JPS6359603B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for short-circuiting a diode loading point at an intermediate frequency signal frequency of a mixer circuit using a microwave integrated circuit whose basic configuration is a strip line or a microstrip line. The present invention provides a method for shorting diode loading points when the frequency signal frequency is high.

In a conventional mixer circuit using a microwave integrated circuit, a circuit as shown in FIG. 1 has been used as a method of short-circuiting a diode loading point at an intermediate frequency signal frequency. In FIG. 1, a high frequency signal input from a high frequency signal input terminal 1 and a local oscillation signal input from a local oscillation signal input terminal 2 propagate through a main line 3 and are applied to a mixer diode 4. Reference numeral 5 designates a low-pass filter that extracts an intermediate frequency signal, which is the frequency component of the difference between the high frequency signal and the local oscillation signal, from the intermediate frequency signal output terminal 6. The length provided to short-circuit the terminal A at high frequency is composed of an open-terminated stub with a quarter wavelength (λ/4) of a high-frequency signal or local oscillation signal, and a series inductance. 7 is an intermediate frequency signal shorting circuit for shorting terminal B of mixer diode 4 to the intermediate frequency signal, which connects a 1/4 wavelength (λ/4) line with high characteristic impedance and a 1/4 wavelength line with low characteristic impedance. This is a low-pass filter consisting of an open-ended stub and a terminal short-circuited to ground.

In such a conventional intermediate frequency signal short circuit 7 using a low-pass filter whose terminal end is short-circuited to ground,
There was no problem when the intermediate frequency signal frequency was relatively low, but as the intermediate frequency signal frequency increases, the impedance of the intermediate frequency signal short circuit 7 can no longer be ignored, and it is no longer considered a short circuit. Not done. At this time, the impedance of the intermediate frequency signal short circuit 7 exhibits the characteristics of an inductance circuit having a certain finite magnitude. This intermediate frequency signal short circuit 7 is connected in series with the mixer diode 4 when viewed from the intermediate frequency signal output terminal 6, so as the impedance of the intermediate frequency signal short circuit 7 increases, the matching bandwidth from the intermediate frequency signal side increases. is limited, ultimately limiting the bandwidth of the mixer circuit. At the same time, the main line 3 is connected to the terminal B of the mixer diode 4, so when the impedance of the intermediate frequency signal short circuit 7 increases, it is connected to the high frequency signal input terminal 1 side and the local oscillation signal input terminal 2 side of the main line 3. Depending on the state of the circuit, the intermediate frequency signal output impedance viewed from the intermediate frequency signal output terminal 6 to the mixer diode 4 side is greatly affected, and the performance of the mixer circuit is degraded due to mismatching of the intermediate frequency signal output impedance. There were flaws.

In order to reduce the impedance of the intermediate frequency signal short circuit 7 in an attempt to alleviate this drawback, the dimensions of the intermediate frequency signal short circuit 7 may be shortened, or the width of the strip line constituting the intermediate frequency signal short circuit 7 may be increased. One possible method is to lower the characteristic impedance of the line, but if the dimensions are shortened or the line width is widened, the effect of the intermediate frequency signal short circuit 7 on the high frequency signal and local oscillation signal propagating through the main line 3 will be ignored. Therefore, there are new problems such as greatly disturbing the line impedance of the main line 3 and increasing propagation loss.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional example.The main line has a pass characteristic for high frequency signals and local oscillation signals in series with the main line, but has an open impedance for intermediate frequency signals. By providing an intermediate frequency signal blocking circuit that exhibits an intermediate frequency signal and short-circuiting the loading point of the mixer diode at high frequency using the line length of this main line, the loading point of the mixer diode can be prevented even when the intermediate frequency signal frequency is high. This ensures that the points are short-circuited.

Embodiments of the present invention will be sequentially described below.

