WO2023138615A1 - 一种具有电流保护的射频前端模块及电子设备 - Google Patents

一种具有电流保护的射频前端模块及电子设备 Download PDF

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Publication number
WO2023138615A1
WO2023138615A1 PCT/CN2023/072885 CN2023072885W WO2023138615A1 WO 2023138615 A1 WO2023138615 A1 WO 2023138615A1 CN 2023072885 W CN2023072885 W CN 2023072885W WO 2023138615 A1 WO2023138615 A1 WO 2023138615A1
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Prior art keywords
current
radio frequency
protection
transistor
power
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PCT/CN2023/072885
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English (en)
French (fr)
Inventor
李�浩
白云芳
Original Assignee
唯捷创芯（天津） 电子技术股份有限公司
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Application filed by 唯捷创芯（天津） 电子技术股份有限公司 filed Critical 唯捷创芯（天津） 电子技术股份有限公司
Priority to CN202380009635.5A priority Critical patent/CN116803000A/zh
Priority to KR1020247000380A priority patent/KR20240017922A/ko
Publication of WO2023138615A1 publication Critical patent/WO2023138615A1/zh
Priority to US18/416,841 priority patent/US20240235496A1/en

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/189—High-frequency amplifiers, e.g. radio frequency amplifiers
    • H03F3/19—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
    • H03F3/195—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only in integrated circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/52—Circuit arrangements for protecting such amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/56—Modifications of input or output impedances, not otherwise provided for
    • H03F1/565—Modifications of input or output impedances, not otherwise provided for using inductive elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H03F3/213—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only in integrated circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H03F3/245—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/222—A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/267—A capacitor based passive circuit, e.g. filter, being used in an amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/426—Indexing scheme relating to amplifiers the amplifier comprising circuitry for protection against overload
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/447—Indexing scheme relating to amplifiers the amplifier being protected to temperature influence
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier

Definitions

  • the invention relates to a radio frequency front-end module with current protection, and also relates to electronic equipment including the radio frequency front-end module, belonging to the technical field of radio frequency integrated circuits.
  • the increase or decrease of the working environment temperature has reached or exceeded the limit of the required temperature range (the general temperature range is -25°C to 85°C or -40°C to 110°C).
  • the safe working area of the power device will be reduced, and even when the operating current on the power device exceeds the maximum withstand current of the device, it will cause irreversible damage or destruction of the power device. Therefore, in order to ensure the normal operation of power devices, it is necessary to take appropriate protection measures to limit the excessive operating current of power devices in harsh environment scenarios, so as to ensure that power devices always work in a safe working area.
  • a typical RF front-end module in the prior art includes an input matching module, a power amplifier (Power Amplifier, PA for short), an output matching module and a power supply module.
  • the power amplifier usually includes a two-stage or three-stage power amplification unit, which is the main power device for current protection.
  • the high-frequency power amplifier circuit of the fourth embodiment includes a high-frequency power amplifier transistor, and a matching circuit and a matching circuit, and a bias power transistor, and a passive element; wherein the passive element is connected between a common power supply terminal and a collector of a bias power transistor connected to the first-stage transistor. Passive components are realized by resistors and inductors connected in series. In this high frequency power amplifier circuit, the passive element improves the linearity at high output by preventing the electric power reduction of the bias power transistor.
  • the technical problem to be solved by the present invention is to provide a radio frequency front-end module with current protection.
  • Another technical problem to be solved by the present invention is to provide a Blocks of electronic devices.
  • a radio frequency front-end module with current protection including an input matching module, a power amplifier, an output matching module, a power supply module and a protection unit;
  • the input end of the input matching module is connected to the input end of the external radio frequency signal, and the output end is connected to the input end of the power amplifier, so as to realize impedance matching between the power amplifier and the input end of the external radio frequency signal;
  • the power amplifier is used to amplify the power of the input radio frequency signal, and its output terminal is connected to the input terminal of the output matching module;
  • the output terminal of the output matching module is connected to the output terminal of the radio frequency signal, and is used to realize the power matching between the power amplifier and the output terminal of the radio frequency signal;
  • the output end of the protection unit is connected to the power amplifier, and the threshold voltage generated by the protection unit limits the current of the power amplifier to realize current protection.
  • the protection unit includes at least one current limiting resistor and one filter capacitor; wherein,
  • the current limiting resistor is used to generate the threshold voltage; the filter capacitor is used to present a low resistance state at the radio frequency and envelope signal frequency, so that the threshold voltage does not change with the radio frequency signal and envelope signal.
  • the protection unit further includes a notch branch, and the notch branch is connected in parallel with the filter capacitor.
  • the power amplifier includes at least one stage of power amplifying unit, and the power amplifying unit includes a bias circuit and a power amplifying circuit; the protection unit is at least connected to the bias circuit of one stage of the power amplifying unit.
  • the bias circuit includes a first transistor, a second transistor, a third transistor, a first bias resistor, and a first filter capacitor;
  • the power amplifier circuit includes a fourth transistor, a first ballast resistor, and a first inductor;
  • the protection unit includes a first current-limiting resistor and a second filter capacitor;
  • the emitter of the third transistor is connected to the ground potential terminal, the base and the collector of the third transistor are short-circuited and connected to the emitter of the second transistor, the base and the collector of the second transistor are short-circuited and connected to the first bias resistor on the one hand, and on the other hand
  • it is connected to the base of the first transistor and the first filter capacitor, the other end of the first bias resistor is connected to a bias power supply, the other end of the first filter capacitor is connected to the ground potential end, the collector of the first transistor is connected to the second filter capacitor and the first current limiting resistor, the other end of the second filter capacitor is connected to the ground potential end, the other end of the first current limiting resistor is connected to the second power supply end;
  • the base of the fourth transistor is connected to the ground potential terminal, the collector of the fourth transistor is connected to the output terminal on the one hand, and is connected to the first inductor on the other hand, and the other end of the first inductor is connected to the first power supply terminal.
  • the bias circuit and the power amplifier circuit enter the current limiting protection working state:
  • V 1c V 1b - V th_bc
  • V 1C VDD-V R
  • V 1C is the collector voltage of the first transistor
  • V 1b is the base voltage of the first transistor
  • V th_bc is the threshold voltage between the base and the collector of the first transistor
  • VR is the voltage drop on the first current limiting resistor
  • I 1 is the collector current of the first transistor
  • R is the resistance value of the first current limiting resistor
  • VDD is the voltage of the second power supply.
  • the current-limiting resistor in the protection unit is a thermistor with a temperature coefficient; for the power amplifier that is prone to burnout at low temperature, the current-limiting resistor is a thermistor with a negative temperature coefficient; for the power amplifier that is prone to burnout at a high temperature, the current-limiting resistor is a thermistor with a positive temperature coefficient.
  • the filter capacitor in the protection unit adopts a plurality of capacitors of different sizes, and its capacitance value ranges from pF level to uF level, which are used to filter out radio frequency signals and envelope signals of different frequencies to realize broadband filtering.
