JP2009118254A - High frequency signal output circuit - Google Patents

Abstract

A high-frequency signal output circuit that realizes optimum impedance satisfying both low power consumption and low distortion by extending the degree of freedom of matching, further suppressing induction of 1/2 oscillation and reducing noise characteristics of high-frequency signals. provide.
In a high-frequency signal output circuit, a high-frequency signal input from a signal input terminal is input to a base of a transistor through a first matching capacitor and a second matching capacitor. The The base bias to the transistor 101 is supplied from the bias circuit 107 via the shunt inductor 103 and the base current adjustment resistor 105. Since the shunt inductor 103 is grounded via a bypass capacitor 106 having a sufficiently large capacitance value, the shunt inductor 103 has a function of releasing a high-frequency signal branched to the shunt inductor 103 to the ground and a DC signal from the bias circuit 107 of the transistor 101. And a function of transmitting to the base.
[Selection] Figure 1

Description

  The present invention relates to a high-frequency signal output circuit, and more particularly to a high-frequency signal output circuit used in a multistage high-frequency power amplifier that amplifies a high-frequency signal.

  As a high-frequency power amplifier using a bipolar transistor, there is a multi-stage high-frequency power amplifier used in a transmission unit such as a portable terminal (see Non-Patent Document 1). 6A is a circuit diagram of a high-frequency signal output circuit 60 used in an interstage portion of a conventional multistage high-frequency power amplifier, and FIG. 6B is used in a first stage portion (hereinafter referred to as a driver stage) of the conventional multistage high-frequency power amplifier. 3 is a circuit diagram of a high-frequency signal output circuit 61. FIG.

  As shown in FIG. 6A, in the high-frequency signal output circuit 60 used in the interstage portion of the conventional multi-stage high-frequency power amplifier, the high-frequency signal amplified by the transistor 601 in the driver stage is passed through the matching capacitor 603 to the power stage. Input to the base terminal 607 of the transistor 602. A base bias to the base terminal 607 of the power stage transistor 602 is supplied from the bias circuit 604 via the base current adjustment resistor 605. Thus, the high-frequency signal amplified by the driver stage transistor 601 is further amplified by the power stage transistor 602.

  On the other hand, as shown in FIG. 6B, in the high-frequency signal output circuit 61 used in the driver stage of the conventional multi-stage high-frequency power amplifier, the high-frequency signal input from the signal input terminal 610 includes the first matching capacitor 616 and the first matching capacitor 616. The signal is input to the base terminal 615 of the driver stage transistor 611 via the second matching capacitance 612. The base bias to the base terminal 615 of the driver stage transistor 611 is supplied from the bias circuit 613 via the base current adjustment resistor 614. Thus, the high frequency signal input from the signal input terminal 610 is amplified by the driver stage transistor 611. A grounded shunt inductor 617 is connected to a connection point between the first matching capacitor 616 and the second matching capacitor 612. The first matching capacitor 616, the second matching capacitor 612, and the shunt inductor 617 constitute a matching circuit unit 618.

As described above, the high-frequency signal output circuits 60 and 61 shown in FIGS. 6A and 6B constitute a multistage high-frequency power amplifier, and a high-frequency signal is amplified.
Yoshihiro Konishi, edited by Kazuhiko Honjo, “Practical Microwave Technology Course Integrated Circuits and Applications (Volume 6)”, Kay Lab Publishing, Nikkan Kogyo Shimbun, June 25, 2002, p. 91, 119-122

  However, the matching circuit of the high-frequency signal output circuit 60 used in the interstage portion of the above-described conventional multi-stage high-frequency power amplifier is a simple configuration including only the inductor 606 on the collector bias line of the driver stage transistor 601 and the matching capacitor 603. Circuit. For this reason, it is difficult to finely adjust the matching of the high frequency signal input to the base terminal 607 of the power stage transistor 602. Further, when the communication data rate is high as in the current mobile terminal communication system, the power amplifier used in the mobile phone is required to have not only low power consumption characteristics but also low distortion characteristics. For this reason, the conventional simple matching circuit as described above has a low degree of freedom, and it has been difficult to realize an optimum impedance satisfying low power consumption and low distortion. In order to improve the gain performance in the power amplifier, it is generally sufficient to use a large capacity capacitor as the matching capacitor 603. However, when a large-capacitance capacitor is used as the matching capacitor 603, the gain performance not only in the high band but also in the low band is improved, so that there is a problem that 1/2 oscillation is easily induced.

