JPH11154829A - Common amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve distortion compensation shortage by providing a fourth directional coupler which makes an output of feed forward type common amplifying device one input and a signal that is extracted by a fifth directional coupler which is provided between stages of an auxiliary amplifier the other input via a third vector adjusting device and a third delay line and offsetting a distortion component that remains in a multiple frequency amplification signal. SOLUTION: A circuit between directional couplers 1 and 5 is distortion detection loop, a circuit between directional couplers 5 and 10 is a distortion elimination loop, and the coupler 10 performs anti-phase addition of a signal which amplifies a distortion component detected by the distortion detection loop into prescribed value by an auxiliary amplifier 12 and inverts phase and an amplification signal that the includes a distortion component inputted via a delay line 9, eliminates the distortions and outputs them. Directional couplers 13 and 16, a vector adjusting device 14 and a delay line 15 are added to the distortion elimination loop. Consequently, it is possible to compensate the shortage of request performance with respect the distortion elimination loop by securing suppression quantity of the added loop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency common amplifying apparatus for a microwave band or the like, and more particularly to a self-adjusting feed-forward (SAFF).
) The present invention relates to a common amplifying device using a method.

[0002]

2. Description of the Related Art Transmission of base stations in mobile communications such as automobile telephones and mobile telephones is intended to improve the performance and reduce the size of the antenna duplexer by amplifying a plurality of wireless carriers in common. In order to suppress intermodulation distortion due to common amplification, a common amplifier of a self-adjustment type feedforward system is used.

FIG. 2 is a structural example of a conventional SAFF type common amplifying device. In the figure, 1, 5, and 10 are directional couplers, 2, 7 are vector adjusters, 3 is a main amplifier, 4
Is a pilot generator, 6 and 9 are delay lines, 8 is an auxiliary amplifier, and 11 is a control circuit.

The circuit between the directional couplers 1 and 5 is a distortion detection loop, and detects distortion components such as intermodulation distortion and noise generated when the input multi-frequency signal is amplified by the main amplifier 3.

[0005] The circuit between the directional couplers 5 and 10 is a distortion removing loop. The auxiliary amplifier 8 amplifies the distortion component detected by the distortion detecting loop to a desired value and inverts the phase. , And the amplified signal including the distortion component input to the directional coupler 10 via the delay line 9 is added in reverse phase to remove the distortion and output.

[0006] The vector adjusters 2 and 7 adjust the phase and the amount of attenuation by a control signal of the control circuit 11 set in accordance with the input level and the ambient temperature. As the adjustment method, there is a method in which the control amount is fixedly set by setting as needed, or a method in which the loop output is detected and the dynamic adjustment operation is performed.

FIG. 3 shows a basic model of a signal / error suppression circuit in a SAFF circuit. The distortion suppression amount K is determined by the deviation from the opposite phase and equal amplitude conditions of the feedforward loop.

FIG. 4 shows the signal suppression amount K (dB), amplitude deviation d (dB), and phase deviation θ (degr) in the interference circuit of FIG.
ee), the amplitude and phase deviation must be in the ranges of ± 0.1 dB and ± 1 °, respectively, in order to suppress the amount of suppression K at −30 dB or less.

[0009]

However, in the above-mentioned conventional circuit, if the frequency band is wide or the amount of suppression is further required, the required characteristics for the loop become strict and adjustment becomes difficult. There's a problem.

It is an object of the present invention to provide a common amplifying device that can eliminate the conventional insufficient distortion compensation by simply adding a simple additional circuit (loop) in the conventional SAFF type common amplifying device. It is in.

