JP4504326B2 - High frequency amplifier circuit - Google Patents

Description

  The present invention relates to a semiconductor device, and more particularly to a bipolar transistor and a high-frequency amplifier circuit including a bipolar transistor.

  Currently, mobile communication power amplifiers include GaAs-MESFETs (Metal Semiconductor Field Effect Transistors), GaAs-HEMTs (High Electron Mobility Transistors), heterojunction bipolar transistors (HBTs), and the like as amplification elements. It is used. In particular, the heterojunction bipolar transistor (hereinafter simply referred to as HBT) can be operated as a single positive power supply because it does not require a negative power supply, compared with a GaAs-MESFET, and (2) a collector current density is increased. As a result, the chip size can be reduced.

  In general, in a bipolar transistor, when the temperature of the element rises, the on-voltage of the base-emitter voltage (hereinafter, the base-emitter voltage is sometimes abbreviated as Vbe and the base-emitter on-voltage is abbreviated as Vf) may decrease. Therefore, it is known that the collector current increases. For this reason, in the high-frequency power amplifier having a plurality of transistors, when the collector current is concentrated, the temperature of the local element rises due to the increase in power consumption, which further increases the collector current in the local element. It falls into a vicious circle. Therefore, if the current between the transistors becomes uneven, it not only adversely affects the performance and life of the power amplifier, but also concentrates the current further, which may cause the transistor to fall into a state of thermal runaway and break down. .

  For such a problem, a base ballast resistor connected to the base of a bipolar transistor and giving negative feedback to the base-emitter voltage (Vbe) with respect to the temperature rise of the element has been used. By this negative feedback of Vbe, an increase in collector current due to temperature rise can be offset and thermal runaway can be prevented. The prior art of the high frequency amplifier circuit using the conventional base ballast resistor is shown below.

  FIG. 19A is an equivalent circuit diagram of a conventional high-frequency amplifier circuit. Bipolar transistors 101-1, 101-2, and 101-n (hereinafter referred to as “101” as representative) are bipolar transistors having n cells. A collector voltage is applied to the collector terminal 115, and the emitter terminal is grounded. A direct current (DC) bias is supplied from a DC terminal 148 and radio frequency (RF) power is input from an RF terminal 149. The DC terminal 148 is connected to the base electrodes 105-1, 105-2, and 105 -n (hereinafter referred to as “105” representatively) of the bipolar transistor 101 via a resistor 147 as a base ballast resistor. . The RF terminal 149 is connected to the base electrode 105 of the bipolar transistor 101 via the capacitor 163. The high frequency power amplified by the bipolar transistor 101 is output from the collector terminal 115.

  FIG. 19B is a diagram showing an outline of the voltage and current at each terminal of FIG. The current amplification factor (hFE) of the bipolar transistor 101 is 50, the number of cells of the bipolar transistor 101 is n = 20, and the resistance value of the resistor 147 is 5Ω. When the total amount of collector current is 1 A and there is no current non-uniformity, for each bipolar transistor 101, the collector current is 50 mA and the base current is 1 mA. The total amount of base current is 20 mA, and the voltage drop caused by the resistor 147 is 0.1V. Therefore, when 1.3 V is applied to the DC terminal 148, 1.2 V is applied to the base electrode 105.

  In FIG. 19, a case where current concentration occurs in an arbitrary bipolar transistor is considered. For example, it is assumed that a collector current of 60 mA corresponding to 1.2 times that of the other bipolar transistor 101-n flows through the bipolar transistor 101-2. At this time, since the hFE of the bipolar transistor 101 is 50, the base current flowing through the resistor 147 increases from 1 mA to 1.2 mA, and the base current flowing through the resistor 147 increases from 20 mA to 20.2 mA. The negative feedback of Vbe generated in the resistor 147 due to the increase in base current (0.2 mA) is 1 mV at most. On the other hand, the junction temperature of bipolar transistor 101-2 rises from the initial 80 ° C. to 90 ° C. due to the increase in current. With this temperature increase (10 ° C.), the on-voltage (Vf) of Vbe decreases by 0.017V. Thus, since the negative feedback (1 mV) of Vbe generated by the resistor 147 is smaller than the decrease of Vf (17 mV) due to the temperature increase, the collector current continues to increase. Specifically, if Vf is reduced by 17 mV and the negative feedback of Vbe is 1 mV, this is equivalent to a decrease in Vf of 16 mV as a whole, and the current flowing through bipolar transistor 101-2 is increased by 60% to 80 mA. Become. Here, when the resistance value of the resistor 147 is increased, the amount of negative feedback of Vbe obtained also increases, but in this case, the voltage drop at the resistor 147 increases even in normal operation, and the required DC is increased. This is not appropriate because the voltage applied to terminal 148 increases.

  As described above, the problem of the conventional high frequency amplifier circuit of FIG. 19 is that the negative feedback voltage of Vbe obtained by the resistor 147 is insufficient to offset the decrease in Vf due to the increase in collector current. When the collector current of the transistor is increased by 20%, the thermal runaway of the bipolar transistor cannot be prevented.

  FIG. 20 is an equivalent circuit diagram of another conventional high-frequency amplifier circuit (see Patent Document 1).

  The difference between the present high-frequency amplifier circuit and the conventional high-frequency amplifier circuit of FIG. 146) are connected to each other. At this time, when the number of cells of the bipolar transistor 101 is n = 20, in order to set the parallel resistance value of the resistor 146 connected between the DC terminal 148 and the base electrode 105 to 5Ω, the individual resistors 146 The resistance value may be set to 100Ω.

  In FIG. 20, a resistor 146 is provided in each bipolar transistor 101. At first glance, it appears that the negative feedback of Vbe by the resistor 146 can be increased, but this is not sufficient effectively. This is because the base electrode 105 of the bipolar transistor 101 is commonly connected by a wiring 145 that transmits a high frequency. As a result, when the current of an arbitrary bipolar transistor (for example, 101-2) increases, supply of the base current that increases with this increases not only from the current passed through the resistor 146-2 but also from other resistors 146-n. Is also performed via the wiring 145. This phenomenon can be understood from the fact that the base electrode 105-2 and the other base electrode 105-n have the same circuit potential.

  As described above, the problem of the conventional high frequency amplifier circuit of FIG. 20 is that the negative feedback voltage of Vbe obtained by the resistor 146 is equivalent to the conventional high frequency amplifier circuit of FIG. It is still insufficient to prevent runaway.

  FIG. 21 is an equivalent circuit diagram of another conventional high-frequency amplifier circuit (see Patent Document 2).