  On the other hand, in the high-frequency signal output circuit 61 used in the driver stage of the conventional multi-stage high-frequency power amplifier described above, the DC signal path from the bias circuit 613 and the high-frequency signal path are not sufficiently separated, and the bias circuit 613 generates the signal. There is a problem that low-frequency DC signals are mixed in the high-frequency signal path, resulting in poor noise characteristics. The high-frequency signal output circuit 60 used in the interstage portion of the conventional multistage high-frequency power amplifier also has a problem that the noise characteristics are similarly deteriorated.

  Therefore, an object of the present invention is to expand the degree of freedom of matching, realize an optimum impedance satisfying low power consumption and low distortion, further suppress induction of 1/2 oscillation, and reduce noise characteristics of high-frequency signals. A high frequency signal output circuit is provided.

  In order to achieve the above object, a first high-frequency signal output circuit of the present invention is a high-frequency signal output circuit including a matching circuit for matching a high-frequency signal and a bias circuit, one end connected to a signal input end First matching capacitor, a second matching capacitor having one end connected to the other end of the first matching capacitor, and a first matching capacitor and a second matching capacitor having one end connected to the other end of the first matching capacitor An inductor connected to the connection point of the transistor, a base connected to the other end of the second matching capacitor, an emitter connected to the ground, one end connected to the other end of the inductor, and the other end grounded Bypass capacitor, a base current adjusting resistor connected in parallel with the second matching capacitor, and a bias for supplying a bias voltage to the connection point between the inductor and the bypass capacitor And a road, the bias voltage supplied from the bias circuit via an inductor and a base current regulation resistor, and wherein the input to the base of the transistor.

  A preferred first high-frequency signal output circuit is inserted between the inductor and the bypass capacitor, and has an input terminal connected to the other end of the inductor, a first output terminal connected to one end of the bypass capacitor, When the switch element having two output ends and the input end and the first output end are connected to the switch element, the bias circuit is turned on, and the input end and the second output end are connected to the switch element. A control unit that turns off the bias circuit.

  The second high-frequency signal output circuit of the present invention is a high-frequency signal output circuit including a matching circuit for matching a high-frequency signal and a bias circuit, the first matching having one end connected to the signal input end. And a plurality of second matching capacitors having one end connected to the other end of the first matching capacitor, and one end having a first matching capacitor and a plurality of second matching capacitors. An inductor connected to the connection point; a base connected to the other end of each of the plurality of second matching capacitors; a plurality of transistors connected to the common signal output terminal; A bypass capacitor having one end connected to the other end of the inductor and the other end grounded; a plurality of base current adjusting resistors connected in parallel with each of the plurality of second matching capacitors; A bias circuit for supplying a bias voltage to the connection point between the inductor and the bypass capacitor, and the bias voltage supplied from the bias circuit is applied to the bases of a plurality of transistors via an inductor and a plurality of base current adjusting resistors. It is input.

  A preferred second high-frequency signal output circuit is inserted between the inductor and the bypass capacitor, and has an input terminal connected to the other end of the inductor, a first output terminal connected to one end of the bypass capacitor, When the switch element having two output ends and the input end and the first output end are connected to the switch element, the bias circuit is turned on, and the input end and the second output end are connected to the switch element. A control unit that turns off the bias circuit.

