Power amplifier circuit

Abstract

Provided is a power amplifier circuit capable of improving the withstand voltage of a transistor in a temperature environment at a low temperature. The power amplifier circuit (10) includes: an amplification section that amplifies a radio frequency signal; a heating section (114) that is disposed adjacent to the amplification section and has at least one transistor (11411) that increases the amount of heat generated as the passage current increases; and a control circuit (112) that is connected to the transistor (11411) and increases the passage current when the ambient temperature is below a prescribed threshold value.

Description

Technical Field

[0001] This invention relates to power amplifier circuits. Background Technology

[0002] In communications using mobile devices such as mobile terminals, power amplifier circuits are used to amplify radio frequency (RF) signals. Known control methods for efficiently amplifying RF signals include envelope tracking (ET) control and average power tracking (APT) control. ET and APT control use a power supply voltage that varies according to the amplitude of the radio frequency signal to amplify the power.

[0003] The correlation between the amplitude of the wireless frequency signal and the power supply voltage is set in the control IC. The power supply voltage is set, for example, to a maximum of approximately 5.5V.

[0004] In power amplifier circuits that supply power voltage to transistors, it is required that the external temperature of the power amplifier circuit, i.e., the ambient temperature, is within a certain temperature range (e.g., -30°C to 85°C) so that the transistors will not be damaged even when there are variations in the output load.

[0005] Patent Document 1 shows a clamping circuit consisting of multiple diodes connected in series between the transistor's output and ground to prevent damage to the transistor. The clamping circuit has the function of turning on each diode and suppressing voltage increases above a predetermined threshold when the voltage amplitude of the output signal is too large.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-142688

[0007] However, in low ambient temperatures (e.g., -30°C), there is a problem that the transistors in the output stage may be damaged when the output load changes, even at the maximum power supply voltage (e.g., below 5.5V). Summary of the Invention

[0008] The present invention was made in view of the following circumstances, and its purpose is to provide a power amplifier circuit capable of improving the voltage withstand capability of transistors in low-temperature environments.

[0009] The power amplifier circuit of one side of the present invention includes: an amplification section for amplifying a radio frequency signal; a heating section disposed adjacent to the amplification section and having at least one heating element that generates heat as the current increases; and a control circuit connected to the heating element for increasing the current when the ambient temperature is below a predetermined threshold.

[0010] Another aspect of the power amplifier circuit of the present invention includes: an output transistor that amplifies and outputs a radio frequency signal and generates heat as the current increases; a bias circuit that supplies bias current or voltage to the output transistor; and a control circuit connected to the bias circuit that increases the bias current or voltage when the ambient temperature is below a predetermined threshold.

[0011] According to the present invention, a power amplifier circuit is provided that can improve the voltage withstand capability of transistors in low-temperature environments. Attached Figure Description

[0012] Figure 1 This is a circuit diagram of the power amplifier circuit according to the first embodiment.

[0013] Figure 2 This is a diagram used to illustrate the operation of the power amplifier circuit in the first embodiment.

[0014] Figure 3 This is a layout diagram of the power amplifier circuit according to the first embodiment.

[0015] Figure 4 This is a circuit diagram of the power amplifier circuit according to the second embodiment.

[0016] Figure 5 This is a layout diagram of the power amplifier circuit in the second embodiment.

[0017] Figure 6 This is a circuit diagram of the power amplifier circuit in the third embodiment.

[0018] Figure 7 This is a diagram used to illustrate the operation of the power amplifier circuit in the third embodiment.

[0019] Figure 8 This is a circuit diagram of the power amplifier circuit according to the fourth embodiment.

[0020] Figure 9 This is a layout diagram of the power amplifier circuit according to the fourth embodiment.

[0021] Figure 10 This is a circuit diagram of the power amplifier circuit according to the fifth embodiment.

[0022] Figure 11 This is a circuit diagram of the power amplifier circuit according to the sixth embodiment.

[0023] Figure 12 This is a diagram used to illustrate the operation of the power amplifier circuit in the sixth embodiment.

[0024] Figure 13 This is a diagram used to illustrate the reactive current in the power amplifier circuit of the sixth embodiment.

[0025] Figure 14 This is a circuit diagram of the power amplifier circuit according to the seventh embodiment.

[0026] Figure 15 This is a diagram used to illustrate the operation of the power amplifier circuit in the seventh embodiment.

[0027] Figure 16 This is a diagram used to illustrate the reactive current in the power amplifier circuit of the seventh embodiment.

[0028] Figure 17 This is a circuit diagram of the power amplifier circuit according to the eighth embodiment.

[0029] Figure 18 This is a circuit diagram of the power amplifier circuit according to the ninth embodiment.

[0030] Figure 19 This is a circuit diagram of the power amplifier circuit according to the tenth embodiment.

[0031] Explanation of reference numerals in the attached figures

[0032] 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I… power amplifier circuit, 100… amplifier circuit, 111… clamping circuit, 112… control circuit, 114… heating element, 301, 901… chips, 1101, 1102… bias circuit, 1400… bias selection circuit. Detailed Implementation

[0033] The first embodiment will be described. Figure 1 A circuit diagram of the power amplifier circuit 10 according to the first embodiment is shown. The power amplifier circuit 10 includes an amplifier circuit 100, a clamping circuit 111, a heating unit 114, and a control circuit 112.

[0034] The amplifier circuit 100 includes a transistor 101, an output transistor 102, bias circuits 103 and 104, a matching circuit 105 and 110, capacitors 106 and 107, inductors 108 and 109, and resistors 1036 and 1046.

[0035] The base of transistor 101 is connected to the input terminal Pin via matching circuit 105 and capacitor 106. Additionally, bias current or voltage is supplied to the base of transistor 101 from bias circuit 103. Power supply voltage Vcc is supplied to the collector of transistor 101 via inductor 108. The emitter of transistor 101 is connected to ground. Transistor 101 amplifies the radio frequency signal input through input terminal Pin and outputs it to the base of output transistor 102.