  The difference between this high-frequency amplifier circuit and the conventional high-frequency amplifier circuit of FIG. 20 is that capacitors 150-1, 150-2, and 150-n (hereinafter referred to as “150”) are resistors 146-1 and 150-1, respectively. It is connected in parallel with 146-2 and 146-n. Ideally, the high frequency power passes through the capacitor 150 and is input from the base electrode 105 to the bipolar transistor 101. On the other hand, the DC bias passes through the resistor 146 and is supplied from the base electrode 105 to the bipolar transistor 101. The capacitor 150 needs to be set to a certain large value in order to reduce high frequency loss. When the number of cells of the bipolar transistor 101 is set to n = 20 and the resistance value of the resistor 146 is set to 100Ω, the parallel resistance value of the resistor 146 is 5Ω.

  In this high-frequency amplifier circuit, as in the case of the investigation using the conventional high-frequency amplifier circuit of FIG. 19, it is assumed that a collector current of 60 mA, which is 1.2 times that of the other bipolar transistor 101-n, flows in the bipolar transistor 101-2. To do. Since the hFE of the bipolar transistor 101 is 50, the base current flowing through the resistor 146-2 increases from 1 mA to 1.2 mA. Since the resistor 146 is 100Ω, the negative feedback voltage of Vbe generated by the resistor 146 is 20 mV. On the other hand, the junction temperature of bipolar transistor 101-2 increases from the initial 80 ° C. to 90 ° C. due to the increase in current, and the decrease in Vbe on-voltage (Vf) due to this temperature increase (10 ° C.) becomes 17 mV. In this case, since the negative feedback of Vbe (20 mV) generated by the resistor 146 is larger than the decrease of Vf (17 mV) due to the temperature increase, the collector current starts to decrease. As described above, in this high frequency amplifier circuit, the increase in the collector current can be offset by the negative feedback of Vbe, so that thermal runaway can be prevented.

  However, the problem with the conventional high frequency amplifier circuit of FIG. 21 is that a decrease in gain occurs. This is because a part of the high frequency power input from the RF terminal 149 passes through the resistor 146 and is consumed as heat.

  FIG. 22 is an equivalent circuit diagram of still another conventional high-frequency amplifier circuit (see Patent Document 3).

  The difference between the present high frequency amplifier circuit and the conventional high frequency amplifier circuit of FIG. 21 is that the high frequency power input from the RF terminal 149 is input to the base electrode 105 without passing through the resistor 146. Thereby, a decrease in gain can be avoided.

  However, the problem with the conventional high-frequency amplifier circuit of FIG. 22 is that it is necessary to provide each bipolar transistor 101 with a capacitor 151 for allowing high-frequency power to pass through, so that the layout becomes complicated and the cost increases due to an increase in chip area. That is.

  Further, another problem of the conventional high-frequency amplifier circuit of FIG. 22 is that high-frequency power and DC bias merge at terminals 152-1, 152-2, 152-n (hereinafter referred to as “152” as a representative). In addition, the high-frequency power easily leaks to the DC bias terminal 148, which adversely affects a bias circuit (not shown) for supplying a bias to the DC bias terminal 148. In order to solve this, it is necessary to connect a grounding capacitor to the DC terminal 148. In this case, an increase in the number of components becomes a problem.

FIG. 23A is a cross-sectional view of the structure of the bipolar transistor 101 in the conventional high-frequency amplifier circuit. FIG. 23B is a plan view of the conventional bipolar transistor 101, and the cross-sectional view taken along the alternate long and short dash line AA ′ in FIG. 23 is the cross-sectional view of FIG. However, the emitter wiring 132 is omitted in FIG. 23A, for example, on a substrate 118 made of GaAs, a collector contact layer 117 made of n ⁺ -type GaAs, a collector layer 109 made of n-type GaAs, and a base layer made of p-type GaAs. 108, an emitter layer 111 made of n-type InGaP, and an emitter contact layer 110 made of n-type InGaAs are sequentially formed. An emitter electrode 113 is formed on the emitter contact layer 110, a collector electrode 112 is formed on the collector contact layer 117, and a base electrode 107 is formed on the base layer 108. The p-type GaAs forming the base layer 108 has an impurity concentration of 4 × 10 ¹⁹ cm ⁻³ , a thickness of 80 nm, and a sheet resistance of 250 Ω / sq. In FIG. 23 (b), the emitter electrode 113 is connected to the emitter wiring 132, led out, and connected to the emitter terminal 102. A signal obtained by combining DC and RF is supplied from the terminal 103 to the base electrode 107. In order to improve the high frequency characteristics, the base-emitter resistance 122 needs to be reduced, and the interval 119 between the base electrode 107 and the emitter layer 111 needs to be close. For this reason, when the interval 119 is lengthened, the base-emitter resistance 122 is increased and the negative feedback voltage of Vbe can be increased. On the other hand, the loss of high-frequency power is increased and the high-frequency characteristics are deteriorated.

  Thus, the problem with the conventional bipolar transistor 101 of FIG. 23 is that a combined signal of DC and RF is supplied to the base electrode 107. Therefore, in order to improve the high frequency characteristics, the base-emitter resistor 122 is used. It is necessary to make it small, so that the negative feedback voltage of Vbe cannot be made large.

FIG. 24 is a cross-sectional view of the structure of another bipolar transistor in the conventional high-frequency amplifier circuit. The difference between this bipolar transistor and the conventional bipolar transistor 101 of FIG. 23 is that two mesa-formed emitter layers 111 and three base electrodes 107 are formed on the base layer 108. In general, a bipolar transistor having a plurality of emitter layers is called a multi-finger type bipolar transistor. Even in a multi-finger type bipolar transistor, it is necessary to reduce the base-emitter resistance 122 in order to improve high-frequency characteristics, and it is necessary to make the distances 119-1 to 119-4 between the base electrode 107 and the emitter layer 111 closer. It is said. At this time, the base-emitter spacings 119-1 to 119-4 are designed to have the same length.
US Pat. No. 6,828,816 US Pat. No. 5,321,279 US Pat. No. 5,629,648

  The problem of the conventional high-frequency amplifier circuit of FIG. 19 is that the negative feedback voltage of Vbe obtained by the resistor 147 is insufficient to offset the decrease in Vf due to the increase in collector current. The thermal runaway of this bipolar transistor cannot be prevented when it is increased by 20%.

  The problem of the conventional high frequency amplifier circuit of FIG. 20 is that the negative feedback voltage of Vbe obtained by the resistor 146 is equivalent to the conventional high frequency amplifier circuit of FIG. 19 to prevent thermal runaway of the bipolar transistor. It is not enough.

  The problem with the conventional high-frequency amplifier circuit of FIG. 21 is that a decrease in gain occurs. This is because a part of the high frequency power input from the RF terminal 149 passes through the resistor 146 and is consumed as heat.

  The problem of the conventional high-frequency amplifier circuit of FIG. 22 is that capacitors 151 for passing high-frequency power need to be provided in each bipolar transistor, and the layout becomes complicated, so that the cost increases due to the increase in chip area. .

  In addition, since the high frequency power and the DC bias are combined at the terminal 152, the high frequency power is likely to leak to the DC bias terminal 148, which may adversely affect a bias circuit (not shown) for supplying a bias to the DC terminal 148. It was a challenge. In order to solve this, it is necessary to connect a capacitor for grounding to the DC terminal 148. In this case, an increase in the number of components has been a problem.

