JPH02182005A - Single mixer - Google Patents

Abstract

PURPOSE:To easily realize the matching state between a high frequency signal and a local oscillating signal simultaneously by providing a local oscillating signal matching circuit between a mixer diode and a coupling point of a main line and a local oscillating signal BPF in terms of high frequency and a high frequency signal matching circuit between the coupling point in terms of high frequency and a high frequency signal input terminal. CONSTITUTION:A high frequency signal inputted from an input terminal 11 is fed to a mixer diode 14 through a high frequency signal matching circuit 18, a high frequency signal passing filter 10, an intermediate frequency signal block circuit 20 and a local oscillating signal matching circuit 19. The local oscillating signal inputted from an input terminal 12 is fed to the mixer diode 14 through a local oscillating signal BPF 16 and the local oscillating signal matching circuit 19. A point C is a coupling point in terms of high frequency between the local oscillation signal BPF 18 and a main line through which the high frequency signal inputted from the input terminal 11 is sent to the mixer diode 14 and the point C is selected so that the impedance when viewing the input terminal 11 from the point C represents an open state at the local oscillating signal frequency. A low pass filter 17 extracts an intermediate frequency signal from a terminal A of the mixer diode 14 to an output terminal 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a mixer using a planar circuit such as a strip line or a microstrip line, and in particular to a microwave integrated circuit (
MIC) single mixer.

A conventional mixer using the conventional technology M[C is shown in FIG.
276312) was used.

In FIG. 6, the high frequency signal input from the high frequency signal input terminal 1 propagates through the main line 2 and passes through the mixer diode 3.
is applied to 4 is a high-frequency signal frequency filter (BPF for high-frequency signals) that selectively passes only high-frequency signals, and is composed of a half-wavelength stop line resonator with both ends open, and the impedance when looking from the terminal A of the mixer diode 3 to the input terminal L side. is provided at a position where it is open to the image signal, and the distance between the filter 4 and the mixer diode 3 is selected to be approximately 1/4 wavelength (-λm/4) of the image signal. The local excavation signal inputted from the local signal input terminal 5 is coupled at high frequency with the high frequency signal BPF 4 provided on the main line 2, and the local excavation signal is selectively passed through. BPF for local oscillator signal
6 to the mixer diode 3. 7 is a low-pass filter that extracts an intermediate frequency signal that is the frequency component of the difference between the high frequency signal and the local excavation signal, and is an open-ended stub with a length of approximately 1/4 wavelength (ζλ/4) of the high frequency signal or local oscillation signal. and a series inductance.

Terminal B of mixer diode 3 is connected to the ground conductor of main line 2 (
(not shown), and the intermediate frequency signal generated by the mixer diode 3 is taken out from the intermediate frequency signal output terminal 8. Reference numeral 9 denotes an intermediate frequency signal matching circuit configured such that the impedance seen from the output terminal 8 toward the mixer diode 3 satisfies matching conditions.

In particular, the intermediate frequency signal matching circuit 9 includes a parallel inductance circuit 9', which also forms part of a feedback circuit for the bias current flowing through the mixer diode 3. 1o is a matching line from input terminal 1 to mixer diode 3 (111!). The impedance seen from input terminal 1 to mixer diode 3 is matched at the high frequency signal frequency, and the impedance seen from input terminal 5 to mixer diode 3 is also matched at the local oscillation signal frequency. The matching line 10, which is composed of a low impedance line, serves as a capacitive matching circuit element closest to the mixer diode 3 for intermediate frequency signals. It is functioning.