[0036] The base of output transistor 102 is connected to the collector of transistor 101 via capacitor 107. Additionally, a bias current or voltage is supplied to the base of output transistor 102 from bias circuit 104. A power supply voltage Vcc is supplied to the collector of output transistor 102 via inductor 109. The emitter of transistor 101 is connected to ground. Output transistor 102 amplifies the signal from transistor 101 and outputs the signal from its collector to the output terminal Pout via matching circuit 110.

[0037] The bias circuit 103 has transistors 1031, 1032, and 1033, as well as resistors 1034 and 1035.

[0038] The base of transistor 1031 is connected to resistor 115, the collector is connected to the power supply, and the emitter is connected to resistor 1036. Transistor 1031 switches between on and off states based on the control current supplied from control input BC1 and flowing through resistor 1034 to the base. When transistor 1031 is on, it outputs a bias current or voltage.

[0039] Transistor 1032 is a diode-connected transistor, with its collector connected to resistor 1034 and the base of transistor 1031, and its emitter connected to the collector of transistor 1033. Transistor 1032 outputs current to the collector of transistor 1033 based on the current flowing through its collector.

[0040] Transistor 1033 is a diode-connected transistor, with its collector connected to the emitter of transistor 1032, and the emitter connected to ground via resistor 1035. Transistor 1033 outputs current from its emitter based on the current from transistor 1032.

[0041] Resistor element 1034 and resistor element 1035 are provided to generate a specified voltage drop based on the control current.

[0042] Resistor 1036 is disposed between the collector of transistor 1031 and the base of transistor 101. Resistor 1036 is disposed to generate a predetermined voltage drop based on the bias current from transistor 1031.

[0043] The bias circuit 104 includes transistors 1041, 1042, and 1043, and resistors 1044 and 1045. The components of the bias circuit 104 are connected in the same manner as those in the bias circuit 103. The bias circuit 104 supplies a bias current or voltage to the base of the output transistor 102. Additionally, a resistor 1046 is provided to generate a predetermined voltage drop based on the bias current from transistor 1041.

[0044] Matching circuit 105 is disposed between input terminal Pin and capacitor 106. Matching circuit 105 matches the impedance between input terminal Pin and base of transistor 101.

[0045] Capacitor 106 is disposed between matching circuit 105 and base of transistor 101. Capacitor 106 has the function of cutting off the DC component of the signal input to transistor 101.

[0046] Capacitor 107 is disposed between the collector of transistor 101 and the base of output transistor 102. Capacitor 107 has the function of cutting off the DC component of the signal input to output transistor 102.

[0047] Inductor 108 is disposed between the collector of transistor 101 and the power supply line supplying power supply voltage Vcc. Inductor 109 is disposed between the collector of transistor 101 and the power supply line supplying power supply voltage Vcc. Inductors 108 and 109 function as choke inductors.

[0048] Matching circuit 110 matches the impedance between the collector of output transistor 102 and output terminal Pout.

[0049] The clamping circuit 111 includes diodes 1111 to 1116. Diodes 1111 to 1116 are connected in series. The clamping circuit has the function of turning on each diode and suppressing voltage increases above a specified threshold when the voltage amplitude of the output signal is too large.

[0050] The heating element 114 includes transistors 11411 to 11417, transistors 11421 to 11427, and resistors 11431 to 11437.

[0051] The base of transistor 11411 (a single transistor) is connected to the control circuit described later. A control voltage is supplied to transistor 11411 from the control circuit. The collector of transistor 11411 is connected to the power supply line supplying the power supply voltage Vcc. Based on the control voltage, transistor 11411 outputs the current flowing through it.

[0052] Transistor 11421 is a diode-connected transistor, with its collector connected to the emitter of transistor 11411. The emitter of transistor 11421 is connected to ground via resistor 11431.

[0053] Similar to transistor 11411, control voltage is supplied to transistors 11412 to 11417 from control circuit 112. Transistors 11422 to 11427 and resistors 11432 to 11437 are connected in the same manner as transistors 11421 and 11431.

[0054] The control circuit 112 includes a reference voltage generation circuit 1120 and a control transistor section 1130. The reference voltage generation circuit 1120 includes transistors 1121 and 1122 and resistive elements 1123, 1124, 1125 and 1126.

[0055] The reference voltage generation circuit 1120 is a current mirror circuit, which has the property of low temperature dependence of the output voltage (reference voltage) Vref.

[0056] The control transistor section 1130 includes a control transistor 1131 and resistive elements 1132 and 1133. The collector of the control transistor 1131 is supplied with a power supply voltage Vbat through the resistive element 1132. The emitter of the control transistor 1131 is connected to ground through the resistive element 1133. A reference voltage Vref is supplied to the base of the control transistor 1131 from the reference voltage generation circuit 1120. The collector of the control transistor 1131 is connected to the bases of transistors 11411 to 11417, and a control voltage Vcont is supplied to each base.

[0057] Although the transistors in the control circuit 112 are bipolar transistors, they can also be field-effect transistors (FETs). In this case, the emitter, collector, and base are replaced by the source, drain, and gate of the FET. The control circuit can be configured on the same semiconductor wafer as the power amplifier body, or on a different semiconductor wafer on the same semiconductor module.

[0058] The operation of the control circuit 112 and the heating unit 114 under conditions of decreasing temperature will be explained. The reference voltage Vref output from the reference voltage generation circuit 1120 is almost independent of the ambient temperature. On the other hand, the turn-on voltage of the control transistor 1131, i.e., the base-emitter voltage, increases as the ambient temperature decreases. As a result, the current Ic flowing through the control transistor 1131 and the resistor element 1132 decreases as the ambient temperature decreases. Due to the decrease in current Ic, the voltage drop in the resistor element 1132 decreases, so the control voltage Vcont applied to the bases of transistors 11411 to 11417 increases.

