JPS62102620A - Superconduction driver circuit - Google Patents

Abstract

PURPOSE:To send an output signal of a DCFP circuit to a remote location through a matched transmission line by providing two magnetic flux coupling type quantization interference elements where the direction of a control current or the like flowing to control lines is opposite to each other. CONSTITUTION:When an output current of a DCFP circuit is zero, the two magnetic flux coupling type quantization interference elements 201, 202 of a superconduction driver circuit are in the superconduction state. When an output current is of the DCFP circuit is positive and a current flows to ground, the magnetic flux by the control current of the element 201 is subtracted and the magnetic flux by the control current of the element 202 is added. Thus, the element 201 stays in the superconduction state and the element 202 is switched to the current state. When the output of the DCFP circuit and the current Is are negative, the element 202 remains in conducting state conversely and the element 201 is switched to the current state. That is, a positive or negative signal flows to the load resistor of the transmission line in response to the output signal of the DCFP circuit and the output signal of the DCFP circuit is sent to a remote location through a matched transmission line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electronic circuit using a superconducting element, and particularly to an ultrahigh-speed switching circuit using a Josephson junction.

[Background of the invention]

Switching circuits using Josephson devices are well known in the art, and include those represented by quantum interference devices and direct-coupled devices that utilize the operation of a Josephson device to transition from a superconducting state to a voltage state, and those that use magnetic flux as a signal. A representative example is a DCFP circuit used as a medium. Especially DCF
Since the P circuit does not utilize the voltage transition of the Josephson device, its power consumption is extremely low, and since it uses a bridge-type Josephson junction with extremely low junction capacitance, it can operate at extremely high speed. Further, since the DCFP circuit is a type of parametron circuit, high circuit gain can be achieved. The characteristics of these DCFP circuits are suitable for ultra-high-speed computers, and their applications are expected. This DCFP circuit was described in detail by Goto et al. in the Proceedings of the 1st and 2nd RIKEN Symposium, "Josephson Electronics" (March 16, 1980, March 16, 1985). There is.

As mentioned above, the DCFP circuit does not utilize the voltage transition of a Josephson device, so the basic circuit configuration is made up of multiple superconducting loops without using any resistors. Generally, when transmitting high-speed pulse signals, the wiring for transmitting the signals must be regarded as a transmission line with a finite characteristic impedance. To send a signal through a transmission line, it is common practice to connect a terminating resistor with the same resistance value as the characteristic impedance to the end of the transmission line to achieve matching and prevent signal reflection.

On the other hand, in conventionally proposed DCFP circuits, it is not possible to insert a resistor into the load, so when driving a transmission line, the transmission line cannot be terminated with a resistor and is directly shorted to ground. In this case, there is a large swing at the end of the transmission line. This fluctuation causes malfunction of the DCFP circuit. Furthermore, a transmission line whose terminal end is short-circuited to ground appears to be inductive when viewed from the sending end, but when trying to transmit a signal over a long distance, the inductance becomes large and has the disadvantage of slowing down the switching speed of the DCFP circuit itself. there were. In particular, in order to transmit signals between integrated circuit chips, it is necessary to use transmission lines.
Due to the above-mentioned reasons, conventional DCFP circuits have been unable to send signals to long distances at high speed.

[Purpose of the invention]

An object of the present invention is to provide a driver circuit that transmits the output signal of a DCFP circuit over a long distance using a well-matched transmission line.

[Summary of the invention]

For this purpose, the present invention provides a superconducting driver circuit using a magnetic flux coupling layer quantum interference device that utilizes the operation of a Josephson device to transition from a superconducting state to a voltage state.
Provide a new circuit connected to the circuit. The magnetic flux coupling layer quantum interference device is driven by an AC power source and can drive a transmission line with a finite characteristic impedance. Therefore, by using the driver circuit according to the present invention, it becomes possible to send signals from a DCFP circuit to a long distance at high speed via a transmission line.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

The circuit shown in FIG. 1 is composed of a DCFP circuit and a superconducting driver circuit connected thereto.

In the DCFP circuit, the direction of the current (positive direction or negative direction) corresponds to the signal "Q27%"1".

On the other hand, in flux-coupled quantum interference devices, the presence or absence of current is determined by the signal “
Make it correspond to Q+l, 1lllj. Therefore, simply combining the DCFP circuit and the magnetic flux coupling layer quantum interference device cannot fully demonstrate the function of the circuit. For this reason, the first
The circuit shown in the figure combines two magnetic flux coupling layer quantum interference devices and uses a superconducting driver circuit that uses the current direction (positive direction or negative direction) as an output signal, that is, outputs a signal that matches the signal of the DCFP circuit. We are hiring. The DCFP circuit is composed of a superconducting loop consisting of two Josephson junctions 101 and 102 and excitation inductors 103 and 104. The superconducting loop is amplified by the excitation current flowing through the input terminal oscillating wire 105.