  • the power supply connected to the first current-limiting resistor in the protection unit adopts a stabilized voltage source with a temperature coefficient; for the power amplifier that is prone to burnout at low temperature, the power supply adopts a stabilized voltage source with a positive temperature coefficient; for the power amplifier that is prone to burnout at a high temperature, the power supply adopts a stabilized voltage source with a negative temperature coefficient.
  • the protection unit adds a notch branch, the notch branch is composed of an inductor and a capacitor in series, and the notch branch is connected in parallel with the second filter capacitor; wherein, the inductance end of the notch branch is connected to the node end of the first current limiting resistor and the second filter capacitor, and the capacitor end is connected to the ground potential end.
  • the protection unit further includes an inductor, which forms an RLC combination circuit with the current limiting resistor and the filter capacitor, and further filters out radio frequency signals and envelope signals.
  • the RLC combined circuit includes an eleventh inductor, a current limiting resistor, an eleventh capacitor and a twelfth capacitor; wherein,
  • One end of the current-limiting resistor is connected to the collector of the first transistor in the bias circuit on the one hand, and is connected to the eleventh capacitor on the other hand; the other end of the current-limiting resistor is connected to the eleventh inductance on the one hand, and the twelfth capacitor on the other hand; the other end of the eleventh inductance is connected to the second power supply end; the other end of the eleventh capacitor and the twelfth capacitor are respectively connected to the ground potential end.
  • control switch is further included, the control switch is connected in parallel to both ends of the protection unit, and is used to enable or disable the protection unit; the control signal terminal of the control switch is connected to the first power supply terminal or the output terminal of the power detection circuit.
  • an electronic device including the above radio frequency front-end module with current protection.
  • the radio frequency front-end module with current protection provided by the embodiment of the present invention can play the role of over-current protection, over-voltage protection and over-power protection for the power amplifier by adding a protection unit, thereby greatly improving the reliability and safety of the radio frequency front-end module working in harsh environments.
  • the protection unit only uses the voltage drop change of the current limiting resistor to realize the threshold voltage, and does not introduce additional circuit power consumption and occupy a large circuit area. Therefore, the radio frequency front-end module with current protection provided by the present invention has beneficial effects such as ingenious and reasonable structural design, low design cost, high reliability, and excellent circuit performance, and is suitable for radio frequency front-end modules of various structures.
  • FIG. 1 is a structural block diagram of a typical RF front-end module in the prior art
  • Fig. 2 is the structural block diagram of the radio frequency front-end module with current protection that the embodiment of the present invention provides;
  • Fig. 3 shows the power amplifier, power supply module and protection unit in the first embodiment of the present invention Schematic diagram of the structure
  • Fig. 4 (a) is in the first embodiment of the present invention, the circuit schematic diagram of amplification unit and protection unit;
  • Fig. 4(b) is another schematic circuit diagram of the amplification unit and the protection unit in the first embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of the protection unit providing overcurrent protection for the latter two power amplification units in the first embodiment of the present invention
  • FIG. 6 is a schematic structural diagram of the protection unit providing overcurrent protection for the final power amplifying unit in the first embodiment of the present invention
  • FIG. 7 is a schematic circuit diagram of an amplification unit and a protection unit in the second embodiment of the present invention.
  • Fig. 8 is a schematic structural diagram of a power amplifier, a power module and a protection unit in the second embodiment of the present invention.
  • FIG. 9 is a schematic structural diagram of a protection unit providing overcurrent protection for the latter two stages of power amplifying units in the second embodiment of the present invention.
  • FIG. 10 is a schematic structural diagram of the protection unit providing overcurrent protection for the final power amplifier unit in the second embodiment of the present invention.
  • Fig. 11 is a schematic circuit diagram of an amplification unit and a protection unit in the third embodiment of the present invention.
  • Fig. 12 is a schematic diagram of the first structure of the protection unit with a control switch in the third embodiment of the present invention.
  • Fig. 13 is a second structural schematic diagram of a protection unit with a control switch in the third embodiment of the present invention.
  • Fig. 14 is a graph showing the relationship between the input power and output current of the power amplifier circuit in the technical solution provided by the embodiment of the present invention.
  • Fig. 15 is an example diagram of an electronic device adopting a radio frequency front-end module provided by an embodiment of the present invention.
  • the RF front-end module with current protection includes an input matching module 1 , a power amplifier 2 , an output matching module 3 , a power supply module 4 and a protection unit 5 .
  • the input end of the input matching module 1 and the input end of the external radio frequency signal PA IN connection the output end of the input matching module 1 is connected to the input end of the power amplifier 2, the output end of the power amplifier 2 is connected to the input end of the output matching module 3, the output end of the output matching module 3 is connected to the radio frequency signal output end PA OUT; the power supply module 4 and the protection unit 5 are respectively connected to the power amplifier 2.
  • the input matching module 1 is used to realize the impedance matching between the power amplifier 2 and the radio frequency signal input terminal PA IN; the power amplifier 2 is used for power amplification of the input radio frequency signal, which includes at least one stage of power amplification unit, and the power amplification unit includes a bias circuit and a power amplification circuit; the output matching module 3 is used to realize power matching between the power amplifier 2 and the radio frequency signal output terminal PA OUT; the power supply module 4 provides the bias current and voltage required for the power amplifier 2 to work.
  • the protection unit 5 provides current protection for the power amplifier 2, and is at least connected to the bias circuit of the power amplification unit at one stage; the protection unit 5 includes at least one current limiting resistor and one filter capacitor.
  • the power supply VCC provides power supply voltage and current for the power amplifier; the power supply VDD provides power supply voltage and current for the bias circuit and power module 4 in the power amplifier. Usually, both the power VCC and the power VDD are powered by an external power supply module.
  • the specific circuits of the power amplifier 2 , the power module 4 and the protection unit 5 are shown in FIG. 3 .
  • the power amplifier 2 includes three stages of power amplifying units, namely, the first stage power amplifying unit PA1, the second stage power amplifying unit PA2, and the third stage power amplifying unit PA3, and the three stages of power amplifying units are cascaded in sequence.
  • the first power supply Vreg1, the second power supply Vreg2, and the third power supply Vreg3 output by the power module 4 are respectively connected to the bias power terminals of the first-stage power amplifying unit PA1, the second-stage power amplifying unit PA2, and the third-stage power amplifying unit PA3.
  • One end of the protection unit 5 is connected to the power supply VDD, and the other end is respectively connected to the bias circuits of the first-stage power amplifying unit PA1, the second-stage power amplifying unit PA2, and the third-stage power amplifying unit PA3.
  • the power amplifying unit includes a bias circuit and a power amplifying circuit.
  • the bias circuit includes a first transistor HBT1, a second transistor HBT2, a third transistor HBT3, a first bias resistor R1 and a first filter capacitor C1;
  • the power amplifier circuit includes a fourth transistor HBT4, a first ballast resistor R2 and a first inductor L1;
  • the protection unit includes a first current limiting resistor R and a second filter capacitor C.
  • the second transistor HBT2 and the third transistor HBT3 form a double diode.
