JP2002151905A - Variable delay circuit, amplifier using the variable delay circuit and communication unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive variable delay circuit having a small area for mounting, whose delay characteristic is uniform over frequencies, an amplifier that can output a signal with less distortion over a wide frequency range and a communication unit. SOLUTION: The variable delay circuit of this invention is provided with 1st and 2nd delay lines 3a, 3b that are microstrip lines configured in a 1st layer 2a being a surface layer of a printed circuit board, a 3rd delay line 4a that is a strip line configured in a 3rd layer 2b in a dielectric base member 9 held between 2nd and 4th layer ground planes, and switching sections 5a, 5b that switches the delay lines with an external control signal (ctl). Both terminals of the delay lines are respectively connected to the switching sections 5a, 5b via through-holes 6. The variable delay circuit is employed for an amplifier of this invention, and the amplifier or the variable delay circuit is employed for a communication unit of this invention.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable delay circuit, an amplifier and a communication device using the variable delay circuit, a variable delay circuit for changing a delay amount of a signal, and the variable delay for compensating for distortion by a feedforward method. The present invention relates to an amplifier using a circuit and a communication device including the amplifier.

[0002]

2. Description of the Related Art One of conventional variable delay circuits is disclosed in
There is a variable delay circuit disclosed in Japanese Patent Application Publication No. 1-163608. The variable delay circuit changes the phase and delay amount of the input signal by sliding the conductor of the coaxial line to change the electrical length. A variable delay circuit according to another conventional form shown in FIG. 10 includes a directional coupler 31 and a variable capacitance element 32, and changes the phase value and the delay amount of an input signal by changing the capacitance value of the variable capacitance element 32. Let me.

Further, the conventional variable delay circuit shown in FIG. 11 includes a plurality of delay lines (microstrip lines) 3a to 3c having different lengths, and switching units 5a and 5b. 3a to 3c are mounted on the first layer of the printed circuit board. Since the delay amount of the input signal varies depending on the length of the delay line, the conventional variable delay circuit changes the delay amount stepwise by switching the delay line to be selected.

Meanwhile, a feedforward amplifier is known as an amplifier for simultaneously amplifying multi-channel carriers used in the fields of mobile communication and broadcasting. The feedforward amplifier suppresses signal distortion generated in the amplifier by changing the delay amount of the input signal by using the above-described variable delay circuit, and outputs an amplified signal with the least distortion. FIG. 12 is a block diagram showing the conventional feedforward amplifier.

In FIG. 1, a conventional feedforward amplifier includes a first distribution unit 13a, a first delay circuit 17
a, first variable attenuation circuit 18a, first variable phase shifter 20
a, the main amplifier 15, the second distributor 13b, and the distortion detector 11 including the first synthesizer 14a;
, A first combiner 14a, a second delay circuit 17b, a second variable attenuator 18b, a second variable phase shifter 20b, an auxiliary amplifier 16, and a second combiner 14b. The first variable phase shifter 20a and the second variable phase shifter 20b use the conventional variable delay circuit described above.

In the feed-forward amplifier, distortion occurs in the main amplifier 15, and the distortion is extracted by the distortion detector 11 and removed by the distortion remover 12. In order to minimize the distortion generated in the main amplifying section 15, the distortion detecting section 11 uses the first variable attenuation circuit 18a and the first variable attenuating circuit 18a.
, The amount of amplitude attenuation and the amount of phase change in the variable phase shifter 20a are adjusted, and the second variable attenuator 1
8b and the amount of phase change in the second variable phase shifter 20b are adjusted.

[0007] The feedforward amplifier is mainly used in communication devices such as base stations in order to operate a system with high frequency use efficiency and power efficiency in a wireless communication system such as mobile communication.

[0008]

Although the conventional variable delay circuit, feedforward amplifier and communication apparatus have been described above, the conventional variable delay circuit disclosed in Japanese Patent Application Laid-Open No. 11-163608 has been described. ,
Since the amount of delay is changed by sliding the conductor of the coaxial line, there is a problem that the device is large and expensive.