FIG. 2 shows an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same numbers and will be described. The high frequency signal input from the high frequency signal input terminal 1 and the local oscillation signal input from the local oscillation signal input terminal 2 propagate through the main line 3 and are applied to the mixer diode 4. Reference numeral 5 designates a low-pass filter, which is provided to extract the intermediate frequency signal from the intermediate frequency signal output terminal 6 and at the same time short-circuit the terminal A of the mixer diode 4 for high frequency signals and local oscillation signals. It consists of an open-terminated stub whose length is 1/4 wavelength (λ/4) of a high frequency signal or local oscillation signal, and a series inductance. 8 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 is installed in series with the main line 3 at a distance of . 9 is an intermediate frequency signal blocking circuit that exhibits pass characteristics for local oscillation signals but exhibits open impedance for intermediate frequency signals;
It is provided in series on the main line 3 at a distance of 1/4 wavelength (λ _IF /4) of the intermediate frequency signal from the diode 4.

In the embodiment of FIG. 2, the intermediate frequency signal blocking circuit 8
and 9 both exhibit open impedance for intermediate frequency signals, and the distance from mixer diode 4 to intermediate frequency signal blocking circuits 8 and 9 is selected to be 1/4 wavelength of the intermediate frequency signal. .
Therefore, the impedance viewed from the terminal B of the mixer diode 4 to the high frequency signal input terminal 1 side is short-circuited at high frequency by the open-ended 1/4 wavelength line (with respect to the intermediate frequency signal). Further, the impedance when looking from the terminal B of the mixer diode 4 to the local oscillation signal input terminal 2 side is also short-circuited at high frequency by the open-ended 1/4 wavelength line (with respect to the intermediate frequency signal). In other words, the terminal B of the mixer diode 4 is reliably short-circuited at high frequency by the intermediate frequency signal. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. Furthermore, since the intermediate frequency signal blocking circuits 8 and 9 are provided in series with the main line 3, the short-circuited state of the diode loading point B can be prevented from occurring from the circuit connected to the high frequency signal input terminal 1 or the local oscillation signal input terminal 2 side. The effects can be eliminated.

FIG. 3a shows another embodiment of the present invention, which is basically the same as the embodiment shown in FIG. 2, except that in the embodiment shown in FIG. In contrast, in the embodiment shown in FIG. 3a, the intermediate frequency signal blocking circuit 8 is omitted, and exhibits a pass characteristic for local oscillation signals, but not for intermediate frequency signals. This embodiment differs from the embodiment shown in FIG. 2 in that only an intermediate frequency signal blocking circuit 9 exhibiting open impedance is provided.

In the embodiment shown in FIG. 3a as well, an intermediate frequency signal blocking circuit 9 exhibiting an open impedance to the intermediate frequency signal is provided at a position 1/4 wavelength of the intermediate frequency signal from the mixer diode 4. For,
Local oscillation signal input terminal 2 from diode loading point B
The impedance viewed from the side is short-circuited at high frequencies due to the open-ended 1/4 wavelength line (for intermediate frequency signals). In other words, the diode loading point B is reliably short-circuited at high frequency by the intermediate frequency signal. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. Moreover, since the diode loading point B is reliably short-circuited, the short-circuited state of the diode loading point B is maintained regardless of the impedance when looking from the diode loading point B to the high frequency signal input terminal 1 side. Therefore, the influence from the circuit connected to the high frequency signal input terminal 1 side can be significantly reduced. Furthermore, since no intermediate frequency signal blocking circuit is provided on the main line 3 on the high frequency signal input terminal 1 side, there is no insertion loss of high frequency signals due to the intermediate frequency signal blocking circuit.

FIG. 3b is also another embodiment of the present invention, and in this embodiment, the intermediate frequency signal blocking circuit 9 is removed from the embodiment of FIG. As shown, only an intermediate frequency signal blocking circuit 8 exhibiting open impedance is provided for intermediate frequency signals.