  The conventional bipolar transistor 101 shown in FIGS. 23 and 24 has a problem that a combined signal of DC and RF is supplied to the base electrode 107, so that the base-emitter resistance 122 is reduced in order to improve the high frequency characteristics. Therefore, the negative feedback voltage of Vbe cannot be increased.

  From the above, in the conventional bipolar transistor, when trying to prevent thermal runaway, the high frequency characteristics deteriorate, the gain in the high frequency amplifier circuit decreases, the cost of the high frequency amplifier circuit increases, or the high frequency The bias circuit of the amplifier circuit is adversely affected. That is, the high frequency amplifier circuit is adversely affected.

  In view of the above problems, an object of the present invention is to provide a bipolar transistor and a high-frequency amplifier circuit that can prevent thermal runaway without adversely affecting the high-frequency amplifier circuit.

  The bipolar transistor of the present invention includes a first terminal, a second terminal, a first base electrode connected to the first terminal, and a second base electrode connected to the second terminal. And a base layer connected to the first base electrode and the second base electrode.

  The present invention also includes a first terminal, a second terminal, a first base electrode connected to the first terminal, a second base electrode connected to the second terminal, A high-frequency amplifier circuit including a bipolar transistor including a first base electrode and a base layer connected to the second base electrode may be provided.

  Thereby, a high frequency signal and a direct current bias can be supplied to separate terminals, and they can be synthesized in the base layer. As a result, there is no need to provide a DC-cut coupling capacitor, and thermal runaway can be prevented without increasing the cost of the high-frequency amplifier circuit. Further, since it is not necessary to provide a resistor between the input terminal of the high frequency signal and the base electrode, thermal runaway can be prevented without reducing the gain in the high frequency amplifier circuit. Further, since leakage of the high frequency signal to the DC bias terminal can be prevented, thermal runaway can be prevented without adversely affecting the bias circuit of the high frequency amplifier circuit. Furthermore, in order to prevent thermal runaway, there is no need to provide a grounding capacitor that suppresses the flow of high-frequency components into the DC bias circuit, so thermal runaway can be prevented without increasing the number of components. Moreover, since the distance from the electrode to which the high-frequency signal is input to the emitter electrode and the distance from the electrode to which the DC bias is input to the emitter electrode can be changed, thermal runaway can be prevented without deteriorating the high-frequency characteristics. Can do. That is, thermal runaway can be prevented without adversely affecting the high frequency amplifier circuit.

  Here, a DC bias is supplied to the first terminal, a high-frequency signal is supplied to the second terminal, and the DC bias and the high-frequency signal may be combined in the base layer.

  In operation, the DC potential of the second base electrode may be lower than the DC potential of the first base electrode.

  Furthermore, the bipolar transistor further includes an emitter electrode positioned between the first base electrode and the second base electrode, and a distance from the emitter electrode to the second base electrode is the emitter electrode. To the first base electrode may be substantially closer than the distance from the first base electrode.

  As a result, the negative feedback effect can be increased without sacrificing the high frequency characteristics, so that the thermal runaway of the bipolar transistor can be reliably prevented without adversely affecting the high frequency amplifier circuit.

  According to the present invention, thermal runaway can be prevented even when a collector current 1.2 times that of another bipolar transistor flows through an arbitrary bipolar transistor. Further, it is possible to eliminate a decrease in high frequency gain when trying to prevent thermal runaway. In addition, it is possible to facilitate layout while preventing thermal runaway, and to prevent an increase in cost due to an increase in chip area. In addition, it is possible to prevent the adverse effect of the bias circuit when trying to prevent runaway. In addition, it is possible to prevent an increase in the number of parts when trying to prevent runaway. In addition, it is possible to prevent deterioration of high frequency characteristics when trying to prevent runaway. That is, it is possible to provide a bipolar transistor and a high frequency amplifier circuit capable of preventing thermal runaway without adversely affecting the high frequency amplifier circuit.

  Hereinafter, a high-frequency amplifier circuit according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1A is a structural cross-sectional view of the transistor 1 in the high-frequency amplifier circuit of the present embodiment. FIG. 1B is a structural plan view of the transistor 1 of the present embodiment, and FIG. 1A is a cross-sectional view taken along one-dot chain line aa ′ in FIG. However, in FIG. 1A, the emitter wiring 20 is omitted. 1A is different from the cross-sectional view of the conventional bipolar transistor 101 in FIG. 23A in that a DC terminal 3 to which a direct current (DC) bias is supplied and high frequency (RF) power are supplied. That is, the RF terminal 4 is provided separately. That is, DC bias and RF power are supplied to the base layer 8 from different electrodes (DC base electrode 6 and RF base electrode 7, respectively), and a further essential difference is the DC base electrode 6. The RF base electrode 7 is electrically connected only through the base layer 8. At this time, by making the potential of the DC base electrode 6 higher than the potential of the RF base electrode 7, it is promised that the base current is always supplied from the DC base electrode 6 connected to the ballast resistor. Effective against thermal runaway. The DC terminal 3 and the RF terminal 4 are examples of the first terminal and the second terminal of the present invention, respectively, and the DC base electrode 6 and the RF base electrode 7 are respectively the first base electrode and the RF terminal 4 of the present invention. It is an example of the 2nd base electrode.

The bipolar transistor 1 shown in FIG. 1 is an HBT. On a substrate 18 made of GaAs, a collector contact layer 17 made of n ⁺ -type GaAs, a collector layer 9 made of n-type GaAs, and p-type GaAs. A base layer 8, an emitter layer 11 made of n-type InGaP, and an emitter contact layer 10 made of n-type InGaAs are sequentially formed. An emitter electrode 13 is formed on the emitter contact layer 10, a collector electrode 12 is formed on the collector contact layer 17, a base electrode 6 for direct current (DC) and a base electrode 7 for high frequency (RF) are formed on the base layer 8. Is formed. The p-type GaAs forming the base layer 8 has an impurity concentration of 4 × 10 ¹⁹ cm ⁻³ , a thickness of 80 nm, and a sheet resistance of 250 Ω / sq. Further, the current amplification factor (hFE) of the bipolar transistor 1 using the base layer 8 is 50.

In FIG. 1, the DC bias is supplied to the DC terminal 3 and is supplied from the DC terminal 3 to the DC base electrode 6. The RF power is supplied to the RF terminal 4 and input from the RF terminal 4 to the RF base electrode 7. The collector voltage is supplied to the collector terminal 5 and is supplied from the collector terminal 5 to the collector electrode 12. The emitter layer 11 is formed at a position sandwiched between the DC base electrode 6 and the RF base electrode 7. In the emitter layer 11, the width of the finger-like portion (hereinafter referred to as the finger portion) 15 in the upper surface pattern (width in the arrangement direction of the DC base electrode 6 and the RF base electrode 7) 15 is 2 μm, and the length of the finger portion in the upper surface pattern The length (finger length which is the length in the length direction perpendicular to the arrangement direction) 37 is 20 μm, and the emitter area is 40 μm ² . The width 33 in the alignment direction of the DC base electrode 6 is 1 μm, the width 34 in the alignment direction of the RF base electrode 7 is 1 μm, the distance 14 from the DC base electrode 6 to the emitter layer 11 is 1 μm, and from the RF base electrode 7. The distance 16 to the emitter layer 11 is 1 μm.