Further, the conventional variable delay circuit shown in FIG. 10 has a problem that the delay characteristic using the frequency when the capacitance value of the variable capacitance element 32 is changed as a parameter is not uniform. FIG. 13 shows a phase characteristic (a) and a delay characteristic (b) of the variable delay circuit. In the figure, the broken line indicates an example when the capacitance value of the variable capacitance element 32 is changed. As shown in FIG. 13A, when the capacitance value is changed, the phase changes equally at any frequency.
As shown in FIG. 13B, the delay amount differs depending on the frequency.

In the conventional variable delay circuit shown in FIG. 11, a plurality of delay lines (microstrip lines) having different lengths are provided on the same layer of a printed circuit board while securing isolation between the lines. Since it is provided, there is a problem that the mounting area occupying the substrate of the variable delay circuit increases. If an attempt is made to reduce the mounting area of the variable delay circuit in order to solve this problem, the length of the delay line is limited. There is a problem that the changing step becomes rough.

In the conventional feedforward amplifier, the conventional variable delay circuit is used for the first variable phase shifter 20a and the second variable phase shifter 20b. The problem of each delay circuit affects the feedforward amplifier. For example, the variable delay circuit described in Japanese Patent Application Laid-Open No. H11-163608 has a problem that the device is large and expensive. Therefore, in a feedforward amplifier using the variable delay circuit, the amplifier itself is not used. Large and expensive. Note that a communication device including the feedforward amplifier has a similar problem.

Further, the variable delay circuit shown in FIG. 10 has a problem that the delay characteristics using the frequency as a parameter are not uniform and the amount of delay varies depending on the frequency. Therefore, in a feedforward amplifier using the variable delay circuit, an error occurs in a delay amount in a wide frequency range, and distortion suppression is deteriorated depending on a frequency. There was a problem that it would. Note that a communication device including the feedforward amplifier has a similar problem.

Further, since the variable delay circuit shown in FIG. 11 has a problem that the mounting area is large, the feedforward amplifier using the variable delay circuit has the following problems.
There is a problem that the mounting area of the amplifier increases with the mounting area of the variable delay circuit. Note that a communication device including the feedforward amplifier has a similar problem.

The present invention has been made in view of the above-mentioned conventional problems, and is a variable delay circuit that is inexpensive, has a small mounting area, has a uniform delay characteristic with frequency, and has a low distortion signal over a wide frequency range. It is an object of the present invention to provide an amplifier and a communication device capable of outputting.

[0015]

According to a first aspect of the present invention, there is provided a variable delay circuit comprising at least one microstrip line formed on a multilayer substrate and a plurality of delay lines each including a strip line. A delay line connected to an arbitrary one of the plurality of delay lines and switching the connection to the selected delay line. A large amount of delay line is a strip line covered with a dielectric substrate.

The variable delay circuit according to a second aspect of the present invention is the variable delay circuit according to the first aspect, wherein the multilayer substrate is composed of a plurality of types of dielectric base materials having different dielectric constants, and When a plurality of strip lines are included in the line, the delay line having the largest delay amount is a strip line based on a dielectric substrate having the largest dielectric constant.

Further, the amplifier according to claim 3 is an amplifying means for amplifying an input signal, a distortion extracting means for adjusting an amplitude and a phase of the input signal to extract a distortion component generated by the amplifying means, A distortion for removing the distortion component from the amplified signal by adjusting the amplitude and phase of the distortion component extracted by the distortion extraction unit and re-injecting the adjusted distortion component into the amplified signal output by the amplification unit. 3. An amplifier comprising: a distortion extractor and the distortion remover having the variable delay circuit according to claim 1; and adjusting the phase of the input signal performed by the distortion extractor. The adjustment of the phase of the distortion component performed by the distortion removing unit is performed by the variable delay circuit.

The amplifier according to claim 4 is the same as the amplifier according to claim 3.
Wherein the distortion extracting means and the distortion removing means further include a variable phase shifting means for continuously changing the phase of the signal, and the distortion extracting means adjusts the phase of the input signal and adjusts the phase of the input signal. The adjustment of the phase of the distortion component performed by the distortion removing unit is performed by the variable delay circuit and the variable phase shift unit.

According to a fifth aspect of the present invention, there is provided a communication apparatus including the amplifier according to the third or fourth aspect.

Furthermore, a communication device according to a sixth aspect is provided with the variable delay circuit according to the first or second aspect.

