JP2009010484A - Multi-band amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-band amplifier in which loss in an output compositing circuit is reduced, and a multi-band amplifier whose cost is reduced by reducing the number of components of an output circuit. <P>SOLUTION: The multi-band amplifier has a control means controlling a selecting means from selecting a signal of a single frequency from signals inputted at an input terminal and outputting the signal to a signal path having a proper amplifier and controlling a bias means of N sets of proper amplifiers so that the bias class of an amplifier for amplifying signals may be set at class AB or class A, and the bias class of each of the other (N-1) sets of amplifiers not amplifying signals may be set at class C or zero bias. Thus, the multi-band amplifier allows an impedance at the other (N-1) sets of amplifiers not amplifying signals to be a high impedance considered to be substantially infinite (considered to be open), and eliminates the necessity of a diplexer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multiband amplifier that switches and transmits signals of a plurality of different frequencies.

In recent years, in mobile communications, multiband amplifiers that amplify a plurality of transmission signals having different pass bands are being put into practical use. Usually, in a multiband amplifier, a diplexer for separating a plurality of transmission frequencies is connected to the output side of the amplifier. For example, FIG. 7 is a configuration diagram of a conventional multiband amplifier that switches between two transmission frequencies f1 and f2 for transmission.
The RF input signals having the transmission center frequencies f1 and f2 are input to the amplifier 5 and the amplifier 6 individually matched with the frequencies f1 and f2, respectively, and output to the RF output terminal 2 through the diplexer 23. Is done. The diplexer 23 is composed of a combination of a low-pass filter and a high-pass filter, and performs frequency separation of two transmission signals. (For example, refer to Patent Document 1).
JP 2002-171137 (FIG. 1)

  In the conventional multiband amplifier, a diplexer for separating a plurality of transmission frequencies is connected to the output side of the amplifier. For this reason, there has been a problem that the efficiency of the entire amplifier is lowered due to the circuit loss of the diplexer. In addition, there is a problem that the number of parts increases due to the use of the diplexer.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a multiband amplifier in which the loss of the output synthesis circuit is reduced.
Another object of the present invention is to provide a multiband amplifier that is reduced in cost by reducing the number of components of the output circuit.

In the multiband amplifier according to the present invention, the control means selects one frequency signal from the signal inputted from the input terminal, and sends out the signal to the signal path provided with the corresponding amplifier, and N corresponding amplifiers. The bias class of the amplifier that amplifies the signal is set to class AB or class A, and the bias class of the other (N−1) amplifiers that do not amplify the signal is class C or zero bias. Therefore, the impedance viewed from the other (N-1) amplifiers that do not amplify the signal can be regarded as almost infinite (appears to be open), and the diplexer is not required. is there. Further, by eliminating the diplexer, the loss of the output synthesis circuit and the number of components are realized.
In other words, the multiband amplifier according to the present invention has N amplifiers each provided with N corresponding amplifiers for amplifying each of N signals (integers with N ≧ 2) having different frequencies input from the input terminal. One end of the signal path is connected in parallel to the input end via the switching means, and the other end of the N signal paths is bundled and connected to the output end. The switching means and the N amplifiers , The signal of one frequency is selected from the signals input from the input terminal and sent to the signal path provided with the corresponding amplifier, and the bias class of the corresponding amplifier is class AB or A And a control means for setting the bias class of the other (N-1) amplifiers to class C or zero bias.

  As described above, the present invention controls the bias of the switching means and the N amplifiers, selects a signal of one frequency from the signal input from the input terminal, and sends it to the signal path provided with the corresponding amplifier. And a control means for setting the bias class of the corresponding amplifier to class AB or class A and setting the bias class of the other (N−1) amplifiers to class C or zero bias is provided. And a multiband amplifier in which the loss of the output synthesis circuit is reduced can be obtained. In addition, the present invention has an effect of obtaining a multiband amplifier which is reduced in cost by reducing the number of parts of the output circuit.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating the configuration of a multiband amplifier according to the first embodiment of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1 and f2 of two different passbands will be described as an example. In the figure, 1 is an input terminal, 2 is an output terminal, 3 is a switch for distributing the input signal to a desired amplifier, and 4 is an amplifier 5 and an amplifier 6 for amplifying signals of frequencies f1 and f2 in two different passbands, respectively. Reference numeral 7 denotes an output combining point at which the output terminals of the amplifier 5 are connected, and 7 is a control circuit for switching the bias class of the amplifier 5 and the amplifier 6 and the switch 3 in cooperation with each other.