[0059] As the ambient temperature decreases, the base-emitter voltage of transistors 11411 and 11421 also increases. Here, by setting the resistance value of resistor 1132 and the current of current ic such that the increase in the turn-on voltage of control transistor 1131 due to the decrease in ambient temperature is greater than the sum of the increases in the turn-on voltages of transistors 11411 and 11421, the current flowing through transistors 11411 and 11421 increases as the ambient temperature decreases.

[0060] exist Figure 2 The diagram shows the total current flowing through transistors 11411 to 11417, which is the product of current Ih and supply voltage Vcc. This represents the relationship between the total self-generated heat generated by transistors 11411 to 11417 and transistors 11421 to 11427 and the ambient temperature Ta. The total self-generated heat decreases as the ambient temperature Ta increases, reaching zero at approximately 10°C.

[0061] In this way, transistors 11411 to 11417 and transistors 11421 to 11427 generate heat when the ambient temperature decreases, and in turn heat diodes 1111 to 1116.

[0062] Reference Figure 3 The layout of the heating element and clamping circuit will be described. Diodes 1111 to 1116 are arranged on chip 301 with their long sides facing the same direction and at predetermined intervals in a direction orthogonal to their long sides.

[0063] Furthermore, transistors 11411 to 11417 and transistors 11421 to 11427 are disposed on chip 301. Each transistor, such as transistor 11411, has a base 3011, an emitter 3012, and a collector 3013. Similarly, transistor 11421 also has a base 3021, an emitter 3022, and a collector 3023. Transistors 11411 and 11421 are paired and arranged such that their long sides face the same direction. The same applies to other pairs such as transistors 11412 and 11422; in the gaps and at both ends of each arrangement of diodes 1111 to 1116, their long sides are arranged such that their long sides face the same direction as the long sides of diodes 1111 to 1116.

[0064] Also shown with Figure 1The circuit connections establish the connections between the nodes of the corresponding components. A power supply voltage Vcc is supplied from terminal V1. A control voltage Vcont is supplied from terminal B1. Terminal C1 is connected between output transistor 102 and matching circuit 110, and the output signal is output through terminal C1. Voltages corresponding to the output are applied to diodes 1111 to 1116.

[0065] Transistors 11411 to 11417 and 11421 to 11427 generate heat when the ambient temperature decreases, thus heating diodes 1111 to 1116. By heating diodes 1111 to 1116, the forward voltage of each diode is prevented from increasing due to the decrease in ambient temperature. By preventing the forward voltage of each diode from increasing, the voltage at which the clamping circuit is connected can be kept below a certain level, thereby preventing damage to the output transistor 102 when the ambient temperature decreases.

[0066] The second embodiment will be described. Following the second embodiment, descriptions of items identical to those in the first embodiment will be omitted; only the differences will be explained. In particular, the same effects resulting from the same configuration will not be mentioned sequentially for each embodiment.

[0067] Figure 4 This is a circuit diagram of the power amplifier circuit 10A according to the second embodiment. The configuration of the heating element and part of the configuration of the control circuit are different from those of the power amplifier circuit 10 in the first embodiment.

[0068] In the power amplifier circuit 10A, the heating section has resistive elements 4021 to 4027. Each resistive element is configured to be connected in parallel between the power supply line supplying the power supply voltage Vcc and the collector of the transistor 401, which will be described later.

[0069] In the power amplifier circuit 10A, the control transistor section 1130A, in addition to the configuration of the control transistor section 1130 of Embodiment 1, also includes transistors 401 and 4134 and resistor elements 403 and 4135.

[0070] The collector of transistor 401 is connected to resistors 4021 to 4027, the emitter is connected to ground via resistor 403, and the base is connected to the emitter of transistor 4134.

[0071] The base of transistor 4134 is connected to the collector of control transistor 1131, and the collector is connected to the power supply line supplying the power supply voltage Vbat. The emitter is connected to resistor 4135 and transistor 401. The emitter of transistor 4134 is connected to ground through resistor 4135.

[0072] The operation of the power amplifier circuit 10A in the event of a temperature decrease will be explained. If a temperature decrease occurs, as explained in the power amplifier circuit 10, the current Ic flowing through the control transistor 1131 decreases. This causes the base voltage of transistor 4134 to rise, and the current flowing through transistor 4134 to increase. Consequently, the voltage drop in resistor 4135 increases, thus increasing the base voltage of transistor 401. This causes the current Ih flowing through transistor 401 to increase. Due to the flow of current Ih, resistors 4021 to 4027 heat up, which in turn heats diodes 1111 to 1116.

[0073] Figure 5 This diagram illustrates the component arrangement of the 10A power amplifier circuit. Figure 3 Diodes 1111 to 1116 are configured similarly. Figure 5 In this arrangement, resistors 4021 to 4027 are arranged adjacent to diodes 1111 to 1116. Furthermore, a transistor 401, having a base 5011, an emitter 5012, and a collector 5013, is positioned such that its long side runs along the arrangement direction of the resistors. The connections between the nodes of each element are also shown.

[0074] By heating the resistors 4021 to 4027, the decrease in the diode's forward voltage when the temperature drops can be suppressed. Furthermore, in the power amplifier circuit 10A, each resistor can be formed in a smaller area than the heating element in the power amplifier circuit 10, thus further reducing the size and manufacturing cost of the chip used in the power amplifier circuit.

[0075] The third embodiment will be described. Figure 6 This is a circuit diagram of the power amplifier circuit 10B according to the third embodiment. The configuration of the control circuit of the power amplifier circuit 10B is different from that of the power amplifier circuit 10.

[0076] The control circuit 601 in the power amplifier circuit 10B includes an A / D conversion circuit 6011 (temperature acquisition unit), a memory unit 6012, and a voltage generation unit 6013. Furthermore, the control circuit 601 is connected to a temperature sensor 602.

[0077] The A / D conversion circuit 6011 converts the temperature signal, which is an analog signal, from the temperature sensor 602 that measures the ambient temperature into a digital signal.

[0078] The memory section 6012 stores a control table 60121 that determines the control voltage Vcont based on the temperature signal converted into a digital signal.

