JPH01173878A - Frequency analyzing device - Google Patents

Abstract

PURPOSE:To analyze a high frequency which can not be realized by an oscillator with high accuracy by inputting a signal whose frequency is unknown to a Josephson junction element and comparing an obtained voltage with reference voltages by plural comparators. CONSTITUTION:When the high-frequency signal whose frequency is unknown is inputted to the Josephson junction element 2 applied with electric power from a DC power source 3 from an input terminal 1, the Josephson junction element 2 outputs a voltage corresponding to the frequency with high accuracy. This voltage value is inputted to the comparators 61-66 and compared with reference voltages generated by a variable reference voltage source 4 and resistors 51-55, and the frequency of the input high frequency signal is analyzed from output patterns of output terminals 71-76. Therefore, a high-frequency analysis is taken with high accuracy even when the frequency is a high frequency which is close to the frequency to be measured and can not be generated by the oscillator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency analysis device for analyzing the frequency of an unknown frequency signal.

[Conventional technology]

FIG. 7 is a block diagram of Ichigome's frequency analyzer.

In the figure, fi+ is an input terminal for a high-frequency signal with an unknown frequency, (110) is an input terminal for a local signal, and (111) is an input terminal for a local signal.
is a mixer, (121) to (125) are band pass filters, (131) to (135) are detectors, (140) is a signal detection threshold pressure input terminal, and the gutter is a detector (1).
31) to (135) Comparators for comparing the output with the threshold voltage, (2) to (2) are output terminals of each comparator Cυ.

Next, the operation will be explained. A high frequency signal of an unknown frequency (temporarily assumed to be fI) input from the high frequency input terminal (1) is mixed with a local signal (frequency vifLo> input from the input terminal (110) by a mixer (111), It is converted into a signal with frequency f!-/LO, and is input to band-pass filters (121) to (125).Band-pass filters (121) to (125) each have a center frequency of frr+(nt). xfnw(n −1 to 5
), and the bandwidth is fBy. The outputs of the bandpass filters (121) to (125) are detected by detectors (131) to (135), respectively, and then detected by comparators 6υ to
It is compared with a signal detection threshold voltage input from the threshold voltage input terminal (140) using time, and the result is outputted to the output terminal (company).

Now - If the frequency of the signal input from the high frequency input terminal (1) is flx fLo + /IF + 3fnw, the frequency of the output of the mixer (111) is fl - fL
Since o=flF+3fnw, the signal passes only through the bandpass filter (124) whose center frequency is fIF+39w, and is detected by the detector (134). If the output of the wave detector (134) is higher than the signal detection threshold voltage, the comparator 1641 outputs a signal presence status at the output terminal -. Therefore, the output terminal a11~
The status output to the signal can be analyzed in degrees depending on whether there is a signal or no signal. Also, the frequency analysis band can be changed by changing the local frequency/LO.

[Problems to be solved by the invention] Since the conventional frequency analyzer is configured as described above, in order to perform high-precision broadband frequency analysis, it is necessary to control the unstable local oscillator with high precision. However, it is difficult to obtain such an oscillator, especially in the millimeter wave band. Furthermore, since the frequency analysis accuracy is determined by the bandwidth of the filter, it has the disadvantage that it cannot be varied.

This invention was made to solve the above-mentioned problems. It performs frequency analysis of millimeter-wave band surrounding frequency signals with high accuracy without using high-frequency local oscillators or bandpass filters, and It is an object of the present invention to obtain a frequency analyzer whose analysis accuracy can also be varied.

[Means for solving problems]

The frequency analysis facility according to the present invention inputs an unknown surrounding frequency signal to a Josephson junction element, inputs the obtained voltage value to a plurality of comparators, and compares it with a reference stone pressure.

[Effect]

When a high frequency signal is applied to the Josephson junction element to which a predetermined direct current is applied, the Josephson junction element according to the present invention outputs a voltage corresponding to the frequency with high precision.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is a high-frequency signal input terminal whose frequency is unknown, (2) is a Josephson junction element, (3) is a DC current source for determining the operating point of this Josephson junction element (2), and (4 ) is a variable reference voltage source, 611 to 551 are resistors for dividing the output pressure of this variable reference voltage source (4), and [F]υ~ is a Josephson junction element (2) and resistor 6υ~□ Comparator to compare the pressure of □□, (2) to (to)
are the output terminals of comparison #1611--.

A DC current source (3) causes a current of ll[lo to flow through the Josephson junction element (2), and its operating point is at the second
It is at point ■ on the dotted line in section I, but when a signal with frequency fo is input from the high frequency input terminal, its V-1 characteristic becomes the solid line in Figure 2, so the operating point moves to point ■, and both ends voltage or vO
becomes. Here, the heavy pressure ■0 is expressed by the following formula.

hzf.