Next, the operation will be described.
First, the case of transmitting a signal having the frequency f1 shown in the upper left of FIG. 1 will be described. The control circuit 7 biases the amplifier 5 to class A or class AB and the amplifier 6 to class C, and the switch 3 passes the signal path from the input terminal 1 to the amplifier 5 and the path from the input terminal 1 to the amplifier 6. Set to shut off.
At this time, if the impedance of the output terminal 2 is 50 ohms, the output impedance of the class-C biased amplifier 6 is high impedance that can be regarded as almost infinite as shown in the lower part of FIG. The impedance when the output side is expected from the amplifier 5 set to be biased to approximately 50 ohms.
In a multiband amplifier, a signal is input only to the amplifier 5 biased to class A or class AB, and the amplifier 5 operates with a load impedance of 50 ohms, so that the amplifier operates with desired characteristics such as high efficiency and low distortion.
In addition, since the output impedance of the other amplifier 6 is a high impedance that can be regarded as almost infinite, almost no loss occurs at the output synthesis point 4.

Next, a case where a signal having a frequency f2 shown in the upper right of FIG. 1 is transmitted will be described. In this case, contrary to the frequency f1 transmission, the control circuit 7 biases the amplifier 6 to class A or AB, the amplifier 5 to class C, and the switch 3 has a signal path from the input terminal 1 to the amplifier 6. The passage and the path from the input terminal 1 to the amplifier 5 are set to be cut off.
At this time, if the impedance of the output terminal 2 is 50 ohms, the output impedance of the class C biased amplifier 5 becomes a high impedance that can be regarded as almost infinite as shown in the lower part of FIG. The impedance when the output side is expected from the amplifier 6 set to be biased to approximately 50 ohms.
In a multiband amplifier, a signal is input only to the amplifier 6 biased to class A or class AB, and the amplifier 6 operates with a load impedance of 50 ohms, so that the amplifier operates with desired characteristics such as high efficiency and low distortion.
Further, since the output impedance of the other amplifier 5 is a high impedance which can be regarded as almost infinite, almost no loss occurs at the output synthesis point 4.

From the above, in the first embodiment, the amplifier on the side that does not amplify the signal is biased to class C, and the output impedance of the amplifier on the side that does not amplify the signal is made almost infinite, so that class A or class AB The impedance expected from the output side of the amplifier set to bias can be made substantially equal to the load impedance, and a multi-band amplifier having high efficiency and low distortion characteristics can be obtained.
Further, by making the output impedance of the amplifier on the side that does not amplify the signal almost infinite, it is possible to reduce the occurrence of loss at the output combining point and to reduce the loss of the output combining circuit.
Furthermore, the output circuit can be configured without using a diplexer, and the cost of the multiband amplifier can be reduced by reducing the number of parts of the output circuit.

  In the above description, the amplifier on the side that does not amplify the signal is the amplifier set to be biased to class C. However, the same thing can be said even if an amplifier in a zero bias state without bias is used instead of setting the bias to class C. An effect is obtained.

Embodiment 2. FIG.
FIG. 2 is a diagram illustrating the configuration of the multiband amplifier according to the second embodiment of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1 and f2 of two different passbands will be described as an example. The configuration different from that of the first embodiment is that a distribution circuit 8, a switch 9 and a switch 10 for distributing an input signal to a desired amplifier are provided.

Next, the operation will be described.
When transmitting a signal of frequency f1, the switch 9 is turned on (passed) and the switch 10 is turned off (cut off) so that the signal is input from the input terminal 1 only to the amplifier 5.
On the other hand, when transmitting a signal of frequency f2, the switch 10 is turned on (passed) and the switch 9 is turned off (cut off) so that the signal is input from the input terminal 1 only to the amplifier 6. The
Other operations and effects are the same as those in the first embodiment.

Embodiment 3 FIG.
FIG. 3 is a diagram illustrating the configuration of a multiband amplifier according to the third embodiment of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1, f2, and f3 of three different passbands will be described as an example. In the figure, 11 is an amplifier that amplifies a signal of frequency f3.