Problems to be Solved by the Invention Such a conventional configuration in which a high frequency signal and a local excavation signal are combined, and then a matching state is obtained at the same time using a common matching line 10 for the high frequency signal and the local excavation signal, is as follows. There is no problem when the frequency difference between the high frequency signal and the local excavation signal is small and the element impedance of mixer diode 3 shows a similar value for both signals, but the frequency difference between the high frequency signal and the local excavation signal is large. Sometimes, the element impedance of the mixer diode 3 with respect to the high frequency signal frequency and the element impedance of the mixer diode 3 with respect to the local oscillation signal frequency differ greatly, so if the matching line 10 is set so as to be matched with respect to the high frequency signal. , the matching line 10 cannot sufficiently match the local oscillation signal, and the local excavation signal inputted from the terminal 5 is not efficiently applied to the mixer diode 3. High frequency signal 9 locally generated signal.

A significant drawback to the mixer design was that the impedance matching for intermediate frequency signals could not be adjusted independently of each other.

The present invention has been made in view of the above points, and even when the frequency difference between the high frequency signal and the local oscillation signal is relatively large and the difference in impedance of the mixer diode for the high frequency signal and the local excavation signal cannot be ignored, the high frequency Matching is achieved not only to the signal but also to the local oscillation signal, and as a result, the local excavation signal is efficiently applied to the mixer diode, and it is also well matched to the high frequency signal, reducing mismatch loss. It is an object of the present invention to provide a single mixer in which the impedance matching for intermediate frequency signals is not affected by circuits that function for high frequency signals or local oscillation signals, or is very small even if it is affected.

Means for Solving the Problems The present invention connects a high frequency signal input terminal and one end of a mixer diode through a main line, and connects a high frequency connection point between the main line and a local signal band-pass filter and the mixer diode. A matching circuit for local oscillation signals is provided between the high frequency signal input terminal and the high frequency junction, a high frequency signal passing filter is provided together with a matching circuit for high frequency signals, and a high frequency signal passing filter is provided between the high frequency signal passing filter and the mixer diode. The present invention is characterized in that an intermediate frequency signal blocking circuit with an open impedance for intermediate frequency signals is provided on the main line.

Effect The present invention has the above-described configuration, so that the element impedance of the mixer diode is large between the high frequency signal frequency and the local excavation signal frequency (in contrast, it is possible to match over a wide band at the image frequency of the local oscillation signal as well as the high frequency signal with a simple matching circuit). Even when it is difficult to achieve this, it is possible to simultaneously satisfy the matching for the high frequency signal and the matching for the local oscillation signal, making it possible to improve the efficiency of the local excavation signal (mixer
It can be applied to a diode. The output matching circuit of the mixer for intermediate frequency signals, which tends to be the case, can be determined without being affected by the configuration of filters and matching circuits for high frequency signals and local oscillation signals.

Embodiment FIG. 1 shows a first embodiment of the present invention. In FIG. 1, reference numerals 11, 12, and 13 are a high frequency signal input terminal, a single local oscillation signal input terminal, and an intermediate frequency signal output terminal, respectively. 14 is a mixer diode, and 15, 16, and 17 are a high frequency signal pass filter and a BPF low pass filter for local oscillator signals, respectively.

Reference numerals 18 and 19 designate matching circuits for high frequency signals, and matching circuits for two local oscillator signals, and 20 represents an intermediate frequency signal blocking circuit.

