JP4957095B2 - Multiband high frequency amplifier - Google Patents

Description

  The present invention relates to a multiband high-frequency amplifier provided in a communication terminal that transmits and receives data using radio signals in a plurality of frequency bands, and more particularly to a technique for miniaturizing a multiband high-frequency amplifier.

  As shown in FIG. 5, a mobile communication terminal that selectively uses three frequency bands (for example, 800 MHz, 2 GHz, and 5 GHz) includes high frequency amplifiers 410, 420, and 430 corresponding to these frequency bands. Then, the modulation signal obtained by the modulator 401 modulating the base signal according to the modulation frequency synthesized by the frequency synthesizer 402 is sent to any one of these high-frequency amplifiers 410, 420, and 430 via the multiplexer (MUX) 403. It is input selectively. In addition, transmission signals 1, 2, and 3 obtained by these high-frequency amplifiers 410, 420, and 430 are transmitted to the antenna 405 through the duplexer 404 and transmitted through the antenna 405.

Similarly, a wireless LAN communication device or the like is compatible with a plurality of frequency bands by including a plurality of high-frequency amplifiers having different frequency bands.
As shown in FIG. 6, the high-frequency amplifier 410 described above has an amplification function part for amplifying an input signal composed of the variable amplifier VA1 and the power amplifier PA1, and the gain of the variable amplifier VA1 based on the output signal of the power amplifier PA1. And a control function part for controlling. The amplification function part and the control function part composed of the power detection part PD and the differential amplifier EAMP are coupled by a directional coupler 411, and the output signal is demultiplexed via the directional coupler 411. It is sent to the device 404.

Similarly, the high-frequency amplifiers 420 and 430 also have a configuration in which an amplification function part tuned to each frequency band and a control function part for controlling the gain of the amplification function part are coupled by directional couplers 421 and 431, respectively. It has.
These directional couplers 411, 421, 431 are configured by placing two microstrips close together over a quarter of the wavelength that fits each, as shown in FIG. Distributed constant circuit.

  Most of the high-frequency signal inputted to one end of the main line (indicated by reference numeral P1 in FIG. 7) which is one of these microstrips is outputted from the output end P3 of this main line and sent to the duplexer 404. The At this time, a small part (for example, about 1%) of the input high-frequency signal power is one end (reference numeral P2 in FIG. 7) corresponding to the input end P1 of the main line described above in the sub-line which is the other microstrip. Appears at). The combined output taken out in this way is subjected to gain control processing by the control function part.

  On the other hand, when a reflected wave is generated due to impedance mismatching or the like in the antenna 405, the reflected wave reaches the output end P3 of the main line described above via the duplexer 404, and only a part thereof appears on the sub line. However, since it is consumed by the terminator TM connected to one end (indicated by reference numeral P4 in FIG. 7) corresponding to the above-described main line output end P3 in the sub-line, the combined output appearing at the other end P2 of the sub-line. There is no effect.

As described above, the directional coupler performs a function of extracting a coupled output corresponding to a high-frequency signal output and a function of blocking the influence of a reflected wave generated in the antenna, and constitutes a high-frequency amplifier for a wireless communication device. It is an indispensable part above.
Since such a directional coupler has a configuration in which two microstrips are brought close to each other by an appropriate length, it can also be formed as a wiring pattern on a printed board on which a high-frequency amplifier is mounted (Patent Document 1). reference).

  For example, when three directional couplers corresponding to frequencies of 800 MHz, 2 GHz, and 5 GHz are realized by a printed wiring pattern on a substrate material having a relative dielectric constant εr of about 4.5, respectively, about 44.19 mm, about A pair of microstrips having a length of 17.68 mm and about 7.07 mm will be placed, for a total extension of each microstrip of about 69 mm.