In the variable delay circuit according to the first aspect of the present invention, at least one microstrip line and a strip line are formed on the multilayer substrate, and the switching means is selected from a plurality of delay lines having different delay amounts. The connection is switched to the delay line. In particular, a delay line having a relatively large delay amount is a strip line covered with a dielectric substrate. Since the propagation speed of the strip line is lower than the propagation speed of the microstrip line, the delay amount of the strip line is greater than that of the microstrip line when compared with the same line length.

Therefore, the length of the delay line when a predetermined delay amount is to be obtained is smaller in the strip line than in the microstrip line and the strip line. By using a large delay line as a strip line, the mounting area of the variable delay circuit can be reduced. Therefore, a small and inexpensive variable delay circuit can be realized. Further, in the variable delay circuit, since the phase characteristics and the delay characteristics do not change with the frequency, the amounts of change in the phase and the delay can be made the same over a wide frequency range.

Further, in the variable delay circuit according to claim 2,
The multilayer substrate is composed of a plurality of types of dielectric base materials having different dielectric constants, and a plurality of delay lines include a plurality of strip lines. Since the propagation speed of the delay line becomes smaller as the dielectric constant becomes larger, the delay line having the largest delay amount is made to be a strip line based on a dielectric base material having the largest dielectric constant. The amount of delay can be obtained. As a result, the mounting area of the variable delay circuit can be reduced while increasing the stages of the delay amount.

Further, in the variable delay circuit according to the first and second aspects, since each layer above and below the layer on which the strip line is formed is a ground plane, isolation between the delay lines can be ensured.

Further, in the amplifier according to the third aspect, the input signal is amplified by the amplifying means and the distortion extracting means is amplified by the distortion extracting means.
A distortion component generated by the amplification unit is extracted by adjusting the amplitude and phase of the input signal, and the distortion removal unit adjusts the amplitude and phase of the distortion component extracted by the distortion extraction unit, and amplifies the adjusted distortion component. The distortion component is removed from the amplified signal by re-injecting the amplified signal output by the means. In particular, in the amplifier according to the present invention, the variable delay circuit according to claim 1 or 2 performs the adjustment of the phase of the input signal performed by the distortion extracting unit and the adjustment of the phase of the distortion component performed by the distortion removing unit. I have.

In the variable delay circuit according to the first or second aspect, since there is little error in the amount of change in delay over a wide frequency range, it is possible to suppress the distortion component generated by the amplifying means over a wide frequency range. As a result, an amplified signal with little distortion can be output in a wide frequency range. Further, since the mounting area of the variable delay circuit according to claim 1 or 2 is smaller than that of the related art, the mounting area of the amplifier itself can be reduced.

Further, in the amplifier according to the fourth aspect, the adjustment of the phase of the input signal performed by the distortion extracting means and the adjustment of the phase of the distortion component performed by the distortion removing means are performed by the variable delay circuit according to the first or second aspect. Variable phase shift means that continuously changes the phase of the signal is performed, the variable delay circuit adjusts the phase stepwise over a wide range, and the variable phase shift means continuously adjusts the phase over a narrow range. The phase can be adjusted with high accuracy. Therefore, an amplified signal with less distortion can be output in a wide frequency range.

According to a fifth aspect of the present invention, there is provided a communication apparatus including the amplifier according to the third or fourth aspect. By using the amplifier as a transmission signal amplifying means, transmission with a small distortion in a wide frequency range is achieved. A signal can be output. Further, since the mounting area of the amplifier according to claim 3 or 4 is small, the communication device according to the present invention can be downsized.

Furthermore, the communication device according to claim 6 is provided with the variable delay circuit according to claim 1 or 2, and can output a transmission signal with little distortion in a wide frequency range. Since the variable delay circuit according to claim 1 or 2 has a small mounting area, the communication device according to the present invention can be downsized.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a variable delay circuit according to the present invention will be described below in detail in the order of [first embodiment] and [second embodiment] with reference to the drawings.

[First Embodiment of Variable Delay Circuit] The variable delay circuit of the first embodiment is formed on a printed circuit board having a four-layer structure. FIG. 1 is a top view (a) of the first layer and a top view (b) of the third layer of the variable delay circuit according to the first embodiment of the present invention, and FIG. FIG. 2 is a sectional view of the variable delay circuit according to the embodiment, taken along the line AA shown in FIG. 1. In these drawings, parts that are the same as in FIG. 11 (conventional example) are given the same reference numerals.

