JPS62242Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a microcomputer that is inserted into a transmission line to compensate for amplitude frequency distortion that occurs in wideband microwave communication equipment or signal transmission lines, and achieve flat amplitude frequency characteristics. Concerning a waveband variable amplitude equalizer.

In broadband microwave communication equipment, transmission lines, or microwave band circuit elements used in millimeter-wave waveguide transmission systems, the loss generally increases as the frequency increases due to the skin effect of the conductor, so the primary loss is positive with respect to the frequency. Amplitude distortion with a slope occurs.
This amplitude distortion causes deterioration of communication quality, so
You need to equalize it somehow.

Conventionally, a band-pass waver or a band-stop waver has been used to equalize such amplitude distortion, and the slope portion of the pass or reflection frequency characteristic has been utilized.

However, since there are variations in transmission distortion in communication devices that are actually manufactured, it is desirable that the characteristics of the amplitude equalizer can also be varied to some extent. For this reason, in the case of an amplitude equalizer using a wave generator, it is necessary to change the resonant frequency and the amount of coupling. A wave generator type amplitude equalizer using a rip line has the disadvantage that the resonant frequency and the amount of coupling, that is, the conductor pattern cannot be easily changed. For this reason, a coaxial stub type wave circuit using capacitive coupling has been used as a variable amplitude equalizer. However, the variable mechanism was complicated and electrical adjustment was difficult. Furthermore, since equalizers using wave circuits have poor input/output impedance, it is common to use isolators connected to the input/output terminals of the equalizer, which has the disadvantage of increasing the size.

The purpose of the present invention is to eliminate the above-mentioned drawbacks by creating an amplitude equalizer by combining a microstrip line with a variable attenuator and a variable capacitance element without changing the conductor pattern of the microstrip line. An object of the present invention is to provide a variable amplitude equalizer that is capable of changing the amplitude frequency characteristics of a signal.

According to the present invention, there is provided an amplitude compensation circuit having a first terminal and a shorted or open second terminal, and a transmission signal is applied to the first terminal, and an amplitude compensated signal is taken out from the first terminal. a variable attenuation circuit, the amplitude compensation circuit comprising a signal transmission line having one end coupled to the first terminal, and a variable attenuation provided between the other end of the signal transmission line and the second terminal. and a branch provided between the other end and ground, which transmits signals near the center frequency of the transmission signal toward the attenuator and reflects signals away from the center frequency toward the first terminal side. A variable amplitude equalizer is obtained that includes a resonant path with a line.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows a variable amplitude equalizer according to a first embodiment of the present invention. In a signal transmission line 1 in which a variable attenuator 2 with one end a as an input/output terminal and an open output end c is connected in series to the other terminal b, an output is output between the input/output terminal a and the variable attenuator 2. Branch lines 3 with their ends grounded are connected in parallel, and a transmission signal is applied to an amplitude compensation circuit whose electrical length is selected so that the branch line 3 resonates at a desired frequency, and an input/output terminal a of the amplitude compensation circuit. And the amplitude compensated signal is sent to the terminal a.
A circuit 5 is connected thereto. In this amplitude equalizer, when a signal with a flat amplitude in the used frequency band is input to the terminal 14, the branch line 3, which is a resonator, transmits the signal near the resonant frequency, including the resonant frequency, to the variable attenuator 2. The signal is transmitted to the input side, attenuated by the variable attenuator 2, and returned to the input side.
On the other hand, signals far from the vicinity of the resonant frequency are reflected back to the input side. The line length of the branch line 3 is determined so as to have such characteristics. Therefore, terminal 1
5, an amplitude frequency characteristic as shown in FIG. 2 is obtained.

In FIG. 2, the horizontal axis is frequency and the vertical axis is attenuation. The resonance frequency ₀ is determined by the electrical length of the branch line 3, and the amount of attenuation is determined by the variable attenuator 2. Furthermore, by changing the variable attenuator 2, the characteristics can be changed as indicated by 11, 12, and 13 in FIG. When used as a primary slope amplitude equalizer, the slope part of this characteristic is utilized.