On the other hand, a chip component formed by folding a microstrip small is realized by the fine ceramic lamination technique, and such a chip component can be mounted as a part of a high-frequency amplifier. In this case, it is necessary to secure a space for mounting these chip components.
JP-A-8-307117

As shown in FIG. 5, in the configuration including the high-frequency amplifiers corresponding to the individual radio frequency bands, naturally, the high-frequency amplifiers are arranged on the printed circuit board by the number of frequency bands to be supported by the radio communication device. Become. For this reason, an increase in the number of components of the wireless communication device cannot be avoided, which hinders downsizing and cost reduction of the wireless communication device.
As can be seen from the detailed configuration of the high-frequency amplifier shown in FIG. 6, the amplification function portion is clearly composed of elements having frequency dependence, whereas the power detector and error amplifier constituting the control function portion. Are general-purpose circuit elements having no frequency dependency such as Schottky barrier diodes and differential amplifiers. On the other hand, in the high-frequency amplifier corresponding to each frequency band, each of the directional couplers connecting the amplification function part and the control function part has a length in which the main line and the sub line are arranged close to each other, That is, only the bond length is different.

In other words, the control function part for gain control of the variable amplifier does not necessarily have to be provided corresponding to each frequency band, and it is possible to obtain a combined output according to each frequency band by a directional coupler. For example, gain control of a plurality of variable amplifiers can be realized by one control function part.
An object of the present invention is to provide a multiband high-frequency amplifier that realizes gain control of a plurality of variable amplifiers by one control function part.

A first multiband high-frequency amplifier according to the present invention includes a plurality of variable amplifiers, a pair of microstrips, a coupling length changing unit, a selecting unit, a detecting unit, and an error detecting unit.
The principle of the first multiband high-frequency amplifier according to the present invention is as follows.
The plurality of variable amplifiers amplify input signals modulated in different frequency bands with a gain corresponding to the negative feedback control input. A pair of microstrips is formed as a wiring pattern on a printed circuit board on which a plurality of variable amplifiers are mounted, and a quarter wavelength of a signal in the lowest frequency band in which these variable amplifiers are compatible. It has an extension and is arranged close to each other with a distance that can be electromagnetically coupled to each other. The coupling length changing means is configured to change a length of a section in which electromagnetic coupling occurs in a pair of microstrips according to a switching control input indicating any one of frequency bands corresponding to a plurality of variable amplifiers. Change to a quarter wavelength of the signal in the indicated frequency band. The selection means selectively inputs the output of the variable amplifier corresponding to the frequency band indicated by the switching control input to the main line which is one of the pair of microstrips. The detection means detects the combined output taken out by the sub-line that is the other of the pair of microstrips. The error detection means inputs the difference between the detection output obtained by the detection means and a predetermined reference value to the variable amplifier as a negative feedback control input.

The operation of the first multiband high-frequency amplifier configured as described above is as follows.
Depending on the switching control input, the coupling length changing means changes the coupling length in the pair of microstrips formed on the printed circuit board to a length suitable for the frequency band indicated by the switching control input. When the output of the variable amplifier corresponding to the switching control input described above is input to the main line by the means, the combined output corresponding to the output of the variable amplifier selectively appears on the sub line, and the detection means and the error detection means Provided for negative feedback control processing.

In this way, by detecting the coupling means in a pair of microstrips having an extension corresponding to the lowest frequency band to realize a directional coupler adapted to a plurality of different frequency bands, the detection means and the error can be realized. It is possible to control a plurality of variable amplifiers by commonly using a negative feedback control function part composed of detection means.
A second multiband high-frequency amplifier according to the present invention is the same as the first multiband high-frequency amplifier described above, wherein a plurality of contacts are provided on the sub-line, and the coupling length changing means includes a termination resistor and a changeover switch. The

The principle of the second multiband high-frequency amplifier according to the present invention is as follows.
In the sub-line which is one of the pair of microstrips provided in the first multiband high-frequency amplifier described above, the plurality of contacts are frequency bands to which the plurality of variable amplifiers are respectively adapted from one end corresponding to the input end of the main line. In the extension corresponding to a quarter wavelength of the signal. In the coupling length changing means, the terminating resistor is adapted to the characteristic impedance of the sub line. The changeover switch short-circuits the contact provided on the sub line and the termination resistor corresponding to the frequency band indicated by the changeover control input.

