JPS62243Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is used by being inserted into a transmission line to compensate for distortions in the amplitude frequency characteristics that occur in wideband microwave communication equipment, signal transmission lines, etc. and make the amplitude frequency characteristics flat. This article relates to a microwave band 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, such amplitude distortion equalization has been performed using a bandpass waveform device or a bandstop waveform device, and the sloped portion of the pass or reflection frequency characteristic thereof 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 resistance element or 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 second terminal to which a terminator is connected; a signal transmission line including a circuit taken out from the terminal, and the amplitude compensation circuit is coupled between the first terminal and the second terminal;
a variable attenuation element having one end connected to a certain point of the signal transmission line, and one end connected to the other end of the variable attenuation element to transmit a signal near the center frequency of the transmission signal to the terminator, A variable amplitude device comprising: a resonator having a branch line that reflects a distant signal toward the first terminal; and a circuit that grounds the other end of the resonator or grounds the other end of the resonator via a variable capacitance element. An equalizer is obtained.

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. A branch line 3 is connected to point b via a variable resistance element 4 to the signal transmission line 1, in which one end a of the signal transmission line 1 is used as an input/output terminal and the other terminal is terminated with a non-reflective terminator 2. An amplitude compensation circuit whose electrical length is selected such that the branch line including the variable resistance element 4 resonates at a desired frequency and is grounded, and a transmission signal is applied to the input/output terminal a of the amplitude compensation circuit, and the amplitude compensated signal is transmitted. A circuit 5 taken out from the terminal a 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 non-reflection terminator 2. It is all absorbed and not reflected.

On the other hand, signals far from the vicinity of the resonant frequency are reflected back to the input side. At this time, the signal is attenuated by the variable resistance element 4 by an amount corresponding to the resistance value of the variable resistance element, reflected to the input side, and returned. The line length of the branch line 3 is determined so as to have such characteristics. Therefore, the amplitude frequency characteristic shown in FIG. 2 is obtained at the terminal 15.

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 variable resistance element 4 and the branch line 3, and the amount of attenuation is determined by the resistance value of the variable resistance element 4. Further, by changing the resistance value of the variable resistance element 4, the characteristics can be changed as shown in 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 6 (for example, a PIN diode) whose resistance value changes with a bias current is used as the variable resistance element 4 shown in FIG. In FIG. 3, capacitor 7 is for DC cut. In this case, if the bias terminal is placed outside the device, the amplitude equalizer has the advantage of being able to freely select characteristics with different attenuation amounts as shown in FIG. 2 while being built into the device.

FIG. 4 shows a third embodiment in which the branch line 3 is grounded via a variable capacitance element 9 in the first embodiment shown in FIG. In this case, the amplitude equalizer can change the resonance frequency ₀ using the variable capacitance element 9 and the attenuation amount using the variable resistance element 4.
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 10 whose capacitance changes with a bias voltage as the variable capacitance element 9 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 6 whose resistance value changes depending on the bias current is used as the variable resistance element 4 of FIG. 5, similar to the second embodiment of FIG. 3. This circuit is capable of changing the resonant frequency and the amount of attenuation by changing the bias voltage and current. Therefore, even if it is incorporated into 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 resistance elements and variable capacitance elements, making it possible to adjust the amplitude characteristics. It's easy to do. In particular, the use of these elements using diodes has the advantage that they can be easily adjusted while being incorporated into a device.

Furthermore, although a non-reflection terminator is used in the above embodiment, any terminator that can attenuate the signal may be used as the terminator.

Note that these amplitude equalizers can be easily constructed on a microstrip substrate, making it possible to reduce the size and weight.

[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...Reflection-free terminator, 3
... Branch line that is a resonator, 4 ... Variable resistance element, 5 ... A circuit for giving a transmission signal and taking out an output signal, 6 ... A diode whose resistance value changes with a bias current (for example, a PIN diode), 7, 8...DC cut capacitor, 9...
Variable capacitance element, 10... Variable capacitance diode, 1
4...Signal input terminal, 15...Signal output terminal.

Claims (1)

[Scope of utility model registration request] an amplitude compensation circuit having a first terminal and a second terminal connected to a terminator; and a circuit that applies a transmission signal to the first terminal and extracts an amplitude-compensated signal from the first terminal. and the amplitude compensation circuit includes: a signal transmission line coupled between the first and second terminals; a variable attenuation element having one end connected to a certain point of the signal transmission line; a resonator having a branch line connected to the other end of the variable attenuation element and transmitting a signal near the center frequency of the transmission signal to the terminator and reflecting a signal away from the center frequency toward the first terminal; and a circuit that grounds the other end of the resonator or grounds the other end of the resonator via a variable capacitance element.