Next, the operation will be described.
First, a case where a signal of frequency f1 is transmitted will be described. The control circuit 7 biases the amplifier 5 to class A or class AB, the amplifier 6 and the amplifier 11 to class C, and the switch passes the signal from the input terminal 1 to the amplifier 5, and the input terminal 1 to the amplifier 6 and the amplifier. 11 is set to be blocked.
At this time, if the impedance of the output terminal 2 is 50 ohms, the output impedance of the amplifier 6 and the amplifier 11 biased with class C is high impedance so that it can be regarded as almost infinite, so the bias is set to class A or class AB. The impedance expected from the amplifier 5 on the output side is approximately 50 ohms.
In a multiband amplifier, a signal is input only to the amplifier 5 biased to class A or class AB, and the amplifier 5 operates with a load impedance of 50 ohms, so that the amplifier operates with desired characteristics such as high efficiency and low distortion.
Further, since the output impedances of the other amplifier 6 and amplifier 11 are so high that they can be regarded as almost infinite, almost no loss occurs at the output synthesis point 4.

  Next, in the case of transmitting a signal of frequency f2 or a signal of frequency f3, the bias setting of each of amplifier 5, amplifier 6 and amplifier 11 is switched to class A, class AB or class C by control circuit 7. The operation is the same as in the case of transmitting the signal having the frequency f1.

That is, in the third embodiment, the amplifier on the side that does not amplify the signal is biased to class C, and the effect that the output impedance on the amplifier side biased to class C is almost infinite is utilized. The loss of the band amplifier output synthesis circuit can be reduced.
Further, the cost can be reduced by reducing the number of parts by not using the diplexer.
The same effect can be obtained by using an amplifier with the bias turned off instead of setting the bias to class C.

Embodiment 4 FIG.
FIG. 4 is a diagram illustrating the configuration of a multiband amplifier according to the fourth embodiment of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1 and f2 of two different passbands will be described as an example. In the figure, reference numerals 21 and 22 denote lines for phase adjustment inserted in series between the amplifiers 5 and 6 and the output combining point 4, respectively. The characteristic impedance of the line 21 is set to 50 ohms, and the electrical length is set so that the impedance viewed from the output synthesis point 4 to the amplifier 5 at the frequency f2 can be regarded as almost infinite. The characteristic impedance of the line 22 is set to 50 ohms, and the electrical length is set so that the impedance when the amplifier 6 is viewed from the output synthesis point 4 at the frequency f1 can be regarded as almost infinite. Other configurations are the same as those in FIG. 1 described in the first embodiment.

Next, the operation will be described.
First, the case of transmitting a signal of frequency f1 will be described (upper left in FIG. 4). Assuming that the impedance of the output terminal 2 is 50 ohms, due to the effect of the line 22, the impedance seen from the output synthesis point 4 when the amplifier 6 is biased with class C becomes high impedance that can be regarded as almost infinite. The impedance when the output side is expected from the bias-set amplifier 5 is almost 50 ohms (the lower part of FIG. 4).
Therefore, even if the output impedance of the amplifier 6 biased with class C bias has a reactance component, it does not become infinite, so that the impedance seen from the output synthesis point 4 to the amplifier side biased to class C due to the effect of the line 22 Is converted to a high impedance that can be regarded as almost infinite, so that almost no loss occurs at the output synthesis point 4.

A case of transmitting a signal of frequency f2 will be described (upper right in FIG. 4). Even when a signal of frequency f2 is transmitted, the basic operation is the same as that of transmitting a signal of frequency f1 only by switching the bias setting of the switch 3 and the amplifiers 5 and 6; Since the impedance viewed from the side of the amplifier set to be biased is converted to a high impedance that can be regarded as almost infinite, almost no loss occurs at the output synthesis point 4.
Other operations and effects are the same as those in the first embodiment.

Embodiment 5 FIG.
FIG. 5 is a diagram for explaining the configuration of a multiband amplifier according to the fifth embodiment of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1 and f2 of two different passbands will be described as an example. In the figure, 31 and 32 are lines for phase adjustment, and 33 and 34 are open-ended stubs connected in parallel between the amplifier 5 and the line 31, and between the amplifier 6 and the line 32, respectively. The open end stub 33 and the phase line 31 have an electrical length of 90 deg at the frequency f2, and the open end stub 34 and the phase line 32 have an electrical length of 90 deg at the frequency f1. Other configurations are the same as those in FIG. 4 described in the fourth embodiment.

Next, the operation will be described.
First, a case where a signal of frequency f1 is transmitted will be described.
If the impedance of the output terminal 2 is 50 ohms, the impedance of the output end of the amplifier 6 is short-circuited by the effect of the open-ended stub 34 having an electrical length of 90 deg at the frequency f1, so that the phase line having an electrical length of 90 deg at the frequency f1 The impedance when looking at the amplifier side biased to class C from output composite point 4 through 32 is high impedance so that it can be regarded as almost infinite, and the output side from amplifier 5 biased to class A or class AB is The expected impedance is almost 50 ohms.