  In the base layer 8, if the point P is directly below the right end of the DC base electrode 6 and the point Q is immediately below the center of the emitter layer 11, the resistance value of the resistor 22 between the points P and Q is 25Ω. Similarly, the resistance value of the resistor 23 between the point R and the point Q is 25Ω. The resistor 22 and the resistor 23 are expressed in a distributed constant as can be seen from FIG.

  FIG. 2 is an operation explanatory diagram of the bipolar transistor 1 of the present embodiment. 1.2 V is applied to the DC base electrode 6, and 3.5 V is applied to the collector electrode 12. The emitter electrode 13 is grounded. The DC current 40 input from the DC terminal 3 travels through the base layer 8 as indicated by an arrow 43 and is injected into the base-emitter junction immediately below the emitter layer 11, where a part of the electrons supplied from the emitter layer 11 are regenerated. Join. The RF 42 input from the RF terminal 4 advances through the base layer 8 as indicated by an arrow 44. The DC current 40 and the RF 42 are combined at a portion of the base layer 8 located immediately below the emitter layer 11 and become a DC biased high frequency power. The high frequency power 45 amplified by the transistor operation proceeds through the collector contact layer 17 as indicated by an arrow 46 and is output in the order of the collector electrode 12 and the collector terminal 5. At this time, the collector current flowing through the bipolar transistor 1 is 50 mA, and the base current is 1 mA.

  FIG. 3 shows the relationship between the potential distribution diagram in the base layer 8 of the bipolar transistor 1 of the present embodiment and the cross-sectional view of FIG. In the cross-sectional view of FIG. 3, the substrate 18, the collector contact layer 17, and the collector electrode 12 are omitted from the cross-sectional view of FIG. A 100Ω resistor 47 is connected between the DC terminal 3 and the DC base electrode 6. 1.3V is applied to the DC terminal 3, and the emitter terminal 2 is grounded.

  In such a bipolar transistor 1, it is considered that a base current of 1 mA flows through the base layer 8. The base current supplied from the DC terminal 3 sequentially passes through the resistor 47, the DC base electrode 6, and the resistor 22 and is injected into the base-emitter junction immediately below the emitter layer 11. Since almost all of the base current supplied from the DC base electrode 6 is injected into the base-emitter junction, the current flowing through the resistor 23 can be ignored. The resistance value of the resistor 22 is 25Ω. When a 1 mA base current passes through resistor 22, the potential drop across resistor 22 is 25 mV. On the other hand, since no current flows through the resistor 23, no potential drop occurs. Therefore, the potential at the point P is 1.2V, the potential at the point Q is 1.175V, and the potential at the point R is also 1.175V.

  FIG. 4 is a circuit diagram of a high-frequency amplifier circuit formed by connecting a plurality of the bipolar transistors 1 of FIG. 3 of this embodiment in parallel. n bipolar transistors 1-1 to 1-n are connected in parallel, and each DC terminal 3-1 to 3-n is connected to a terminal 48 to which a DC bias is supplied, and each RF terminal 4- 1-4-n are connected to a terminal 49 to which RF power is supplied. Each emitter terminal 5 is grounded. 1.3V is applied to the terminal 48, and the potential of the DC base electrodes 6-1 to 6-n is 1.2V. The resistance value of each of the resistors 47-1 to 47-n is 100Ω. In each of the bipolar transistors 1-1 to 1-n, the base current is 1 mA and the collector current is 50 mA (in the figure, Ic = 50 mA). The DC base electrodes 7-1 to 7-n have a DC potential of 1.175V. The base-emitter junction temperature of each bipolar transistor 1-1 to 1-n is 80 ° C. When the collector current is equal for each bipolar transistor 1-1 to 1-n, no temperature difference occurs.

  Next, consider a case where current concentration occurs in an arbitrary bipolar transistor. FIG. 5 is a circuit diagram of the high frequency amplifier circuit showing the potential of each terminal when the collector current flowing through the bipolar transistor 1-2 increases in the high frequency amplifier circuit of FIG. 4 of the present embodiment. It is assumed that a collector current of 60 mA corresponding to 1.2 times that of other bipolar transistors flows through the bipolar transistor 1-2. Since the hFE of the bipolar transistors 1-1 to 1-n is 50, the base current flowing through the resistor 47-2 is 1.2 mA. Since the voltage drop caused by the resistor 47-2 is 0.12V, the potential of the DC base electrode 6-2 is 1.18V. As the base current increases, the voltage drop across the resistor 47-2 increases by 0.02V, and a negative feedback of Vbe is obtained. Even in this case, the potential of the RF base electrode 7-2 is 1.175 V because it is equipotential with the other RF base electrodes 7-n (n is 2). Since the potential (1.18V) of the DC base electrode 6-2 is higher than the potential (1.175V) of the RF base electrode 7-2, the RF base electrode 7-2 is directed to the DC base electrode 6-2. DC current does not flow through.

  As the collector current of the bipolar transistor 1-2 increases from 50 mA to 60 mA, the junction temperature of the bipolar transistor 1-2 instantaneously increases from 80 ° C. to 90 ° C. However, since the decrease in Vf (17 mV) of the bipolar transistor 1-2 due to the temperature rise of 10 ° C. is smaller than the negative feedback voltage (20 mV) obtained by the voltage drop of the resistor 47-2, the collector of the bipolar transistor 1-2 Current is reduced, avoiding thermal runaway. That is, even when a current corresponding to 1.2 times that of another bipolar transistor flows through an arbitrary bipolar transistor, thermal runaway of the bipolar transistor can be prevented by the effect of negative feedback of Vbe by the resistor 47-2. .

  Further, since the DC base electrode 6 and the RF base electrode 7 are separated, the RF power passes through the DC base electrode 6 and is connected to the terminal 48 (not shown in the figure). ) And the adverse effect on the bias circuit is eliminated. Due to this effect, it is not necessary to connect a grounding capacitor to the terminal 48, and the number of components can be reduced.

  As described above, the high-frequency amplifier circuit according to the first embodiment has separate terminals to which RF power and DC bias are supplied, that is, has the DC base electrode 6 and the RF base electrode 7 separately. The bipolar transistor 1 is used in which the DC base electrode 6 and the RF base electrode 7 are formed at positions where the emitter layer 11 is sandwiched. The potential of the DC base electrode 6 is higher than the potential of the RF base electrode 7, and the base current is always supplied from the DC base electrode 6 connected to the ballast resistor. Therefore, the following advantageous effects can be obtained. That is, it is possible to prevent thermal runaway even when, for example, 1.2 times the current flows through an arbitrary bipolar transistor as compared with the conventional high-frequency amplifier circuit of FIGS. Further, as compared with the conventional high-frequency amplifier circuit shown in FIG. 21, it is not necessary to provide a resistor between the RF power input terminal and the base electrode, so that it is possible to eliminate a reduction in high-frequency gain.