The high frequency signal input from the high frequency signal input terminal 11 is passed through the high frequency signal matching circuit 18 and the high frequency signal passing filter 15.
, intermediate frequency signal blocking circuit 20, local oscillator signal matching circuit 19
is applied to the mixer diode 14 through the . A local oscillation signal input from the local oscillation signal input terminal 12 passes through a local oscillation signal BPF 16 and a local oscillation signal matching circuit 19 and is applied to the mixer diode 14 . Point C is the main line that transmits the high frequency signal input from the high frequency signal input terminal 11 to the mixer diode 14 (in FIG. 1, the high frequency signal matching circuit 18, the high frequency signal pass filter 15, the intermediate frequency signal blocking circuit 20. It is a high-frequency junction point between the strip line that constitutes the matching circuit 19 for the oscillating signal and the strip line that connects them) and the BPF 16 for the local oscillating signal, and in terms of DC, it is the junction point between the main line and the local oscillating signal. BPF for
16, and is selected at a position where the impedance when looking at the high frequency signal input terminal 11 side from point C is open at the locally sourced signal frequency. The local oscillation signal matching circuit 19 is set so that the impedance seen from the local oscillation signal input terminal 12 satisfies matching conditions at the local oscillation signal frequency. The high-frequency signal pass filter 15 is a filter that has a pass band at the high-frequency signal frequency, but has a stop band at the local oscillation signal frequency and image signal frequency. The frequency is set to satisfy the matching condition. The intermediate frequency signal blocking circuit 20 has a pass band at the high frequency signal frequency, but exhibits an open impedance for the intermediate frequency signal, and the high frequency signal passing filter 15
It is provided on the main line between the local oscillator signal matching circuit 19 and the local oscillator signal matching circuit 19. Low pass filter 17 is mixer diode 1
It is connected to terminal A of 4 and outputs the intermediate frequency signal to the intermediate frequency signal output terminal. Contains a frequency signal matching circuit.

The distance from the terminal A of the mixer diode 14 to the intermediate frequency signal blocking circuit 20 is set so that the impedance viewed from the terminal A to the intermediate frequency signal blocking circuit 20 side shows appropriate capacitance for the intermediate frequency signal. , 1 of the intermediate frequency signal
/8 wavelengths or less.

In the first embodiment, since the impedance viewed from the high-frequency coupling point C to the high-frequency signal input terminal 11 side is open at the local oscillation signal frequency, the matching state for the local oscillation signal is determined by the local oscillation signal matching circuit]9. Since the matching state for the high frequency signal is determined by two independent matching circuits, the high frequency signal matching circuit 18 and the local oscillation signal matching circuit 19, matching can be performed for both the high frequency signal and the local oscillation signal at the same time. can create a state. Moreover, the local signal matching circuit 19, which is the only circuit that exists between the intermediate frequency signal blocking circuit 20 and the mixer diode 14, can be constructed with a line length that is sufficiently short compared to the wavelength of the intermediate frequency signal. Since the influence of the main line on the intermediate frequency signal is only the shape of the local oscillation signal matching circuit 19, matching for the intermediate frequency signal is not affected by the configuration of the filter or matching circuit for the high frequency signal or local oscillation signal. It has an effect that can be determined.

FIG. 2 shows a second embodiment of the present invention, which is a specific example of the configuration of the embodiment shown in FIG. The high frequency signal input from the high frequency signal input terminal 21 propagates through the main line 22 and is applied to the mixer diode 23 . Reference numeral 24 is a high-frequency signal BPF that selectively passes only high-frequency signals, and is constituted by a distributed-coupled line type band-pass filter formed by distributed-coupling of strip lines open at both ends. The local oscillation signal input from the local oscillation signal input terminal 25 is sent to the mixer diode 2 via the local oscillation signal BPF 26 which is composed of a half-wavelength strip line resonator.
3 is applied. Point C is the main line 22 and the local oscillator signal BPF
26 high frequency coupling points from point C to high frequency signal input terminal 2
The impedance looking at the 1 side is chosen so that it is open at the local oscillation signal frequency. 27 is a local oscillation signal matching circuit that matches the impedance seen from the local oscillation signal input terminal 25 with the local oscillation signal. Reference numeral 28 denotes a high frequency signal matching circuit which matches the local oscillator signal matching circuit 27 and the impedance seen from the high frequency signal input terminal 21 with the high frequency signal. The terminals of the high frequency signal BPF 24 are open ends, and exhibit open impedance to intermediate frequency signals.

Therefore, the high frequency signal BPF 24 also serves as an intermediate frequency signal blocking circuit that exhibits open impedance to intermediate frequency signals. 2 are low-pass filters that pass intermediate frequency signals, and 30 is an intermediate frequency signal output terminal that takes out the intermediate frequency signal generated by the mixer diode 23.