In the embodiment shown in FIG. 3b as well, an intermediate frequency signal blocking circuit 8 exhibiting an open impedance to the intermediate frequency signal is provided at a position 1/4 wavelength of the intermediate frequency signal from the mixer diode 4. For,
The impedance viewed from the diode loading point B to the high frequency signal input terminal 1 side is short-circuited at high frequency by the 1/4 wavelength line (with respect to the intermediate frequency signal) with an open end. In other words, diode loading point B
are definitely short-circuited at high frequencies with intermediate frequency signals. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. Moreover, since the diode loading point B is reliably short-circuited, no matter what the impedance is when looking from the diode loading point B to the local oscillation signal input terminal 2 side, the diode loading point B
remains short-circuited. Therefore, the influence from the circuit connected to the local oscillation signal input terminal 2 side can be significantly reduced.

FIG. 4 shows still another embodiment of the present invention,
The same parts as in FIG. 2 will be described with the same numbers assigned. The high frequency signal input from the high frequency signal input terminal 1 and the local oscillation signal input from the local oscillation signal input terminal 2 propagate through the main line 3 and are applied to the mixer diode 4. 5 is a low pass filter,
The length provided in order to take out the intermediate frequency signal from the intermediate frequency signal output terminal 6 and at the same time short-circuit the terminal A of the mixer diode 4 for high frequency signals and local oscillation signals is used to output high frequency signals and local oscillation signals. It consists of an open-ended stub of 1/4 wavelength (λ/4) of the signal and a series inductance. 8
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. Set at a distance. 10 is a low-pass filter whose terminal end is short-circuited to ground, and is connected in parallel to the main line 3 near the intermediate frequency signal blocking circuit 8.
The distance from the ground short-circuited end 11 of the mixer diode 4 to the mixer diode 4 is selected to be 1/2 wavelength (λ _IF /2) of the intermediate frequency signal. Reference numeral 9 denotes an intermediate frequency signal blocking circuit that exhibits pass characteristics for local oscillation signals but exhibits open impedance for intermediate _frequency signals. ) is located at a distance of 12 is a low-pass filter whose terminal end is short-circuited to ground, and is connected in parallel to the main line 3 near the intermediate frequency signal blocking circuit 9, and the distance from the short-circuited end 13 of the low-pass filter 12 to the mixer diode 4 is is selected to be 1/2 wavelength (λ _IF /2) of the intermediate frequency signal. Therefore, the terminal B of the mixer diode 4 is short-circuited at high frequency by the intermediate frequency signal. Furthermore, the low-pass filters 10 and 12 also serve as one end of a feedback circuit for the bias current flowing through the mixer diode 4.

In the embodiment shown in FIG. 4, the distance from the mixer diode 4 to the ground shorting ends 11 and 13 is selected to be half the wavelength of the intermediate frequency signal, and the intermediate frequency signal blocking circuits 8 and 9 are connected to the intermediate frequency signal blocking circuits 8 and 9. Since both of them exhibit open impedance, the terminal B of the mixer diode 4 is short-circuited at high frequency by the intermediate frequency signal. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. Further, since the intermediate frequency signal blocking circuits 8 and 9 are provided in series with the main line 3, the short-circuited state of the diode loading point B can be caused by the high frequency signal input terminal 1 or the local oscillation signal input terminal 2.
It is possible to eliminate the influence from the circuit connected to the side.

FIG. 5 shows a specific method of configuring the intermediate frequency signal blocking circuits 8 and 9 in the embodiment of the present invention. Figure 5a shows a 1/4-wavelength line-coupled interdigital DC blocking circuit, in which two open-ended strip lines are connected from the open end to a high-frequency signal or local oscillation signal about 1/4 wavelength (λ/4) long. It has a simple configuration, small dimensions, and
It has low insertion loss for high frequency signals or local oscillation signals, and exhibits bandpass filter characteristics over a wide band. However, the inter-gap capacitance due to the coupling gap of two distributed-coupled open-ended strip lines is usually less than 0.1 pF when the high frequency signal frequency is 12 GHz, and even if the inter-gap capacitance is 0.1 pF, when the intermediate frequency signal frequency is 1 GHz, In this case, the impedance indicated by the inter-gap capacitance is approximately 1.6KΩ, which is close to the open impedance.