  • the emitter of HBT3 is connected to the ground potential end, the base and collector of the third transistor HBT3 are short-circuited and connected to the emitter of the second transistor HBT2, the base and collector of the second transistor HBT2 are short-circuited and connected to the first bias resistor R1 on the one hand, and on the other hand to the base of the first transistor HBT1 and the first filter capacitor C1.
  • the filter capacitor C is connected to the first current limiting resistor R, the other end of the second filter capacitor C is connected to the ground potential end, the other end of the first current limiting resistor R is connected to the power supply VDD; the emitter of the first transistor HBT1 is connected to the first ballast resistor R2, the other end of the first ballast resistor R2 is connected to the input terminal IN on the one hand, and the base of the fourth transistor HBT4 on the other hand, the emitter of the fourth transistor HBT4 is connected to the ground potential terminal, the collector of the fourth transistor HBT4 is connected to the output terminal OUT on the one hand, and the first inductor L1 on the other hand.
  • the other end of 1 is connected to the power supply VCC.
  • the radio frequency front-end module with current protection in the above-mentioned first embodiment its working principle of current protection is as follows:
  • V R I 1 *R (2)
  • V 1C VDD-V R (3)
  • V 1c V 1b -V th_bc (4)
  • V 1C is the collector voltage of the first transistor HBT1
  • V 1b is the base voltage of the first transistor HBT1
  • V th_bc is the threshold voltage between the base and the collector of the first transistor HBT1
  • VR is the voltage drop on the first current limiting resistor R
  • I 1 is the collector current of the first transistor HBT1
  • I 2 is the collector current of the fourth transistor HBT4
  • R is the resistance value of the first current limiting resistor R
  • ⁇ is the amplification factor of the fourth transistor HBT4
  • VDD is The voltage value of the power supply VDD.
  • the first transistor HBT1 needs to provide a larger output current I 1 , at this time, according to formula 2 and formula 3, due to the increase of the current I 1 , the voltage drop VR on the first current limiting resistor R becomes larger, and the first crystal The collector voltage V 1C of the body tube HBT1 decreases.
  • V 1C decreases to V 1C ⁇ V 1b - V th_bc , the current I 1 decreases sharply, so the current I 2 decreases accordingly, thereby realizing the overcurrent protection function of the circuit.
  • V 1C ⁇ V 1b -V th_bc the bias circuit and the power amplifier circuit enter into the current limiting protection working state.
  • V th_bc is 1.2V
  • V 1b is 2.4V
  • V 1C ⁇ 1.2V the bias circuit and power amplifier circuit enter the current limiting protection working state.
  • the voltage drop V R on the first current limiting resistor R in the protection unit is used as a threshold voltage to limit the maximum current of the power amplifier circuit, thereby realizing the current protection function;
  • the second filter capacitor C acts as a filter, and presents a low resistance state at the radio frequency frequency and the envelope signal frequency, so that the voltage drop VR on the first current limiting resistor R will not change with the change of the radio frequency signal and the envelope signal, ensuring that the first transistor HBT1 is in a stable working state.
  • the protection unit in the above embodiment can also add a trap circuit composed of a second inductor L2 and a third capacitor C4 in series, and the trap circuit is connected in parallel with the second filter capacitor C, wherein the inductor (L2) terminal is connected to the node terminal of the first current limiting resistor R and the second filter capacitor C, and the capacitor terminal (C4) is connected to the ground potential terminal.
  • the notch branch and the second filter capacitor are used together to suppress the radio frequency and the envelope signal frequency, presenting a low-resistance state at the radio frequency and the envelope signal frequency, so as to filter the radio frequency signal and the envelope signal, and at the same time, achieve the effect of broadband filtering.
  • the circuit structure of the power amplifier, power module and protection unit shown in FIG. 3 can have different deformation examples.
  • the power amplifier is not limited to cascaded three-stage power amplifying units, but can also be one-stage, two-stage or even multi-stage power amplifying units cascaded together to realize the technical solution provided by the present invention.
  • the bias circuits shown in FIG. 4( a ) and FIG. 4( b ) may have different deformation examples according to actual needs, which are not limited here.
  • the protection unit provides overcurrent protection for all three-stage power amplification units.
  • the protection unit can also only provide overcurrent protection for the latter two stages of power amplifying units, wherein the output terminals of the protection unit are respectively connected to the bias circuits of the latter two stages of power amplifying units PA2 and PA3 .
  • the protection unit can also only provide overcurrent protection for the final power amplifying unit, wherein the output terminal of the protection unit is connected to the bias circuit of the final power amplifying unit PA3.
  • the wave capacitor is not limited to one capacitor, but can also include multiple capacitors of different sizes, and its capacitance value can range from pF level to uF level, which is used to filter out radio frequency signals of different frequencies and achieve the effect of broadband filtering.
  • the power amplifier 2, the power module 4 and the protection unit 5 in the radio frequency front-end module can adopt the following two technical solutions to solve the problem of overcurrent protection for the situation that the power device is damaged or destroyed due to a large increase or decrease in the working environment temperature.
  • the protection unit in the first technical solution is composed of a first current-limiting resistor R and a second filter capacitor C, wherein the first current-limiting resistor R is a thermistor with a temperature coefficient.
  • the first current-limiting resistor R selects a thermistor with a negative temperature coefficient; for a power amplifying circuit that is prone to burnout at high temperatures, the first current-limiting resistor R selects a thermistor with a positive temperature coefficient; the specific working principle of overcurrent protection is as follows:
  • the circuit is a power amplifier circuit that is prone to burnout at low temperatures
  • the first current-limiting resistor R is a thermistor with a negative temperature coefficient
  • the voltage drop V on the first current-limiting resistor R R becomes larger, the collector voltage V of the first transistor HBT1 1C decreases when V 1C reduced to V 1C ⁇ V 1b -V th_bc , the current I 1 decreases sharply, the current I 2
  • the overcurrent protection effect is realized for the power amplifier circuit that is prone to burnout at low temperature, and compared with the first current-limiting resistor being an ordinary resistor, the first current-limiting resistor adopts a thermistor with a negative temperature coefficient, which can also shorten the protection start-up time and further strengthen the protection effect.
  • the circuit is a power amplifier circuit that is prone to burnout at high temperature
  • the first current-limiting resistor R is a thermistor with a positive temperature coefficient
  • the voltage drop V on the first current-limiting resistor R R becomes larger, the collector voltage V of the first transistor HBT1 1C decreases when V 1C reduced to V 1C ⁇ V 1b -V th_bc , the current I 1 decreases sharply, the current I 2
  • the overcurrent protection function is realized for the power amplifier circuit that is prone to burnout at high temperature, and compared with the first current limiting resistor being an ordinary resistor, the first current limiting resistor adopts a thermistor with a positive temperature coefficient, which can also shorten the protection startup time and further strengthen the protection effect.
  • the bias power Vreg4 in the second technical solution is a bias power with a temperature coefficient output by the power module, which provides protection for all three-stage power supplies through the protection unit.
  • the bias circuit of the rate amplification unit is powered.