[0011]

According to the common amplifying apparatus of the present invention, a multi-frequency input signal is distributed by a first directional coupler, and one signal is amplified by a main amplifier via a first vector adjuster. And a distortion detection loop for detecting a distortion component generated in the main amplifier by performing a reverse phase synthesis of a signal obtained by synchronizing the other signal with a signal obtained by adjusting the timing of the other signal by a first delay line. A signal obtained by amplifying the distortion component output from the second directional coupler by an auxiliary amplifier via a second level adjuster and the main amplifier output from the second directional coupler. A third directional coupler combines the amplified signal with a signal whose timing is adjusted by the second delay line in a reverse phase, thereby canceling the distortion component generated in the main amplifier and outputting a multi-frequency amplified signal. A distortion removal loop, the first and second And a control circuit for controlling the level of the distortion component detected by the distortion detection loop with respect to the vector adjuster. In order to suppress a distortion component remaining in the output multi-frequency amplified signal, a fourth directional coupler having an output of the third directional coupler as one input is provided. Reverse-phase combining a signal extracted by a fifth directional coupler provided between stages as the other input of the fourth directional coupler via a third vector adjuster and a third delay line Thus, the distortion component remaining in the multi-frequency amplified signal is cancelled.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an embodiment of the present invention. 1 to 7, 9 and 10 in the figure are the same parts as in the prior art, and the operation is the same as in the prior art. 12 is an auxiliary amplifier, 1
3, 16 are directional couplers, 14 is a vector adjuster, 15
Is a delay line. The output of the delay line 15 via the vector adjuster 14 has a distortion component (sufficient amount of suppression) still appearing on the output side even when the SAFF operation of the conventional circuit is performed, and a phase difference of 1
By adjusting the amplitude to be equal at 80 ° (opposite phase), it is possible to remove a distortion component that could not be completely removed by the conventional technique.

In fact, the gain G of the path from the output of the directional coupler 13 to the directional coupler 16 through the vector adjuster 14 and the delay line 15 is represented by Q (d
B), the gain from the directional couplers 13 to 10 is represented by G1 (d
B) and CPL1 (dB), CPL2 (dB) and CPL3 (d
B), the loss of the vector adjuster 14 and the delay line 15 is L1
(DB), it is expressed by the following equation.

G = CPL1 + L1 + CPL2 = G1 + CPL3 + Q

According to the above equation, if the coupling amount of the directional couplers 13 and 16 is selected so as not to affect the characteristics of the prior art as much as possible, an amplifier is not required for the added loop.
Further, there is no influence of the signal from the main amplifier 3.

The position where the directional coupler 13 is connected is
It is determined by the presence or absence of the auxiliary amplifier 12, the influence of the signal from the main signal path, and the like, and is not particularly defined.

[0016]

As described above, by implementing the present invention, the required performance of the conventional distortion removal loop can be compensated by securing the suppression amount of the added loop. Further, depending on the characteristics of the added loop, it is possible to realize characteristics that are equal to or greater than the suppression amount of the related art alone.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional common amplifier.

FIG. 3 is a basic model of a signal suppression circuit.

FIG. 4 is a diagram illustrating a relationship between a signal suppression amount and an amplitude / phase deviation.

[Explanation of symbols]

 1,5,10,13,16 Directional coupler 2,7,14 Vector adjuster 3 Main amplifier 4 Pilot generator 6,9,15 Delay line 8,12 Auxiliary amplifier 11,17 Control circuit

Claims (1)

[Claims] 1. A multi-frequency input signal is distributed by a first directional coupler. One signal is amplified by a main amplifier via a first vector adjuster, and the other signal is delayed by a first delay. A distortion detection loop for detecting a distortion component generated in the main amplifier by synthesizing a signal whose timing is adjusted by a line with a second directional coupler in an opposite phase; and outputting the distortion component from the second directional coupler. The signal obtained by amplifying the distortion component by the auxiliary amplifier via the second level adjuster and the signal amplified by the main amplifier output from the second directional coupler are timing-controlled by a second delay line. A third directional coupler that performs anti-phase synthesis on the combined signal to cancel a distortion component generated by the main amplifier and output a multi-frequency amplification signal; and a first and second distortion removal loop. The distortion detector for the vector adjuster And a control circuit for controlling the level of the distortion component detected by the amplifier to be small. A feed-forward type common amplifying device, comprising: a multi-frequency amplification signal output from the third directional coupler; A fourth input having the output of the third directional coupler as one input to suppress the distortion component
And a signal extracted by a fifth directional coupler provided between the stages of the auxiliary amplifier is supplied to the fourth directional coupler via a third vector adjuster and a third delay line. A common amplifying device configured to cancel a distortion component remaining in the multi-frequency amplified signal by performing reverse-phase synthesis as the other input of the coupler.