31 is an intermediate frequency signal matching circuit and intermediate frequency signal output terminal 3
The configuration is such that the impedance viewed from 0 to the mixer diode 23 side satisfies matching conditions with an intermediate frequency signal. In particular, the intermediate frequency signal matching circuit includes a parallel inductance circuit 31', which also forms part of a feedback circuit for the bias current flowing through the mixer diode 23.

In the embodiment shown in FIG. 2, in addition to the effects of the embodiment shown in FIG.
24, there is no need to newly provide an intermediate frequency signal blocking circuit, and the overall configuration of the mixer is simplified.

FIG. 3 shows a third embodiment of the present invention, and the same parts as in FIG. 2 are given the same numbers and will be described. The high frequency signal input from the high frequency signal input terminal 21 propagates through the main line 22 and is applied to the mixer diode 23 . 32 is a band rejection filter that exhibits a pass characteristic for high-frequency signals but suppresses local oscillation signals and image signals, and is formed in parallel with the main line 22 and has four open-ended ends connected to the main line 22. It is made up of lines. A local oscillation signal manually inputted from the local oscillation signal input terminal 25 is applied to the mixer diode 23 via a local oscillation signal BPF 26 composed of a half-wavelength strip line resonator. 33 is an intermediate frequency signal blocking circuit that exhibits a pass characteristic for high frequency signals but exhibits an open impedance for intermediate frequency signals;
It consists of a 1/4 wavelength line type interdigital DC blocking circuit in which an open-ended strip line is distributed and coupled over the length of about 1/4 wavelength of a high frequency signal from the open end. Point C, which is the open end of the open-ended strip line constituting the intermediate frequency signal blocking circuit 33, is the high frequency coupling point of the local oscillation signal BPF 26 to the main line 22, and the impedance when looking at the filter 32 from point C is the local oscillation signal. A high frequency coupling point C is provided at a position where the frequency is open.

Reference numeral 27 denotes a matching circuit for local oscillation signals, which is provided so that the impedance seen from the local oscillation signal input terminal 25 can be matched with the local oscillation signal, and is constructed of an open-terminated stub and a high impedance line. The line length of the matching circuit 27 is long (but it can be set to less than 1/2 wavelength of the local oscillation signal, so even if the distance between the coupling point C and the mixer diode 23 is long, it can be set to about 3 wavelengths of the local oscillation signal). /4 wavelength or less. Reference numeral 28 denotes a high-frequency signal matching circuit, which is provided so that the impedance seen from the high-frequency signal input terminal 21 can be matched with the high-frequency signal, and here it is composed of an open-terminated stub. 30 is an intermediate frequency signal output terminal for taking out the intermediate frequency signal generated by the mixer diode 23; 31 is an intermediate frequency signal matching circuit; the intermediate frequency signal output terminal 30 also includes a mixer diode. The impedance as seen from the mixer diode 23 side is configured such that it satisfies the matching condition.In particular, the intermediate frequency signal matching circuit 31 includes a parallel inductance circuit 31', and this parallel inductance circuit 31' serves as a feedback source for the bias current flowing through the mixer diode 23. It is also part of the circuit.

In the embodiment shown in FIG. 3, in addition to the effects of the embodiment shown in FIG.
Since the structure is simple and small, it is composed of four parallel coupled strip lines with open ends, so there is little loss due to radiation (this means that the high frequency signal manually input from the high frequency signal input terminal 21 can be transferred to mixer diodes with low insertion loss. In order to efficiently convert the image signal propagated to the main line 23 and generated by the mixer diode 23 into an intermediate frequency signal again, mixer characteristics with low conversion loss can be obtained.Furthermore, the intermediate frequency signal blocking circuit 33 Moreover, since the local oscillator signal BPF 26 is separated from the main line 22 in terms of direct current, the intermediate frequency signal frequency from the terminal A of the mixer diode 23 to the intermediate frequency signal blocking circuit 33 is The impedance of the high frequency signal input terminal 21
It is possible to eliminate the influence from the circuit connected to the local oscillator signal input terminal 25 side. Therefore, it is possible to eliminate the influence of the matching state of the intermediate frequency signal by the circuit connected to the input terminal 21 or 25 side.

