JPH0210902A - Distortion compensation device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Distortion compensation relating to a distortion compensator that is placed before a microwave high power amplifier and outputs a compensating microwave distortion signal that preemptively compensates for distortion generated by the high power amplifier. The level of the distorted signal output from the device is divided by the microwave input for generating the distorted signal.
The purpose of this input is to split the microwave signal input into two signals with a phase difference of 90", with the aim of eliminating errors from the normal phase difference of 90 degrees between signals. The side hybrid, the output of a phase shifter that imparts a phase shift to one of the two branched signals in order to maintain the correct phase difference of 90° between both signals, and the output of a phase shifter that nonlinearly amplifies the other branched signal and converts it into a main signal at a predetermined level. The two signals, the distortion signal and the output of the distortion generator, are input and combined in reverse phase, and the input main signal components are mutually canceled and output to a distortion compensator consisting of an output hybrid that outputs only the distortion signal component. a control signal generating section that generates a control signal C according to the level of the in-phase combined microwave signal appearing at the terminal terminal of the side hybrid; a variable phase shifter that imparts a phase shift using the control signal C; and the variable phase shifter. The variable phase shifter and the variable attenuator are independently controlled by the control signal C of the output of the control signal generator to compensate for the change in the output level of the output hybrid. The variable phase shifter applies a phase shift for phase error correction to one of the microwave branch signals so that the signal level appearing at the output terminal is constant, and the variable attenuator changes the output level of the variable phase shifter. Configure.

[Industrial application field]

The present invention relates to a microwave band distortion compensator placed in the preceding stage in order to improve the amplitude distortion of a high power amplifier that amplifies the power of a modulated microwave signal input. The hybrid branches the signals into two signals S1 and S2 with a phase difference of 90 degrees, one of which is passed through a phase shifter that provides the necessary phase shift to maintain the normal phase difference of 90 degrees, and the other is The two microwave signals S1 and S2, which have a normal phase difference of 90' and have no level difference, are passed through a non-linear amplification microwave amplifier to generate a distortion signal for compensation, and are again converted into a branch linear type microwave signal. The present invention relates to a distortion compensator for a microwave band that is synthesized by an output-side hybrid and outputs only the distortion signal generated by the non-linear amplifying microwave amplifier to compensate for the linear distortion of the next-stage high-power amplifier.

[Conventional technology]

Conventionally, the above-mentioned distortion compensator for the microwave band is a branch line type in which the input side t2 is terminated by a resistor R1, in which a microwave modulated signal Sin having a plurality of carrier waves is modulated, as shown in the block diagram of FIG. Two microwave signals St are input to the input side t1 of the input side hybrid 10^, and the amplitudes are approximately 1/2 and the same and the phases are 90° different from each other at the output ends t3 and t4. .

S1 is adjusted to zero by a phase shifter 11A so that the phase error ε from the normal phase difference of 90° between the two branched signals becomes zero, and the other S1 is outputted as S1c.
2 is input to the microwave amplifier 21A and non-linearly amplified to generate a microwave distortion signal Sd■ of a predetermined level, and the main signal S
The output signal (S2c+Sd) of the sum of 2c and the distortion signal Sd is the input side t1 of the branch type output side hybrid 20A,
Send to t2.

Then, in the output side hybrid 20A, two series of output S1c and output (S2
c+Sd) are manually synthesized at the input sides t1 and t2, respectively, and the microwave main signals S1c and S2 are output from the output end t3.
The components of c are synthesized in opposite phases and cancel each other out,
Only the distorted signal component Sd generated by the nonlinear amplification microwave amplifier 21A is output as the output signal Sout. ■ Output signal S output from this output terminal t3
The distortion signal that is out is input to the next stage compensated high power amplifier 100, and the distortion characteristics generated are compensated for. The termination terminal t4 of the other output end of the output hybrid 20A is terminated with a resistor R2, and two series of microwave signals S input to the input sides t1 and t2.
1c and S2c are combined in the same phase, and the maximum level is reached when the phase difference is the normal phase difference of 90°, and the normal phase difference is 90°.
A microwave signal Sc whose level decreases in proportion to the phase error ε is outputted from the termination terminal t4 when the phase error deviates from the angle.

[Problem to be solved by the invention]

In the conventional distortion compensator, as described above, the two series of microwave signals S1c and S2c obtained by branching the microwave signal Sin into two at the input hybrid IOA are kept with a phase difference of 90 degrees by the phase shifter 11A. However, if the normal phase difference of 90° cannot be maintained at the input sides t1 and t2 of the output hybrid 20A and there is a phase error ε, the output of the output hybrid 20A The microwave main signals S1c and S2c at the end t3 are not sufficiently canceled, and the main signal S1c is outputted from the output terminal t3 as the distorted signal output Sout.