  In the high-frequency amplifier circuit according to the first embodiment, the potential of the DC base electrode 6 is higher than the potential of the RF base electrode 7, and no DC current flows from the RF base electrode 7 toward the DC base electrode 6. . Therefore, as compared with the conventional high frequency amplifier circuit shown in FIG. 22, it is not necessary to provide a DC cut capacitor 151 in each bipolar transistor, layout is easy, and an increase in cost due to an increase in chip area is prevented. be able to. In addition, the RF component can be prevented from flowing into the DC bias circuit, and adverse effects on the DC bias circuit can be prevented. Further, it is not necessary to connect a grounding capacitor to the terminal 48, and the number of components can be reduced.

  In the bipolar transistor of the first embodiment, the distance from the RF base electrode 6 to the emitter electrode 13 and the distance from the DC base electrode 6 to the emitter electrode 13 can be freely changed. Therefore, compared with the bipolar transistor of FIGS. 23 and 24, the high frequency characteristics are improved by making the distance from the RF base electrode 6 to the emitter electrode 13 shorter than the distance from the DC base electrode 6 to the emitter electrode 13. In addition, thermal runaway can be largely prevented.

  As a result, thermal runaway can be prevented without adversely affecting the high frequency amplifier circuit as compared with the conventional high frequency amplifier circuit.

  In the high-frequency amplifier circuit of the present embodiment, the case where the DC base electrode 6 and the RF base electrode 7 are formed at positions sandwiching the emitter layer 11 has been described, but the positional relationship between them is not limited to this case. .

(Second Embodiment)
Next, in the high-frequency amplifier circuit shown in FIG. 4 in the first embodiment, a case is considered where a collector current of 70 mA corresponding to 1.4 times that of other bipolar transistors flows through the bipolar transistor 1-2. As shown in FIG. 5, since the hFE of the bipolar transistors 1-1 to 1-n is 50, the base current flowing through the resistor 47-2 is 1.4 mA, the voltage drop generated by the resistor 47-2 is 0.14 V, and the electrode 6 -2 potential is 1.16V. On the other hand, the potential of the electrode 7-2 is 1.175V. In this case, since the potential of the electrode 7-2 (1.175V) is higher than the potential of the electrode 6-2 (1.16V), the base current of the bipolar transistor 1-2 is supplied from the electrode 7-2. Is done. That is, the negative feedback voltage of Vbe is 0.025V obtained by subtracting 1.175V from 1.2V. On the other hand, when the collector current of the bipolar transistor 1-2 is increased from 50 mA to 70 mA, the junction temperature of 1-2 is instantaneously increased from 80 ° C. to 100 ° C. by 20 ° C., and Vf is decreased by 0.034V. . Therefore, in this case, since the decrease in Vf (0.034V) is larger than the negative feedback voltage (0.025V) of Vbe, the collector current of the bipolar transistor 1-2 continues to increase and finally escapes thermal runaway. Absent. That is, thermal runaway cannot be prevented when a current corresponding to 1.4 times that of another bipolar transistor flows through an arbitrary bipolar transistor. Hereinafter, a high-frequency amplifier circuit according to a second embodiment for solving this problem will be described.

  FIG. 6 is a structural cross-sectional view of the bipolar transistor 60 in the high-frequency amplifier circuit of the present embodiment. The difference from the structural cross-sectional view of the bipolar transistor 1 of the first embodiment in FIG. The distance 16 from 11 to the RF base electrode 7 is shorter than the distance 61 from the emitter layer 11 to the DC base electrode 6. That is, the distance 61 from the DC base electrode 6 to the emitter layer 11 is increased from 1 μm to 3 μm. As a result, the resistance 62 at point P−point Q in the base layer 8 increases from 25Ω to 50Ω. Therefore, the voltage drop generated in the resistor 62 when the base current flows 1 mA increases from 0.025V to 0.05V. Next, considering the high frequency characteristics of the bipolar transistor 60, the distance 16 between the RF base electrode 7 through which the high frequency power passes and the emitter layer 11 is the same as that of the bipolar transistor 1 of FIG. It does not change.

  FIG. 7 is a circuit diagram of a high frequency amplifier circuit formed by connecting a plurality of the bipolar transistors 60 of FIG. 6 of this embodiment in parallel. It is assumed that a collector current of 70 mA corresponding to 1.4 times that of the other bipolar transistor flows through the bipolar transistor 60-2. The voltage applied to the terminal 48 is 1.325V. Since the hFE of the bipolar transistors 60-1 to 60-n is 50, the base current flowing through the resistors 47-1 to 47-n (n excludes 2) is 1 mA, and the resistors 47-1 to 47-n (n is 2). The voltage drop that occurs in (except for the above) is 0.1V, and the potentials of the electrodes 6-1 to 6-n (where n is 2) are 1.225V. On the other hand, the base current flowing through the resistor 47-2 is 1.4 mA, the voltage drop generated by the resistor 47-2 is 0.14V, and the potential of the DC base electrode 6-2 is 1.185V. Even in this case, the potential of the RF base electrode 7-2 is 1.175 V because it is equipotential with the other RF base electrodes 7-1 to 7-n (n is 2). At this time, since the potential (1.185 V) of the DC base electrode 6-2 is higher than the potential (1.175 V) of the RF base electrode 7-2, the base current of the bipolar transistor 60-2 is the RF base electrode. It is not supplied from 7-2.

  Here, the reason why the resistance 62 of point P-point Q is increased instead of the resistance 47 will be described. When the resistor 47 is designed to be 125Ω and the resistor 62 is designed to be 25Ω, when a current of 1.4 mA flows through the resistor 47-2, the voltage drop at the resistor 47-2 becomes 0.175V, and the potential at the point 6-2 Becomes 1.15V. In this case, since the potential of the electrode 6-2 (1.15 V) is lower than the potential of the RF base electrode 7-2 (1.175 V), the base current of 60-2 is changed to the RF base electrode 7-2. Inconvenience arises because it is supplied from the factory.

  As the collector current of the bipolar transistor 60-2 increases from 50 mA to 70 mA, the junction temperature of the bipolar transistor 60-2 instantaneously increases from 80 ° C. to 100 ° C. by 20 ° C., and the Vf of the bipolar transistor 60-2 increases. It decreases by 0.034V. However, even in this case, the decrease in Vf (0.034V) of the bipolar transistor 60-2 is smaller than the negative feedback voltage (0.04V) obtained by the resistor 47-2. Collector current is reduced, avoiding thermal runaway. That is, even when a current corresponding to 1.4 times that of another bipolar transistor flows through an arbitrary bipolar transistor, thermal runaway of the bipolar transistor can be prevented by the effect of negative feedback of Vbe by the resistor 47-2. .

