JPS585010A - mixer circuit - Google Patents

Abstract

PURPOSE:To constitute a mixing circuit so that a short-circuited state of a diode loading point is not influenced by a circuit of an input side, by providing an intermediate frequency obstructing circuit on a main line. CONSTITUTION:A high frequency signal inputted from a terminal 1 is propagated through a main line 2, and is applied to a mixer diode 3. On the other hand, a local oscillating signal inputted from a terminal 4 is coupled with the main line 2 through a local oscillating BPF5, and is applied to the mixer diode 3. An intermediate frequency signal is fetched from a terminal 8 through a low-pass filter 6. An intermediate frequency signal obstructing circuit 9 which shows a passing characteristic against a high frequency signal, but shows open-circuit impedance against an intermediate frequency signal is connected in series to the main line 2, and in the vicinity of this intermediate frequency obstructing circuit, a low-pass filter 10 whose terminal has been grounded short-circuited is connected in parallel to the main line 2. Subsequently, a distance between a ground and short-circuited terminal 11 of this low-pass filter 10 and the mixer diode 3 is set to 1/2 wavelength of the intermediate frequency signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the realization of a method for short-circuiting a load 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. This invention provides a method for shorting diode loading points when the intermediate 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 terminal 1 is propagated through a main line 2 and applied to a mixer diode 3. On the other hand, the local oscillation signal input from the terminal 4 is coupled to the main line 2 at high frequency, passes through the local oscillation signal band-pass filter 6 that selectively passes the local oscillation signal, and is applied to the mixer diode 3. 6 is a low-pass filter that extracts an intermediate frequency signal, which is the chest wave frequency component of the difference between the high frequency signal and the local oscillation signal, and at the same time filters the terminals of mixer diode 3 to high frequency signals for high frequency signals and local oscillation signals. The length λ provided for short-circuiting is composed of an open-terminated stub with two wavelengths (^) of a high frequency signal or a local oscillation signal, and a series inductance.

7 is an intermediate frequency signal shorting circuit for shorting terminal B of the mixer diode 3 with respect to the intermediate frequency signal, which connects two wavelength (A) m paths with high characteristic impedance and one wave 4 with low characteristic impedance.
This is a low-pass filter consisting of four long stubs with open ends, and the ends of which are connected and connected. 8
is an intermediate frequency signal output terminal for taking out the intermediate frequency signal generated by the mixer diode 3.

In the conventional intermediate frequency signal shorting 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 increased to 1,000, As a result, the impedance of the intermediate frequency signal short circuit 7 can no longer be ignored, and it is no longer considered a short circuit. 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 to an intermediate frequency signal output terminal 8.
When viewed from the side, it is in line with mixer diode 3, so
As the impedance of the intermediate frequency signal short circuit 7 increases, the matching bandwidth from the intermediate frequency signal side is limited.
This ultimately limits the bandwidth of the mixer circuit. At the same time, the mixer
Since the main line 2 is connected to the terminal B of the diode 3, if the impedance of the intermediate frequency signal short circuit 7 becomes large, the intermediate frequency signal output terminal 8 will change depending on the state of the circuit connected to the terminal 1 side of the main line 2. From mixer diode 3
The impedance when viewed from the side is greatly affected by 6 Boehre', and there is a drawback that the performance of the mixer path is degraded due to mismatching of the output impedance in the intermediate frequency signal.

In an attempt to alleviate this drawback, intermediate frequency signal shorting circuit 7
In order to reduce the impedance of the intermediate frequency signal short circuit 7, the width of the strip constituting the intermediate frequency signal frequency 7 is widened to lower the characteristic impedance of the line. There are ways to think of it, but
When the dimensions are shortened or the line width is widened, the influence of the intermediate frequency signal short circuit 7 on the high frequency signals and local oscillation signals propagating through the main line 2 cannot be ignored, and the line impedance of the main line 2 is reduced. There is a drawback that new problems arise such as large disturbances and increased propagation loss.

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples.The main line has a power that exhibits a passing characteristic for high frequency signals in series with the main line; and an open impedance for intermediate frequency signals. By providing an intermediate frequency signal blocking circuit that exhibits a high frequency signal and using this main line to short-circuit the loading point of the mixer diode at high frequency, it is possible to close the loading point of the mixer diode even when the intermediate frequency signal frequency is high. This is actually short-circuiting.

An embodiment of the present invention is shown in FIG. 2, and the same parts as in FIG. 1 are given the same numbers and will be explained. The high frequency signal input from terminal 1 propagates through main line 2 and passes through mixer diode 3.
is applied to - The local oscillation signal inputted from the terminal 4 is coupled to the main line 2 at high frequency, and is applied to the mixer diode 3 through the local oscillation signal band-pass filter 6 that selectively passes the local oscillation signal. Reference numeral 6 denotes a low-pass filter, which has a length provided to short-circuit the terminals of the mixer diode 3 at high frequencies for high-frequency signals and local oscillation signals, while at the same time extracting intermediate frequency signals. It is composed of an open-ended stub of two waves of a local oscillation signal and a series inductance. 8 is an intermediate frequency signal output terminal from which the intermediate frequency signal generated by the mixer diode 3 is taken out. Reference numeral 9 denotes an intermediate frequency signal blocking circuit which exhibits a pass characteristic of 7 to 7 for high frequency signals, but exhibits an open impedance to intermediate frequency signals.
In the vicinity of r9, a low-pass filter 10 whose terminal end is short-circuited to ground is connected in parallel to the main line 2, and the distance from the short-circuited end 11 of the low-pass filter 1o to the mixer diode 3 is determined by the intermediate frequency. 100 wavelengths of the signal - the length of the signal is chosen in the old days.