[0079] The voltage generation unit 6013 is connected to the base of each of transistors 11411 to 11417. The voltage generation unit 6013 outputs a control voltage Vcont based on the control table 60121.

[0080] The operation of the power amplifier circuit 10B when the temperature decreases will be explained. A temperature signal is sent from the temperature sensor 602 to the A / D conversion circuit 6011. When the ambient temperature decreases, the voltage generation unit 6013 increases the control voltage Vcont supplied to the bases of transistors 11411 to 11417 based on the temperature signal converted into a digital signal and the control table 60121.

[0081] exist Figure 7 ,and Figure 2 Similarly, this shows the relationship between the product of current Ih and supply voltage Vcc, i.e., the total self-generated heat, and ambient temperature Ta. The total self-generated heat decreases as the ambient temperature Ta increases, becoming zero at approximately 10°C. Figure 7 The relationship between the changes in total spontaneous heat generation and the discrete changes based on digital signals is consistent with this. Figure 2 The relationships are different.

[0082] In the power amplifier circuit 10B, by using digital signal control, the control accuracy can be improved compared to the case of using analog signals, and power consumption can be further reduced.

[0083] Furthermore, the control circuit 601 can be configured on a different semiconductor chip than the power amplifier circuit 10B, or on the same semiconductor chip. The temperature sensor 602 can be configured on the same semiconductor chip as the power amplifier circuit 10B, on a different semiconductor chip, or at a predetermined position on the mobile terminal where the semiconductor chip is mounted.

[0084] The fourth embodiment will be described. Figure 8 A circuit diagram of the power amplifier circuit 10C according to the fourth embodiment is shown. In the power amplifier circuit 10C, the object heated by the heating element differs from that of the power amplifier circuit 10. Specifically, in the power amplifier circuit 10C, the heating element heats the transistor that outputs the output signal of the power amplifier circuit 10C.

[0085] The power amplifier circuit 10C has output transistors 80211 to 80217 that output signals. Output transistors 80211 to 80217 are connected in parallel. The base of each of the output transistors 80211 to 80217 is connected to transistor 101 via capacitors 80221 to 80227. Furthermore, the base of each of the output transistors 80211 to 80217 is connected to bias circuit 104 via resistors 80231 to 80237.

[0086] In the power amplifier circuit 10C, the heating section includes transistors 81411 to 81418. The emitters of transistors 81411 to 81418 are connected to ground via resistors 81431 to 81438, respectively. A control voltage Vcont is supplied to the bases of transistors 81411 to 81418 from the control transistor section 1130C.

[0087] The operation in the power amplifier circuit 10C under the condition of a temperature decrease will be explained. If a temperature decrease occurs, as explained in the power amplifier circuit 10, the current Ic flowing through the control transistor 1131 decreases. The base voltage of transistors 81411 to 81418 rises, and current flows through transistors 81411 to 81418. As a result, transistors 81411 to 81418 generate heat, which in turn heats the output transistors 80211 to 80217.

[0088] When the temperature decreases, the influence of lattice vibrations is reduced compared to room temperature. Consequently, avalanche phenomena, which cause a large current to flow at a certain voltage value, are more likely to occur in the output transistors 80211-80217 under lower electric fields. This avalanche phenomenon leads to damage to the output transistors 80211-80217 at even lower supply voltages (Vcc).

[0089] In the power amplifier circuit 10C, by heating the output transistors 80211 to 80217, the junction temperature of the output transistors 80211 to 80217 is increased, making it less likely for avalanche phenomena to occur, thereby improving the voltage withstand capability of transistors in low-temperature environments.

[0090] Reference Figure 9 The layout of the power amplifier circuit 10C will be described below. Output transistors 80211 to 80217 are arranged on chip 901 with their long sides facing the same direction and spaced at predetermined intervals in a direction orthogonal to the long side direction. Each transistor, for example, like output transistor 80211, has a base 9011, an emitter 9012, and a collector 9013.

[0091] Transistors 81411 to 81418 are disposed on chip 901. Each transistor, such as transistor 81411, has a base 9021, an emitter 9022, and a collector 9023. Transistors 81411 to 81418 are configured such that their long sides face the same direction as those of the output transistors 80211 to 80217 at the gaps and ends of each arrangement.

[0092] Also shown with Figure 8The circuit connections establish the connections between the nodes of the corresponding components. Bias current or voltage is supplied to terminal B2 from the bias circuit 104. A signal from transistor 101, which functions as a driver stage, is supplied to terminal D1. Terminal C1 is connected to the output terminal Pout, and an output signal is output through terminal C1.

[0093] The fifth embodiment will be described. Figure 10 This is a circuit diagram of the power amplifier circuit 10D according to the fifth embodiment. The power amplifier circuit 10D is... Figure 6 The same applies to the circuit after replacing the control circuit with the control circuit 601 and the temperature sensor 602.

[0094] The operation of the power amplifier circuit 10D when the temperature decreases will be explained. A temperature signal is sent from the temperature sensor 602 to the A / D conversion circuit 6011. When the ambient temperature decreases, the voltage generation unit 6013 increases the control voltage Vcont supplied to the bases of transistors 81411 to 81418 based on the temperature signal converted into a digital signal and the control table 60121.

[0095] In the power amplifier circuit 10D, by using digital signal control, the control accuracy can be improved compared to the case of using analog signals, and power consumption can be further reduced.

[0096] The sixth embodiment will be described. Figure 11 A circuit diagram of the power amplifier circuit 10E according to the sixth embodiment is shown.

[0097] In power amplifier circuit 10E, the amplifier circuit includes transistor 101, output transistor 102, bias circuit 103, matching circuits 105 and 110, capacitors 106 and 107, inductors 108 and 109, and resistors 1036, 11051, and 11052. The amplifier circuit in power amplifier circuit 10E differs from the circuit in power amplifier circuit 10 in that it does not have bias circuit 104 and resistor 1037. Furthermore, power amplifier circuit 10E includes bias circuits 1101 and 1102. In power amplifier circuit 10E, bias circuits 1101 and 1102 are bias circuit sections.