  As described above, according to the high-frequency signal output circuit of the present invention, an optimum impedance satisfying low power consumption and low distortion is realized by expanding the degree of freedom of matching, and further, induction of 1/2 oscillation is suppressed, It becomes possible to reduce the noise characteristics of the high-frequency signal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a circuit diagram of a high-frequency signal output circuit 10 according to the first embodiment of the present invention. As shown in FIG. 1, in the high-frequency signal output circuit 10, one end of a first matching capacitor 102 is connected to a signal input end 100, and a second matching capacitor is connected to the other end of the first matching capacitor 102. One end of the transistor 104 is connected, and the base of the transistor 101 is connected to the other end of the second matching capacitor 104. The emitter of the transistor 101 is grounded. One end of the shunt inductor 103 is connected to a connection point between the first matching capacitor 102 and the second matching capacitor 104. The other end of the shunt inductor 103 is grounded via a bypass capacitor 106 having a sufficiently large capacitance value. A bias circuit 107 that supplies a bias voltage is connected to a connection point 108 between the shunt inductor 103 and the bypass capacitor 106. Further, a base current adjusting resistor 105 is connected in parallel with the second matching capacitor 104.

  In the high-frequency signal output circuit 10, the high-frequency signal input from the signal input terminal 100 is input to the base of the transistor 101 via the first matching capacitor 102 and the second matching capacitor 104. The base bias to the transistor 101 is supplied from the bias circuit 107 via the shunt inductor 103 and the base current adjustment resistor 105. Thus, the high frequency signal input from the signal input terminal 100 is amplified by the transistor 101.

  Here, the shunt inductor 103 is grounded via a bypass capacitor 106 having a sufficiently large capacitance value. As a result, the connection point 108 between the shunt inductor 103 and the bypass capacitor 106 is short in terms of alternating current, so that the high-frequency signal branched to the shunt inductor 103 is released to the ground. On the other hand, since the connection point 108 is open in terms of direct current, the direct current signal from the bias circuit 107 flows to the shunt inductor 103 side, and further to the base terminal 109 of the transistor 101 via the base current adjustment resistor 105. Entered. As described above, the shunt inductor 103 of the high-frequency signal output circuit 10 shown in FIG. It has the function to do.

  The conventional high-frequency signal output circuit 60 shown in FIG. 6A is configured to perform interstage coupling using only the matching capacitor 603. However, in the high-frequency signal output circuit 10 of the present invention, the first matching capacitor 102, the second matching capacitor 104, and the shunt inductor 103 constitute a matching circuit (hereinafter referred to as a CLC matching circuit). Therefore, when the high-frequency signal output circuit 10 is used in an interstage portion of a multistage high-frequency power amplifier, the degree of freedom in matching is higher than that of the conventional high-frequency signal output circuit 60 shown in FIG. 6A. Furthermore, since the degree of freedom of matching is increased, the impedance of the high-frequency signal output circuit 10 can be easily adjusted to an optimum impedance range that satisfies low power consumption and low distortion.

  Furthermore, according to the configuration of the high-frequency signal output circuit 10 of the present invention, the low-band pass characteristic can be suppressed, so that there is an effect that the oscillation resistance can be improved. FIG. 2 is a diagram showing pass characteristics S21 between the conventional high-frequency signal output circuit 60 shown in FIG. 6A and the high-frequency signal output circuit 10 of the present invention. In FIG. 2, the pass characteristic A indicated by a broken line is the pass characteristic S21 of the conventional high-frequency signal output circuit 60, and the pass characteristic B indicated by the solid line is the pass characteristic S21 of the high-frequency signal output circuit 10 of the present invention. . fo is a fundamental frequency, and ½fo is a ½ frequency. In the high-frequency signal output circuit 10 of the present invention, the suppression of the pass characteristic S21 at 1/2 frequency is improved. The conventional high-frequency signal output circuit 60 includes the inductor 606 in the collector bias line of the driver stage transistor 601, but only the matching capacitor 603 is configured between the stages. On the other hand, the high-frequency signal output circuit 10 of the present invention forms a CLC matching circuit in the interstage portion. For this reason, the high-frequency signal output circuit 10 of the present invention can suppress the induction of 1/2 oscillation by the function of the shunt inductor 103 of the CLC matching circuit suppressing the low-band pass characteristic.

  On the other hand, when the high-frequency signal output circuit 10 of the present invention is used in the driver stage of a multistage high-frequency power amplifier, the low-frequency DC signal from the bias circuit 107 is suppressed by the shunt inductor 103 and the bypass capacitor 106. Therefore, low frequency DC signals generated by the bias circuit 107 are not mixed in the high frequency signal path, and noise characteristics can be improved.

