JPH0478203A - Mixer - Google Patents

Abstract

PURPOSE:To decrease number of signal branching filters by providing a 1st line whose other terminal is opened and a 2nd line whose other terminal is short-circuited, whose electric length is both selected to be nearly 1/4 wavelength or its multiple with respect to an input output signal frequency to/from a nonlinear element and whose one terminal connects respectively to a 1st terminal (by 1st line) and to a 2nd terminal (by 2nd line) of the element. CONSTITUTION:The mixer consists of a 1st terminal 11, a 2nd terminal 12 of an anti-parallel diode pair 5 being a nonlinear element, a branching filter 13 comprising a band pass filter 10 passing a high frequency signal and a low pass filter 6 passing an intermediate frequency signal, a 1st line 14 whose one end is opened and whose length is nearly 1/4 wavelength with respect to a local oscillating signal frequency flo and a 2nd line 15 whose one end is short- circuited and whose length is nearly 1/4 wavelength with respect to a local oscillating signal frequency flo. A local oscillating signal is inputted from a terminal 2 and fed to the diode pair 5 and a high frequency signal is inputted from a terminal 1 and fed to the diode pair 5, and a mixed frequency fout is provided across the diode pair 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to mixers, and particularly to the reduction of filters in mixers.

[Conventional technology] Figure 10 shows, for example, the 16th Eur in 1986.

pean Microwave Conference
ence Proceedings p418~
This is a configuration diagram showing an example of a conventional mixer as described on p. This is an example of an even harmonic mixer for a down converter that outputs a frequency that is the difference between an even multiple of f, . and f rr.In the figure, (1) is a high frequency signal terminal, (
2) is the local oscillator signal terminal, (3) is the intermediate frequency signal terminal, and (4) is the intermediate frequency signal terminal.
a) and (4b) are diodes, (5) is an anti-parallel diode pair consisting of diodes (4a) and (4b) of opposite polarity connected in parallel, and (6) is a low pass that passes intermediate frequency signals. filter, (7) is a high-pass filter that passes the local signal, (8) is a low-pass filter (6
) and a high-pass filter (7),
(9) is a band rejection filter that blocks high frequency signals, (1
0) is a bandpass filter that passes high frequency signals.

Next, the operation will be explained.

In the conventional mixer as described above, by using the above-mentioned filters (6), (7), (9), and (10), the signal terminals (1), (2), and (3) are The signals of each frequency are input and output to and from the anti-parallel diode pair (5) efficiently. In such an even harmonic mixer, the local oscillator signal is input from the local oscillator signal terminal (2),
When added to the anti-parallel diode pair (5) via a high-pass filter (7) and a band-stop filter (9),
The values of the junction resistance and junction capacitance of the diodes (4a) and (4b) change over time depending on the local oscillation signal. At this time, the high frequency signal is input to the high frequency signal terminal (1), passed through the band pass filter (10), and then passed through the anti-parallel diode pair (
5), the mixed wave (frequency fo
, , ) occur at both ends of the anti-parallel diode pair (5).

fo,t=l f,,±2mfrol (1
) where m is an integer. In this conventional mixer, among these mixed waves, for example, the frequency f given by the following equation
The signal of i(
) and output it to the intermediate frequency signal terminal (3) as an intermediate frequency signal.

f,,-f,,-2f,. (2) Note that such a harmonic mixer has a local oscillation frequency f. Because it operates at a frequency that is 1/2 m of a normal mixer, it is often used in millimeter wave receivers and the like.

[Problem to be solved by the invention] In the conventional mixer as described in 2, each signal terminal (1),
Many filters are used to separate between (2) and (3).
(6), (7), (9), and (10) are required. Therefore, there was a problem that the circuit configuration was complicated and large. Further, there is a problem in that it is difficult to monolithically integrate the semiconductor substrate on a semiconductor substrate.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a mixer which is small in size, easy to monolithically integrate on a semiconductor substrate, and has a structure in which the number of filters is reduced.