[0098] The bias circuit 1101 (first bias circuit) includes a reference voltage generation circuit 11102 and a control transistor section 11101. The reference voltage generation circuit 11102 includes transistors 11011 and 11012, and resistors 11013, 11014, 11015, and 11016. The reference voltage generation circuit 11102 is a current mirror circuit, which has the property of low temperature dependence of the reference voltage Vref. The power supply voltage VB1 is supplied to the reference voltage generation circuit 11102 through the resistor 11013.

[0099] The control transistor unit 11101 includes transistors 11017 and 11021, and resistive elements 11018 and 11019. The collector of transistor 11017 is supplied with a power supply voltage Vbat through resistive element 11018. The emitter of transistor 11017 is connected to ground through resistive element 11019. A reference voltage Vref is supplied to the base of transistor 11017 from the reference voltage generation circuit 11102. The collector of transistor 11017 is connected to the base of transistor 11021 to supply a control voltage Vcont.

[0100] For transistor 11021, a power supply voltage Vbat is supplied to its collector. The emitter of transistor 11021 is connected to the base of output transistor 102 through resistor element 11051. Based on the control voltage Vcont supplied to its base, transistor 11021 supplies a bias current I1 (first bias current) to the base of output transistor 102.

[0101] The bias circuit 1102 (second bias circuit) includes a reference voltage generation circuit 11103 and a transistor 11041. The reference voltage generation circuit 11103 includes transistors 11031, 11032, 11033, and 11034, and resistors 11035, 11036, 11037, and 11038. The reference voltage generation circuit 11103 supplies a base voltage to transistor 11041. The reference voltage generation circuit 11103 is a current mirror circuit, a bias circuit with relatively low temperature dependence of the output current.

[0102] Transistor 11041 outputs a bias current I1 to output transistor 102 based on the voltage from reference voltage generation circuit 11103.

[0103] With the current gain of the output transistor 102 set to β, the reactive current Iq flowing through the collector of the output transistor 102 connected to the bias circuits 1101 and 1102 is Iq=β(I1+I2).

[0104] The operation of the power amplifier circuit 10E under decreasing temperature conditions will be explained. The reference voltage Vref output from the reference voltage generation circuit 11102 is almost independent of the ambient temperature. On the other hand, the turn-on voltage of transistor 11017, i.e., the base-emitter voltage, increases as the ambient temperature decreases. Consequently, the current Ic flowing through transistor 11017 and resistor 11018 decreases as the ambient temperature decreases.

[0105] As the current Ic decreases, the voltage drop in resistor 11018 decreases, causing the control voltage Vcont applied to transistor 11021 to rise. If the control voltage Vcont rises, the bias current I1 increases.

[0106] On the other hand, the bias current I2 (second bias current) supplied from the bias circuit 1102 is almost independent of the ambient temperature.

[0107] exist Figure 12 The diagram illustrates the relationship between the reactive current βI1 from bias circuit 1101, the reactive current βI2 from bias circuit 1102, and their sum, Iq, and the ambient temperature Ta. Since the bias current I1 decreases as the ambient temperature Ta increases due to the aforementioned action, βI1 becomes zero at approximately 10°C. βI2 is not constant regardless of changes in the ambient temperature Ta. Consequently, Iq decreases as Ta increases and converges to a constant value above approximately 10°C.

[0108] Reference Figure 13 The time variation of Iq of the output transistor 102 in the power amplifier circuit 10E is explained. Figure 13 The horizontal axis represents time, and the vertical axis represents reactive current and power transmission. Reactive current is shown as a solid line, and power transmission is shown as a dashed line.

[0109] The power amplifier circuit 10E operates in FDD (Frequency Division Duplex) mode. Therefore, as... Figure 13 The output power is continuously transmitted, and the output transistor 102 continuously amplifies the power. Iq is set to a continuous value β(I1+I2) based on the ambient temperature Ta.

[0110] That is, in low-temperature environments, by increasing the bias current I1, Iq continuously increases compared to room temperature. This causes the power amplifier circuit 10E to operate closer to Class A operation, reducing power-added efficiency and increasing self-heating. On the other hand, Iq is set to converge to a constant low value βI2 as the temperature rises, reducing self-heating. Therefore, when the ambient temperature Ta is constant, the amount of reactive current remains constant.

[0111] Although the transistors in bias circuits 1101 and 1102 are bipolar transistors, they can also be field-effect transistors (FETs). In this case, the emitter, collector, and base are replaced by the source, drain, and gate of the FET.

[0112] In the power amplifier circuit 10E, there is no need to configure a dedicated transistor for heating. Therefore, the proprietary area of ​​the region where the transistor is configured can be reduced, thereby lowering manufacturing costs.

[0113] The seventh embodiment will be described. Figure 14 A circuit diagram of the power amplifier circuit 10F according to the seventh embodiment is shown.

[0114] The power amplifier circuit 10F further incorporates the baseband IC 1401, control unit 1402, and switches 14031, 14032, 14041, and 14042 within the power amplifier circuit 10E. The baseband IC 1401, control unit 1402, and switches 14031, 14032, 14041, and 14042 are elements of the bias selection circuit 1400. The power amplifier circuit 10F amplifies data for communication based on TDD (Time Division Duplex) technology.

[0115] The baseband IC1401 output indicates whether the communication in TDD mode requires signal amplification in the transmit time slot or not in the receive time slot.

[0116] Based on the signal from the baseband IC 1401, the control unit 1402 outputs the on / off signals of the switching switches 14031, 14032, 14041, and 14042.

[0117] Switch 14031 switches the connection between the bias circuit 1101 and the power supply line supplying the power supply voltage VB1. Switch 14032 switches the connection between the bias circuit 1101 and the ground wire. That is, the bias circuit 1101 can be switched on and off by switching 14031 and 14032.