FIG. 4 shows the band rejection filter 32 in the embodiment of FIG.
This shows an example of the configuration. Parallel coupled lines 35, 36, 37, and 38 with open ends having lengths I l l and +2゛, respectively, are provided on the main line 34 in parallel with the main line 34 and coupled in a distributed manner, and coupled in parallel with the main line 34. Lines 35, 36, 37, 38 are spaced 1° and 1, respectively.
1. It is connected to the main line 34 at io'. Furthermore, the parallel coupled lines 37 and 38 are connected to the main line 34 so that the parallel coupled lines 35 and 36 are opposed to the main line 34.
It is configured to face 4.

Length of parallel coupled line 35.36.37.38 1 1
1. 12' is within the band of the image signal 2'
3-3 Alternatively, the length is selected to be 1/4 wavelength or approximately 1/4 wavelength of the image signal so that the attenuation pole is near the band. And the length l of the parallel coupled line 35, 36, 37, 38
l l', 12' and between 21 3'
3 The distance is 1°, 11, io' is 11 < (13 and 13'
) <(I2 and 11,')<(1° and I.')<2
13 and 213°) or 11
<13# 11'<12#I2'< 1. #
The length of IoJo' is chosen to be around 1.5 times the 1/4 wavelength of the Takaoka wave signal, and the length of 11 is selected to satisfy the condition 11'< (21° and 212'). The wavelength is selected to be around 0.5 to 1.0 times the 1/4 wavelength of the signal. Moreover, the characteristic impedance of the parallel coupled lines 36 and 37 whose attenuation pole is in the high frequency range of the image signal, that is, on the side close to the high frequency signal, is the characteristic impedance of the main line 34 connected to the input and output sides of the band rejection filter ( Usually 50Ω)
I chose it so that it would be higher than that. Note that Figure 5 shows the dielectric constant of the microwave integrated circuit board in Figure 4, which is 2.15.
Thickness 0.4mm, parallel coupled lines 35, 36, 37.38
The characteristic impedance of is approximately 110Ω, and the characteristic impedance of the main line 34 connected to the input/output side of the band rejection filter is 50Ω, io = lo' = 3.75Ω,
The characteristic of the band rejection filter is shown in the case where 12=12' to 2.86 13-13'=2.74m+o. However, an edge capacitance occurs at the open ends of the parallel coupling lines 35, 36, 37, 38 due to an edge effect, and calculations are made taking this edge capacitance effect into consideration. In the band rejection filter shown in Fig. 4, the VSWR is 1 in the frequency range of 22.2 to 25 GHz.
．． 6 or less, and a characteristic having an attenuation amount of 30 dB or more in the frequency range of 19.6 to 212 I GHx has been obtained. Therefore, a filter having the characteristics shown in FIG. 5 has a high frequency signal frequency of 22.5 to 23 GHz.
It is particularly effective as a band rejection filter for a mixer in which the image signal frequency is 20 to 20.5 GHz and the local oscillation signal frequency is 2125 GHz. Moreover, the band rejection filter shown in FIG. 4 has small dimensions and uses parallel coupled lines with low radiation loss, so the insertion loss for high frequency signals is small.

Effects of the Invention As described above, in the embodiment according to the present invention, (1) a local oscillator signal matching circuit is provided between the high-frequency coupling point of the main line and the local oscillator signal BPF and the mixer diode, and the high-frequency coupling point and By providing a high-frequency signal matching circuit between the high-frequency signal input terminals, it is possible to easily match the high-frequency signal and the local oscillation signal at the same time, even when there is a large difference in the element impedance of the mixer diode between the high-frequency signal and the local oscillation signal. It can be realized.