The S2c component is included, and the level of the distortion signal output Sout, which is the output of the distortion compensator, fluctuates, making it difficult to perform distortion compensation in the subsequent microwave high power amplifier.

To avoid this, the input side t of the output side hybrid 20A
1, two series of microwave signals S1c and S2 at t2
It is necessary to carefully adjust the phase shifter 11A so that the phase error ε from the normal phase difference of 90° does not appear in c.
The adjustment of this phase shifter 11A is performed on the output side hybrid 20A.
The output signal of the output terminal t3 is observed with a spectrum analyzer or the like, and the microwave main signal S at the output terminal t3 is determined.
Change the phase shift amount of the phase shifter 11A so that the levels of components 1c and S2c are minimized, and adjust the conductor pattern length of the microwave transmission line between the input hybrid IOA and the output hybrid 20A as necessary. I had to manually adjust it by changing it.

Therefore, there is a problem that adjustment to the phase shifter 11 takes time and effort, which increases the manufacturing cost.To solve this problem, a phase shifter 11A was invented by the same inventor as the inventor of the present invention. We have provided a microwave band distortion compensator that automates the adjustment.

However, in the distortion compensator that automated the adjustment of the phase shifter 11A, there was no problem in adjusting the phase difference by the phase shifter 11, but the adjustment of the phase shifter 11 due to the phase shift operation of the phase shifter 11 A change in the output level occurs, and as a result, the level of the microwave distortion signal Sout, which is the output of the distortion compensator, which is the output of the output hybrid 20A, changes, and the distortion compensation of the microwave high power amplifier 100 in the subsequent stage is performed successfully. The problem is that it is not done.

The present invention provides a microwave distortion signal output So of the output of the distortion compensator.
It is an object of the present invention to solve the problem that the level of u t changes with the phase shifting operation of the phase shifter 11, and distortion compensation in the subsequent stage is not performed well.

[Means for solving the problem] This problem is solved by the output side hybrid 20 in FIG.
A control signal generator 30 generates a control signal C according to the level of the microwave signal appearing at the terminal terminal t4 of In addition to the variable phase shifter 11 that maintains the output level at The variable phase shifter 11 controls the microwave branch signal S1c so that the microwave signal level Sc appearing at the terminal terminal t4 of the hybrid 20 on the output side is maximized by separately controlling the phase shifter 11 and the variable attenuator 12. This problem is solved by the distortion compensator of the present invention, in which the variable attenuator 12 is configured to change the output level of the variable phase shifter 11.

In the principle diagram of FIG. 1 showing the configuration of the distortion compensator of the present invention, 10 is a microwave signal S having a plurality of modulated carrier waves.
input, and two microwave signals s1.in are input, and the two microwave signals s1. The input-side hybrid 11 that branches and outputs the output from the input-side hybrid 10 shifts the phase of one microwave branch signal S1 output from the input hybrid 10 using a control signal C, and changes the phase between the output signal S2c of the other branch signal S2. A variable peak phase shifter 12 outputs a microwave signal S1c with zero phase error ε from a normal phase difference of 90゛. A variable attenuator 21 outputs a microwave main signal S1c at a level equal to the level of the output main signal S2c, and a variable attenuator 21 inputs the microwave branch signal S2 output from the input hybrid 10, nonlinearly amplifies it, and generates a distorted signal Sd. A main microwave signal S2c and a distortion signal Sd of a predetermined level are generated.
The distortion generator 20 outputs the sum signal (S2c+Sd) of the output S1c of the variable attenuator 12 of the first series branched into two of the input side hybrid 10, and the output of the distortion generator 21 of the second series (S2c + Sd) is input to the input side terminals t, I, t2, the output signal 5out obtained by anti-phase synthesis is outputted from its output terminal t3, and the microwave signal Sc obtained by in-phase synthesis is outputted from its terminal terminal t4. 22 is a terminating circulator connected to the terminating terminal t4 of the hybrid 20 on the output side; 30 is an in-phase synthesis micro output from the terminating terminal t4 of the hybrid 20 through the terminating circulator 22; A control signal generating section 100 generates a control signal C according to the level of the wave signal Sc, and 100 is a compensated high-power amplifier that receives the output signal Sout of the distortion compensator of the present invention and compensates for the generated distortion. It is.