The variable delay circuit according to the present embodiment is for changing the phase stepwise. As shown in FIG.
A first delay line 3a and a second delay line 3b corresponding to a microstrip line, a third delay line 4a corresponding to a strip line, and switching units 5a and 5b corresponding to switching means. It is provided with.
However, as shown in FIG. 2, the first delay line 3a, the second delay lines 3a and 3b, and the switching units 5a and 5b are configured on a first layer 2a which is a surface layer of a printed circuit board. Further, the third delay line 4a is formed by a third delay line 4a in the dielectric base material 9 sandwiched by the ground planes 8 of the second and fourth layers formed to secure isolation between the lines. It is configured as a layer 2b. Note that the ground plane 8 corresponds to a ground plane in the claims.

Each of the first and second delay lines 3a and 3b has a microstrip line (MS) having a different length.
L), the two ends of which are respectively provided with switching units 5a, 5b
It is connected to the. In the present embodiment, the first delay line 3
a is shorter than the second delay line 3b. On the other hand, the third delay line 4a is constituted by a strip line (SL), and both ends thereof are switched through switching holes 5a and 5
b.

Further, since the entire periphery of the third delay line 4a is covered with the dielectric substrate 9, if the light speed is C and the effective dielectric constant of the dielectric is ε _eff , the third delay line 4a the propagation velocity v _p of the formula (1) shown below.

[0035]

(Equation 1)

The effective permittivity of the line whose entire periphery is covered with a dielectric (the third delay line 4a) is the effective permittivity of the line whose entire periphery is not covered with a dielectric (the first and second delay lines 3a).
a, 3b) is larger than the effective permittivity of
As shown in (2), between a line covered with a dielectric having the same line length and a line not covered with a dielectric, a line covered with a dielectric has a lower propagation speed. This indicates that if the line length is the same, the delay amount of the line not covered with the dielectric is larger than that of the line covered with the dielectric.

For example, the dielectric substrate 9 has a relative dielectric constant of 4.8.
Characteristic impedance is 50Ω using glass epoxy
When the delay amount is the same, the third
With the delay line 4a, the line length can be reduced by about 15%. Therefore, when trying to obtain the same delay amount, the third delay line 4a of the variable delay circuit of the present embodiment is the third delay line of the conventional variable delay circuit shown in FIG.
May be shorter than the delay line 3c.

However, in the variable delay circuit of this embodiment, the first and second delay lines 3a and 3b and the third delay line 4
Since each delay amount of a needs to be different,
The line length of the third delay line 4a is determined based on the delay amount of the second delay line 3b and the dielectric constant of the dielectric base material 9 covering the periphery.

The switching units 5a and 5b are switching circuits for switching the delay line in response to an external control signal (ctl). The switching units 5a and 5b perform electrical switching using transistors, diodes, and the like, and mechanically move contacts. The connection is made to any one of the first delay line 3a, the second delay line 3b, and the third delay line 4a by mechanical switching to be performed or manual switching of switching the connection point of the delay line by soldering or the like. is there.

In the variable delay circuit of this embodiment having such components, an input signal is output after passing through any one of the three delay lines selected by the switching units 5a and 5b. FIG. 3 shows a phase characteristic (a) and a delay characteristic (b) using frequency as a parameter in the variable delay circuit of the present embodiment. In the figure, the broken line shows an example when the delay line through which the signal flows is changed. As shown in FIG. 3, even if the delay line is changed, the characteristics of the phase change amount and the delay amount do not change at any frequency.

As described above, in the variable delay circuit of the present embodiment, the third delay line 4a having the largest delay amount is formed on the third layer 2b of the printed circuit board, and its periphery is covered with the dielectric. Therefore, the same delay amount can be obtained with a shorter line length than the third delay line 3c included in the conventional variable delay circuit shown in FIG. Therefore, the mounting area of the variable delay circuit can be reduced. Further, the size and the cost can be reduced as compared with the variable delay circuit described in JP-A-11-163608 shown in the prior art. Further, since the phase characteristics and the delay characteristics do not change with the frequency, the amounts of change of the phase and the delay can be made the same over a wide frequency range.