  From the above, regardless of the output impedance of the amplifier 6 biased in class C, the impedance seen from the output synthesis point 4 to the amplifier side biased to class C due to the effects of the open-ended stub 34 and the phase line 32 is almost the same. Since the impedance is converted into a high impedance that can be regarded as infinite, almost no loss occurs at the output synthesis point 4.

  Even when a signal of frequency f2 is transmitted, the basic operation is the same as that of transmitting a signal of frequency f1 only by switching the bias setting of the switch 3 and the amplifiers 5 and 6, and the tip open stub 33 and Due to the effect of the phase line 31, the impedance seen from the amplifier side biased to class C from the output synthesis point 4 is converted to a high impedance that can be regarded as almost infinite, so that almost no loss occurs at the output synthesis point 4. .

Embodiment 6 FIG.
FIG. 6 is a diagram for explaining the configuration of a multiband amplifier according to Embodiment 6 of the present invention. Here, a multiband amplifier that switches and transmits frequencies f1 and f2 of two different passbands will be described as an example. In the figure, 41 and 44 are inductors, 42 and 45 are capacitors, and 43 and 46 are grounds. The resonance frequency of the inductor 41 and the capacitor 42 connected in series is the frequency f2, and the resonance frequency of the inductor 44 and the capacitor 45 connected in series is the frequency f1, and is between the amplifier 5 and the line 31 and between the amplifier 6 and the line 32, respectively. It is a series resonant circuit connected in parallel. Other configurations are the same as those in FIG. 4 described in the fourth embodiment.

Next, the operation will be described.
First, a case where a signal of frequency f1 is transmitted will be described. If the impedance of the output terminal 2 is 50 ohms, the inductor 44 and the capacitor 45 resonate at the frequency f1, so that the impedance at the output end of the amplifier 6 is short-circuited. As a result, the impedance seen from the output synthesis point 4 through the phase line 32 having an electrical length of 90 deg at the frequency f1 and viewed from the side of the amplifier 6 biased to the class C becomes a high impedance that can be regarded as almost infinite. , The impedance when the output side is expected from the amplifier 5 biased to class A or class AB is approximately 50 ohms.

  From the above, regardless of the output impedance of the amplifier 6 biased in class C, the impedance seen from the output synthesis point 4 to the amplifier side biased to class C due to the effect of the series resonance circuit composed of the inductor 44 and the capacitor 45. Is converted to a high impedance that can be regarded as almost infinite, so that almost no loss occurs at the output synthesis point 4.

  Even when a signal of frequency f2 is transmitted, the basic operation is the same as that of transmitting a signal of frequency f1, just by switching the bias settings of the switch 3 and the amplifiers 5 and 6, and an inductor 41 and a capacitor 42 are used. Due to the effect of the series resonance circuit, the impedance when looking at the amplifier 5 side biased to the class C from the output synthesis point 4 is converted to a high impedance that can be regarded as almost infinite, so the loss at the output synthesis point 4 is It hardly occurs.

1 is a configuration explanatory diagram of a multiband amplifier showing a first embodiment according to the present invention. FIG. It is a block diagram explanation of the multiband amplifier showing Embodiment 2 according to the present invention. It is a block diagram explanation of the multiband amplifier showing Embodiment 3 according to the present invention. It is a block diagram explanation of a multiband amplifier showing a fourth embodiment according to the present invention. FIG. 10 is a configuration diagram of a multiband amplifier showing Embodiment 5 according to the present invention. It is a block diagram explanation of a multiband amplifier showing a sixth embodiment according to the present invention. It is a block diagram of the conventional multiband amplifier.