  As described above, according to the high-frequency signal output circuit 10 according to the first embodiment of the present invention, an optimum impedance satisfying low power consumption and low distortion is realized by expanding the degree of freedom of matching, (2) Induction of oscillation can be suppressed and noise characteristics of the high frequency signal can be reduced.

(Second Embodiment)
FIG. 3A is a circuit diagram of the high-frequency signal output circuit 30 according to the second embodiment of the present invention. The high-frequency signal output circuit 30 shown in FIG. 3A has a configuration in which a switch element 300 and a control unit 303 are added to the high-frequency signal output circuit 10 according to the first embodiment shown in FIG. In the high-frequency signal output circuit 30 shown in FIG. 3A, the same components as those shown in FIG.

  As shown in FIG. 3A, in the high-frequency signal output circuit 30, the switch element 300 has an input terminal a connected to the shunt inductor 103, one output terminal b connected to the bypass capacitor 106, and the other output terminal c connected to the branch output. It is connected to the terminal 301. The switch element 300 connects the input terminal a to either the output terminal b on the bypass capacitor 106 side or the output terminal c on the branch output terminal 301 side. The control unit 303 controls the switching operation of the switch element 300 and the on / off operation of the bias circuit 107 according to the output power required for the output signal from the high-frequency signal output circuit 30. FIG. 3B is a diagram illustrating operations of the switch element 300 and the bias circuit 107 at the time of high output and at the time of low output.

  When the output power is set to high output, the control unit 303 connects the switch element 300 to the output terminal b and the bias circuit 107 is turned on by the control unit 303. In this case, as described in the first embodiment, the high-frequency signal input from the signal input terminal 100 is amplified by the transistor 101 by being supplied with a bias by the bias circuit 107 and output from the normal output terminal 302. The Although the switch element 300 has a certain amount of insertion loss, it is not inserted in series in the high-frequency signal path, so that when the high-frequency signal input from the signal input terminal 100 is amplified, the switch element 300 There is no effect of insertion loss.

  At the time of low output where the output power is set to low output, the control unit 303 causes the switch element 300 to connect the input terminal a to the output terminal c, and the bias circuit 107 is turned off. As a result, the high frequency signal input from the signal input terminal 100 is branched to the shunt inductor 103 side and output as it is from the branch output terminal 301.

  Thus, the control unit 303 causes the switching operation of the switch element 300 and the on / off operation of the bias circuit 107 to be linked. Accordingly, the high-frequency signal output circuit 30 amplifies the high-frequency signal input from the signal input terminal 100 by the transistor 101 and outputs the high-frequency signal, and the high-frequency signal input from the signal input terminal 100 without driving the transistor 101. Can be realized in a two-stage mode including a low-output mode that outputs the signal as it is.

  When output control is possible according to the distance from the base station, such as a mobile phone terminal, it is possible to reduce power consumption by using an optimum circuit configuration corresponding to the magnitude of output power.

  As described above, according to the high-frequency signal output circuit 30 according to the second embodiment of the present invention, an optimum circuit configuration corresponding to the magnitude of the output power can be realized, and the power consumption of the portable terminal can be reduced. Has an effect.

(Third embodiment)
FIG. 4 is a circuit diagram of the high-frequency signal output circuit 40 according to the third embodiment of the present invention. The high-frequency signal output circuit 40 shown in FIG. 4 has the high-frequency signal output circuit 10 according to the first embodiment shown in FIG. 1 arranged in the driver stage, and the high-frequency signal output according to the second embodiment shown in FIG. 3A. It is a circuit diagram of the multistage high frequency power amplifier which has arrange | positioned the circuit 30 in the interstage part. In the high-frequency signal output circuit 40 shown in FIG. 4, the same components as those shown in FIGS. 1 and 3A are denoted by the same reference numerals, and the description thereof is omitted. However, the first matching capacitor, the transistor, the second matching capacitor, the shunt inductor, the bypass capacitor, the bias circuit, and the base current adjusting resistor are included in the first matching capacitor 102a and the transistor 101a in the driver stage. , Second matching capacitor 104a, shunt inductor 103a, bypass capacitor 106a, bias circuit 107a, and base current adjustment resistor 105a. In the interstage portion, the first matching capacitor 102b, the transistor 101b, the second matching capacitor 104b, the shunt inductor 103b, the bypass capacitor 106b, the bias circuit 107b, and the base current adjustment resistor 105b are used. Note that an inductor 400 is provided in the collector bias line of the transistor 101a in the driver stage.