In the distortion compensator of the present invention, the variable phase shifter 11 and the variable attenuator 12 are controlled by the control signal C generated by the control signal generator 30.
The variable phase shifter 11 imparts a phase shift to the microwave branch signal S1 so that the output level of the microwave signal Sc appearing at the termination terminal t3 of the hybrid 20 on the output side is maximized. The variable attenuator 12 is configured to change the output level of the variable phase shifter 11.

[Effect]

The input side hybrid 7 10 receives a modulated microwave signal Sin having a plurality of carrier waves, and has a mutual phase difference of 90°.
The branched microwave signal S1 of the first series is outputted to the variable phase shifter 11, and the branched signal S2 of the second series is outputted to the distortion generator 21. Output to.

The variable phase shifter 11 controls the phase of the first series microwave branch signal S1 output from the input hybrid 10. Ill
The second
Microwave main signal S2c output from the series distortion generator 21
The variable attenuator 12 transmits the first series of microwave signals Sac with the phase error ε removed from the normal phase difference of 90° with respect to the phase of the variable attenuator 12.
It is outputted to the input side t1 of the output side hybrid 20 through the.

The distortion generator 21 outputs the second output of the input hybrid 10.
A series microwave branch signal S2 is inputted, non-linearly amplified to generate a microwave distortion signal Sd, and output together with the main signal S2c, which is the sum of the microwave main signal S2c and the distortion signal Sd at a predetermined level. (S2c+Sd) is sent to the second input side child t2 of the output side hybrid 20.

The hybrid 20 on the output side includes a first series variable phase shifter 1
The microwave signal S1c sent from 1 through the variable attenuator 12 and the microwave distortion signal (S2c + Sd) from the second series distortion generator 11 are connected to the input side t1゜t.
2, and the output terminal t3 outputs a differential output signal Sout obtained by anti-phase synthesis of the two microwave signal inputs, which is used as the output of the distortion compensator of the present invention. At this time, the hybrid 20 on the output side outputs a microwave signal Sc obtained by combining the microwave main signals S1c and S2c in the same phase from the termination terminal t4, and sends it to the control signal generation section 30.

The control signal generator 30 generates human-powered microwave main signals S1c and S2 from the terminal terminal t4 of the output hybrid 20.
The maximum level is reached when the phase difference of c is the normal 90°,
A microwave signal Sc whose level decreases in proportion to the phase error ε is detected, and a control signal C corresponding to the detected level is generated and supplied as the control signal C to the variable phase shifter 11 and variable attenuator 12.

If the phase difference between the first series microwave signal S1c and the second series microwave main signal S2c input to the output hybrid 20 is maintained at the normal 90° by the variable phase shifter 11, then The output signal 5out from the output terminal L3 that has been synthesized in reverse phase becomes a microwave signal mainly containing the distortion signal Sd. However, if there is a level difference between the input main signal S1c and the main signal S2c, the output level will be increased by that difference. fluctuate.

Then, the variable attenuator 12 changes the output level of the variable phase shifter 11 using the control signal C corresponding to the detection level 1, and converts the first series microwave signal S1c into the output of the second series distortion generator 21. It is sent to the first input side t1 of the output side hybrid 20 at a level equal to the level of the microwave main signal S2c.

Then, since the levels of the input main signal S1c and the main signal S2c are equal, the level change of the output signal Sout at the output end t3 of the output side hybrid 20 disappears and remains constant, and the problem is solved because the output signal Sout of the bell is output. be done.

〔Example〕

FIG. 2 is a block diagram showing the configuration of a distortion compensator according to an embodiment of the present invention, and FIG. 3 is a vector diagram for explaining its operation.

In the block diagram of Figure 2, the hybrid 1 on the input side
0 is composed of a branch line type orthogonal hybrid such as a microstrip line, and the input side t2 is terminated with a gummy resistor R1, and as a microwave input signal Sin, for example, a microwave signal that is quadrature amplitude modulated QAM and has multiple carrier frequency signals is input. Input to side t1 and output end t3. From t4, two series of branch signals S with the same level and a mutual phase difference of 90°
t, S2, and the - first series branch signal S1
is output to the variable phase shifter 11, and the other second series branch signal S2 is output to the distortion generator 21.