Figure 5b shows a band-pass filter using a half-wavelength stripline resonator, and by selecting the length of the half-wavelength stripline resonator to be 1/2 wavelength (λ/2) of the high-frequency signal or local oscillation signal, the high-frequency signal can be transmitted. Alternatively, it exhibits a pass characteristic for local oscillation signals, but for intermediate frequency signals, since one end of the line is open, it operates as an intermediate frequency signal blocking circuit and exhibits open impedance.

FIG. 6 shows still another embodiment of the present invention,
This is a somewhat modified version of the mixer circuit in the embodiment shown in FIG. 3a, in which the intermediate frequency signal blocking circuit 9 shown in FIG. 5b is used. The high-frequency signal input from the high-frequency signal input terminal 1 propagates through the main line 3 to the mixer.
applied to diode 4. On the other hand, the local oscillation signal input from the local oscillation signal input terminal 2 is applied to the mixer diode 4 via the local oscillation signal band-pass filter 14 coupled to the main line 3 in high frequency. The intermediate frequency signal generated by mixer diode 4 is extracted from intermediate frequency signal output terminal 6 via low pass filter 5. The main line 3, which is closer to the local oscillation signal input terminal 2 than the mixer diode 4, has an open end, and the distance from the open end of the main line 3 to the mixer diode 4 is 1/4 wavelength of the intermediate frequency signal ( λ _IF /4), and set the high frequency so that the impedance viewed from the high frequency coupling point C of the local oscillation signal bandpass filter 14 to the main line 3 to the open end side of the main line 3 becomes open at the local oscillation signal. The location of the target connection point C is chosen.

In the embodiment shown in Fig. 6, the distance from the open end of the main line 3 to the mixer diode 4 is selected to be 1/4 wavelength (λ _IF /4) of the intermediate frequency signal, so the mixer diode Terminal B of No. 4 is short-circuited at high frequency by an intermediate frequency signal. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. Moreover, since the diode loading point B is reliably short-circuited, the influence from the circuit connected to the high frequency signal input terminal 1 side can be greatly reduced. Furthermore, since no intermediate frequency signal blocking circuit is provided on the main line 3 on the high frequency signal input terminal 1 side, there is no insertion loss of high frequency signals due to the intermediate frequency signal blocking circuit.

FIG. 7 shows still another embodiment of the present invention,
It is basically the same as the embodiment shown in FIG. 4, and the same parts as in FIG. 4 will be described with the same numbers. In the embodiment shown in FIG. 4, two intermediate frequency signal blocking circuits 8 and 9 are provided simultaneously on the main line 3, and a low-pass filter 10 whose two terminal ends are short-circuited to ground,
12 are connected to the main line 3 at the same time. In contrast, in the embodiment shown in FIG. 7, only the intermediate frequency signal blocking circuit 8 and low pass filter 10 are provided, and the other intermediate frequency signal blocking circuit 9 and low pass filter 12 are excluded. This is different from the embodiment shown in FIG.

In the embodiment shown in FIG. 7 as well, the distance from the mixer diode 4 to the ground short-circuited end 11 is the length of 1/2 wavelength of the intermediate frequency signal, and the intermediate frequency signal blocking circuit 8 is connected to the intermediate frequency signal. shows an open impedance, so the impedance when looking from the terminal B of the mixer diode 4 to the high frequency signal input terminal 1 side maintains a short-circuited state in terms of high frequency due to the intermediate frequency signal, as in the case of Fig. 4. has been done. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted as in the embodiment shown in FIG.