FIG. 3 shows a variable amplitude equalizer according to a second embodiment of the present invention. In this circuit, a diode-type variable attenuator 4 whose attenuation amount changes depending on the bias current is used in place of the variable attenuator 2 shown in FIG. 1, and the terminal terminal c is grounded. In Figure 3, capacitor 7 is DC
It's for Katsuto. In the case of this circuit, if the bias terminal is placed outside the device, the amplitude equalizer has the advantage of being built into the device and allows you to freely select characteristics with different attenuation amounts as shown in Figure 2. .

FIG. 4 shows a third embodiment in which the branch line 3 is grounded via a variable capacitance element 6 in the first embodiment shown in FIG. In this case, the amplitude equalizer can change the resonance frequency ₀ using the variable capacitance element 6 and change the attenuation amount using the variable attenuator 2. Therefore, there is an advantage that the resonance frequency and the amount of attenuation can be freely selected.

FIG. 5 shows a variable capacitance diode 9 whose capacitance changes with a bias voltage as the variable capacitance element 6 in FIG.
This is the fourth embodiment using the above, and has a circuit configuration that can be controlled from the outside like the above.

FIG. 6 shows a fifth embodiment in which a diode-type variable attenuator whose attenuation amount can be changed by a bias current is used in place of the variable attenuator 2 shown in FIG. 5, similar to the second embodiment shown in FIG. This is an example. In the circuit of FIG. 6, capacitor 8 is for DC cut. This circuit is capable of changing the resonant frequency and the amount of attenuation by changing the bias voltage and current. Therefore, even when installed in a device, if the bias terminal is provided externally, the amplitude frequency characteristics can be freely changed by external bias control.

As explained above, in this invention, the amplitude characteristics can be freely changed by combining branch lines that can be easily constructed with microstrip lines using variable attenuators and variable capacitance elements, making it possible to adjust the amplitude characteristics. It's easy to do. Particularly, when diodes are used as these elements, there is an advantage that they can be easily adjusted while being incorporated into the device.

Furthermore, since these amplitude equalization circuits can be easily constructed on a microstrip substrate, they can be made smaller and lighter.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a circuit configuration showing a first embodiment of the present invention, Fig. 2 is an amplitude frequency characteristic diagram for explaining the embodiment of Fig. 1, and Fig. 3 is a diagram showing a second embodiment of the present invention. An explanatory diagram of a circuit configuration showing an example, FIG. 4 is an explanatory diagram of a circuit configuration showing a third embodiment of the present invention, FIG. 5 is an explanatory diagram of a circuit configuration showing a fourth embodiment of the invention, and FIG. It is a circuit configuration explanatory diagram showing a fifth embodiment of the present invention. 1... Signal transmission line, 2... Variable attenuator, 3...
Branch line which is a resonator, 4... Diode type variable attenuator whose attenuation amount changes depending on the bias current, 5... Circuit for giving a transmission signal and taking out an output signal, 6... Variable capacitance element, 7, 8... ...DC cut capacitor, 9...Variable capacitance diode, 1
4...Signal input terminal, 15...Signal output terminal.

Claims (1)

[Claims for Utility Model Registration] (1) An amplitude compensation circuit having a first terminal and a short-circuited or open second terminal; a signal transmission line whose one end is coupled to the first terminal, and between the other end of the signal transmission line and the second terminal. a variable attenuator provided, and a variable attenuator provided between the other end and ground, transmitting a signal near the center frequency of the transmission signal to the attenuator, and transmitting a signal away from the center frequency to the first terminal. a resonator with side reflecting branch lines; and a variable amplitude equalizer. (2) The variable amplitude equalizer according to claim 1, wherein the resonator includes a variable capacitance element connected in series with the branch line.