Vo　--(1) Here, h is a blank constant and e is the amount of charge of the electron.

Resistors (51) to (to) are variable groups +1! Stone pressure source (4)
Since they are connected in series, a voltage obtained by dividing the output pressure of the variable reference voltage source (4) is generated at both ends of each.

That is, the resistor 6D- (to) operates as a plurality of variable reference voltage generators, and the output of the variable reference voltage source (4) is
, the resistance values of resistor 6D- (to) are all equal,
The reference level input VTR of the voltage comparator (6υ~(661) is as follows.

VTH--VST (n=0.1.-5) (2
1 Now, a high-frequency signal with an unknown frequency fO or an input terminal (1)
Assuming that the output terminal qD~ of the comparator Sυ~- has the output pattern as shown in Fig. 3, the following equation holds true.

Therefore, it is possible to analyze the frequency of the high-frequency signal input from the output patterns of the output terminals (2) to σe.

Furthermore, the frequency analysis band can be changed by changing the nominal output voltage of the variable reference voltage source (4), and
By increasing the number of voltage dividing resistors (5 in the above example) and the number of Honjo comparators (number of resistors + 1),
It is possible to improve frequency analysis accuracy.

In addition, in the above embodiment, a variable reference voltage source (4) and a resistor (511-1) were used as a plurality of reference 1N5 juice generators, or a plurality of reference voltage generators were constructed using a variable reference voltage source (4) and a resistor (511-1).
The variable high-frequency oscillator (8), the DC current source (9), and the output signals of these variable high-frequency oscillators (8) shown in the figure are connected to the output current of DC current m19+ by the Josephson junction system until~0!19. may be configured.

A current of 1 nw is flowing through the Josephson junction elements (111 to Q51) by the DC current source (9), and a high frequency signal of a predetermined frequency fnvt is applied from the variable high frequency oscillator (8). Each point is the 5th
point ■ in the figure, and the voltage across them is VBw, respectively.
becomes. Here, voltage VBW is expressed by the following equation similarly to equation (1).

zfnw VBW= -f51 Therefore, ~pressure comparator +611~ (output to 6I19 is V
TR=nVBw. Voltage comparator (611-can output terminal (company) ~■
Assuming that the output pattern of is as shown in FIG. 6, the following equation holds true.

2VBW < Vo (3Vnw
+71 formula (7) plus formula +11. Substituting +51 and transforming it gives 2fBW < fo < 3/BY
(8) Therefore, the frequency of the high frequency signal inputted from the output terminal surface to the output pattern can be directly determined using the output frequency of the variable high frequency oscillator (8). Furthermore, the frequency analysis band can be changed by changing the output frequency of the variable high frequency oscillator (8).

Further, by increasing the number of Josephson junction elements Uυ˜QS, it is possible to improve the accuracy of one frequency analysis.

〔Effect of the invention〕

As described above, since the frequency analyzer according to the present invention is constructed using a Josephson junction element, there is no need for a high frequency oscillator close to the frequency of the high frequency signal to be measured. It is possible to realize a frequency analysis device for a frequency band, and the frequency analysis accuracy can also be easily varied.

[Brief explanation of the drawing]

The first picture is a block diagram showing a frequency analyzer according to an embodiment of the present invention, the second figure is a characteristic diagram showing the ■-■ characteristics and operating points of the Josephson junction element used in this invention, and the third figure is a block diagram showing a frequency analyzer according to an embodiment of the present invention.
Figure 4 is a diagram showing the relationship between the input level and output of the comparator used in this invention, Figure 4 is a block diagram of a reference voltage generator showing another embodiment of this invention, and Figure 5 is another embodiment of this invention. Figure 6 is a diagram showing the relationship between the input level and output of the comparator used in another embodiment of the present invention, and Figure 7 is a diagram showing the relationship between the V-1 characteristic and the operating point of the Josephson junction element used in another embodiment of the present invention. FIG. 2 is a block diagram showing conventional frequency analysis accuracy. (2) and αD~t151 are Josephson junction elements, (3) and (
9) is a direct current source, (4) is a variable reference voltage source, and 61 to 61 are resistors -+bn- cans are voltage comparators.

Claims (2)

[Claims] (1) A Josephson junction element to which a DC current and a high-frequency signal of unknown frequency are applied, a plurality of variable reference voltage generators, and a plurality of variable reference voltage generators that compare the output of the Josephson junction element and the output of the reference voltage generator. A frequency analysis device characterized by being equipped with a comparator. (2) The plurality of variable reference voltage generators are configured using a variable high-frequency signal generator and a plurality of Josephson junction elements to which the output of the variable high-frequency signal generator and a direct current are applied. A frequency analysis device according to claim 1.