FIG. 8 shows still another embodiment of the present invention, which is basically the same as the embodiment shown in FIG. 4, and the same parts as those in FIG. 4 will be described with the same reference numerals. In the embodiment shown in FIG. 4, two intermediate frequency signal blocking circuits 8 and 9 are provided simultaneously on the main line 3, and low-pass filters 10 and 1 whose two terminal ends are short-circuited to ground are provided.
2 are grounded to the main line 3 at the same time. In contrast, in the embodiment shown in FIG. 8, only the intermediate frequency signal blocking circuit 9 and low pass filter 12 are provided, and the other intermediate frequency signal blocking circuit 8 and low pass filter 10 are excluded. This is different from the embodiment shown in FIG.

In the embodiment shown in FIG. 8 as well, the distance from the mixer diode 4 to the ground short-circuit end 13 is equal to the length of 1/2 wavelength of the intermediate frequency signal, and the intermediate frequency signal blocking circuit 9 is connected to the intermediate frequency signal. On the other hand, since it shows an open impedance, the impedance when looking from the terminal B of the mixer diode 4 to the local oscillation signal input terminal 2 side remains short-circuited at high frequency due to the intermediate frequency signal, as in the case of Fig. 4. ing.
Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted as in the embodiment shown in FIG.

As explained above, in the present invention, an intermediate frequency signal blocking circuit is provided on the main line, which exhibits a pass characteristic for high frequency signals or local oscillation signals, but exhibits open impedance for local oscillation signals, and this intermediate frequency signal blocking circuit is provided on the main line. Select the distance between the blocking circuit and the mixer diode to be 1/4 wavelength of the intermediate frequency signal, and use a full wavelength line with an open end for the intermediate frequency signal, or short-circuit the end to ground. A low-pass filter is connected in parallel to the main line, and the end is short-circuited to ground.The distance between the short-circuited end of this low-pass filter and the mixer diode is selected to be the length of 1/2 wavelength of the intermediate frequency signal. By using a 1/2 wavelength line whose termination is short-circuited to the frequency signal, the loading point of the mixer diode is short-circuited at high frequency with the intermediate frequency signal. Therefore,
Even when the intermediate frequency signal frequency is high, the diode loading point can be reliably shorted. In addition, since the intermediate frequency signal blocking circuit is provided in series with the main line, the influence of the short-circuited state of the diode loading point from the circuit connected to the high frequency signal input terminal or local oscillation signal input terminal side is reduced or eliminated. You can As a result, the performance of the mixer circuit is improved.

[Brief explanation of the drawing]

Fig. 1 is a pattern diagram of a conventional mixer circuit using a microwave integrated circuit, Fig. 2 is a pattern diagram of a mixer circuit according to an embodiment of the present invention, and Figs.
4 are pattern diagrams of mixer circuits according to other embodiments of the present invention, and FIG. 5 is a specific configuration of the intermediate frequency signal blocking circuit in the embodiments of FIGS. 2, 3, and 4. In the circuit pattern diagram, a is a 1/4 wavelength line coupled interdigital DC blocking circuit, b
6 is a diagram showing a bandpass filter using a half-wavelength strip line resonator, FIG. 6 is a pattern diagram of a mixer circuit according to yet another embodiment of the present invention, and FIG.
FIG. 8 is also a pattern diagram of a mixer/circuit according to another embodiment. 1...High frequency signal input terminal, 2...Local oscillation signal input terminal, 3...Main line, 4...Mixer diode, 5...Low pass filter, 6...Intermediate frequency signal output terminal, 8, 9 ...Intermediate frequency signal blocking circuit.

Claims (1)