[Means for solving the problem] It has a first terminal and a second terminal for inputting and outputting signals, and frequency-mixes two signals inputted from each of the first terminal and the second terminal. A non-linear element and a non-linear element having an electrical length of approximately 1/4 wavelength or a multiple thereof at a signal frequency input and output to the non-linear element, one end of which is connected to the first terminal of the non-linear element, and the other end of which is open. 1 line, and a second line whose one end is connected to the second terminal of the nonlinear element and whose other end is short-circuited.

[Function] In the mixer configured as described above, the electrical length is approximately 1/4 wavelength or a multiple thereof at the signal frequency input/output to the nonlinear element, and the first terminal and the second terminal of the nonlinear element are connected to each other. The impedance of each of the first line, which is connected at one end and open at the other end, and the second line, whose other end is short-circuited, is such that the electrical length of the first line and the second line is approximately 1.
For a signal with a frequency that is an odd multiple of a /4 wavelength, it will be shorted or open, and for a signal that has a frequency that is an even multiple of a quarter wavelength, the electrical length of the first line and second line will be approximately an even multiple of a quarter wavelength. Since it becomes an open circuit and a short circuit, the signal whose frequency is such that the electrical length input and output to the nonlinear element is approximately an even multiple of 1/4 wavelength, and the electrical length is approximately an odd multiple of 1/4 wavelength. Separate and demultiplex the frequency signal.

[Example code] FIG. 1 is a block diagram of an embodiment of the mixer of the present invention.

Here, as in the conventional example, a high frequency signal (frequency f1.)
and a local oscillator signal (frequency fzo) are input, and f, as an intermediate frequency signal (frequency f1.). Frequency of even multiple of and fr
(In the figure, (1
) to (6) and (10) are the same or equivalent parts to those of the conventional example shown in FIG.
), and (13) is a duplexer consisting of a bandpass filter (10) that passes a high frequency signal and a low pass filter (6) that passes an intermediate frequency signal; 14) has an open end and a length of local signal frequency f. The first line (15) with approximately 1/4 wavelength is short-circuited at the tip, and the length is approximately 1 at the local oscillation signal frequency fjo.
/4 wavelength second line.

Next, the operation will be explained.

If the local oscillator signal is input from the local oscillator signal terminal (2) and added to the anti-parallel diode pair (5), and the high frequency signal is input from the high frequency signal terminal (1) and added to the anti-parallel diode pair (5), the conventional Similarly to the example, the above (1
) The mixed wave (frequency f...,
) occurs at both ends of the anti-parallel diode pair (5).

f. ,,=lf,,±2mfzol (1)
Here, m is an integer. Among these mixed waves, for example, a signal with a frequency f+f given by the following equation is selected and output as an intermediate frequency signal to an intermediate frequency signal terminal (3).

f :r= f rr 2m f so
(3) Here, for example, f:r<<fn. <f,,,
f, (<0, 4 f to, f, t';
2 m f no, the intermediate frequency signal frequency f1. An example will be explained in which the signal frequency is sufficiently low compared to other signal frequencies.

FIG. 2 shows a list of the electrical lengths of the first line (14) and the second line (15) at each of the above frequencies and the impedance of the lines as seen from the anti-parallel diode pair (5) side. The electrical lengths of the first line (14) and the second line (15) are set to approximately 1/4 wavelength at the local signal frequency flo, and f at the frequency f rf. At frequencies that are even multiples of , the electrical length is approximately an even multiple of 1/4 wavelength,
At frequency fat, f rr<0. 4 f r. In this case, the electrical length becomes negligible, approximately 1/10 wavelength or less.

Therefore, the impedance of the line viewed from the anti-parallel diode pair (5) side is as shown in FIG.

In line impedance, a short circuit can be treated as a ground plane, and an open end is the same as nothing. Furthermore, no signal passes through the cutoff ranges of the bandpass filter (10) and the lowpass filter (6). From these facts, the equivalent circuit of the mixer at each frequency can be represented by the circuit shown in FIG.