  In the high-frequency signal output circuit 40 shown in FIG. 4, the control unit 303 controls the switching element 300 according to the output power required for the output signal from the high-frequency signal output circuit 40 as described in the second embodiment. The switching operation and the on / off operation of the bias circuit 107b are controlled.

  When the output power is set to a high output level, the control unit 303 causes the switch element 300 to connect the input terminal a to the output terminal b, and the bias circuit 107b is turned on. In this case, the high-frequency signal amplified in the driver stage is further amplified by the interstage transistor 101b and output from the normal output terminal 302.

  At the time of low output where the output power is low, the control unit 303 causes the switch element 300 to connect the input terminal a to the output terminal c, and the bias circuit 107b is turned off. In this case, the high-frequency signal amplified in the driver stage is branched to the shunt inductor 103b side and output as it is from the branch output terminal 301.

  As described above, in the interstage portion of the multistage high-frequency power amplifier, the control unit 303 causes the switching operation of the switch element 300 and the on / off operation of the bias circuit 107b to be linked. As a result, the high-frequency signal output circuit 40 has a high-output mode that is a configuration of a multi-stage high-frequency power amplifier that amplifies the high-frequency signal amplified in the driver stage by the inter-stage transistor 101b and outputs the amplified signal. It is possible to realize a two-stage mode including a low output mode in which the high frequency signal amplified in the driver stage is output as it is without driving the transistor 101b.

  As described above, according to the high-frequency signal output circuit 40 according to the third embodiment of the present invention, a high-frequency signal can be amplified by the multistage high-frequency power amplifier, and the degree of freedom of matching is expanded to reduce power consumption and low power. An optimum impedance satisfying the distortion can be realized, and further, induction of ½ oscillation can be suppressed and noise characteristics of the high frequency signal can be reduced. In addition, when output control is possible according to the distance from the base station, such as a mobile phone terminal, an optimal circuit configuration can be realized according to the magnitude of the output power, and the low power consumption of the mobile terminal It is more effective in making it easier.

(Fourth embodiment)
FIG. 5 is a circuit diagram of a high-frequency signal output circuit 50 according to the fourth embodiment of the present invention. A high-frequency signal output circuit 50 shown in FIG. 5 includes a transistor 101, a second matching capacitor 104, and a base current adjustment resistor 105 of the high-frequency signal output circuit 10 according to the first embodiment shown in FIG. A plurality of transistors 500, a second matching capacitor 502, and a base current adjustment resistor 503 are configured. In the high-frequency signal output circuit 50 shown in FIG. 5, the same components as those shown in FIG.

  In the plurality of transistors 500, the collector electrodes are commonly connected to the signal output terminal 501 and the emitter electrodes are grounded. The plurality of transistors 500 synthesize high-frequency signals by parallel synthesis. However, when bipolar transistors are used as the plurality of transistors 500, current is locally concentrated in any one of the transistors 500 due to nonuniform operation, and a thermal runaway phenomenon occurs.

  In order to prevent this thermal runaway phenomenon, unit cells 504 are configured and synthesized in parallel. The unit cell 504 is configured by connecting a second matching capacitor 502 and a base current adjusting resistor 503 to one transistor 500. Thus, since the second matching capacitor 502 and the base current adjusting resistor 503 are provided one by one in one unit cell 504, the base current to each transistor 500 can be suppressed.

  As described above, according to the high-frequency signal output circuit 50 according to the fourth embodiment of the present invention, the plurality of transistors 500 can operate uniformly and can prevent thermal runaway in which current is locally concentrated, and can withstand breakdown. Has an effect on sex.

  The circuit technology of the present invention realizes a circuit excellent in low power consumption characteristics, low distortion characteristics, and noise characteristics, and can be used for a high frequency power amplifier or the like. Further, since it can be used for the power mode switching function, it can be used for a power amplifier of a transmission unit of a cellular mobile terminal that needs to control its output according to the distance between the mobile terminal and the base station.