[Claims] 1. One end of a mixer diode is connected to a main line composed of a strip line or a microstrip line, and a high frequency signal is transmitted from one end of the main line, and a local oscillation signal is transmitted from the other end of the main line. A mixer circuit using a microwave integrated circuit configured to apply a signal to each of the mixer diodes and extract an intermediate frequency signal that is a frequency component of a difference between a high frequency signal and a local oscillation signal from the other end of the mixer diode, A first intermediate frequency signal blocking circuit exhibits a pass characteristic for high frequency signals but exhibits an open impedance for intermediate frequency signals, and a first intermediate frequency signal blocking circuit exhibits a pass characteristic for local oscillation signals but exhibits an open impedance for intermediate frequency signals. At least one of the second intermediate frequency signal blocking circuits exhibiting an open impedance is provided on the main line at a position 1/4 wavelength of the intermediate frequency signal from the mixer diode, and the first intermediate frequency signal A mixer circuit characterized in that a blocking circuit is provided at one end of the main line, and a second intermediate frequency signal blocking circuit is provided at the other end of the main line. 2 At least one of the first and second intermediate frequency signal blocking circuits is connected to two open-ended strip lines distributed over a length of about 1/4 wavelength of the high-frequency signal or local oscillation signal from the open end of the open-terminated strip line. 2. The mixer circuit according to claim 1, wherein the mixer circuit is constituted by a 1/4 wavelength line coupled interdigital DC blocking circuit. 3. One end of a mixer diode is connected to a main line composed of a strip line or a microstrip line, and a high frequency signal is transmitted from one end of the main line, and a local oscillation signal is transmitted from the other end of the main line to the mixer diode. In a mixer circuit using a microwave integrated circuit configured to apply an intermediate frequency signal, which is a frequency component of the difference between a high frequency signal and a local oscillation signal, from the other end of the mixer diode, An intermediate frequency signal blocking circuit exhibiting pass characteristics but open impedance for intermediate frequency signals is provided on one end side of the main line at a position 1/4 wavelength of the intermediate frequency signal from the mixer diode. In addition, a low-pass filter with a short-terminated end is connected near the intermediate frequency signal blocking circuit and in parallel to the main line on the mixer diode side, and the low-pass filter with a short-terminated end is connected to the mixer diode and the low-pass filter with a short-terminal short circuit. A mixer circuit characterized in that the distance from the short-circuited end of the mixer circuit is selected to be 1/2 wavelength of the intermediate frequency signal. 4 Connect one end of a mixer diode to a main line composed of a strip line or a microstrip line, and send a high frequency signal from one end of the main line and a local oscillation signal from the other end of the main line to the mixer diode. In a mixer circuit using a microwave integrated circuit, the mixer circuit uses a microwave integrated circuit configured to apply a signal to each of connects an intermediate frequency signal blocking circuit exhibiting pass characteristics but open impedance to intermediate frequency signals to the other end of the main line at a position 1/4 wavelength of the intermediate frequency signal from the mixer diode. and near the intermediate frequency signal blocking circuit, and
A short-terminated low-pass filter is connected in parallel to the main line on the mixer diode side, and the distance between the mixer diode and the short-circuited end of the short-terminated low-pass filter is set to 1/2 of the intermediate frequency signal. A mixer circuit characterized by being selected according to the length of the wavelength. 5 Connect one end of a mixer diode to a main line composed of a strip line or a microstrip line, and send a high frequency signal from one end of the main line and a local oscillation signal from the other end of the main line to the mixer diode. In a mixer circuit using a microwave integrated circuit configured to apply an intermediate frequency signal, which is a frequency component of the difference between a high frequency signal and a local oscillation signal, from the other end of the mixer diode, A first intermediate frequency signal blocking circuit exhibiting a pass characteristic but an open impedance for the intermediate frequency signal, and a second intermediate frequency signal blocking circuit exhibiting a pass characteristic for the local oscillation signal but an open impedance for the intermediate frequency signal. both intermediate frequency signal blocking circuits at a length of 1/4 wavelength of the intermediate frequency signal from the mixer diode,
The first intermediate frequency signal blocking circuit is provided at one end of the main line, and the second intermediate frequency signal blocking circuit is provided at the other end of the main line. A low-pass filter with a short-terminated end is connected near at least one of the intermediate frequency signal blocking circuits and in parallel with the main line on the side of the mixer diode, and the low-pass filter with a short-terminated end is connected to the mixer diode and the low-pass filter with a short-terminated end. A mixer circuit characterized in that the distance from the short-circuited end of the mixer circuit is selected to be 1/2 wavelength of the intermediate frequency signal.