  • the bias power supply Vreg4 chooses a voltage regulator with a positive temperature coefficient; for the power amplifier circuit that is prone to burnout at a high temperature, the bias power supply Vreg4 chooses a voltage regulator with a negative temperature coefficient.
  • the working principle of its overcurrent protection is as follows:
  • the bias power supply Vreg4 selects a positive temperature coefficient regulator
  • the collector voltage V of the first transistor HBT1 1C decreases when V 1C reduced to V 1C ⁇ V 1b -V th_bc
  • the current I 1 decreases sharply
  • the current I 2 It decreases accordingly, so that the overcurrent protection effect is realized for the power amplifier circuit that is prone to burnout at low temperature, and compared with the constant power supply VDD, the bias power supply Vreg4 chooses a voltage regulator with a positive temperature coefficient, which can also shorten the protection startup time and strengthen the protection function.
  • the bias power supply Vreg4 selects a negative temperature coefficient regulator
  • the collector voltage V of the first transistor HBT1 1C decreases when V 1C reduced to V 1C ⁇ V 1b -V th_bc
  • the current I 1 decreases sharply
  • the current I 2 It decreases accordingly, so that the overcurrent protection effect is realized for the power amplifier circuit that is prone to burnout at high temperature, and compared with the constant power supply VDD, the bias power supply Vreg4 chooses a stabilized voltage source with a negative temperature coefficient, which can also shorten the protection startup time and play a role in strengthening protection.
  • the circuit structures of the power amplifier, the power module and the protection unit can also have different modified examples.
  • the power amplifier is not limited to being formed by cascading three-stage power amplifying units, but may also be one-stage, two-stage or even multi-stage power amplifying units cascaded together to realize the technical solution provided by the present invention.
  • the protection unit provides overcurrent protection for all three-stage power amplifying units.
  • the protection unit can also provide overcurrent protection only for the latter two stages of power amplification units, wherein the protection unit is composed of a first current-limiting resistor and a second filter capacitor, one end of the first current-limiting resistor and the second filter capacitor are respectively connected to the bias circuits of the latter two stages of power amplifier units PA2 and PA3, and the other end of the first current-limiting resistor is connected to a bias power supply Vreg4 with a temperature coefficient.
  • the protection unit can also be only the last stage
  • the power amplification unit provides overcurrent protection, wherein the protection unit is composed of a first current-limiting resistor and a second filter capacitor, one end of the first current-limiting resistor and the second filter capacitor are connected to the bias circuit of the final power amplifier unit PA3, and the other end of the first current-limiting resistor is connected to the bias power supply Vreg4 with a temperature coefficient.
  • the protection unit in the radio frequency front-end module can be implemented by using an RLC combination circuit.
  • the RLC combined circuit is composed of an eleventh inductor L, an eleventh resistor R (ie, a current limiting resistor), an eleventh capacitor C2 and a twelfth capacitor C3.
  • One end of the eleventh resistor R is connected to the collector of the first transistor HBT1 in the bias circuit on the one hand, and the eleventh capacitor C2 on the other hand; the other end of the eleventh resistor R is connected to the eleventh inductor L on the one hand, and the twelfth capacitor C3 on the other hand; the other end of the eleventh inductor L is connected to the power supply VDD; the other ends of the eleventh capacitor C2 and the twelfth capacitor C3 are respectively connected to the ground potential terminal.
  • the eleventh resistor R in the above RLC combined circuit is a current limiting resistor, and the eleventh capacitor C2 and the twelfth capacitor C3 are filter capacitors. It should be noted that the RLC combined circuit may also be in other combined forms, but it includes at least one current limiting resistor and one filter capacitor.
  • the RLC combination circuit can also realize the input and exit of the protection unit through a control switch SW, and the control switch SW can be turned on to limit the current under high power, high current or high voltage, so that the RLC combination circuit will not affect the working performance of the power amplifier under normal conditions.
  • the protection unit is implemented by an RLC combination circuit
  • the control switch SW is connected in parallel to both ends of the RLC combination circuit
  • the control signal terminal of the control switch SW is connected to the power supply VCC3.
  • the control switch SW is closed to make the protection unit exit the working state without affecting the working performance of the power amplifier.
  • the control switch SW is turned off to put the RLC combination circuit into operation, so as to play a protective role of limiting the overvoltage of the circuit.
  • the protection unit is implemented by an RLC combination circuit
  • the control switch SW is connected in parallel to both ends of the RLC combination circuit
  • the control signal terminal of the control switch SW is connected to the output terminal of the power detection circuit Vdet.
  • the control switch SW is closed to make the protection unit exit the working state, without affecting the working performance of the power amplifier.
  • the control switch SW is turned off to make the RLC combination circuit Putting into work, so as to play a protective role in limiting the overpower of the circuit.
  • the technical solution provided by the above-mentioned third embodiment can also be applied to the circuit structure of the first embodiment and the second embodiment according to the needs of specific circuits, and a control switch SW is connected in parallel at both ends of the protection unit to realize the input and exit of the protection unit, so as to optimize the protection function and working performance of the circuit.
  • the inventor conducted a simulation test of input power and output current on the technical solution of the present invention and the existing technical solution (without protection unit).
  • the test results are shown in Figure 14, the abscissa is the input power, and the ordinate is the output current. It can be seen from Fig. 14 that when the input power continues to increase, the output current in the power amplifier circuit of the prior art scheme continues to rise with the increase of the input power; while in the power amplifier circuit with current protection provided by the present invention, when the input power continues to increase, the output current is constantly limited to about 800mA, thereby realizing the overcurrent protection of the power amplifier circuit.
  • the radio frequency front-end module with current protection provided by the present invention can be used in electronic equipment as an important part of communication components.
  • the electronic devices mentioned here refer to computer devices that can be used in a mobile environment and support various communication standards such as GSM, EDGE, TD_SCDMA, TDD_LTE, FDD_LTE, 5G, including mobile phones, notebook computers, tablet computers, vehicle-mounted computers, etc.
  • the technical solutions provided by the present invention are also applicable to other radio frequency integrated circuit applications, such as communication base stations, intelligent networked vehicles, and the like.
  • the electronic device includes at least a processor, a communication component, and a memory, and may further include a sensor component, a power supply component, a multimedia component, and an input/output interface according to actual needs.
  • memory, communication components, sensor components, power supply components, multimedia components and input/output interfaces are all connected with the processor.
  • the memory can be static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, etc.
  • the processor can be central processing unit (CPU), graphics processing unit (GPU), field programmable logic gate array (FPGA), application-specific integrated circuit (ASIC), digital signal processing (DSP) chip, etc.
  • CPU central processing unit
  • GPU graphics processing unit
  • FPGA field programmable logic gate array
  • ASIC application-specific integrated circuit
  • DSP digital signal processing
  • the RF front-end module with current protection provided by the embodiment of the present invention can play the role of over-current protection, over-voltage protection and over-power protection for the power amplifier by adding a protection unit, thereby greatly improving the reliability and safety of the RF front-end module working in harsh environments.