The output current Is of the DCFP circuit flows out to the load inductor 108 via the output line 107. The superconducting driver circuit is composed of two magnetic flux coupling layer quantum interference devices 201 and 202, bias resistors 203 and 204 that bias each magnetic flux coupling layer quantum interference device, and load resistances 205 and 206 of each magnetic flux coupling layer quantum interference device. ing. One end of the magnetic flux coupling layer quantum interference elements 201 and 202 is grounded, and the other end is connected to one end of bias resistors 203 and 204 and one end of load resistors 205 and 206, respectively. The magnetic flux coupling layer quantum interference elements 201 and 202 each have a bias resistor 2.
It is biased by the current g210, 211 via 03, 204. The current of this current source 210 flows through the magnetic flux coupling layer quantum interference element 201, the bias resistor 203, and the current g210. The current of the current source 211 is the current g21
1. Bias resistor 204, magnetic flux coupling layer quantum interference element 20
The direction of flow is through 2. Load resistance 205, 20 respectively
One end of 6 is connected to one end of transmission line 207 . The other end of the transmission line 207 is grounded via a terminating resistor 208. The resistance value of the terminating resistor 208 is the same value as the characteristic impedance of the transmission line 207, and since the transmission line 207 is matched terminated, no signal reflection occurs at the termination. An output line 107 of the DCFP circuit is coupled to the magnetic flux coupling layer quantum interference elements 201 and 202 as a first control line. Further, a second control line 209 is coupled to the magnetic flux coupling layer quantum interference elements 201 and 202, and a control current is supplied from a current source 212 to this second control line 209. The second control line 209 connects the ground to the second magnetic flux coupling layer quantum interference element 2.
02, the control current flows in the order of the first flux-coupled quantum interference 201. The magnetic flux coupling layer quantum interference elements 201 and 202 include the first. The added magnetic flux generated by the current flowing through the second control line 107° 209 interlinks. Here, the first magnetic flux coupling layer quantum interference Element 20
The direction in which the first control line is installed (the direction in which the wiring is wound) is opposite to that of the second magnetic flux coupling layer quantum interference element 202. Next, the operation of the circuit shown in FIG. 1 will be explained. When the output current of the DCFP circuit is zero, both of the two magnetic flux coupling layer quantum interference elements 201 and 202 of the superconducting driver circuit are in a superconducting state.

When the output current Is of the DCFP circuit is positive, that is, when the current flows from the DCFP circuit toward the ground, the magnetic flux due to the control current of the first magnetic flux coupling layer quantum interference element 201 is subtracted, and the second magnetic flux coupling layer quantum interference The magnetic fluxes due to the control current of element 202 are added.

Therefore, the first magnetic flux coupling layer quantum interference device 201 remains in the superconducting state, and the second magnetic flux coupling layer quantum interference device 202 switches to the current state. Therefore, a current flows from the current g211 to the terminating resistor 208 via the bias resistor 204, the load resistor 205, and the transmission line 207. In this case, a load current flows through the terminating resistor 208 from the transmission 1/1A 207 in the direction toward the ground (positive direction). On the other hand, DCFP
When the output current Is of the circuit is negative, that is, when the current flows from the ground toward the DCFP circuit, the magnetic flux due to the control current of the first magnetic flux coupling layer quantum interference device 201 is added, and the magnetic flux is added to the second magnetic flux coupling layer quantum interference device 201. The magnetic flux due to the control current 202 is subtracted. Therefore, the second magnetic flux coupling layer quantum interference element 2
02 remains in the superconducting state, and the second magnetic flux coupling layer quantum interference element 201 switches to the current state. Therefore, a current flows from the current 111210 to the terminating resistor 208 via the transmission line 207, the load resistor 206, and the bias resistor 203.

In this case, a load current IL- flows through the terminating resistor 208 in a direction from the ground toward the transmission line 207 (negative direction). From the above explanation, it is clear that the superconducting driver circuit operates as a driver circuit that sends a positive or negative signal to the load resistance of the transmission line in response to the output signal of the DCFP circuit. The first superconducting driver circuit is a circuit that outputs a negative signal, but if the direction of the current in the second control line 209 is reversed, a so-called inverter driver circuit that outputs a negative signal can be constructed. is also clear. Although there is no specification as a flux-coupled layer quantum interference device, this device may be a flux-coupled two-junction quantum interference device or a flux-coupled three-junction quantum interference device.
It is clear that flux-coupled devices such as junction quantum interference devices can be used.

As described above, according to this embodiment, DCFP circuits can be connected via a transmission line, and signals can be sent to distant DCFP circuits at high speed.

〔Effect of the invention〕

According to the present invention, signals can be transmitted at high speed between DCFP circuits via a transmission line. This shows that high-speed transmission is possible even with a large load, such as transmission between integrated circuits, and it becomes possible to create a logic system using a large number of DCFP circuits. This makes it possible to construct high-speed, large-scale logic systems with DCFP circuits, and
It can demonstrate the high-speed, low-consumption performance that characterizes the P circuit.

For this reason, it is possible to create a computer with unprecedented high performance,
The effects of the present invention are extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. 101.102...Josephson junction, 103°10
4... Excitation inductor, 105... Excitation line, 106
... Input terminal, 107 ... Output line, 108 ... Load inductor, 201, 202 ... Magnetic flux coupling layer quantum interference element, 203, 204 ... Bias resistance, 205,
206...Load resistance, 207...Transmission line, 208...
...Terminal resistor, 209...Control line, 210°211,
212...Current source

Claims (1)

[Claims] 1. Two flux-coupled quantum interference devices with the output line of the DCFP circuit as the first control line, and one end of each of the two load resistors of the two flux-coupled quantum interference devices connected to each other to form an output terminal. A driver circuit, wherein the current bias directions of the first flux-coupled quantum interference device and the second flux-coupled quantum interference device are opposite directions, and the second flux-coupled quantum interference device of the two flux-coupled quantum interference devices is A superconducting driver circuit characterized in that the directions of control currents flowing through the control lines are opposite to each other.