(2) By providing an intermediate frequency signal blocking circuit on the main line, the influence of the output impedance matching in the intermediate frequency signal from the circuit connected to the high frequency signal input terminal side and the shape of the filter provided on the main line is removed. Therefore, the matching band for intermediate frequency signals is not limited by external circuits.

(3) Since it is a single mixer, only one mixer diode is required, and the manufacturing cost of the mixer can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a single mixer according to an embodiment of the present invention, FIG. 2 is a pattern diagram of a single mixer according to an embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. Figure 4 is a pattern diagram of a band-stop filter composed of four open-ended parallel coupled lines used in the embodiment of Figure 3, and Figure 5 is a diagram of the embodiment of Figure 4. Figure 6 is a frequency characteristic diagram of the insertion loss of a band-stop filter according to Figure 6 is a pattern diagram of a conventional single mixer.
・High-frequency signal passing filter, 6...Band-pass filter for local oscillator signals, 7...Low-pass filter, ...Matching circuit for high-frequency signals, 9... ...Local signal matching circuit, 20...Intermediate frequency signal matching circuit.

Claims (4)

[Claims] (1) In a single mixer using a microwave integrated circuit whose basic configuration is a strip line or a microstrip line, the high frequency signal input terminal and one end of the mixer diode are connected to the main unit that transmits the high frequency signal to the mixer diode. The other end of the mixer diode is grounded, and a local oscillation signal band-pass filter that selectively passes the local oscillation signal is coupled to the main line at a high frequency. A local signal matching circuit is provided on the main line between the high-frequency coupling point of the band-pass filter and the mixer diode, and the main line is between the high-frequency coupling point and the high-frequency signal input terminal. On the road, there is a high-frequency signal passing filter that has a passband at the high-frequency signal frequency but a stopband at the local oscillation signal frequency and image signal frequency, and the impedance when looking from the high-frequency coupling point to the high-frequency signal input terminal side is the local oscillation signal. A matching circuit for high frequency signals is provided on the main line between the high frequency signal input terminal and the high frequency coupling point, and the high frequency signal matching circuit is provided at a position where the high frequency signal passing filter and the mixer diode are open. An intermediate frequency signal blocking circuit that exhibits open impedance for an intermediate frequency signal that is a frequency component of the difference between a high frequency signal and a local oscillation signal is provided on the main line, and is parallel to the main line near one end of the mixer diode. A single mixer characterized by connecting a low-pass filter to take out an intermediate frequency signal. (2) The high frequency signal passing filter is composed of a distributed coupled line band pass filter formed by distributed coupling of strip lines open at both ends, and the distributed coupled line band pass filter is also used as an intermediate frequency signal blocking circuit. 2. The single mixer according to claim 1. (3) As an intermediate frequency signal blocking circuit, 1/4 wavelength line coupling is formed by distributively coupling two open-ended strip lines over a length of approximately 1/4 wavelength of the high-frequency signal from the open end of the open-ended strip line. 2. The single mixer according to claim 1, wherein the mixer is constructed of a type interdigital DC blocking circuit. (4) A high frequency signal passing filter is installed on the main line at 1_0,1
It is composed of first, second, third, and fourth parallel coupled lines with open ends, each of which has one end connected sequentially at an interval of _1, 1_0'(1_0≈1_0'), and the first, The second, third, and fourth parallel coupled lines have lengths of 1_2, 1_3, 1_3', and 1_2', respectively, are distributed coupled to the main line, and are provided in parallel thereto, and have lengths of 1_2, 1_3, , 1_3', 1_2' are selected to have a length of 1/4 wavelength of the image signal so that the attenuation pole is within the image signal frequency band, and 1_1<(1_3
and 1_3') < (1_2 and 1_2') < (1_0 and 1_0') < (21_3 and 21_2'), or 1_1 < 1_3 ≒ 1_3'< 1_2
≒1_2'<1_0≒1_0'<(21_3 and 21_
3') 1_0, 1_0', 1_
3. The single mixer according to claim 2, wherein the lengths are 1, 1_2, 1_2', 1_3, 1_3'.