The variable phase shifter 11 is, for example, a fixed step phase shifter 111.
and a variable step phase shifter 112, both of which are digital phase shifters that shift the phase of the input signal by a fixed amount, and the fixed step phase shifter 111 shifts the phase of the input signal by a predetermined phase step. The variable step phase shifter 112 is a phase shifter that switches and applies a constant phase step using a changeover switch operated by the control signal C from the control signal generator 30. 10, the phase of the first series branch signal S1 of the output of the distortion generator 21 is shifted, and the main signal S2 of the output of the second series distortion generator 21 is changed.
The microwave signal S1c is output to the variable attenuator 12 while maintaining a correct phase difference of 90° with respect to the phase of signal S1c and having no phase error ε.

The variable attenuator 12 is composed of a variable resistance attenuator, and changes the level of the microwave signal output from the variable phase shifter 11 of the first series using the control signal C from the same control signal generator 30. The microwave signal S1c■ is input to the input side t1 of the output side hybrid 20 at a level equal to the level of the main signal S2c output from the second series distortion generator 21.

The distortion generator 21 is, for example, a microwave GaAs PE.
A microwave amplifier composed of a T element, a microstrip line, etc., whose DC bias is selected to perform nonlinear amplification, and into which the second series microwave branch signal S2 of the output of the input hybrid 10 is input. At the same time, the main signal S2 is amplified and outputted by non-linear amplification.
3rd and 5th order distortion signals S due to cross-modulation products of multiple carrier waves
d, and the main signal S2c and distortion signal S at a predetermined level are generated together.
Second series microwave signal of the sum of d (S2c+Sd) ■
is input to the input side t2 of the output side hybrid 20.

The output side hybrid 20 is composed of the same branch line type orthogonal hybrid as the input side hybrid 10, and outputs an output signal Sout t obtained by combining the microwave signals inputted to the input side child t1 and the input side child t2 in opposite phases to the output terminal. The output signal Sc output from t3 and synthesized in phase with the microwave signals input to the input side child t1 and the input side child t2 is connected to its terminal terminal t.
Output from 4. The termination terminal t4 is terminated by a termination circulator 22 which is a Y-shaped circulator 221 whose one end is terminated with a gummy resistor 222.

The output hybrid 20 receives the microwave signal S1c from the first series variable attenuator 12 and the microwave distortion signal (S2c and Sd) from the second series distortion generator 11.
(2) is inputted to its input sides t1 and t2, and at the output end t3, as shown in the vector diagram of FIG. 3, reverse phase synthesis is performed and an output signal 5out (2) is output.

If the phase difference between the microwave signal S1c■ from the variable attenuator 12 and the main microwave signal S2c■ from the distortion generator 11 is a normal 90°, then as shown in FIG. Microwave main signals S1c and S2 at output terminal t3
c is synthesized in opposite phase and canceled, and a constant level microwave output signal Sou L of only the distorted signal component Sd generated by the distortion generator 21 is outputted, thereby generating the distortion i of the embodiment of the present invention.
1t' is the output of the compensator. At that time, as shown in FIG. When the phase difference is the normal 90°, the maximum level microwave signal Sc is output as shown in Figure 3. 53! Control (sent to the No. 3 generator 30) from the child t4 via the termination circulator 22.

The control signal generator 30 includes a detector 31 and a pulse generator 32.
The detector 31 detects the microwave No. 18 Sc■ outputted from the terminal t4 of the output hybrid 20 via the circulator 22, and
is a control pulse C proportional to the detection output level of the detector 31
The variable phase shifter 11 and variable attenuator 12 are set so that the output level of the detector 31 reaches the maximum level.

The variable phase shifter 11 controls the output of the control signal generator 30 tB.
The first series of branch signals S1 from the output terminal L3 of the input side high print 10 is driven to 1 by the pulse C, and as described above,
At the input side of the output hybrid 20, the phase difference between the first series microwave main signal S1c and the second series microwave main signal S2c input to [2] is maintained at the normal 90', and the phase error ε is A phase shift is applied so as to make the signal zero, and the signal is sent to the variable attenuator 12°.

The variable attenuator 12 is driven by the same control pulse C,
The level of the microwave signal output from the variable phase shifter 11 is adjusted, and specifically, when the output level of the detector 31 of the control signal generator 30 is high, the output of the detector 31 is operated in the direction of reducing the amount of attenuation. Operate in the direction where the level reaches the maximum level.

That is, as shown in the third diagram, the vector OA indicating the output of the variable phase shifter 11 is reduced by the external vector ΔB, and the vector OB indicating the output of the output terminal t3 of the output side hybrid 20 and the vector OB indicating the output of the output terminal t4 Vector OB' indicating the output
As shown in the figure, the amplitude of vector OA and the amplitude of vector OB are not equal. In this case, if the variable attenuator 12 is operated to increase the amplitude of vector OA by AA' (=BC), Vector OB is vector OC
Therefore, it becomes equal to the amplitude to vector 〇.