  • the protection unit only uses the voltage drop change of the current limiting resistor to realize the threshold voltage, and does not introduce additional circuit power consumption and occupy a large circuit area. Therefore, the radio frequency front-end module with current protection provided by the present invention has beneficial effects such as ingenious and reasonable structural design, low design cost, high reliability, and excellent circuit performance, and is suitable for radio frequency front-end modules of various structures.
  • first and second are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as “first” and “second” may explicitly or implicitly include one or more of these features.
  • “plurality” means two or more, unless otherwise specifically defined.
  • radio frequency front-end module and electronic equipment with current protection provided by the present invention have been described in detail above.
  • any obvious changes made to it without departing from the essence of the present invention will constitute an infringement of the patent right of the present invention and will bear corresponding legal responsibilities.

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Abstract

本发明公开了一种具有电流保护的射频前端模块及电子设备。该射频前端模块包括输入匹配模块、功率放大器、输出匹配模块、电源模块和保护单元；其中，输入匹配模块的输入端与外部射频信号输入端连接，输入匹配模块的输出端与功率放大器的输入端连接，功率放大器的输出端与输出匹配模块的输入端连接，输出匹配模块的输出端与射频信号输出端连接，电源模块和保护单元的输出端分别与功率放大器连接。保护单元能够对射频前端模块中的功率放大器起到电流保护、电压保护和功率保护的作用，从而提高射频前端模块在恶劣环境下工作的可靠性和安全性。

Description

一种具有电流保护的射频前端模块及电子设备 技术领域
本发明涉及一种具有电流保护的射频前端模块，同时也涉及包括该射频前端模块的电子设备，属于射频集成电路技术领域。
背景技术
随着集成电路技术的不断发展，现代电子设备对射频前端模块的要求越来越高，特别是在恶劣环境中工作的场景越来越多，例如工作环境温度的升高或降低已达到或超过所要求的温度范围的极限(一般温度范围为－25℃～85℃或者－40℃～110℃)。对于功率器件来说，当工作在高温或者低温环境下，功率器件的安全工作区域就会缩小，甚至当功率器件上的工作电流超过器件最大承受电流时，就会造成功率器件不可逆的损伤或毁坏。因此，为了保证功率器件的正常工作，需要采用适当的保护措施，限制功率器件在恶劣环境场景下的过大工作电流，以保证功率器件始终工作在安全工作区域。
如图1所示，现有技术中的一个典型的射频前端模块包括输入匹配模块、功率放大器(Power Amplifier，简写为PA)、输出匹配模块和电源模块。其中，功率放大器通常包括两级或三级功率放大单元，是电流保护的主要功率器件。
在公开号为US2009256637A1的美国专利申请中，公开了一种高频功率放大器。其中，第四实施例的高频功率放大器电路包括高频功率放大器晶体管，以及匹配电路和匹配电路，以及偏置电源晶体管，以及无源元件；其中，无源元件连接在公共电源端子和偏置电源晶体管的集电极之间，该偏置电源晶体管连接到第一级晶体管。无源元件由电阻器和感电器串联连接实现。该高频功率放大器电路中，无源元件通过防止偏置电源晶体管的电功率降低来改善高输出时的线性度。
发明内容
本发明所要解决的技术问题在于提供一种具有电流保护的射频前端模块。
本发明所要解决的另一技术问题在于提供一种包括该射频前端模 块的电子设备。
为了实现上述目的，本发明采用以下的技术方案：
根据本发明实施例的第一方面，提供一种具有电流保护的射频前端模块，包括输入匹配模块、功率放大器、输出匹配模块、电源模块和保护单元；其中，
所述输入匹配模块的输入端与外部射频信号输入端连接，输出端与所述功率放大器的输入端连接，用于实现所述功率放大器和所述外部射频信号输入端之间的阻抗匹配；
所述功率放大器用于对输入射频信号进行功率放大，其输出端与所述输出匹配模块的输入端连接；
所述输出匹配模块的输出端与射频信号输出端连接，用于实现所述功率放大器和所述射频信号输出端之间的功率匹配；
所述保护单元的输出端与所述功率放大器连接，通过所述保护单元产生的门限电压限制所述功率放大器的电流，实现电流保护。
其中较优地，所述保护单元至少包括一个限流电阻和一个滤波电容；其中，
所述限流电阻用于产生所述门限电压；所述滤波电容用于在射频频率及包络信号频率处呈现低阻状态，使所述门限电压不随射频信号及包络信号产生变化。
其中较优地，所述保护单元还包括陷波支路，所述陷波支路与所述滤波电容并联连接。
其中较优地，所述功率放大器包括至少一级功率放大单元，所述功率放大单元包括偏置电路和功率放大电路；所述保护单元至少与一级所述功率放大单元的所述偏置电路连接。
其中较优地，所述偏置电路包括第一晶体管、第二晶体管、第三晶体管、第一偏置电阻和第一滤波电容；所述功率放大电路包括第四晶体管、第一镇流电阻和第一电感；所述保护单元包括第一限流电阻和第二滤波电容；其中，