[Second Embodiment of Variable Delay Circuit] The variable delay circuit of the second embodiment is formed on a printed circuit board having a six-layer structure. FIG. 4 is a top view (a) of the first layer, a top view (b) of the third layer, and a top view (c) of the fifth layer of the variable delay circuit according to the second embodiment of the present invention. FIG. 5 shows a variable delay circuit according to the second embodiment of the present invention, as shown in FIG.
FIG. 4 is a cross-sectional view taken along line B. In these drawings, the same parts as those in FIGS. 1 and 2 (first embodiment) are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 4, the variable delay circuit according to the present embodiment includes a fourth delay line 4 corresponding to a strip line, in addition to the components included in the variable delay circuit according to the first embodiment.
b. However, as shown in FIG.
The fourth delay line 4b is formed in the fifth layer 2c in the dielectric base material 9 'sandwiched between the fourth layer and the sixth layer ground plane 8. Note that the dielectric constant of the dielectric substrate 9 ′ is larger than the dielectric constant of the dielectric substrate 9.

The fourth delay line 4b is connected to the third delay line 4
Similar to a, it is composed of a microstrip line (MSL), and both ends are connected to switching units 5a and 5b via through holes 6 ', respectively. Also, the fourth
The propagation speed of the delay line 4b is lower than that of the third delay line 4a because the entire periphery of the delay line 4b is covered with the dielectric substrate 9 '. Therefore, even if the fourth delay line 4b has the same line length as the third delay line 4a, the fourth delay line 4b has a larger delay amount than the other delay lines.

As described above, in the variable delay circuit of the present embodiment, the fourth delay line is based on the dielectric substrate 9 'having a higher dielectric constant than the dielectric substrate 9 of the first embodiment. 4b, a desired amount of delay can be obtained with a shorter line length. Therefore, the mounting area of the variable delay circuit can be reduced.

Next, an embodiment of a feedforward amplifier using a variable delay circuit according to the present invention will be described in detail in the order of [first embodiment] and [second embodiment] with reference to the drawings. I do.

[First Embodiment of Feedforward Amplifier] FIG. 6 is a block diagram showing a feedforward amplifier according to a first embodiment of the present invention. In the figure, the same reference numerals are given to the same parts as those in FIG. 12 (prior art).

In FIG. 6, the feedforward amplifier according to the first embodiment includes a first distribution unit 13a, a first delay circuit 17a, a first variable attenuator circuit 18a, a first variable delay circuit 19a. The main amplifying unit 15, the second distributing unit 13b, and the first combining unit 1 corresponding to the amplifying means in the range of
4a, a distortion detection unit 11 corresponding to a distortion detection unit, a second distribution unit 13b, and a first synthesis unit 14
a, second delay circuit 17b, second variable attenuation circuit 18
b, a second variable delay circuit 19b, a distortion remover 12 corresponding to a distortion remover, which is constituted by an auxiliary amplifier 16 and a second synthesizer 14b, and comprises a first variable delay circuit 19a and a second The variable delay circuit 19b described above uses the variable delay circuit according to the present invention described above.

The feedforward of the present embodiment (hereinafter referred to as
Simply referred to as an amplifier) in the same manner as in the prior art.
, The distortion is extracted by the distortion detection unit 11, the amplitude and phase of the distortion component extracted by the distortion detection unit 11 are adjusted, and the distortion component is re-injected into the output signal of the main amplification unit 15. This is to remove distortion generated in the amplification unit 15. Hereinafter, the operation of the amplifier will be described in detail.

First, the distortion detecting section 11 includes the first distributing section 1
In 3a, the input signal is distributed to the first variable attenuation circuit 18a and the first delay circuit 17a. First variable attenuation circuit 1
The signal distributed to the 8a side is attenuated by the first variable attenuator 18a, the phase is changed by the first variable delay circuit 19a, and then amplified by the main amplifier 15. The amplified signal is
The signal is distributed to the second delay circuit 17b and the first combiner 14a by the second distributor 13b. The signal distributed to the first delay circuit 17a has its phase changed by the first delay circuit 17a, and is then combined with the amplified signal by the first combining unit 14a.

In the distortion detecting section 11, the first synthesizing section 14a
The amplitude is adjusted by the first variable attenuating circuit 18a so that the signal level at
Use to adjust the phase. This adjustment is performed by the first variable delay circuit 1
The signal on the 9a side and the signal on the first delay circuit 17a side are
° The phase is shifted so that the amplitude of each signal is the same.
By this adjustment, the signal output from the first synthesis unit 14a becomes a signal in which the distortion generated in the main amplification unit 15 is dominant.