That is, the anti-barrel diode pair (5) is connected to the high frequency signal terminal (1) via the band pass filter (10) at the high frequency signal frequency, to the local signal terminal (2) at the local signal frequency, and further, At intermediate frequency signal frequencies, it is coupled only to the intermediate frequency signal terminal (3) via a low-pass filter (6). In this way, the mixer uses the first line (14) and the second line (15) to separate and branch the local oscillation signal from other signals.

As described above, in the mixer according to the present invention, the first
The line (14) and the second line (15) produce a signal at a frequency whose electrical length is approximately an even multiple of a quarter wavelength, and a signal at a frequency whose electrical length is an odd multiple of approximately a quarter wavelength. Since it can separate and demultiplex, it has the effect of reducing the number of filters.

Further, in the above embodiment, the branching filter (13) used separates a high frequency signal and an intermediate frequency signal. This branching filter (13) is compared with the branching filter (8) shown in the conventional example shown in FIG. 10, which separates the local oscillator signal and the intermediate frequency signal.
As shown in FIG. 4, since the frequency intervals for demultiplexing are far apart, it is possible to construct the filter using a smaller filter.

As described above, in the mixer according to the present invention, the number of filters can be reduced, and each signal terminal can be separated without using many large-sized filters with complicated configurations. Therefore, it is possible to obtain a mixer that is small in size and has a structure that is easily monolithically integrated.

In addition, in the above embodiment, an anti-parallel diode pair (5
) and the high frequency signal terminal (1), a bandpass filter (
10), and as a specific example, an example using a coupled line will be shown.

FIG. 5 is a pattern diagram of a bandpass filter (7) using a coupled line, and (16) has a length of a high frequency signal frequency f.
The RF coupling line has 174 wavelengths, and (17a) and (17b) are connection lines. This coupled line (16) has an image impedance Z of the following equation at a frequency where the electrical length is 90 degrees.
It operates as an impedance transformer with an impedance of 1.

Z, −(Z −Z )/2 (4
) even odd where 2. 2 is the coupled line (16) e
These are the even mode impedance and odd mode impedance of ven odd. On the other hand, since the coupled line (16) operates almost as an open end at the intermediate frequency signal frequency f + (, the band-pass filter (
10) works well.

Furthermore, if the image impedance Z1 of the bandpass filter (lO) using the above-mentioned coupled line (16) is set to the following equation, this also operates as a matching circuit.

z12-2d -Zo (5) Here, Zd is the impedance at the high frequency signal frequency frr when looking from the coupled line (16) to the anti-parallel diode pair (5) side, and Zo is the characteristic impedance of the high frequency signal terminal (1) It is.

As described above, by using this coupling line (16), a matching circuit can be provided without increasing the size of the circuit.

In the above embodiment, an anti-parallel diode pair (5) was used as the nonlinear element for frequency mixing, but the present invention uses a normal diode (4) as shown in FIG. It is obvious that this method can also be applied to other cases, and the same effect can be achieved.

Furthermore, in the above embodiment, f Ht<< f ro< f
, rf H(<0.4 fjo, f r+”=
2m f+o (m=1.2°...), and the case where the intermediate frequency signal frequency fir is sufficiently low compared to other signal frequencies has been described, but other than this may be used as shown below.

FIG. 7 is a configuration diagram of still another embodiment of the present invention, and in the figure, (18) is a first line whose tip is open and whose length is approximately 1/4 wavelength at intermediate frequency signal frequency fi1. ,(
Reference numeral 19) is a second line whose tip is short-circuited and whose length is approximately 1/4 wavelength at the intermediate frequency signal frequency f tl, and is otherwise the same as that shown in FIG. 1 or FIG. 6.

Next, the operation will be explained.