Explanation of symbols

1 input terminal, 2 output terminal, 3 switch, 4 output synthesis point, 5, 6 amplifier, 7 control circuit, 8 distribution circuit, 9, 10 switch, 11 amplifier, 21, 22 line, 23 diplexer, 31, 32 line, 33, 34 Open end stub, 41, 44 Inductor, 42, 45 Capacitor, 43, 46 Ground

Claims (8)

One end of N signal paths each provided with N corresponding amplifiers for amplifying each of N signals (N ≧ 2 integers) having different frequencies input from the input terminal is switched to the input terminal And the other ends of the N signal paths are bundled and connected to the output terminal, and the input of the switching means and the N amplifiers is controlled by controlling the bias of the switching means and the N amplifiers. A signal of one frequency is selected from the received signals and sent to a signal path provided with a corresponding amplifier, and the bias class of the corresponding amplifier is set to class AB or class A, and the other (N−1 A multiband amplifier provided with control means for setting the bias class of the amplifiers to class C or zero bias. 2. A multiband amplifier according to claim 1, wherein said switching means is configured to have a switch of 1: N (N ≧ 2). 2. A multiband amplifier according to claim 1, wherein said switching means comprises an N distribution circuit (an integer of N ≧ 2) and an ON / OFF switch connected to each output terminal of said N distribution circuit. . One end of two signal paths each provided with an amplifier that amplifies corresponding to signals of different frequencies f1 and f2 input from the input end are connected in parallel to the input end via a switching means, and The other ends of the two signal paths are bundled and connected to the output end, and the bias of the switching means and the two amplifiers is controlled to select one frequency signal from the signal input from the input end. And a control means for setting the bias class of the corresponding amplifier to class AB or class A, and setting the bias class of the other amplifier to class C or zero bias. And having a predetermined characteristic impedance (about 50 ohms) in the signal path between the amplifier and the amplifier that amplifies corresponding to the signal of the frequency f1, and the frequency For the number f2, there is provided a first line having an electrical length in which the signal path side provided with an amplifier that amplifies the signal corresponding to the signal of the frequency f1 from the binding site is open, and corresponds to the signal of the frequency f2. The signal path between the amplifier to be amplified and the bundling is provided with an amplifier having a predetermined characteristic impedance and amplifying the frequency f1 corresponding to the signal of the frequency f2 from the bundling portion. A multiband amplifier provided with a second line having an electrical length in which the signal path side appears to be open. One end of two signal paths each provided with an amplifier that amplifies corresponding to signals of different frequencies f1 and f2 input from the input end are connected in parallel to the input end via a switching means, and The other ends of the two signal paths are bundled and connected to the output end, and the bias of the switching means and the two amplifiers is controlled to select one frequency signal from the signal input from the input end. And a control means for setting the bias class of the corresponding amplifier to class AB or class A, and setting the bias class of the other amplifier to class C or zero bias. And a third line having an electrical length of 90 degrees with respect to the frequency f2 is connected to the signal path between the amplifier and the amplifier that amplifies the signal corresponding to the signal of the frequency f1, and A first open-ended stub having an electrical length of 90 degrees with respect to the frequency f2 is connected to the signal path between the amplifier that amplifies in response to the signal of the frequency f1 and the third line, and the frequency f2 A fourth line having an electrical length of 90 degrees with respect to the frequency f1 is connected to the signal path between the amplifier that amplifies the signal corresponding to the signal f and the bundling, and is amplified corresponding to the signal of the frequency f2. A multiband amplifier in which a second open-ended stub having an electrical length of 90 degrees with respect to the frequency f1 is connected to the signal path between the amplifier and the fourth line. One end of two signal paths each provided with an amplifier that amplifies corresponding to signals of different frequencies f1 and f2 input from the input end are connected in parallel to the input end via a switching means, and The other ends of the two signal paths are bundled and connected to the output end, and the bias of the switching means and the two amplifiers is controlled to select one frequency signal from the signal input from the input end. And a control means for setting the bias class of the corresponding amplifier to class AB or class A, and setting the bias class of the other amplifier to class C or zero bias. And a third line having an electrical length of 90 degrees with respect to the frequency f2 is connected to the signal path between the amplifier and the amplifier that amplifies the signal corresponding to the signal of the frequency f1, and A series resonance circuit consisting of an inductor and a capacitor and resonating at the frequency f2 is connected to the signal path between the amplifier that amplifies the signal corresponding to the signal at the frequency f1 and the third line, and corresponds to the signal at the frequency f2. A fourth line having an electrical length of 90 degrees with respect to the frequency f1 is connected to the signal path between the amplifier to be amplified and the bundling; A multiband amplifier in which a series resonance circuit composed of an inductor and a capacitor and resonating at the frequency f1 is connected to the signal path between the fourth lines. The multiband amplifier according to any one of claims 4 to 6, wherein the switching means includes a one-to-two selector switch. The multi-band according to any one of claims 4 to 6, characterized in that the switching means includes a two distribution circuit and an ON / OFF switch connected to each output terminal of the two distribution circuit. amplifier.

Images