Next, in the distortion removing section 12, the amplified signal distributed to the second delay circuit 17b side by the second distribution section 13b is changed in phase by the second delay circuit 17b,
Is input to the synthesizing unit 14b. Also, the first combining unit 14
a from the second variable attenuating circuit 18
After the signal is attenuated by b and the phase is changed by the second variable delay circuit 19b, it is amplified by the auxiliary amplifier 16. The amplified signal is input to the second synthesizing unit 14b, and the second delay circuit 1
7b is combined with the signal output from 7b. Strain remover 12
Then, the amplitude is adjusted by the second variable attenuation circuit 18b and the phase is adjusted by the second variable delay circuit 19b so that the distortion generated in the main amplification unit 15 of the distortion detection unit 11 is reduced.

As described above, the feedforward amplifier according to the present embodiment uses the variable delay circuit according to the present invention as a circuit for adjusting the phase (first and second variable delay circuits 19a and 19b). Since the variable delay circuit does not cause much error in the amount of change in delay over a wide frequency range as described above, the feedforward amplifier according to the present embodiment reduces distortion generated in the main amplifier 15 inside the amplifier. It is possible to suppress over a wide frequency range. As a result, an amplified signal with little distortion can be output in a wide frequency range. Further, since the mounting area of the variable delay circuit of the present invention is smaller than that of the related art, the mounting area occupied by the feedforward amplifier itself on the printed circuit board can be reduced.

[Second Embodiment of Feedforward Amplifier] FIG. 7 is a block diagram showing a feedforward amplifier according to a second embodiment of the present invention. In the same figure, the same parts as those in FIG. 6 (first embodiment) are denoted by the same reference numerals, and the description is omitted.

In FIG. 7, the feed-forward amplifier according to the second embodiment includes, in addition to the components included in the feed-forward amplifier according to the first embodiment, a first embodiment corresponding to the variable phase shift means in the claims. It comprises a variable phase shifter 20a and a second variable phase shifter 20b. In this embodiment, the first variable phase shifter 20a is provided between the first variable attenuator 18a and the first variable delay circuit 19a, and the second variable phase shifter 20b is connected to the second variable attenuator 20a. 18
b and the second variable delay circuit 19b,
The phase adjustment in the distortion detection unit 11 and the distortion removal unit 12 is performed by using both the variable delay circuit and the variable phase shift unit.

In the present embodiment, for example, the first and second
The phase change amount of the variable delay circuits 19a and 19b is 30 °.
The delay lines having different delay amounts are configured so that the phase can be changed stepwise up to 75 ° in six steps of 15 °. Further, the first and second variable phase shifters 20a and 20b are configured so that the phase can be continuously changed within a range of 15 ° when the phase is 15 °. Therefore, in the present embodiment, it is relatively 0 °.
The phase can be continuously adjusted within the range of up to 90 °.

As described above, the phase can be adjusted with high accuracy by adjusting the phase stepwise in a wide range in the variable delay circuit and continuously adjusting the phase in the narrow range in the variable phase shift section. Therefore, in the feedforward amplifier according to the present embodiment, since the phase adjustment of the signal can be continuously performed in a wide range, the distortion generated in the main amplifier 15 can be suppressed to a minimum. As a result, the feedforward amplifier can output an amplified signal that does not further include a distortion component, as compared with the amplified signal output by the amplifier of the first embodiment.

Next, an embodiment of a communication apparatus having a feedforward amplifier according to the present invention will be described in detail in the order of [first embodiment] and [second embodiment] with reference to the drawings. .

[First Embodiment of Communication Apparatus] FIG. 8 is a block diagram showing a communication apparatus according to a first embodiment of the present invention. In the figure, the communication device of the first embodiment is used in a base station or the like of a wireless communication system, and an antenna 2
2, a common unit 23, a receiving unit 24, a transmitting unit 25, and an amplifying unit 26. The amplifying unit 26 uses the above-described feedforward amplifier according to the present invention.

First, the antenna 22 transmits and receives a radio signal. The common unit 23 shares the antenna 22 for transmission and reception, and is realized by an antenna duplexer filter, an antenna switch, and the like. Also,
The receiving unit 24 is a receiving circuit including a low noise amplifier, a local oscillator, a demodulator, and the like. Also, the transmission unit 25
Is a transmission circuit composed of a local oscillator, a modulator and the like, and outputs a transmission signal modulated by a carrier wave in a radio frequency band.