[0118] Switch 14041 switches the connection between the bias circuit 1102 and the power supply line supplying the power voltage VB2. Switch 14042 switches the connection between the bias circuit 1102 and the ground wire. That is, the bias circuit 1102 can be switched on and off by switching 14041 and 14042.

[0119] In the power amplifier circuit 10F, by controlling the on and off of switches 14031, 14032, 14041, and 14042, only one of the bias circuits 1101 or 1102 is activated.

[0120] Switches 14031, 14032, 14041, and 14042 are, for example, constructed from field-effect transistors. Furthermore, switches 14031, 14032, 14041, 14042, and control unit 1402 can be integrated onto the same semiconductor chip as the power amplifier circuit 10F, or onto a different semiconductor chip than the power amplifier circuit 10F.

[0121] exist Figure 15 The diagram shows the relationship between the reactive currents βI1 from bias circuit 1101 and βI2 from bias circuit 1102 in the power amplifier circuit 10F and the ambient temperature Ta. βI1 becomes zero at approximately 10°C because the bias current I1 decreases as the ambient temperature Ta increases due to the aforementioned operation. βI2 is not constant regardless of changes in the ambient temperature Ta.

[0122] Reference Figure 16 The time variation of Iq of the output transistor 102 in the power amplifier circuit 10F is explained. Figure 16 The horizontal axis represents time, and the vertical axis represents reactive current and power transmission. Reactive current is shown as a solid line, and power transmission is shown as a dashed line.

[0123] The power amplifier circuit 10F operates in TDD mode. Therefore, as follows... Figure 16 As shown, the output power is output during transmission time slots T1 and T2, and the output transistor 102 only performs amplification operation during transmission time slots T1 and T2. On the other hand, during reception time slot R1, no transmission power is output, so the output transistor 102 does not perform amplification operation.

[0124] During transmission time slots T1 and T2, control unit 1402 supplies bias current I2 from bias circuit 1102. During reception time slot R1, control unit 1402 supplies bias current I1 from bias circuit 1101.

[0125] That is, when the ambient temperature is low, during the receiving time slot R1 when no amplification operation is performed, a large current, which is associated with the ambient temperature, flows from the bias circuit of the output bias current I1 to the output transistor 102, causing it to generate heat and thus heating the output transistor 102. This improves the voltage withstand capability of the transistor in low-temperature environments.

[0126] Furthermore, in the TDD mode, heating is performed based on the output signal during transmission, and a larger bias current is supplied to the output transistor 102 during reception than during transmission. This allows for more efficient heating of the output transistor 102 compared to the case where bias currents I1 and I2 are supplied regardless of whether the transmission or reception is performed.

[0127] The eighth embodiment will be described. Figure 17A circuit diagram of the power amplifier circuit 10G according to the eighth embodiment is shown.

[0128] In power amplifier circuit 10G, the amplifier circuit is the same as that of power amplifier circuit 10, including transistor 101, output transistor 102, bias circuits 103 and 104, matching circuits 105 and 110, capacitors 106 and 107, inductors 108 and 109, and resistors 1036 and 1046. In power amplifier circuit 10G, bias circuit 104 is a bias circuit section. Power amplifier circuit 10G includes control circuit 1701, temperature sensor 1702, and baseband IC 1703.

[0129] The control circuit 1701 includes an A / D conversion circuit 17011, a memory unit 17012, and a voltage generation unit 17014. Additionally, the control circuit 1701 is connected to a temperature sensor 1702.

[0130] The A / D conversion circuit 17011 converts the temperature signal, which is an analog signal, from the temperature sensor 1702 that measures the ambient temperature into a digital signal.

[0131] The memory section 17012 stores a control table 17013 that determines the control voltage Vcont based on the signal from the baseband IC 1703 and the temperature signal converted into a digital signal.

[0132] The voltage generation unit 17014 is connected to terminal BC2 of the bias circuit 104. Based on the control table 17013, the voltage generation unit 17014 outputs a control voltage Vcont.

[0133] The control circuit 1701 receives a signal from the baseband IC 1703 that distinguishes between transmit and receive time slots. Additionally, the ambient temperature is measured as an analog signal by the temperature sensor 1702 and input to the control circuit 1701. The temperature signal is converted into a digital signal by the A / D conversion circuit 17011. The signal from the baseband IC 1703 and the converted digital temperature signal are sent to the memory unit 17012. Based on the control table 17013 stored in the memory unit 17012, the voltage output by the voltage generation unit 17014 is determined. The voltage generation unit 17014 supplies voltage to the bias circuit 104 based on the determined voltage.

[0134] When the ambient temperature is low, the voltage generation unit 17014 supplies a bias current to the output transistor 102 so that the reactive current in the receiving time slot is higher than the reactive current in the transmitting time slot.

[0135] According to the power amplifier circuit 10G, the circuit that controls the reactive current flowing through the output transistor 102 based on the ambient temperature is a digital control circuit. Therefore, compared with the analog circuit, it can improve the control accuracy and further reduce power consumption.

[0136] The ninth embodiment will be described. Figure 18 A circuit diagram of the power amplifier circuit 10H according to the ninth embodiment is shown. The power amplifier circuit 10H is a circuit that combines a configuration for heating diodes 1111 and the like, and a configuration for heating output transistors 80211 and the like. This further improves the withstand voltage of the output stage transistors in low-temperature environments.

[0137] The tenth embodiment will be described. Figure 19 A circuit diagram of the power amplifier circuit 10I according to the tenth embodiment is shown. The power amplifier circuit 10I is a circuit that combines a configuration for heating diodes 1111 and the like, and a configuration for heating output transistor 102 via reactive current. This further improves the withstand voltage of the output stage transistor in low-temperature environments. Furthermore, a dedicated heating transistor is not required. Therefore, it also reduces the proprietary area of ​​the output stage transistor, thus lowering manufacturing costs.