所述第三晶体管的发射极与地电位端连接，所述第三晶体管的基极和集电极短接连接后与所述第二晶体管的发射极连接，所述第二晶体管的基极和集电极短接连接后一方面与所述第一偏置电阻连接，另 一方面与所述第一晶体管的基极及所述第一滤波电容连接，所述第一偏置电阻的另一端接连偏置电源，所述第一滤波电容的另一端与地电位端连接，所述第一晶体管的集电极与所述第二滤波电容及所述第一限流电阻连接，所述第二滤波电容的另一端与地电位端连接，所述第一限流电阻的另一端与第二电源端连接；所述第一晶体管的发射极与所述第一镇流电阻连接，所述第一镇流电阻的另一端一方面与输入端连接，另一方面与所述第四晶体管的基极连接，所述第四晶体管的发射极与地电位端连接，所述第四晶体管的集电极一方面与输出端连接，另一方面与所述第一电感连接，所述第一电感的另一端与第一电源端连接。
其中较优地，当所述偏置电路、所述功率放大电路和所述保护单元满足如下公式时，所述偏置电路和所述功率放大电路进入限流保护工作状态：
V1C<V1b－Vth_bc
V1C＝VDD－VR
VR＝I1*R
其中，V1C为第一晶体管的集电极电压，V1b为第一晶体管的基极电压，Vth_bc为第一晶体管的基极和集电极之间的阈值电压；VR为第一限流电阻上的电压降，I1为第一晶体管的集电极电流，R为第一限流电阻的电阻值，VDD为第二电源的电压。
其中较优地，所述保护单元中的所述限流电阻采用带有温度系数的热敏电阻；对于低温下容易发生烧毁的所述功率放大器，所述限流电阻采用负温度系数的热敏电阻；对于高温下容易发生烧毁的所述功率放大器，所述限流电阻采用正温度系数的热敏电阻。
其中较优地，所述保护单元中的所述滤波电容采用多个不同大小的电容，其电容值从pF级到uF级，用于滤除不同频率的射频信号和包络信号，实现宽带滤波。
其中较优地，与所述保护单元中的所述第一限流电阻连接的电源采用带有温度系数的稳压源；对于低温下容易发生烧毁的所述功率放大器，所述电源采用正温度系数的稳压源；对于高温下容易发生烧毁的所述功率放大器，所述电源采用负温度系数的稳压源。
其中较优地，所述保护单元增加陷波支路，所述陷波支路由一个电感和一个电容串联构成，该陷波支路与所述第二滤波电容并联连接；其中，所述陷波支路的电感端与所述第一限流电阻和所述第二滤波电容的节点端连接，电容端与地电位端连接。
其中较优地，所述保护单元还包括电感，与所述限流电阻和所述滤波电容构成RLC组合电路，进一步滤除射频信号和包络信号。
其中较优地，所述RLC组合电路包括第十一电感、限流电阻、第十一电容和第十二电容；其中，
所述限流电阻的一端一方面与偏置电路中的第一晶体管的集电极连接，另一方面与第十一电容连接；所述限流电阻的另一端一方面与所述第十一电感连接，另一方面与所述第十二电容连接；所述第十一电感的另一端与第二电源端连接；所述第十一电容和所述第十二电容的另一端分别与地电位端连接。
其中较优地，还包括控制开关，所述控制开关并联在所述保护单元的两端，用于实现所述保护单元的投入或者退出；所述控制开关的控制信号端连接第一电源端或者功率检测电路的输出端。
根据本发明实施例的第二方面，提供一种电子设备，包括上述具有电流保护的射频前端模块。
与现有技术相比较，本发明实施例提供的具有电流保护的射频前端模块通过增设保护单元，可以对功率放大器起到过流保护、过压保护和过功率保护的作用，从而极大提高了射频前端模块在恶劣环境下工作的可靠性和安全性。同时，保护单元仅利用限流电阻的压降变化实现门限电压，不会引入额外的电路功耗和占用较大的电路面积，因此，本发明所提供的具有电流保护的射频前端模块具有结构设计巧妙合理、设计成本较低、可靠性高，以及电路性能优异等有益效果，适用于各种结构的射频前端模块之中。
附图说明
图1为现有技术中，一个典型的射频前端模块的结构框图；
图2为本发明实施例提供的具有电流保护的射频前端模块的结构框图；
图3为本发明第一实施例中，功率放大器、电源模块和保护单元 的结构示意图；
图4(a)为本发明第一实施例中，放大单元和保护单元的电路原理图；
图4(b)为本发明第一实施例中，放大单元和保护单元的另一种电路原理图；
图5为本发明第一实施例中，保护单元为后两级功率放大单元提供过电流保护的结构示意图；
图6为本发明第一实施例中，保护单元为末级功率放大单元提供过电流保护的结构示意图；
图7为本发明第二实施例中，放大单元和保护单元的电路原理图；
图8为本发明第二实施例中，功率放大器、电源模块和保护单元的结构示意图；
图9为本发明第二实施例中，保护单元为后两级功率放大单元提供过电流保护的结构示意图；
图10为本发明第二实施例中，保护单元为末级功率放大单元提供过电流保护的结构示意图；
图11为本发明第三实施例中，放大单元和保护单元的电路原理图；
图12为本发明第三实施例中，保护单元带控制开关的第一结构示意图；
图13为本发明第三实施例中，保护单元带控制开关的第二结构示意图；
图14为本发明实施例提供的技术方案中，功率放大电路输入功率和输出电流的关系曲线图；
图15为采用本发明实施例提供的射频前端模块的电子设备的示例图。
具体实施方式
下面结合附图和具体实施例对本发明的技术内容进行详细具体的说明。
如图2所示，本发明实施例提供的具有电流保护的射频前端模块包括输入匹配模块1、功率放大器2、输出匹配模块3、电源模块4和保护单元5。其中，输入匹配模块1的输入端与外部射频信号输入端 PA IN连接，输入匹配模块1的输出端与功率放大器2的输入端连接，功率放大器2的输出端与输出匹配模块3的输入端连接，输出匹配模块3的输出端与射频信号输出端PA OUT连接；电源模块4和保护单元5分别与功率放大器2连接。
输入匹配模块1用于实现功率放大器2和射频信号输入端PA IN之间的阻抗匹配；功率放大器2用于对输入射频信号进行功率放大，其包括至少一级功率放大单元，功率放大单元包括偏置电路和功率放大电路；输出匹配模块3用于实现功率放大器2和射频信号输出端PA OUT之间的功率匹配；电源模块4为功率放大器2提供工作所需要的偏置电流和电压。保护单元5为功率放大器2提供电流保护，其至少与一级所述功率放大单元的所述偏置电路连接；保护单元5至少包括一个限流电阻和一个滤波电容。
电源VCC为功率放大器提供电源电压和电流；电源VDD为功率放大器中的偏置电路和电源模块4提供电源电压和电流。通常，电源VCC和电源VDD均由外部供电模块提供电源。
在本发明的第一实施例中，功率放大器2、电源模块4和保护单元5的具体电路如图3所示。其中，功率放大器2包括三级功率放大单元，分别为第一级功率放大单元PA1、第二级功率放大单元PA2、第三级功率放大单元PA3，三级功率放大单元采用顺序级联连接。电源模块4输出的第一路电源Vreg1、第二路电源Vreg2、第三路电源Vreg3分别与第一级功率放大单元PA1、第二级功率放大单元PA2、第三级功率放大单元PA3的偏置电源端对应连接。保护单元5的一端与电源VDD连接，另一端分别与第一级功率放大单元PA1、第二级功率放大单元PA2、第三级功率放大单元PA3的偏置电路连接。