  As described above, in the high-frequency amplifier circuit according to the second embodiment, the distance 61 between the DC base electrode 6 and the emitter layer 11 is made longer than the distance 16 between the RF base electrode 7 and the emitter layer 11. A bipolar transistor 60 is used. Therefore, as compared with the high frequency amplifier circuit of the first embodiment, the potential of the DC base electrode 6 is RF even when a collector current 1.4 times that of other bipolar transistors flows through any bipolar transistor. The base current is always supplied from the DC base electrode 6 which is higher than the potential of the base electrode 7 and connected to the ballast resistor. As a result, the thermal runaway of the bipolar transistor can be prevented by the negative feedback effect of Vbe by the resistor 47.

  Further, in the bipolar transistor of the second embodiment, the distance from the DC base electrode 6 to the emitter electrode 13 is smaller than that of the RF base electrode 6 to the emitter electrode 13 as compared with the high-frequency amplifier circuit of the first embodiment. Farther away. Therefore, thermal runaway can be reliably prevented without sacrificing high frequency characteristics.

(Third embodiment)
FIG. 8 is a cross-sectional view of the structure of the bipolar transistor 70 in the high-frequency amplifier circuit according to the third embodiment. The difference from the bipolar transistor 60 of the second embodiment shown in FIG. 6 is that it has a plurality of DC base electrodes 6-1 and 6-2, and further includes a plurality of emitter layers 11-1 and 11-2. It is to have. Compared with the bipolar transistor 60 of FIG. 6, the emitter area is doubled, and the current capacity can be doubled in the unit cell. Similarly to the bipolar transistor 60 of FIG. 6, the distance 61 from the DC base electrode 6-1 to the emitter layer 11-1 and from the DC base electrode 6-2 to the emitter layer 11-2 is 3 μm, and the RF base is set. By setting the distance 16 from the electrode 7 to the emitter layers 11-1 and 11-2 to 0.5 μm, the bipolar transistor heats up with respect to the current concentration of any bipolar transistor as in the bipolar transistor 60 of FIG. 6. Destruction due to runaway can be avoided. In addition, thermal runaway can be reliably prevented without sacrificing high frequency characteristics.

(Fourth embodiment)
FIG. 9 is a structural cross-sectional view of the bipolar transistor 71 in the high-frequency amplifier circuit of the fourth embodiment. The difference from the bipolar transistor 60 of the second embodiment shown in FIG. 6 is that it has a plurality of RF base electrodes 7-1 and 7-2, and further includes a plurality of emitter layers 11-1 and 11-2. It is to have. Compared with the bipolar transistor 60 of FIG. 6, the emitter area is doubled, and the current capacity can be doubled in the unit cell. Similarly to the bipolar transistor 60 of FIG. 6, the distance 61 from the DC base electrode 6 to the emitter layers 11-1 and 11-2 is 3 μm, the RF base electrode 7-1 to the emitter layer 11-1, and RF By setting the distance 16 from the base electrode 7-2 to the emitter layer 11-2 to 0.5 μm, the current of the bipolar transistor is controlled against the current concentration of an arbitrary bipolar transistor as in the bipolar transistor 60 of FIG. Destruction due to runaway can be avoided. In addition, thermal runaway can be reliably prevented without sacrificing high frequency characteristics.

(Fifth embodiment)
FIG. 10 is a circuit diagram of a high frequency amplifier circuit using the bipolar transistor 1 according to the first embodiment. This corresponds to a circuit diagram of the high-frequency amplifier circuit of FIG. 4 formed by connecting a plurality of the bipolar transistors 1 of the first embodiment in parallel and re-fired as an equivalent circuit. The difference from the conventional high frequency amplifier circuit shown in FIGS. 20, 21 and 22 is that the DC bias supplied from the terminal 48 and the RF power supplied from the terminal 49 are applied to the bipolar transistors 1-1 to 1-n. It is supplied separately and is not electrically synthesized outside the bipolar transistors 1-1 to 1-n. As a result, as described with reference to FIG. 3, an essential difference occurs in that the DC base electrode 6 and the RF base electrode 7 have different DC potentials.

  In the high frequency amplifier circuit of FIG. 10, n bipolar transistors 1-1 to 1-n are connected in parallel. In this case, as the bipolar transistors 1-1 to 1-n, any of the bipolar transistors 60, 70, and 71 in the second to fourth embodiments may be used. The DC bias terminal 48 is connected in the order of DC terminals 3-1 to 3-n, resistors 47-1 to 47-n, and DC base electrodes 6-1 to 6-n. The RF terminal 49 is connected in the order of a capacitor 63, RF terminals 4-1 to 4-n, and RF base electrodes 7-1 to 7-n.

FIG. 11 is a circuit diagram of a two-stage power amplifier circuit using the high-frequency amplifier circuit of FIG. In the two-stage power amplifier circuit, the high-frequency amplifier circuit is used for the front-stage transistor 100 and the rear-stage transistor 72. That is, in the pre-stage transistor 100, bipolar transistors 1-1 to 1-n having an emitter area of 120 μm ² are connected in parallel in four cells. In the post-stage transistor 72, bipolar transistors 1-1 to 1-n having an emitter area of 120 μm ² are connected in parallel in 20 cells. 3.5 V is applied to the collector voltage terminal 91 for the front-stage transistor and the collector voltage terminal 93 for the back-stage transistor. This two-stage power amplifier circuit has a frequency of 800 MHz, a high-frequency gain of 28 dB, a maximum output of 2.3 W, the current consumption of the front-stage transistor 100 is 200 mA, and the current consumption of the rear-stage transistor 72 is 1000 mA. The conversion efficiency is 55%.

  The pre-stage transistor bias circuit 92 supplies a DC bias to the DC base electrode 6 of the pre-stage transistor 100 via the resistor 47. The rear-stage transistor bias circuit 69 supplies a DC bias to the DC base electrodes 6-1 to 6-n of the rear-stage transistor 72 via resistors 47-1 to 47-n. The input matching circuit 73 includes an inductor 83, a capacitor 84, and a capacitor 85. Interstage matching between the front-stage transistor 100 and the rear-stage transistor 72 is configured by a capacitor 63 and a bias supply line 89 for the front-stage transistor 100. The load matching circuit 74 includes a line 94, a line 95, a capacitor 96, and a capacitor 97. The load matching circuit 74 is connected to the bias supply line 98 for the post-stage transistor 72.