[0138] The exemplary embodiments of the present invention have been described above. The power amplifier circuit 10 includes an amplification section for amplifying radio frequency signals, a heating section 114 having at least one transistor 11411 disposed adjacent to the amplification section and generating heat as the current increases, and a control circuit 112 connected to the transistor 11411 that increases the current when the ambient temperature is below a predetermined threshold.

[0139] Therefore, when the ambient temperature is below a specified threshold, the transistor 11411 can be activated to heat the components of the amplification section, thereby improving the voltage withstand capability of the transistor in low-temperature environments. Furthermore, since current flows to the transistor 11411 for heating only at extremely low ambient temperatures, the power consumption of the mobile terminal does not increase. Therefore, as long as continuous use is not performed in extremely low-temperature environments, the battery life can be prevented from becoming drastically shortened.

[0140] In addition, in the power amplifier circuit 10, the control circuit 112 includes a reference voltage generation circuit 1120 that generates a control voltage Vcont that increases as the ambient temperature decreases, and a control transistor section 1130.

[0141] The control transistor section 1130 supplies a reference voltage Vref, which is less affected by temperature changes, from the reference voltage generation circuit 1120. The control transistor section 1130 includes a control transistor 1131 that generates a control voltage Vcont that increases as the ambient temperature decreases. By using the control transistor 1131, the control voltage supplied to the heating element can be controlled, thereby improving the voltage withstand capability of the transistor in low-temperature environments.

[0142] The power amplifier circuit 10B includes an A / D conversion circuit 6011 that receives a temperature signal corresponding to the ambient temperature from a temperature sensor, and a voltage generation unit 6013 that generates a control voltage Vcont based on the temperature signal. Therefore, the heating element can be controlled based on a digital signal, resulting in more precise heating.

[0143] In the power amplifier circuit 10, the heating element is a transistor 11411 that carries current based on the control voltage Vcont. Therefore, by amplifying the current of the transistor 11411, the heat generated based on the control voltage Vcont can be ensured to adequately heat the amplification section.

[0144] Furthermore, in the power amplifier circuit 10A, the heating element is a resistive element 4021 through which current flows, based on the control voltage Vcont. In the power amplifier circuit 10A, each resistive element can be formed in a smaller area than the heating element in the power amplifier circuit 10, thus further reducing the size and manufacturing cost of the chip used to install the power amplifier circuit.

[0145] In addition, the power amplifier circuit 10 also includes a chip 301 having a main surface parallel to a plane defined by a first direction and a second direction that intersect each other. The amplification section includes an amplifier circuit 100 that outputs an amplified wireless frequency signal, a clamping circuit 111 provided between the output of the amplifier circuit and the ground line, having an anode connected to the amplifier circuit side and a cathode connected to the ground side, connected in series with each other and provided on the chip 301, and a transistor 11411 provided adjacent to the diode 1111 on the chip 301.

[0146] Therefore, when the ambient temperature decreases, transistor 11411 generates heat and heats diodes 1111 to 1116. By heating diodes 1111 to 1116, the turn-on voltage of each diode is prevented from decreasing due to the drop in ambient temperature. By preventing the turn-on voltage of each diode from decreasing, the voltage at which the clamping circuit is connected is ensured, thus preventing damage to the output transistor 102 when the ambient temperature decreases.

[0147] The power amplifier circuit 10C also includes a chip 901 having a main surface parallel to a plane defined by a first direction and a second direction that intersect each other. The amplification section has an output transistor 80211 disposed on the chip 901. Transistor 81411 is disposed adjacent to the output transistor 80211 on the chip.

[0148] When the temperature drops, transistor 81411 heats output transistor 80211, thereby increasing the junction temperature of output transistor 80211, making avalanche less likely to occur, and thus improving the voltage withstand capability of transistors in low-temperature environments.

[0149] The power amplifier circuit 10E includes an output transistor 102 that amplifies and outputs a radio frequency signal and generates heat as the current increases, and bias circuits 1101 and 1102 that supply bias current or voltage to the output transistor 102. The bias circuit 1101 includes a control circuit 11101 that increases the bias current or voltage when the ambient temperature is below a predetermined threshold, and a voltage generation unit 11102 that generates a reference voltage independent of temperature changes. The output transistor 102 experiences an increase in current as the control voltage increases.

[0150] Therefore, the reactive current of the output transistor 102 can be increased at low temperatures, thereby heating the output transistor 102. By raising the junction temperature of the output transistor 102, avalanche phenomena are less likely to occur, and the voltage withstand capability of the transistor in low-temperature environments can be improved.

[0151] The power amplifier circuit 10F includes a bias circuit 1101 and a bias circuit 1102, and also includes a bias selection circuit 1400. This bias selection circuit switches the supply state so that either the bias circuit 1101 or the bias circuit 1102 supplies bias current or voltage to the output transistor 102. Therefore, the connection between the bias circuit 1101 and the bias circuit 1102 can be switched according to the temperature condition, thus allowing for appropriate heating of the output transistor 102.

[0152] In the power amplifier circuit 10F, the radio frequency signal is the transmission signal of the time-division multiplexing transmission time slot, and the control signal is the signal indicating whether the timing is in the above-mentioned transmission time slot or the above-mentioned time-division multiplexing reception time slot. When the timing is in the reception time slot, the bias selection circuit 1400 supplies bias current I1 from the bias circuit 1101 to the output transistor 102, and when the timing is in the transmission time slot, it supplies bias current I2 from the bias circuit 1102 to the output transistor 102.

[0153] In low ambient temperatures, during the receiving time slot R1 without amplification, a large current, corresponding to the ambient temperature, flows from the bias circuit of the output bias current I1 to the output transistor 102, causing it to self-heat and thus heating the output transistor 102. This improves the voltage withstand capability of the transistor in low-temperature environments. Furthermore, in the TDD mode, during transmission, heating is based on the output signal; during reception, a larger bias current is supplied to the output transistor 102 than during transmission. This significantly improves heating efficiency compared to supplying bias currents I1 and I2 regardless of whether transmission or reception is involved.

