-frequency characteristics. Can be driven while fully exhibiting its original high speed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a preferred embodiment of a high frequency power supply device for a Josephson integrated circuit according to the present invention.

FIG. 2 is an explanatory diagram related to a planar configuration of an impedance conversion transformer that can be used in the present invention.

FIG. 3 is a schematic configuration diagram of a typical example of a conventional high-frequency power supply device for Josephson integrated circuits.

FIG. 4 is an explanatory diagram related to a planar configuration of an impedance conversion transformer used in the conventional device shown in FIG.

[Explanation of symbols]

 11 high frequency power source, 12 DC bias current source, 20 impedance conversion transformer, 21 primary winding, 22 secondary winding, 23 ground plane, 24 aperture, 25 ground contact, 26 base contact, 31 voltage regulator (current clamper), 40 substrate chips, 41 Josephson integrated circuits.

Claims (4)

[Claims] 1. A power supply current output from the high-frequency power source according to a balanced power supply method, interposed between a high-frequency power source provided outside the substrate chip and a Josephson integrated circuit provided on the substrate chip. A high-frequency power supply device for a Josephson integrated circuit having an impedance conversion transformer for impedance matching between the high-frequency power source and the Josephson integrated circuit for the supply of Set a midpoint;
After connecting the middle point of the primary winding to a ground plane provided on a substrate chip on which a Josephson integrated circuit is mounted; an output line of a first-phase power supply current output from the high-frequency power source according to the balanced feeding method. Is connected to one end of the primary winding, and the other end is connected to an output line of a second-phase power supply current having a phase difference of 180 ° from the first-phase power supply current; Power supply device. 2. The apparatus of claim 1, wherein the secondary winding of the impedance transformation transformer also has a midpoint;
A direct current bias current is supplied to the middle point of the secondary winding; a winding portion between one end side and the middle point of the secondary winding, between the other end side and the middle point Voltage regulators are provided in parallel in the respective winding portions of the windings; the Josephson integrated circuit has at least a first set and a second set; from the one end of the secondary winding to the first set of Josephson For integrated circuits,
A power supply current is supplied to the second set of Josephson integrated circuits from the other end of the secondary winding, respectively. 3. A device according to claim 1 or 2;
The impedance conversion transformer is mounted on the same substrate chip as the substrate chip on which the Josephson integrated circuit is provided; 4. The device according to claim 1 or 2, wherein:
The impedance conversion transformer is provided on a chip carrier that supports the substrate chip on which the Josephson integrated circuit is provided.