在本发明的第一实施例中，三级功率放大单元中的任意一级功率放大单元与保护单元的电路结构如图4(a)所示。功率放大单元包括偏置电路和功率放大电路。偏置电路包括第一晶体管HBT1、第二晶体管HBT2、第三晶体管HBT3、第一偏置电阻R1和第一滤波电容C1；功率放大电路包括第四晶体管HBT4、第一镇流电阻R2和第一电感L1；保护单元包括第一限流电阻R和第二滤波电容C。其中，第二晶体管HBT2、第三晶体管HBT3组成双二极管(double diode)。第三晶体管 HBT3的发射极与地电位端连接，第三晶体管HBT3的基极和集电极短接连接后与第二晶体管HBT2的发射极连接，第二晶体管HBT2的基极和集电极短接连接后一方面与第一偏置电阻R1连接，另一方面与第一晶体管HBT1的基极及第一滤波电容C1连接，第一偏置电阻R1的另一端接连偏置电源Vreg，第一滤波电容C1的另一端与地电位端连接，第一晶体管HBT1的集电极与第二滤波电容C及第一限流电阻R连接，第二滤波电容C的另一端与地电位端连接，第一限流电阻R的另一端与电源VDD连接；第一晶体管HBT1的发射极与第一镇流电阻R2连接，第一镇流电阻R2的另一端一方面与输入端IN连接，另一方面与第四晶体管HBT4的基极连接，第四晶体管HBT4的发射极与地电位端连接，第四晶体管HBT4的集电极一方面与输出端OUT连接，另一方面与第一电感L1连接，第一电感L1的另一端与电源VCC连接。
上述第一实施例中具有电流保护的射频前端模块，其实现电流保护的工作原理如下：
如图4(a)所示，正常工作时，偏置电路、功率放大电路和保护单元满足如下公式：
I2≈β*I1     (1)
VR＝I1*R         (2)
V1C＝VDD－VR        (3)
V1C>V1b－Vth_bc         (4)
其中，V1C为第一晶体管HBT1的集电极电压，V1b为第一晶体管HBT1的基极电压，Vth_bc为第一晶体管HBT1的基极和集电极之间的阈值电压，VR为第一限流电阻R上的电压降，I1为第一晶体管HBT1的集电极电流，I2为第四晶体管HBT4的集电极电流，R为第一限流电阻R的电阻值，β为第四晶体管HBT4的放大系数，VDD为电源VDD的电压值。此时，偏置电路和功率放大电路没有进入限流保护状态，公式4为第一晶体管HBT1的启动工作条件。
当外部电路使第四晶体管HBT4上的电流I2增大时，根据公式1，需要第一晶体管HBT1提供更大的输出电流I1，此时根据公式2和公式3，由于电流I1的增大，第一限流电阻R上的压降VR变大，第一晶 体管HBT1的集电极电压V1C减小，当V1C减小至V1C<V1b－Vth_bc时，电流I1急剧减小，因此，电流I2随之减小，从而实现了电路的过电流保护作用。也就是说，当V1C<V1b－Vth_bc时，偏置电路和功率放大电路进入限流保护工作状态。通常，在GaAs HBT工艺中，Vth_bc为1.2V，V1b为2.4V，所以当V1C<1.2V时，偏置电路和功率放大电路进入限流保护工作状态。
保护单元中第一限流电阻R上的电压降VR作为一个门限电压，限制功率放大电路的最大电流，从而实现电流保护功能；第二滤波电容C起到滤波作用，在射频频率处及包络信号频率处呈现低阻状态，使第一限流电阻R上的电压降VR不会随着射频信号及包络信号的变化而变化，保证第一晶体管HBT1处于一个稳定的工作状态。
如图4(b)所示，上述实施例中的保护单元还可以增加一个由第二电感L2和第三电容C4串联组成的陷波支路(trap circuit)，该陷波支路与第二滤波电容C并联连接，其中，电感(L2)端与第一限流电阻R和第二滤波电容C的节点端连接，电容端(C4)与地电位端连接。陷波支路与第二滤波电容共同用来抑制射频频率和包络信号频率，在射频频率处及包络信号频率处呈现低阻状态，实现滤除射频信号和包络信号，同时，也可以实现宽带滤波的效果。
上述第一实施例提供的技术方案，根据对电路性能的要求不同，图3所示的功率放大器、电源模块和保护单元的电路结构可以有不同的变形示例，例如功率放大器并不限于由三级功率放大单元级联而成，还可以是一级、两级甚至多级功率放大单元级联在一起，用于实现本发明所提供的技术方案。图4(a)和图4(b)所示的偏置电路，根据实际需求还可以有不同的变形示例，在此不做限制。
另外，在图3所示的技术方案中，保护单元为全部三级功率放大单元提供过电流保护。如图5所示，保护单元还可以仅为后两级功率放大单元提供过电流保护，其中，保护单元的输出端分别与后两级功率放大单元PA2、PA3的偏置电路连接。如图6所示，保护单元还可以仅为末级功率放大单元提供过电流保护，其中，保护单元的输出端与末级功率放大单元PA3的偏置电路连接。
需要说明的是，根据功率放大电路的实际需要，保护单元中的滤 波电容并不限于采用一个电容，还可以包括多个不同大小的电容，其电容值可以从pF级到uF级，用来滤除不同频率的射频信号，实现宽带滤波的效果。
在本发明的第二实施例中，对于因工作环境温度大幅度升高或降低会引起功率器件损伤或毁坏的情况，射频前端模块中的功率放大器2、电源模块4和保护单元5可以采取以下两种技术方案来解决过电流保护的问题。
如图7所示，第一种技术方案中的保护单元由第一限流电阻R和第二滤波电容C构成，其中，第一限流电阻R采用带有温度系数的热敏电阻。对于低温下容易发生烧毁的功率放大电路，第一限流电阻R选择负温度系数的热敏电阻；对于高温下容易发生烧毁的功率放大电路，第一限流电阻R选择正温度系数的热敏电阻；具体实现过电流保护的工作原理如下：
假设电路是低温下容易发生烧毁的功率放大电路，第一限流电阻R选择了负温度系数的热敏电阻的情况下，当温度降低时，第一限流电阻R的电阻值增大，此时根据公式1、公式2和公式3，第一限流电阻R上的压降VR变大，第一晶体管HBT1的集电极电压V1C减小，当V1C减小至V1C<V1b－Vth_bc时，电流I1急剧减小，则电流I2随之减小，从而对低温下容易发生烧毁的功率放大电路实现了过电流保护作用，并且与第一限流电阻为普通电阻相比较，第一限流电阻采用带有负温度系数的热敏电阻，还可以缩短保护启动时间，进一步加强保护作用。
假设电路是高温下容易发生烧毁的功率放大电路，第一限流电阻R选择了正温度系数的热敏电阻的情况下，当温度升高时,第一限流电阻R的电阻值增大，此时根据公式1、公式2和公式3，第一限流电阻R上的压降VR变大，第一晶体管HBT1的集电极电压V1C减小，当V1C减小至V1C<V1b－Vth_bc时，电流I1急剧减小，则电流I2随之减小，从而对高温下容易发生烧毁的功率放大电路实现了过电流保护作用，并且与第一限流电阻为普通电阻相比较，第一限流电阻采用带有正温度系数的热敏电阻，还可以缩短保护启动时间，进一步加强保护作用。
如图8所示，第二种技术方案中的偏置电源Vreg4是由电源模块输出的一个带有温度系数的偏置电源，其通过保护单元为全部三级功 率放大单元的偏置电路供电。对于低温下容易发生烧毁的功率放大电路，偏置电源Vreg4选择正温度系数的稳压源；对于高温下容易发生烧毁的功率放大电路，偏置电源Vreg4选择负温度系数的稳压源。其过电流保护的工作原理如下：
假设电路是低温下容易发生烧毁的功率放大电路，偏置电源Vreg4选择正温度系数稳压源的情况下，当温度降低时，偏置电源Vreg4的电压输出降低，此时根据公式1和公式3(此时，Vreg4代替公式中的VDD)，第一晶体管HBT1的集电极电压V1C减小，当V1C减小至V1C<V1b－Vth_bc时，电流I1急剧减小，则电流I2随之减小，从而对低温下容易发生烧毁的功率放大电路实现了过电流保护作用，并且与恒定的电源VDD相比较，偏置电源Vreg4选择了正温度系数的稳压源，还可以缩短保护启动时间，起到加强保护作用。