[0154] The power amplifier circuit 10G includes an A / D conversion circuit 17011 that receives a temperature signal corresponding to the ambient temperature from a temperature sensor, and a voltage generation unit 17014 that generates a control voltage based on the temperature signal. Therefore, the reactive current of the output transistor 102 can be controlled based on the digital signal, resulting in more precise heating.

[0155] In the power amplifier circuit 10G, the radio frequency signal is a transmission signal in the time-division multiplexing transmission time slot, and the control signal is a signal indicating whether the timing is in the aforementioned transmission time slot or the aforementioned time-division multiplexing reception time slot. When the timing is in the reception time slot, the control circuit 1701 supplies a bias current I1 from the bias circuit 1101 to the output transistor 102, and when the timing is in the transmission time slot, it supplies a bias current I2 from the bias circuit 1102 to the output transistor 102. This allows for efficient heating of the output transistor 102.

[0156] Furthermore, the embodiments described above are intended to facilitate understanding of the present invention and are not intended to limit the scope of the invention. The present invention can be modified / improved without departing from its spirit, and its equivalents are also included. That is, any embodiment with appropriate design modifications by those skilled in the art, provided it possesses the features of the present invention, is also included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, and dimensions of each embodiment are not limited to the examples and can be appropriately modified. Additionally, each embodiment is illustrative; naturally, different substitutions or combinations of the components shown in the embodiments are possible, and these embodiments are also included within the scope of the present invention as long as they contain the features of the present invention.

Claims

1. A power amplification circuit comprising: an amplification section that amplifies a radio frequency signal; a heating section that is provided adjacent to the amplification section and has at least one heating element whose heat generation amount increases with an increase in a passing current; and a control circuit that is connected to the heating element and increases the passing current when an ambient temperature is below a prescribed threshold value, the power amplification circuit further comprising a chip that has a main surface parallel to a plane defined by a first direction and a second direction that intersect each other, the amplification section comprising: an amplification circuit that outputs an output signal in which the radio frequency signal is amplified; and a clamping circuit that is provided between an output of the amplification circuit and a ground line and has at least one diode that is connected to the amplification circuit side at an anode and to one side of the ground line at a cathode and is provided in the chip in series connection with each other, the heating element being provided in the chip adjacent to the diode.

2. The power amplification circuit according to claim 1, wherein the control circuit comprises a control voltage generation section that generates a control voltage that increases with a decrease in the ambient temperature, the passing current in the at least one heating element increasing with an increase in the control voltage.

3. The power amplification circuit according to claim 2, wherein the control voltage generation section comprises: a reference voltage generation circuit that generates a reference voltage; and a control transistor section that includes a control transistor whose base is supplied with the reference voltage and outputs the control voltage that increases with a decrease in the ambient temperature on the basis of the ambient temperature and the reference voltage.

4. The power amplification circuit according to claim 2, wherein the control voltage generation section comprises a temperature acquisition section that is supplied with a temperature signal corresponding to the ambient temperature from a temperature sensor, the control voltage generation section generating the control voltage on the basis of the temperature signal.

5. The power amplification circuit according to claim 3 or 4, wherein the heating element is a unit transistor that outputs the passing current on the basis of the control voltage.

6. The power amplification circuit according to claim 3 or 4, wherein the heating element is a resistive element through which the passing current passes on the basis of the control voltage.

7. A power amplification circuit comprising: an amplification section that amplifies a radio frequency signal; a heating section that is provided adjacent to the amplification section and has at least one heating element whose heat generation amount increases with an increase in a passing current; and a control circuit that is connected to the heating element and increases the passing current when an ambient temperature is below a prescribed threshold value, the power amplification circuit further comprising a chip that has a main surface parallel to a plane defined by a first direction and a second direction that intersect each other, the amplification section having at least one output transistor provided in the chip, the at least one heating element being provided in the chip adjacent to the at least one output transistor.

8. A power amplification circuit comprising: an output transistor that amplifies and outputs a radio frequency signal and whose heat generation amount increases with an increase in a passing current. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a bias circuit section that supplies a bias current or a voltage to the output transistor, a control circuit that is connected to the bias circuit section and increases the bias current or the voltage when an ambient temperature is below a predetermined threshold value, the control circuit includes a control voltage generation section that generates a control voltage that increases as the ambient temperature decreases, the output transistor increases the pass current as the control voltage increases, the control voltage generation section includes: a reference voltage generation circuit that generates a reference voltage, and a control transistor section that includes a control transistor that outputs the control voltage that increases as the ambient temperature decreases based on the ambient temperature and the reference voltage when a base of the control transistor is supplied with the reference voltage, the bias circuit section includes a first bias circuit and a second bias circuit, a bias selection circuit that switches a supply state so that the first bias circuit or the second bias circuit supplies the bias current or the voltage to the output transistor based on a control signal.

9. The power amplification circuit according to claim 8, wherein the radio frequency signal is a transmission signal in a transmission time slot of a time division multiplexing scheme, the control signal is a signal that indicates whether a timing is located in the transmission time slot or in a reception time slot of the time division multiplexing scheme, the bias selection circuit supplies the bias current or the voltage to the output transistor from the first bias circuit when the timing is located in the reception time slot, and supplies the bias current or the voltage to the output transistor from the second bias circuit when the timing is located in the transmission time slot.

10. The power amplification circuit according to claim 8, wherein the control voltage generation section includes a temperature acquisition section that is supplied with a temperature signal corresponding to the ambient temperature from a temperature sensor, the control voltage generation section generates the control voltage based on the temperature signal.

11. The power amplification circuit according to claim 10, wherein the radio frequency signal is a transmission signal in a transmission time slot of a time division multiplexing scheme, the control signal is a signal that indicates whether a timing is located in the transmission time slot or in a reception time slot of the time division multiplexing scheme, the control voltage generation section supplies a first bias current or a voltage to the output transistor when the timing is located in the reception time slot, and supplies a second bias current or a voltage that is smaller than the first bias current or the voltage to the output transistor when the timing is located in the transmission time slot.

Images