The operation of the second multiband high-frequency amplifier configured as described above is as follows.
For example, a pair of microstrips having a length corresponding to a quarter wavelength of a signal having a frequency band of 800 MHz is formed, and 4 signals of signals having a frequency band of 5 GHz and 2 GHz are formed from the input end of the microstrip corresponding to the sub line. A contact is provided at a position corresponding to a wavelength of 1 / min. Then, in response to a switching control input indicating any one of these frequency bands, a corresponding contact (for example, a contact corresponding to the frequency band 2 GHz) and a termination resistor are short-circuited by a changeover switch so that a pair of micros The coupling length in the strip can be changed to a length corresponding to the selected frequency band.

In this way, the coupling length of a pair of microstrips having extensions corresponding to the frequency band 800 MHz is changed according to the switching control input, thereby operating as a directional coupler corresponding to the frequency band 2 GHz or the frequency band 5 GHz. Can be made.
The principle of the third multiband high-frequency amplifier according to the present invention is as follows.
In the changeover switch provided in the second multiband high-frequency amplifier described above, a termination resistor is connected to the termination terminal. At least one connection terminal corresponds to each contact provided on the sub-line arranged at an appropriate interval from each other. The switch element integrates a path switching circuit that short-circuits the terminal terminal and the plurality of connection terminals according to the switching control input. The pair of microstrips are arranged in a pattern in which contacts provided on the sub-line corresponding to the plurality of variable amplifiers are arranged corresponding to the arrangement of the connection terminals in the switch element.

The operation of the third multiband high-frequency amplifier configured as described above is as follows.
For example, in the switch elements constituting the changeover switch, when the connection terminals are arranged in a straight line, correspondingly, the contacts provided on the sub line are arranged at the same interval as the corresponding connection terminals. A meander pattern is drawn on the printed circuit board. When a switch element is mounted on a printed circuit board on which such a microstrip is arranged, each connection terminal that is operated to open and close a short circuit path by a path switching circuit integrated in the switch element and a corresponding contact on the sub line are provided. They can be connected directly or with a very simple wiring pattern.

As described above, in the multiband high-frequency amplifier according to the present invention, the coupling length in a pair of microstrips having extensions corresponding to the lowest frequency band is dynamically switched, so that other frequency bands can be used as necessary. It is possible to take out the coupling output necessary for the negative feedback control.
As a result, gain control of multiple variable amplifiers can be realized by a single control function part, and the number of parts constituting a multiband high-frequency amplifier can be greatly reduced to promote downsizing and cost reduction. Can do.

  In particular, the connection terminal of the switch element and the contact provided on the sub line formed as a wiring pattern on the printed circuit board can be connected directly or by an extremely simple wiring pattern by mounting the switch element on the printed circuit board. As a result, the wiring pattern between the elements can be reduced, and the cost required for designing the printed circuit board can also be measured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a first embodiment of a multiband high-frequency amplifier according to the present invention.
1 that are the same as those shown in FIG. 6 are denoted by the same reference numerals as those shown in FIG. 6 and description thereof is omitted.
In the multi-band high-frequency amplifier shown in FIG. 1, it is obtained by a high-frequency amplification function part including variable amplifiers VA1, VA2, and VA3 and power amplifiers PA1, PA2, and PA3 corresponding to each frequency band (for example, 800 MHz, 2 GHz, and 5 GHz). The high-frequency signal is input to the input terminal P1 of the directional coupler 212 via the multiplexer (MUX) 211. The high-frequency signal that has passed through the directional coupler 212 is taken out from the terminal P3 and sent to the duplexer DIS as an output signal of the multiband high-frequency amplifier.

The terminal P4 of the directional coupler 212 shown in FIG. 1 is terminated by the terminator 213, while the coupled output taken out from the terminal P2 is input to the power detector 214. The detection output obtained by the power detector 214 and a predetermined reference voltage V _ref are compared by the error amplifier 215, and the output signal of the error amplifier (EAMP) 215 is used for gain control of the variable amplifiers VA1, VA2, and VA3. It is provided.

  Further, the switching control signal shown in FIG. 1 indicates the frequency band of the modulation signal input to the modulator 401 by the frequency synthesizer 402 shown in FIG. 5, for example. The multiplexer 211 shown in FIG. The output of the power amplifier corresponding to the frequency band indicated by the switching control signal is selected and sent to the directional coupler 212. This switching control signal is also input to the directional coupler 212 and is used for a coupling length changing operation to be described later.

