JPH02184086A - Chip holder for josephson integrated circuit - Google Patents

Abstract

PURPOSE:To transmit a high-speed signal from a signal line at room temperature to a cryogenic Josephson integrated circuit chip without causing a greater reflection by connecting a passive element of inductance and capacitance between a strip line and an electrode electrically connected to this strip line in a chip holder. CONSTITUTION:An inductance element 6 and a capacitance element 7 inserted between a strip line 4 and a contact electrode 8 on a chip holder constitutes a resonance circuit, which transmits a signal onto a chip at a resonance frequency f0. The inserted inductance and capacitance plays a role of an impedance conversion circuit for the characteristic impedance of a signal line and the characteristic impedance on the chip. In this chip holder, the resonance frequency f0 can be changed easily by varying the values of the inserted inductance and capacitance, and a high-speed signal can be transmitted.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a Josephson integrated circuit chip holder for electrically connecting a Josephson integrated circuit chip to an external circuit, especially when performing high-speed operation measurements. This relates to a chip holder used for.

(Prior Art) In Josephson integrated circuits, Nb, which is a superconducting material, is used as a contact pad for electrical connection with the outside.
Nb alloys are commonly used. Since Josephson integrated circuits require measurements in liquid helium, it is difficult to say that connecting them by wire bonding, as is the case with general semiconductor integrated circuits, is an efficient method. Therefore, a chip holder as shown in FIG. 3 is used. This involves placing a chip holder against a Josephson integrated circuit chip on which strip lines 24 and contact electrodes are formed on an insulating substrate 22 at positions corresponding to the contact pads of the Josephson integrated circuit chip 25, and establishing an electrical connection through contact. A method is used in which the signal line 23 is connected to the back surface of the board 22. At this time, electrical connection is ensured by providing a spring action to the contact electrode on the chip holder side. Since this method is simpler than methods such as soldering, it is very effective for measuring Josephson integrated circuits, which must be measured in liquid helium.

(Problems to be Solved by the Invention) However, this method is not suitable for high-speed measurements where signal reflection between the strip line and the Josephson integrated circuit chip becomes a problem. A Josephson integrated circuit is a current-driven circuit, and its input impedance is generally on the order of several milliohms to several ohms, which is lower than the impedance of an external circuit or a strip line. Therefore, when transmitting signals at a frequency of several 100 MHz or higher, an impedance conversion circuit is required. Signal reflection is a big problem, especially in power lines that need to transmit large amounts of power. Conventionally, this conversion circuit was thought to propagate high-speed signals by attaching a transformer on the chip or providing an LC resonant circuit, but this method required a complicated circuit configuration on the chip. There are problems such as the fact that the frequency band is constant, the upper frequency limit is limited, and the frequency band is constant.

An object of the present invention is to provide a chip holder that eliminates the above-mentioned problems.

(Means for Solving the Problem) According to the present invention, in a chip holder in which a plurality of strip lines and a plurality of electrodes electrically connected to the strip lines are formed on an insulating substrate, the strip line A chip holder for a Josephson integrated circuit is obtained, characterized in that a passive element consisting of an inductance and a capacitance is connected between the electrode and the electrode.

(Function) The strip line on the chip holder is usually designed to have an impedance of 50Ω in order to achieve frequency matching with an external circuit. On the other hand, since the input impedance of the Josephson integrated circuit is from several mΩ to several Ω, which is smaller than that of a strip line, a conversion circuit is required for matching. A resonant circuit made of inductance and capacitance provided on the strip line serves to match impedance for signals in a certain frequency band. Unlike passive elements provided on a chip, passive elements provided on a strip line can be easily removed, and parameters can be selected according to the required measurement frequency.

(Example) FIG. 1 is a schematic diagram of a chip holder for explaining the present invention in detail. In the figure, 1 is a chip mounting part, 2 is an insulating substrate, 3 is a signal line, 4 is a strip line, 5 is a Josephson integrated circuit chip, 6 is an inductance element, and 7 is a capacitance element. Figure 2 shows the equivalent circuit of the chip holder. In FIG. 2, 11 is an inductance, 12 is a capacitance, 13 is a signal characteristic impedance, 14 is a power supply, 15 is an input impedance of the Josephson integrated circuit chip, 16 is an equivalent circuit of the Josephson integrated circuit chip, and 17 is an electrode. , and the parasitic inductance of the wiring on the chip. As shown in FIG. 1, a Josephson integrated circuit chip 5 is pressed onto a chip mounting portion 1 on a chip holder and is brought into electrical contact with spring-like contact electrodes. For example, consider the case where a current is supplied to the gate level power supply line 8 at a frequency of 500 MHz. The characteristic impedance of the signal line 3 and the strip line 4 is typically 50Ω, and the characteristic impedance of the Josephson integrated circuit chip 5 is
The characteristic impedance of is approximately 3 mΩ, which is very low. In this state, the impedances of both sides are mismatched, and large reflections occur when high-speed signals are propagated. 7 constitutes a resonant circuit as shown in FIG. 2(a), and as shown in FIG. 2(b), a certain resonant frequency fo
signals can be propagated onto the chip at In the original case, assuming that the inductance of the electrode and wiring is approximately 40 pH, L = 87 pH, C = 794 pF, and f
□ = Can supply current to the Josephson integrated circuit at a resonant frequency of 500 MHz. In other words, the inserted inductance and capacitance play the role of an impedance conversion circuit between the characteristic impedance of the signal line and the characteristic impedance on the chip. In this chip holder, the resonant frequency f0 can be easily changed by changing the values of the inserted inductance and capacitance, and the necessary high-speed signal can be transmitted.

Additionally, this chip holder can also be used for quasi-static measurements.

(Effects of the Invention) By using the chip holder of the present invention, high-speed signals from signal lines at room temperature can be transmitted in the necessary frequency band.
It can be propagated to cryogenic Josephson integrated circuit chips without significant reflection. The value of this frequency can be easily changed by changing the values of inductance and capacitance on the chip holder. Additionally, it can also be used for quasi-static measurements.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the embodiment, and FIG. 3 is a schematic diagram of a conventional example of the present invention. In the figure, 1.21...chip mounting part, 2,22...
...Insulating substrate, 3,23...Signal line, 4,24...
Strip line, 5, 25... Josephson integrated circuit chip, 6... Inductance element, 7... Capacitance element, 8... Contact electrode, 11... Inductance 1.12... Capacitance, 13・・・
- Impedance, 14... Power supply, 15... Impedance on the chip, 16... Josephson integrated circuit chip portion, 17... Parasitic inductance of electrodes and wiring.

Claims (1)

[Claims] In a chip holder in which a plurality of strip lines and a plurality of electrodes electrically connected to the strip lines are formed on an insulating substrate, a passive element consisting of an inductance and a capacitance is provided between the strip line and the electrode. A chip holder for a Josephson integrated circuit, characterized by a connection.