1 is a circuit diagram of a high-frequency signal output circuit according to a first embodiment of the present invention. Diagram showing pass characteristics of high-frequency signal output circuit The circuit diagram of the high frequency signal output circuit concerning a 2nd embodiment of the present invention. The figure which shows the switching operation | movement which concerns on the 2nd Embodiment of this invention. Circuit diagram of high-frequency signal output circuit according to third embodiment of the present invention Circuit diagram of a high-frequency signal output circuit according to a fourth embodiment of the present invention Circuit diagram of interstage in conventional power amplifier circuit technology Circuit diagram of the first stage in conventional power amplifier circuit technology

Explanation of symbols

10, 30, 40, 50, 60, 61 High-frequency signal output circuit 100, 600, 610 Signal input terminal 101, 101a, 101b, 500, 601, 602, 611 Transistor 102, 102a, 102b, 616 First matching capacitor 103, 103a, 103b, 400, 606, 617 Inductors 104, 104a, 104b, 502, 612 Second matching capacitors 105, 105a, 105b, 503, 605, 614 Base current adjusting resistors 106, 106a, 106b Bypass capacitors 107, 107a, 107b, 604, 613 Bias circuit 108 Bias circuit connection points 109, 607, 615 Transistor base terminal 300 Switch element 301 Branch output terminal 302 Normal output terminal 303 Control unit 501 Signal output terminal 5 04 unit cell 603 matching capacitor 618 matching circuit part A, B pass characteristic S21
a, b, c switch terminals

Claims (4)

A high-frequency signal output circuit including a matching circuit for matching a high-frequency signal and a bias circuit,
A first matching capacitor having one end connected to the signal input end;
A second matching capacitor having one end connected to the other end of the first matching capacitor;
An inductor having one end connected to a connection point between the first matching capacitor and the second matching capacitor;
A transistor having a base connected to the other end of the second matching capacitor and an emitter grounded;
A bypass capacitor having one end connected to the other end of the inductor and the other end grounded;
A base current adjusting resistor connected in parallel with the second matching capacitor;
A bias circuit for supplying a bias voltage to a connection point between the inductor and the bypass capacitor;
The high-frequency signal output circuit according to claim 1, wherein the bias voltage supplied from the bias circuit is input to a base of the transistor via the inductor and the base current adjusting resistor. An input end inserted between the inductor and the bypass capacitor and connected to the other end of the inductor, a first output end connected to one end of the bypass capacitor, and a second output end Having a switch element;
When the switch element is connected to the input terminal and the first output terminal, the bias circuit is turned on, and when the switch element is connected to the input terminal and the second output terminal, The high-frequency signal output circuit according to claim 1, further comprising a control unit that turns off the bias circuit. A high-frequency signal output circuit including a matching circuit for matching a high-frequency signal and a bias circuit,
A first matching capacitor having one end connected to the signal input end;
A plurality of second matching capacitors having one end connected to the other end of the first matching capacitor;
An inductor having one end connected to a connection point between the first matching capacitor and the plurality of second matching capacitors;
A plurality of transistors having a base connected to the other end of each of the plurality of second matching capacitors, an emitter grounded, and a collector connected to a common signal output end;
A bypass capacitor having one end connected to the other end of the inductor and the other end grounded;
A plurality of base current adjusting resistors connected in parallel with each of the plurality of second matching capacitors;
A bias circuit for supplying a bias voltage to a connection point between the inductor and the bypass capacitor;
The high-frequency signal output circuit, wherein the bias voltage supplied from the bias circuit is input to the bases of the plurality of transistors via the inductor and the plurality of base current adjustment resistors. An input end inserted between the inductor and the bypass capacitor and connected to the other end of the inductor, a first output end connected to one end of the bypass capacitor, and a second output end Having a switch element;
When the switch element is connected to the input terminal and the first output terminal, the bias circuit is turned on, and when the switch element is connected to the input terminal and the second output terminal, The high-frequency signal output circuit according to claim 3, further comprising a controller that turns off the bias circuit.

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