At this time, the vector OB' indicating the output of the output terminal 4 increases to become the vector OC', so the operation of the variable attenuator 12 is to change the vector OB to the vector OC' by operating the variable attenuator 12 in the direction in which the vector OR' increases. can be a vector OC equal in magnitude to .

In other words, by the operation of the variable attenuator 12, the first series microwave main signal S1c having a level equal to the level of the microwave main signal S2c output from the second series distortion generator 21 is inputted to the output side hybrid 20. It turns out.

Then, the output hybrid 20 has the correct phase difference of 90
Since the main signal S1c of the microwave of the first series and the main signal S2C of the second series, which have a phase difference of ' and the same level, are input, the main signal S1c and The main signals S2c are combined in reverse phase and completely cancel each other out, and only the distorted signal component Sd is outputted at a constant level as the output signal Sout.

As described above, the distortion compensator according to the embodiment of the present invention shown in FIG. The phase difference of the signal S2c is maintained at the normal phase difference of 90°, but since the levels of the main signal S1c and the main signal S2c are uneven, a difference between the main signals S1c and S2c appears at the output terminal t3 of the output hybrid 20 and is output. The problem of varying the level of the signal 5out is eliminated by the operation of the variable attenuator 12, which is simultaneously controlled independently by the control pulse C, to output the output signal 5out at a constant level. Therefore, there is no problem when inputting the constant level output signal 5out of the distortion compensator of the present invention to the subsequent high power amplifier to compensate for its distortion characteristics.

〔Effect of the invention〕

As explained above, according to the present invention, the phase of the variable phase shifter is optimized to suppress the leakage of the microwave input signal for generating distortion No. 18, which is directly unnecessary and harmful, as the output of the distortion compensator. The adjustment and the optimal adjustment of the level of the variable attenuator are automatically performed, and the output level of the necessary distortion signal is constant, making it possible to realize a distortion compensator that does not fluctuate. By inputting the signal to the subsequent high-power amplifier, the effect of making it possible to compensate for the distortion characteristics over a wide band can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram showing the configuration of a distortion compensator according to the present invention, FIG. 2 is a block diagram showing the configuration of a distortion compensator according to an embodiment of the present invention, and FIG. 3 is a vector explanation for explaining its operation. FIG. 4 is a block diagram of a conventional distortion compensator. In the figure, 10 is an input hybrid, 20 is an output hybrid, 11 is a variable phase shifter, 12 is a variable attenuator, 21 is a distortion generator, 22 is a terminating circulator, 30 is a control signal generator, and 31 is a detection unit. 32 is a pulse generator, and 100 is a compensated high power amplifier. This month's actual baldness distortion "Rain'i wo Eimi h heavy 77 ("f' beg blind also Bn7ro T Kome no bet lshi D] 3rd C Tsutomu

Claims (1)

[Claims] An input side hybrid (10) that inputs a microwave signal (Sin) and branches it into two signals (S1, S2) having a phase difference of 90°, and The output (S1c) of a phase shifter (11) that gives one of the two branched signals (S1) a phase shift to maintain the above-mentioned 90° phase difference between both signals (S1, S2), and the input The output (S2c) of the distortion generator (21) non-linearly amplifies the other signal (S2) branched by the side hybrid (10) and simultaneously generates the sum of the main signal (S2c) and the distortion signal (Sd) at a predetermined level.
+Sd) are input and combined in reverse phase, the main signal components (S1c, S2c) of the input microwaves cancel each other out, and only the distorted signal component (Sd) is sent to the output terminal (t
3) In the distortion compensator consisting of the output hybrid (20) output from the output hybrid (20), the control signal C is output according to the level of the in-phase synthesized microwave (Sc) appearing at the terminal terminal (t4) of the output hybrid (20). The control signal generator (30) that generates the control signal and the two signals (S1, S2) branched at the input hybrid (10)
) to one (S1) of both signals (S1, S
a variable phase shifter (11) that provides a phase shift that makes the error ε from the normal phase difference of 90° between A variable attenuator (12) for level correction is provided, and the variable phase shifter (1) is controlled by the control signal C generated by the control signal generator (30).
1) and the variable attenuator (12) so that the level of the microwave signal appearing at the output terminal (t3) of the output hybrid (20) is constant.
1) imparts a phase shift to the microwave signal (S1) output from the input hybrid (10), and the variable attenuator (12)
) is a distortion compensator characterized by changing the output level of a variable phase shifter (11).