  The high-frequency power input from the terminal 81 passes through the input matching circuit 73 and the RF base electrode 7 of the previous transistor 100 and is input to the previous transistor 100. The high frequency power amplified by the front-stage transistor 100 passes through the interstage matching capacitor 63 and the RF base electrodes 7-1 to 7-n of the rear-stage transistor 72 and is input to the rear-stage transistor 72. The high frequency power amplified by the post-stage transistor 72 passes through the load matching circuit 74 and is output from the terminal 82. In the pre-stage transistor 100, a series circuit of a resistor 87 and a capacitor 86 is connected between the collector terminal 5 of the pre-stage transistor 100 and the RF base electrode 7. This circuit is used as a feedback circuit to stably operate the amplifier circuit. It is used.

(Sixth embodiment)
FIG. 12 is a circuit diagram of another high-frequency amplifier circuit using the bipolar transistor 1 of the first embodiment. The difference from the high frequency amplifier circuit of the fifth embodiment shown in FIG. 10 is that the resistors 47-1 to 47-n are not provided in the bipolar transistors 1-1 to 1-n, but one resistor 77 is provided. It is connected to the DC base electrodes 6-1 to 6-n of the plurality of bipolar transistors 1-1 to 1-n. In this case, the resistance value of the resistor 77 may be 5Ω. The advantage of this circuit configuration is that only one resistor is required, so that the layout can be simplified and the cost can be reduced by reducing the chip area. However, when the conventional bipolar transistor 101 is used, as described with reference to FIG. 19, the resistor 77 (resistor 147 in FIG. 19) is bipolar transistors 1-1 to 1-n (in FIG. 19, bipolar transistor 101-1). ˜101−n) cannot provide sufficient negative feedback. On the other hand, the bipolar transistor 1 of the present embodiment has a resistance that can freely set a resistance value due to its unique configuration, and is effective in suppressing thermal runaway due to negative feedback of Vbe. Have. As a result, even with the configuration of FIG. 12, it is possible to suppress thermal runaway by optimizing the design of the bipolar transistors 1-1 to 1-n.

  As described above, in the high-frequency amplifier circuit according to the present embodiment, by using the bipolar transistor 1 according to the first embodiment, it is possible to suppress thermal runaway, and at the same time, according to the fifth embodiment. Compared with a high-frequency amplifier circuit, the layout can be simplified and the cost can be reduced by reducing the chip area.

(Seventh embodiment)
FIG. 13 is a circuit diagram of still another high-frequency amplifier circuit using the bipolar transistor 1 of the first embodiment. The difference from the high frequency amplifier circuit of the sixth embodiment shown in FIG. 11 is that the resistor 77 is omitted. Bipolar transistors 1-1 to 1-n according to the present embodiment have a resistance that can be freely set by their own configuration, and suppress thermal runaway due to negative feedback of Vbe. Has an effect. As a result, even with the configuration of FIG. 13, thermal runaway can be suppressed as in the high-frequency amplifier circuit of FIG.

  As described above, in the high-frequency amplifier circuit according to the present embodiment, by using the bipolar transistor 1 according to the first embodiment, it is possible to suppress thermal runaway, and at the same time, according to the sixth embodiment. Compared with a high-frequency amplifier circuit, the layout can be simplified and the cost can be reduced by reducing the chip area.

(Eighth embodiment)
FIG. 14 is a circuit diagram of still another high-frequency amplifier circuit using the bipolar transistor 1 of the first embodiment. The difference from the circuit diagram of the high frequency amplifier circuit of the fifth embodiment shown in FIG. 10 is that one capacitor 63 is not provided between the terminal 49 and the RF terminals 4-1 to 4-n. The plurality of capacitors 76-1 to 76-n are connected between the RF terminals 4-1 to 4-n and the RF base electrodes 7-1 to 7-n. As described in FIG. 10, the capacitor 63 is used for impedance matching. In order to satisfy this matching condition in FIG. 14, the sum of the capacitance values of the capacitors 76-1 to 76-n may be designed to be equal to that of the capacitor 63. As a result, DC can be reliably cut in a path to which RF power is supplied.

(Ninth embodiment)
FIG. 15 is a circuit diagram of still another high-frequency amplifier circuit using the bipolar transistor 1 of the first embodiment. The difference from the high-frequency amplifier circuit of the eighth embodiment shown in FIG. 14 is that the resistors 47-1 to 47-n are not provided in the bipolar transistors 1-1 to 1-n, but one resistor 77 is provided. It is connected to the DC base electrodes 6-1 to 6-n of the plurality of bipolar transistors 1-1 to 1-n. In this case, the resistance value of the resistor 77 may be 5Ω. Bipolar transistors 1-1 to 1-n according to the present embodiment have a resistance that can be freely set by their own configuration, and suppress thermal runaway due to negative feedback of Vbe. Has an effect. As a result, even with the configuration of FIG. 15, thermal runaway can be suppressed by optimizing the design of the bipolar transistors 1-1 to 1-n. Further, in the high frequency amplifier circuit of the present embodiment, it is possible to suppress thermal runaway, and at the same time, the layout is simplified and the cost is reduced by reducing the chip area as compared with the high frequency amplifier circuit of the eighth embodiment. Can be realized.

(Tenth embodiment)
FIG. 16 is a circuit diagram of a high frequency amplifier circuit using the bipolar transistor 1 according to the first embodiment. The difference from the high frequency amplifier circuit of the ninth embodiment shown in FIG. 15 is that the resistor 77 is omitted. Bipolar transistors 1-1 to 1-n according to the present embodiment have a resistance that can be freely set by their own configuration, and suppress thermal runaway due to negative feedback of Vbe. Has an effect. As a result, even if the resistor 77 is omitted, thermal runaway can be suppressed as in the high frequency amplifier circuit of FIG. Further, in the high frequency amplifier circuit of the present embodiment, thermal runaway can be suppressed, and at the same time, the layout is simplified and the cost is reduced by reducing the chip area as compared with the high frequency amplifier circuit of the ninth embodiment. Can be realized.

(Eleventh embodiment)
FIG. 17 is a structural plan view of the bipolar transistor 78 in the present embodiment. The difference from the plan view of the bipolar transistor 1 of the first embodiment shown in FIG. 1B is that the upper surface shapes of the DC base electrode 6 and the RF base electrode 7 are different. That is, the DC base electrode 6 has a notch in a portion adjacent to the emitter electrode 13, and the distance 14 from the DC base electrode 6 to the emitter layer 11 is not uniformly the same, but the length of the finger portion. It is longer at the center of the direction and shorter at the end. In this case, in the resistors 22-1 to 22-3 of the base layer 8 formed in a distributed constant manner between the DC base electrode 6 and the emitter electrode 13, for example, the resistance value of the resistor 22-2 in the central portion is large. Thus, the resistance values of the end resistors 22-1 and 22-3 are reduced. This makes it possible to increase the negative feedback voltage of Vbe at the center of the bipolar transistor that is likely to overheat within the bipolar transistor. Since high frequency does not pass between the DC base electrode 6 and the emitter electrode 13, even if the distribution of the resistors 22-1 to 22-3 is not uniform, the high frequency characteristics are not adversely affected.