Further, the amplifying section 26 amplifies the transmission signal output from the transmitting section 25 after compensating for the distortion by a feedforward method. However, since the feedforward amplifier according to the present invention is used, It is possible to output an amplified transmission signal with little distortion in a wide frequency range.

Therefore, since the communication apparatus of the present embodiment uses the feedforward amplifier according to the present invention as the transmission signal amplifying means, it can output a transmission signal with little distortion over a wide frequency range. Further, as described above, since the feedforward amplifier according to the present invention has a small mounting area, the communication device according to the present embodiment can be downsized.

[Second Embodiment of Communication Apparatus] FIG. 9 is a block diagram showing a communication apparatus according to a second embodiment of the present invention. In the figure, the same reference numerals are given to the same parts as those in FIG. 8 (first embodiment), and the description is omitted. In FIG. 9, the communication device according to the second embodiment includes a distribution unit 1 in addition to the components included in the communication device according to the first embodiment.
3. It further includes variable delay circuits 1a and 1b, amplifying sections 26a and 26b, and a combining section 14, and has variable delay circuits 1a and 1b at inputs of a plurality of amplifying sections 26a and 26b operating in parallel.

The distribution unit 13 distributes the transmission signal output from the transmission unit 25 to the subsequent variable delay circuits 1a and 1b. The variable delay circuits 1a and 1b vary the delay amount of the transmission signal, and use the above-described variable delay circuits according to the present invention. In addition, the amplification unit 26
a and 26b are distributed by the distribution unit 13 and
This amplifies the transmission signal whose phase has been adjusted in a and 1b. Further, the combining unit 14 combines the transmission signals output from the amplifying units 26 a and 26 b and outputs the combined signal to the common unit 23.

In the communication device of the present embodiment, in order to efficiently amplify the transmission signal output from the transmission unit 25, it is necessary to reduce the error in the phase characteristics from the distribution unit 13 to the synthesis unit 14. Therefore, in the present embodiment, in particular, the variable delay circuit 1 is designed to maximize the signal level of the transmission signal.
The delay amounts of a and 1b are adjusted.

As described above, since the phase characteristic and the delay characteristic of the variable delay circuit according to the present invention do not change with frequency, the communication apparatus of the present embodiment can output a transmission signal with little distortion over a wide frequency range. it can. Also, since the variable delay circuit according to the present invention has a small mounting area,
The communication device of the present embodiment can also be downsized. The same effect can be obtained even if the feedforward amplifier according to the present invention is used for the amplifiers 26a and 26b.

[0067]

As described above, according to the variable delay circuit of the present invention, at least one microstrip line and a strip line are formed on a multi-layer substrate, and the switching means switches a plurality of delay lines having different delay amounts. The connection is switched to the delay line selected from among them. In particular, a delay line having a relatively large delay amount is a strip line covered with a dielectric substrate. Since the propagation speed of the strip line is lower than the propagation speed of the microstrip line, the delay amount of the strip line is greater than that of the microstrip line when compared with the same line length.

For this reason, when trying to obtain a predetermined delay amount, the length of the delay line is shorter when compared with the microstrip line and the strip line. By using a large delay line as a strip line, the mounting area of the variable delay circuit can be reduced. Therefore, a small and inexpensive variable delay circuit can be realized. Further, in the variable delay circuit, since the phase characteristics and the delay characteristics do not change with the frequency, the amounts of change in the phase and the delay can be made the same over a wide frequency range.

Further, when the multilayer substrate is composed of a plurality of types of dielectric base materials having different dielectric constants, and a plurality of delay lines include a plurality of strip lines, the propagation speed of the delay lines is large. Since a delay line having the largest delay amount is a strip line based on a dielectric substrate having the largest dielectric constant, a desired delay amount can be obtained with a shorter line length. as a result,
The mounting area of the variable delay circuit can be reduced while increasing the stages of the delay amount.

In the amplifier according to the present invention using such a variable delay circuit, the distortion component generated by the amplifying means can be suppressed over a wide frequency range, and as a result, the amplified signal with little distortion can be widened. It can output in the frequency range. Further, in such an amplifier or a communication device including the variable delay circuit according to the present invention, it is possible to output a transmission signal with little distortion in a wide range.

