JPH0815245B2 - Non-linear distortion compensation circuit - Google Patents

Description

The present invention relates to a non-linear distortion compensating circuit for compensating for non-linear distortion of an amplifier by a predistortion method, and more particularly to a non-linear distortion compensating circuit using a diode as a distortion generating element.

"Prior Art" Conventionally, this type of non-linear distortion compensating circuit has been disclosed in Japanese Patent Application No. 60-110905.
No. “Nonlinear distortion generation circuit” and Japanese Utility Model Application No. 60-138174 “Nonlinear distortion compensation device”. That is, the structure is as shown in FIG.

In FIG. 6, the input signal input from the input terminal 11 is divided into two by the power distributor 12, and one of the signals is input to the nonlinear route 15 composed of the distortion generating circuit 13 and the variable attenuator 14. , And the other signal is added to a linear route 18 consisting of a delay line 16 and a variable phase shifter 17. The outputs of both routes 15 and 18 were subjected to reverse phase combination by the power combiner 19 and output to the output terminal 21. Distortion generator 13
Is composed of a circulator 22, diodes 23 and 24 connected in reverse polarity in parallel, and a terminating resistance element 25. Although not shown in the drawing, an amplifier is connected to the output terminal 21, and the non-linear distortion generated in the amplifier is canceled by the non-linear distortion generated in the distortion generating circuit 13.

In the conventional non-linear compensating circuit described above, the non-linearity of the non-linear route 15 and the linear route 18 is poor, and the phase difference between the two routes has frequency dependence. However, there is a drawback in that it is difficult to obtain uniform characteristics due to variations in characteristics due to the connection because the individual terminals are formed and connected.

An object of the present invention is to provide a small-sized and wide-band nonlinear distortion compensating circuit which solves the characteristic variations and narrow band characteristics of the conventional nonlinear distortion compensating circuit.

[Means for Solving the Problems] According to the present invention, one hybrid is used for each of the input side and the output side of a signal, and two reverse polarities as nonlinear elements are provided at one distribution port of the input side hybrid. A non-linear element and a terminating resistance element connected in parallel to
The other distribution port is connected through the main signal path to the input port of the same output-side hybrid as the input-side hybrid. The isolation port of the input hybrid is connected to the isolation port of the output hybrid through the main signal path. One distribution port of the output side hybrid is terminated, and an output is output from the other distribution port.

In this way, it is possible to configure the distortion generator using the input side hybrid, it is not necessary to use a circulator, the circuit is simple, and the main signal path and the distortion path can be configured symmetrically, One that operates in a wide band can be easily obtained.

[Examples] Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. Input terminal 11
The input signal from is split into two distribution ports 32 and 33 at the input side hybrid 31. One distribution port 32 is grounded through diodes 23 and 24 connected in antiparallel as non-linear elements and a terminating resistance element 25, and the other distribution port 33 is connected to a main signal path 34.

Here, the distribution port 32 to which the diodes 23 and 24 are connected
When the signal level is low, the impedance of is matched with the impedance of the terminating resistance element 25, and a good matching condition is realized. The other distribution port 33 is also connected with the delay line 16 having an impedance equal to the termination impedance. Therefore, no signal is output from the isolation port 35 when the signal level is low.

However, at the distribution port 32 to which the diodes 23, 24 are connected as the signal level gradually increases, the diodes 23, 24
The matching condition is broken due to the influence of the nonlinearity of 24, and only the distortion signal is output from the isolation port 35 as an unbalanced component.

The distortion component generated by the distortion generator 36 including the input side hybrid 31 and the diodes 23, 24 is adjusted in amplitude and phase by the variable attenuator 14 and the variable phase shifter 17 of the distortion path 37,
It is connected to the input port 38a of the output hybrid 38 for combining and is combined with the signal of the main signal path 34. The same ones as the input side hybrid 31 and the output side hybrid 38 are used. The delay path 16 performs delay matching between the main signal path 34 and the distortion path 37. That is, the distortion path 37 is connected between the isolation port 35 of the input side hybrid 31 and the input port of the output side hybrid 38, and the main signal path 34 is the isolation of the distribution port 33 of the input side hybrid 31 and the output side hybrid 38. Connected to the port 38b, one distribution port 38c of the output hybrid 38 is connected to the terminating element 39,
The other distribution port 38d is connected to the output terminal 21.