  The shape of the DC base electrode 6 is not limited to the example of the present embodiment, and the effect is exhibited because the size of the resistor 22 is not uniform in terms of distributed constants. Normally, in a high frequency bipolar transistor, the RF base electrode 7 is rectangular so that the resistors 23-1 to 23-n between the RF base electrode 7 and the emitter electrode 13 through which the high frequency passes have a uniform distribution. Designed to. In the bipolar transistor 78 of the present embodiment, the DC base electrode 6 does not need to be rectangular for the above-described reason, and the high frequency characteristics are obtained by forming the DC base electrode 6 and the RF base electrode 7 in different shapes. Without deteriorating, it becomes possible to optimally design the negative feedback of Vbe in the bipolar transistor, which is effective in suppressing thermal runaway.

(Twelfth embodiment)
FIG. 18 is a structural cross-sectional view of the bipolar transistor 79 in the high-frequency amplifier circuit according to the twelfth embodiment. The difference from the bipolar transistor 71 of the fourth embodiment shown in FIG. 9 is that it has a plurality of RF terminals 401 and 402 and RF base electrodes 7-1 and 7-2 connected to the RF terminals 401 and 402, respectively. Another high-frequency signal RF1, RF2 is input from the RF terminals 401, 402 to the base electrodes 7-1, 7-2. Since the RF base electrodes 7-1 and 7-2 are separated from the DC base electrode 6 and the two systems of RF signals, the two systems of RF signals can be sufficiently separated in terms of high frequency. Note that RF1 and RF2 are examples of the first high-frequency signal and the second high-frequency signal of the present invention, respectively, and the RF terminal 401 and the RF terminal 402 are examples of the second terminal and the third terminal of the present invention, respectively. The RF base electrode 7-1 and the RF base electrode 7-2 are examples of the second base electrode and the third base electrode of the present invention, respectively.

  INDUSTRIAL APPLICABILITY The present invention can be used for high frequency bipolar transistors and high frequency amplifier circuits, and is particularly useful for applications such as wireless communication terminals such as mobile phones.

(A) Structural sectional drawing of the bipolar transistor in the high frequency amplifier circuit of the 1st Embodiment of this invention. (B) The structure top view of the bipolar transistor in the high frequency amplifier circuit of the embodiment. FIG. 5 is an operation explanatory diagram of the bipolar transistor according to the first embodiment. FIG. 2 is a partial structure cross-sectional view of a bipolar transistor according to a first embodiment and a potential distribution diagram of a base layer. FIG. 4 is a circuit diagram of a high-frequency amplifier circuit formed by connecting the bipolar transistors of FIG. 3 in parallel. The circuit diagram which shows the electric potential when the electric current which flows into a bipolar transistor increases in the high frequency amplifier circuit formed by connecting the bipolar transistor in parallel. Sectional drawing of the structure of the bipolar transistor in the high frequency amplifier circuit of the 2nd Embodiment of this invention. FIG. 7 is a circuit diagram of a high-frequency amplifier circuit formed by connecting the bipolar transistors of FIG. 6 in parallel. Sectional drawing of the structure of the bipolar transistor in the high frequency amplifier circuit of the 3rd Embodiment of this invention. Sectional drawing of the structure of the bipolar transistor in the high frequency amplifier circuit of the 4th Embodiment of this invention. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 5th Embodiment of this invention. The circuit diagram of the two-stage power amplifier circuit using the high frequency amplifier circuit of 5th Embodiment. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 6th Embodiment of this invention. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 7th Embodiment of this invention. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 8th Embodiment of this invention. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 9th Embodiment of this invention. The circuit diagram of the high frequency amplifier circuit using the bipolar transistor of FIG. 1 of the 10th Embodiment of this invention. The structure top view of the bipolar transistor in the high frequency amplifier circuit of the 11th Embodiment of this invention. The structure sectional drawing of the bipolar transistor in the high frequency amplifier circuit of the 12th Embodiment of this invention. (A) The equivalent circuit schematic of the conventional high frequency amplifier circuit. (B) The figure which shows the value of the voltage and electric current in each terminal of the same high frequency amplifier circuit. The equivalent circuit diagram of the conventional high frequency amplifier circuit. The equivalent circuit diagram of the conventional high frequency amplifier circuit. The equivalent circuit diagram of the conventional high frequency amplifier circuit. (A) Structural sectional drawing of the bipolar transistor in the conventional high frequency amplifier circuit. (B) The structure top view of the bipolar transistor in the conventional high frequency amplifier circuit. Sectional drawing of the structure of another bipolar transistor in the conventional high frequency amplifier circuit.

Explanation of symbols

1, 60, 70, 71, 78, 79, 101 Bipolar transistor 2, 102 Emitter terminal 3, 148 DC bias (DC) terminal 4, 149, 401, 402 High frequency power (RF) terminal 5, 115 Collector terminal 6 DC bias (DC) base electrode 7 high frequency power (RF) base electrode 8, 108 base layer 9, 109 collector layer 10, 110 emitter contact layer 11, 111 emitter layer 12, 112 collector electrode 13, 113 emitter electrode 14, 16, 61 Distance 15, 33, 34, 35 Width 17, 117 Collector contact layer 18, 118 Substrate 20, 132 Emitter wiring 22, 23, 47, 62, 77, 87, 146, 147 Resistance 37, 137 Finger length 40 DC current 42 RF
43, 44, 46 Arrow 45 High frequency power 48, 49, 81, 82, 103, 152 Terminals 63, 76, 84, 85, 86, 90, 96, 97, 99, 150, 151, 163 Capacitor 69 Bias for subsequent transistors Circuit 72 Subsequent transistor 73 Input matching circuit 74 Load matching circuit 83 Inductor 89, 98 Bias supply line 91 Collector voltage terminal for previous stage transistor 92 Bias circuit for previous stage transistor 93 Collector voltage terminal for subsequent stage transistor 94, 95 Line 100 Prestage transistor 105, 107 Base electrode 119 Interval 122 Base-emitter resistance 145 Wiring

Claims (4)

A first terminal;
A second terminal;
A first base electrode connected to the first terminal; a second base electrode connected to the second terminal; and the first base electrode and the second base electrode connected to the first terminal. A plurality of bipolar transistor cells each including a base layer and only one emitter electrode located between the first base electrode and the second base electrode ;
The plurality of bipolar transistor cells are connected in parallel,
A DC bias is supplied to the first terminal,
A high frequency signal is supplied to the second terminal,
The high frequency amplifier circuit, wherein the DC bias and the high frequency signal are combined in the base layer . In operation, the DC potential of the second base electrode is lower than the DC potential of the first base electrode
The high-frequency amplifier circuit according to claim 1. The high frequency amplifier circuit further high-frequency amplifier circuit according to claim 1 or 2, characterized in that it comprises a resistive element connected in series between the first terminal first base electrode . The high frequency amplifier circuit further high-frequency amplifier circuit according to claim 1 or 2, characterized in that it comprises a capacitive element connected in series between the second terminal and the second base electrode .

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