In the embodiment shown in FIG. 2, the distance from the ground short-circuited end 11 of the low-pass filter 1o to the mixer diode 3 is selected to be the length of the i wavelength of the intermediate frequency signal, and the intermediate frequency signal blocking circuit 9 is Since it exhibits an open impedance for intermediate frequency signals, the terminal B of the mixer diode 3 is short-circuited at high frequencies for intermediate frequency signals. Therefore, even if the intermediate frequency signal frequency is high, the diode loading point can be reliably short-circuited by the intermediate frequency signal. Further, since the intermediate frequency signal blocking circuit 9 is provided in series with the main line 2, it is possible to eliminate the effects of the short-circuited state of the diode loading point B from the circuit connected to the terminal 1 side. Furthermore, since the low-pass filter 10 also serves as a part of the feedback circuit for the bias current flowing through the mixer diode 3, there is no need to form a new feedback circuit for the bias current.

FIG. 3 shows an intermediate frequency signal blocker m in an embodiment of the present invention.
9 shows a specific configuration method.

Figure 3 a is a wave meal # approximately shield trapezoid interdigital first flow prevention l! l! (l omitted, two open-ended terminals) The IJ tube line has a length of about 1 wavelength (A) of the high-frequency signal from the open end.
It has a simple configuration, small size, low insertion loss for high frequency signals, and exhibits wide band pass filter characteristics. However, each award between the gear knobs due to the IJ knob (two terminal open terminals that are distributed coupled), for example, when the high frequency signal frequency is 12Gliz, the sound path is 0.
Even if the gear gap is 0.1 pF and the intermediate frequency signal frequency is I GHz, the impedance shown by the gear block is about 1.6 λ, which is close to the open impedance. . Figure 4 shows a half-wavelength strip [a band-pass filter using a resonator, and the half-wavelength strip shows the I-liquid passage characteristics of the cylindrical frequency signal, but for intermediate frequency signals, one end of the line is Since it is open, it operates as an intermediate frequency signal blocking circuit and exhibits open impedance.

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 and an open impedance for intermediate frequency signals. A low-pass filter whose terminal end is short-circuited to ground is connected in parallel to the main line near the terminal 7! By selecting the distance from the ground-shorted end of the low-pass filter to the mixer diode to the length of the i-wavelength (JrF) of the intermediate frequency signal, the mixer diode can be loaded. This short-circuits points at high frequency using an intermediate frequency signal. Therefore, it is possible to reliably short-circuit the diode loading point with the intermediate frequency signal even when the intermediate frequency signal frequency power (high) is high.Furthermore, since the intermediate frequency signal blocking circuit is provided in series with the main line, the diode loading point Short-circuit state power; influences from circuits connected to the input terminal side of high-frequency signals can be removed.Moreover, the low-pass filter whose terminal end is short-circuited to ground is a feedback circuit for the bias current flowing through the mixer diode. Since it is also a part of the mixer circuit, there is no need to form a new (Iasumi style) feedback circuit, which simplifies the configuration of the mixer circuit.This in turn improves the performance of the mixer circuit.

In the embodiment described above, in order to apply the local oscillation signal to the mixer diode, the local oscillation signal band-pass which is high-frequency coupled to the main line between the intermediate frequency signal blocking circuit and the mixer diode is used. Although this is done through a filter, the method described in the embodiments does not necessarily have to be used. For example, a local oscillation signal may be input from terminal 1 at the same time as the high-frequency signal, or the local oscillation signal may be applied to the mixer diode via a local oscillation signal band-pass filter that is high-frequency coupled with low-pass filter 6. Needless to say, it is okay.

[Brief explanation of drawings]

Figure 1 shows Mi-11, which uses a microwave output circuit.
-: A pattern diagram of a mixer circuit; FIG. 2 is a pattern diagram of a mixer circuit according to an embodiment of the present invention; FIGS. In the pattern diagram, a is a four-wavelength line combination type interdigital DC blocking circuit, and b is a band-pass filter for high-frequency signals using a half-wavelength strip line resonator. 1... High frequency signal input terminal, 2... Main line, 3... Mixer diode, 4...
... Local oscillation signal input terminal, 6 ... Band pass filter for local oscillation signal, 6 ... Low pass filter,
8...Intermediate frequency signal output terminal, 9...
Intermediate frequency signal blocking circuit, 10...Low pass filter.

Claims (1)

[Claims] (1) One end of the mixer diode is connected to the end of the main line that transmits the high frequency signal to the mixer diode, and a local oscillation signal is applied to the mixer diode, and the other end of the mixer diode is connected to the high frequency signal. In a mixer circuit using a microwave integrated circuit configured to extract an intermediate frequency signal that is a frequency component of the difference between the signal and the local oscillation signal, a low-pass filter with a short-terminated end is connected in parallel to the main diverter, The distance from the short-circuited end of the short-circuited low-pass filter at the end to the mixer diode is selected to be the length of the i wavelength of the intermediate frequency signal, and the distance from the short-circuited end of the low-pass filter at the short-circuited end to the mixer diode is selected to be the length of the i wavelength of the intermediate frequency signal. , and on the main line on the input side of the high frequency signal, in series with the main line, an intermediate frequency signal blocking circuit 2, -1 that exhibits a pass characteristic for high frequency signals but exhibits an open impedance for intermediate frequency signals. A mixer circuit characterized by being provided with. (Smell) The intermediate frequency signal blocking circuit is a two-wavelength line combination in which two open-ended strip lines are coupled in a distributed manner from the open ends of the open-ended strip lines over the length of approximately -wavelength of the high-frequency signal. Interdigital DC blocking Igl
2. The mixer circuit according to claim 1, characterized in that the mixer circuit is constructed by a circuit.