  As shown in FIG. 2, the directional coupler 212 shown in FIG. 1 includes a main line and a sub line which are a pair of microstrips arranged in a meander pattern on a printed circuit board. The extension of the main line and the sub line shown in FIG. 2 corresponds to a quarter wavelength of the signal in the lowest frequency band (for example, 800 MHz) in which the multi-band high-frequency amplifier is compatible. Both ends are connected to terminals P1 and P3 of the directional coupler 212, and both ends of the sub line are similarly connected to terminals P2 and P4.

  Further, on the sub line shown in FIG. 2, a contact C1 is provided at a position corresponding to a quarter wavelength of a signal in a frequency band (for example, 5 GHz) having the highest extension from the terminal P2, and further, A contact C2 is provided at a position corresponding to a quarter wavelength of a signal in a very high frequency band (for example, 2 GHz). Similarly, a contact C3 is also provided at the end point of the sub-line connected to the terminal P4 of the directional coupler 212, and the path between these contacts C1 and C2 and the path between the contacts C2 and C3 are respectively The switch (SW) 1 and the switch (SW) 2 are opened and closed by opening and closing according to the switching control input.

  That is, when both the switch 1 and the switch 2 are opened according to the switching control input, the coupling length between the main line and the sub line in the directional coupler 212 shown in FIG. , That is, a length corresponding to a quarter wavelength of a signal in the frequency band 800 MHz, and conversely, when both the switch 1 and the switch 2 are closed, the coupling length is a signal in the frequency band 5 GHz. The length corresponds to a quarter wavelength. On the other hand, the coupling length when the switch 1 is opened and the switch 2 is closed according to the switching control input is the length from the end point P2 to the contact C2, that is, a quarter of the signal in the frequency band 2 GHz. The length corresponds to the wavelength.

As described above, the opening / connection of the path between the contacts C1, C2, and C3 provided on the sub-line is controlled by opening and closing the two switches 1 and 2 to dynamically change the coupling length, thereby providing a directional coupler. The frequency band to which 212 is applicable can be switched and operated.
In this way, the single directional coupler 212 is operated in the same manner as when three directional couplers each adapted to different frequency bands are selectively operated, and the power of the input high-frequency signal is reduced. The coupled output shown can be taken from terminal P2 of this directional coupler 212 and sent to the power detector 214.

  In the multiband high-frequency amplifier according to the present invention shown in FIG. 1, the directional coupler 212, the power detector 214, and the error amplifier 215 are shared by a plurality of amplification function parts having frequency dependence. As a result, the number of components for configuring the multiband high-frequency amplifier can be greatly reduced as compared with a case where a directional coupler, a power detector, and an error amplifier are provided corresponding to each frequency band. .

The switches 1 and 2 shown in FIG. 2 can be realized by, for example, an FET high-frequency switch element as shown in FIG.
For example, the terminals T1 and T2 shown in FIG. 3 are connected to the contacts C1 and C3 shown in FIG. 2, respectively, the terminal COM shown in FIG. 3 is connected to the contact C2 shown in FIG. 3 is input to the control terminals VCTL1 and VCTL2 shown in FIG. 3, respectively, by switching each bit of the switching control signal indicating the selected frequency band with a 2-bit code, so that the FET1 and FET2 shown in FIG. 2 can be operated.
(Second Embodiment)
FIG. 4 shows an implementation of the directional coupler according to the present invention.

  In the printed wiring board shown in FIG. 4, the main line and the sub line of the directional coupler 212 shown in FIG. 1 are formed by inner layer wiring (shown by lines in FIG. 4), and are shown in FIG. Through holes are provided at the positions of the contacts C1, C2, and C3 on the sub-line. In FIG. 4, the display of the main line is omitted, and only the sub-line is shown. Further, the terminal P4 of the directional coupler 212 and the through hole corresponding to the contact C3 described above are connected by an inner layer wiring as shown by a broken line in FIG.

  The high-frequency FET switch shown in FIG. 3 is mounted on the printed wiring board formed in this way, and terminals T1 and T2 and a common terminal COM of the high-frequency FET switch, and through-holes corresponding to the above-described contacts C1 and C3 and The directional coupler 212 shown in FIG. 2 can be realized by connecting the through hole corresponding to the contact C2 with a wiring pattern as shown by a thick solid line.