FIG. 2 shows an example in which the hybrids 31 and 38 shown in FIG. 1 are formed by 90-degree hybrids, and the variable attenuator 14 and the variable phase shifter 17 are also formed by using the same hybrids. However, in this case, the variable phase shifter 17 is inserted in the main signal path 34, and 90 degree hybrids 41 and 42 are inserted in the main signal path 34 and one in the distortion path 37, respectively. The track is not inserted. Pin diodes 51, 52 are connected to both distribution ports of the hybrid 42 of the variable attenuator 14, and the forward bias of the pin diodes 51, 52 is controlled by a bias circuit not shown in the figure, so that the pin diodes 51, 52 The resistance changes, that is, the amount of reflection changes, and the signal level obtained at the isolation port of the hybrid 42 is adjusted. Hybrid 41 in variable phase shifter 17
Distribution port varactor diodes 53 and 54 are connected, the reverse bias is controlled by a bias circuit not shown in the figure, and the phase of the reflected signal of the diodes 53 and 54 is controlled.
The phase-controlled reflection signal is combined at the isolation port of the hybrid 41.

FIG. 4 shows a circuit similar to that of the present invention for hybrid 31,38,
It is a figure at the time of comprising using a 180 degree hybrid as 41 and 42.

FIG. 4 shows that the diodes connected in anti-parallel constituting the distortion generator 36 are separated by capacitors 43, 44 and 45 in a direct current manner, and the bias of each diode 23 and 24 is set to each voltage −V of the terminals 46 and 47. _A ,
-V _B is adjusted so that it can be adjusted independently.

FIG. 5 shows the distortion generator 36 when the transistors 48 and 49 are non-linear elements. The variable attenuator circuit 14, the variable phase circuit 17, and the hybrid circuits 31 and 38 are all composed of distributed constant lines formed on a dielectric substrate, so that the microwave integrated circuit can be easily made.

"Effects of the Invention" As described above, the nonlinear distortion compensation circuit according to the present invention can generate a distortion signal by utilizing the hybrid on the input side without using a circulator. Since it can be configured as a hybrid, it has a simpler configuration and can be made smaller than the conventional non-linear distortion compensation circuit using a circulator shown in FIG. Further, in the above example, the main signal path and the distortion path can be configured symmetrically, variation in the characteristics of the main signal path and the distortion path can be suppressed, and delay matching is easy.
Therefore, there is an advantage that a wider band can be achieved.

[Brief description of drawings]

1 is a diagram showing a non-linear distortion compensating circuit according to the present invention, FIG. 2 is a diagram showing an example in which the circuit of FIG. 1 is constructed using a 90-degree hybrid, and FIG. 3 is a diagram showing the circuit of FIG. Fig. 4 shows an example of a configuration using a 180-degree hybrid, and Fig. 4 shows that each of the diodes connected in anti-parallel is DC-separated by a capacitor so that the bias of each diode can be adjusted independently. FIG. 5 is a diagram showing the configuration of the above-mentioned distortion generator, FIG. 5 is a diagram showing a non-linear distortion generator configured using transistors, and FIG. 6 is a diagram showing a conventional non-linear distortion compensation circuit.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takehiro Murase 1-2356 Take, Yokosuka City, Kanagawa Nippon Telegraph and Telephone Corporation, Research Institute for Communication Networks No. 2 (56) Reference JP-A-56-83104 (JP, A)

Claims (1)

[Claims] 1. A distortion generator is constructed by connecting an input-side hybrid to an input terminal, and connecting a nonlinear element and a terminating element to one distribution port of the input-side hybrid, and distributing the other of the input-side hybrid. The port is connected to the main signal path, the distortion path is connected to the isolation port of the input side hybrid, and the other end of the distortion path and the other end of the main signal path are of the same output side hybrid as the input side hybrid. A non-linear distortion compensation circuit that is connected to an input port and an isolation port respectively, and one distribution port of the output side hybrid is connected to a terminating element, and the other distribution port is connected to an output terminal.