Note that here, the frequency of each signal is f,, = f,
.

f. , f , ,=a f 1r, fj. =2
A case where the setting is set as f-t will be explained as an example. FIG. 8 shows a list of the electrical lengths of the first line (18) and the second line (19) at each of the above frequencies and the impedance of the lines as seen from the diode (4) side. In line impedance, a short circuit can be treated as a ground plane, and an open end is the same as nothing. Furthermore, no signal passes through the cutoff ranges of the bandpass filter (10) and the lowpass filter (6). From these facts, the equivalent circuit of the mixer at each frequency can be represented by the circuit shown in FIG. That is, the diode (4) is connected to the high frequency signal terminal (1) via the band pass filter (10) at the high frequency signal frequency, to the local oscillation signal terminal (2) at the local oscillation signal frequency, and further to the intermediate frequency signal. In frequency, a low pass filter (6
) to the intermediate frequency signal terminal (3). In this way, the mixer uses the first line (18) and the second line (19) to transmit the local signal and other signals, that is, the frequency signal whose electrical length is approximately an even multiple of a quarter wavelength. Since it is possible to separate and demultiplex a signal and a signal having a frequency whose electrical length is approximately an odd multiple of 1/4 wavelength, there is an effect that the number of filters can be reduced, and an effect similar to that of the embodiment shown in FIG. 1 is achieved.

Furthermore, in the above embodiments, the first line (14) and the second line (15) and the first line (18) and the second line (
19), the electrical lengths of the first line and the second line are equal, but the relationship between the electrical lengths of the first line and the second line may be different as long as one is an odd multiple of the other, and the same effect can be achieved. play.

Note that although the above embodiment has been explained using a down-converter mixer, the intermediate frequency signal is transferred to the intermediate frequency signal terminal (3
), input the local oscillator signal to the local oscillator signal terminal (2),
It may be an up-converter mixer that outputs a high frequency signal from the high frequency signal terminal (1), and the arrangement of the signal terminals is not limited to the above embodiment, and may be replaced.
It is obvious that the same effects as described above can be achieved.

[Effects of the Invention] As described above, in the mixer of the present invention, the electrical length becomes approximately 1/4 wavelength or a multiple thereof at the signal frequency input/output to the nonlinear element, and the first terminal and the second terminal of the nonlinear element
Since the first line has one end connected to each terminal and the other end is open, and the second line is short-circuited at the other end, the first line and the second line become nonlinear elements. It acts as a short-circuit, an open circuit, an open circuit, and a short-circuit for the input and output signal frequencies, respectively, and demultiplexes the input and output signals to the nonlinear element, which has the effect of reducing the number of filters.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an embodiment of the mixer of the present invention, Figure 2 is a list of line impedances, Figure 3 is an equivalent circuit diagram of the mixer at each frequency, and Figure 4 is a duplexer. FIG. 5 is a pattern diagram of a bandpass filter using coupled lines, FIG. 6 is a configuration diagram of another embodiment of the mixer of the present invention, and FIG. 7 is a diagram of the mixer of the present invention. In addition, they are configuration diagrams of other embodiments, and FIG. 8 is a diagram showing a list of line impedances, FIG. 9 is an equivalent circuit diagram of the mixer at each frequency, and FIG. 10 is a configuration showing an example of a conventional mixer. It is a diagram. In the figure, (1) is a high frequency signal terminal, (2) is a local signal terminal, (3) is an intermediate frequency signal terminal, (4a), (4b)
) is a diode, (5) is an anti-parallel diode pair, (6) is a low-pass filter, (7) is a high-pass filter, (8) is a duplexer, (9) is a band-stop filter, (
10) is a bandpass filter, (11) and (12) are the first and second terminals of the nonlinear element, (13) is a duplexer, (
14) is the first line, (15) is the second line, (16)
are coupling lines, (17a) and (17b) are connecting lines, (1
8) is the first line, and (19) is the second line. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] It has a first terminal and a second terminal for inputting and outputting a signal, and the signal is inputted from each of the first terminal and the second terminal.
A nonlinear element frequency-mixes two signals, and the electrical length is approximately 1/4 wavelength or a multiple thereof at the signal frequency input and output to the nonlinear element, and one end is connected to the first terminal of the nonlinear element, and the other end is connected to the first terminal of the nonlinear element. A mixer comprising: a first line which is open; and a second line whose one end is connected to the second terminal of the nonlinear element and whose other end is short-circuited.