  Further, the sub-line meander pattern is arranged so that the contacts C1, C3, C2 provided on the sub-line of the directional coupler 212 are arranged at positions corresponding to the arrangement of the terminals T1, T2, and COM of the high-frequency FET switch. It is also possible to directly connect the terminals T1, T2, and COM corresponding to the high-frequency FET switch to the through holes that are adjusted and provided corresponding to the contacts C1, C3, and C2.

As described above, in the multiband high-frequency amplifier according to the present invention, the directional coupler and the gain control function part can be shared between the high-frequency amplification functions corresponding to a plurality of frequency bands, thereby allowing a plurality of different frequencies. It is possible to greatly reduce the number of parts constituting the multiband high-frequency amplifier that switches and transmits the high-frequency signal of the band.
As a result, in the fields of mobile communication terminals and wireless LAN communication terminals typified by mobile phones, both the addition of functions for multi-band compatibility and the demand for downsizing and cost reduction for these wireless communication devices Therefore, it is extremely useful in the field of wireless communication equipment.

It is a figure which shows embodiment of the multiband high frequency amplifier concerning this invention. It is a figure which shows the detailed structure of a directional coupler. It is explanatory drawing of a FET high frequency switch element. It is a figure which shows the mounting form of the directional coupler concerning this invention. It is a figure which shows the structural example of a radio | wireless transmission part. It is a figure which shows the structural example of a high frequency amplifier. It is explanatory drawing of a directional coupler.

Explanation of symbols

211, 403 Multiplexer (MUX)
212, 411, 421, 431 Directional coupler 213 Terminator 214 Power detector 215 Error amplifier (EAMP)
410, 420, 430 High-frequency amplifier 401 Modulator 402 Frequency synthesizer 404 Demultiplexer 405 Antenna

Claims (3)

A plurality of variable amplifiers for amplifying input signals modulated in different frequency bands with gains corresponding to negative feedback control inputs;
Formed as a wiring pattern on a printed circuit board on which the plurality of variable amplifiers are mounted, these variable amplifiers have an extension of a quarter wavelength of the signal in the lowest frequency band in which the variable amplifiers are compatible, and electromagnetically mutually A pair of microstrips arranged in close proximity with a field-coupled distance;
The frequency indicated by the switching control input indicates the length of a section where electromagnetic coupling occurs in the pair of microstrips in response to the switching control input indicating one of the frequency bands corresponding to the plurality of variable amplifiers. A coupling length changing means for changing to a quarter wavelength of the band signal;
Selection means for selectively inputting an output of the variable amplifier corresponding to a frequency band indicated by the switching control input to a main line which is one of the pair of microstrips;
Detecting means for detecting a combined output taken out by a sub-line which is the other of the pair of microstrips;
A multiband high-frequency amplifier comprising: error detection means for inputting a difference between a detection output obtained by the detection means and a predetermined reference value to the variable amplifier as the negative feedback control input. The multiband high-frequency amplifier according to claim 1,
The sub-line, which is one of the pair of microstrips, extends from one end corresponding to the input end of the main line to the quarter wavelength of the signal in the frequency band to which the plurality of variable amplifiers respectively fit. Each with a contact point,
The coupling length changing means is
A terminating resistor adapted to the characteristic impedance of the sub-line;
A multiband high-frequency amplifier, comprising: a selector switch that short-circuits a contact provided on the sub-line and the termination resistor corresponding to the frequency band indicated by the switching control input. The multiband high-frequency amplifier according to claim 2,
The changeover switch is
A termination terminal to which the termination resistor is connected;
A connection terminal corresponding to each contact provided on the sub-line arranged at an appropriate interval from each other;
A switching element in which a path switching circuit that short-circuits the termination terminal and the plurality of connection terminals according to the switching control input is integrated,
The pair of microstrips is arranged in a pattern in which contacts provided on the sub-line corresponding to the plurality of variable amplifiers are arranged corresponding to the arrangement of connection terminals in the switch element. A multiband high-frequency amplifier characterized.

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