[Brief description of the drawings]

FIG. 1 is a top view (a) of a first layer and a top view (b) of a third layer of a variable delay circuit according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the variable delay circuit according to the first embodiment of the present invention, taken along line AA of FIG. 1;

FIG. 3 is an explanatory diagram showing a phase characteristic (a) and a delay characteristic (b) of the variable delay circuit according to the first embodiment of the present invention.

4A is a top view of a first layer, FIG. 4B is a top view of a third layer, and FIG. 4C is a top view of a fifth layer of the variable delay circuit according to the second embodiment of the present invention. It is.

FIG. 5 is a cross-sectional view of the variable delay circuit according to a second embodiment of the present invention, taken along line BB shown in FIG. 4;

FIG. 6 is a block diagram showing a feedforward amplifier according to the first embodiment of the present invention.

FIG. 7 is a block diagram showing a feedforward amplifier according to a second embodiment of the present invention.

FIG. 8 is a block diagram showing a communication device according to the first embodiment of the present invention.

FIG. 9 is a block diagram showing a communication device according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram showing a conventional variable delay circuit.

FIG. 11 is a block diagram showing another conventional variable delay circuit.

FIG. 12 is a block diagram showing a conventional feedforward amplifier.

13 is an explanatory diagram showing a phase characteristic (a) and a delay characteristic (b) of the conventional variable delay circuit of FIG.

[Explanation of symbols]

 3a 1st delay line 3b 2nd delay line 4a 3rd delay line 4b 4th delay line 5a, 5b switching part 6, 6 'through hole 8 ground plane 9, 9' dielectric base material 11 distortion detecting part Reference Signs List 12 distortion removing unit 13a first distributing unit 13b second distributing unit 14a first combining unit 14b second combining unit 15 main amplifier 16 auxiliary amplifier 17a first delay circuit 17b second delay circuit 18a second 1 variable attenuation circuit 18b second variable attenuation circuit 19a first variable delay circuit 19b second variable delay circuit 20a first variable phase shift unit 20b second variable phase shift unit 22 antenna 23 common unit 24 reception unit 25 transmitter 26 amplifier

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Naoki Matsubara 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. No.3-1, Matsushita Communication Industrial Co., Ltd. F-term (reference) 5J012 GA13 5J090 AA04 AA41 CA21 FA11 FA15 GN05 GN07 KA15 KA23 MA14 SA13 TA01

Claims (6)

[Claims] 1. A plurality of delay lines formed of at least one microstrip line and a strip line formed on a multilayer substrate, connected to an arbitrary one of the plurality of delay lines, and connected to a selected delay line. Switching means for switching, wherein each delay line has a different delay amount, and the delay line having a relatively large delay amount is a strip line covered with a dielectric base material. 2. The multi-layer substrate is composed of a plurality of types of dielectric base materials having different dielectric constants, and when the plurality of delay lines include a plurality of strip lines, the delay line having the largest delay amount is a dielectric line. 2. The variable delay circuit according to claim 1, wherein the variable delay circuit is a strip line based on a dielectric substrate having the highest rate. 3. An amplifying means for amplifying an input signal, a distortion extracting means for adjusting an amplitude and a phase of the input signal to extract a distortion component generated by the amplifying means, and a distortion extracted by the distortion extracting means. A distortion removing unit that removes the distortion component from the amplified signal by adjusting the amplitude and phase of the component and re-injecting the adjusted distortion component into the amplified signal output by the amplification unit. The distortion extracting means and the distortion removing means have the variable delay circuit according to claim 1 or 2, wherein the distortion extracting means adjusts the phase of the input signal and the distortion removing means performs An amplifier, wherein the phase of the distortion component is adjusted by the variable delay circuit. 4. The distortion extracting means and the distortion removing means further include a variable phase shift means for continuously changing a phase of a signal, wherein the distortion extracting means adjusts the phase of the input signal and performs the distortion. 4. The amplifier according to claim 3, wherein the phase adjustment of the distortion component performed by the removing unit is performed by the variable delay circuit and the variable phase shift unit. 5. A communication device comprising the amplifier according to claim 3 or 4. 6. A communication device comprising the variable delay circuit according to claim 1.