假设电路是高温下容易发生烧毁的功率放大电路，偏置电源Vreg4选择负温度系数稳压源的情况下，当温度升高时，偏置电源Vreg4的电压输出降低，此时根据公式1和公式3(此时，Vreg4代替公式中的VDD)，第一晶体管HBT1的集电极电压V1C减小，当V1C减小至V1C<V1b－Vth_bc时，电流I1急剧减小，则电流I2随之减小，从而对高温下容易发生烧毁的功率放大电路实现了过电流保护作用，并且与恒定的电源VDD相比较，偏置电源Vreg4选择了负温度系数的稳压源，还可以缩短保护启动时间，起到加强保护作用。
上述第二实施例所提供的技术方案，根据对电路性能的要求不同，功率放大器、电源模块和保护单元的电路结构还可以有不同的变形示例。例如功率放大器并不限于由三级功率放大单元级联而成，还可以是一级、两级甚至多级功率放大单元级联在一起，用于实现本发明所提供的技术方案。
另外，图8所示的技术方案中保护单元为全部三级功率放大单元提供过电流保护。如图9所示，保护单元还可以仅为后两级功率放大单元提供过电流保护，其中，保护单元由第一限流电阻和第二滤波电容构成，第一限流电阻和第二滤波电容的一端分别与后两级功率放大单元PA2、PA3的偏置电路连接，第一限流电阻的另一端与带有温度系数的偏置电源Vreg4连接。如图10所示，保护单元还可以仅为末级 功率放大单元提供过电流保护，其中，保护单元由第一限流电阻和第二滤波电容构成，第一限流电阻和第二滤波电容的一端与末级功率放大单元PA3的偏置电路连接，第一限流电阻的另一端与带有温度系数的偏置电源Vreg4连接。
在本发明的第三实施例中，如图11所示，对于射频阻抗匹配存在问题而影响电路性能的情况，射频前端模块中的保护单元可以采取RLC组合电路实现。RLC组合电路由第十一电感L、第十一电阻R(即限流电阻)、第十一电容C2和第十二电容C3构成。其中，第十一电阻R的一端一方面与偏置电路中的第一晶体管HBT1的集电极连接，另一方面与第十一电容C2连接；第十一电阻R的另一端一方面与第十一电感L连接，另一方面与第十二电容C3连接；第十一电感L的另一端与电源VDD连接；第十一电容C2、第十二电容C3的另一端分别与地电位端连接。
上述RLC组合电路中第十一电阻R为限流电阻，第十一电容C2、第十二电容C3均为滤波电容。需要说明的是，RLC组合电路也可以是其它组合形式，但其中至少包括一个限流电阻和一个滤波电容。
另外，RLC组合电路还可以通过一个控制开关SW来实现保护单元的投入和退出，该控制开关SW可以在大功率或者大电流或者大电压下开启进行电流限制，使得RLC组合电路在正常情况下不会影响功率放大器的工作性能。
如图12所示，保护单元采用RLC组合电路实现，控制开关SW并联在RLC组合电路两端，控制开关SW的控制信号端连接电源VCC3。正常工作时，控制开关SW闭合使保护单元退出工作状态，不影响功率放大器的工作性能。当电源VCC3电压增大并达到某个门限值时，控制开关SW断开使RLC组合电路投入工作，从而起到限制电路过电压的保护作用。
如图13所示，保护单元采用RLC组合电路实现，控制开关SW并联在RLC组合电路两端，控制开关SW的控制信号端连接功率检测电路Vdet的输出端。正常工作时，控制开关SW闭合使保护单元退出工作状态，不影响功率放大器的工作性能。当功率检测电路Vdet的输出功率增大并达到某个门限值时，控制开关SW断开使RLC组合电路 投入工作，从而起到限制电路过功率的保护作用。
上述第三实施例提供的技术方案，也可以根据具体电路的需要，同样适用于第一实施例和第二实施例的电路结构，在保护单元两端并联一个控制开关SW，来实现保护单元的投入和退出，从而起到优化电路的保护功能和工作性能的作用。
为了验证本发明实施例提供的射频前端模块的技术效果，发明人对本发明技术方案和现有技术方案(无保护单元)进行了输入功率与输出电流的仿真测试。测试结果如图14所示，横坐标为输入功率，纵坐标为输出电流。从图14中可以看出，当输入功率持续增大时，现有技术方案的功率放大电路中输出电流随输入功率的增大而持续上升；而本发明所提供的具有电流保护的功率放大电路中，当输入功率持续增大时，输出电流被恒定限制在800mA左右，从而实现了功率放大电路的过电流保护。
本发明所提供的具有电流保护的射频前端模块可以被用在电子设备中，作为通信组件的重要组成部分。这里所说的电子设备是指可以在移动环境中使用，支持GSM、EDGE、TD_SCDMA、TDD_LTE、FDD_LTE、5G等多种通信制式的计算机设备，包括移动电话、笔记本电脑、平板电脑、车载电脑等。此外，本发明所提供的技术方案也适用于其他射频集成电路的应用场合，例如通信基站、智能网联汽车等。
如图15所示，该电子设备至少包括处理器、通信组件和存储器，还可以根据实际需要进一步包括传感器组件、电源组件、多媒体组件及输入/输出接口。其中，存储器、通信组件、传感器组件、电源组件、多媒体组件及输入/输出接口均与该处理器连接。存储器可以是静态随机存取存储器(SRAM)、电可擦除可编程只读存储器(EEPROM)、可擦除可编程只读存储器(EPROM)、可编程只读存储器(PROM)、只读存储器(ROM)、磁存储器、快闪存储器等，处理器可以是中央处理器(CPU)、图形处理器(GPU)、现场可编程逻辑门阵列(FPGA)、专用集成电路(ASIC)、数字信号处理(DSP)芯片等。其它通信组件、传感器组件、电源组件、多媒体组件等均可以采用通用部件实现，在此就不具体说明了。
通过上述实施例对本发明技术方案的具体描述可以看出，与现有 技术相比较，本发明实施例提供的具有电流保护的射频前端模块通过增设保护单元，可以对功率放大器起到过流保护、过压保护和过功率保护的作用，从而极大提高了射频前端模块在恶劣环境下工作的可靠性和安全性。同时，保护单元仅利用限流电阻的压降变化实现门限电压，不会引入额外的电路功耗和占用较大的电路面积，因此，本发明所提供的具有电流保护的射频前端模块具有结构设计巧妙合理、设计成本较低、可靠性高，以及电路性能优异等有益效果，适用于各种结构的射频前端模块之中。
需要说明的是，上述多个实施例只是举例，各个实施例的技术方案之间可以进行组合，均在本发明的保护范围内。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本发明的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
以上对本发明提供的具有电流保护的射频前端模块及电子设备进行了详细的说明。对本领域的一般技术人员而言，在不背离本发明实质内容的前提下对它所做的任何显而易见的改动，都将构成对本发明专利权的侵犯，将承担相应的法律责任。

Claims (14)

  1. 一种具有电流保护的射频前端模块，包括输入匹配模块、功率放大器、输出匹配模块、电源模块，其特征在于还包括保护单元；其中，
    所述输入匹配模块的输入端与外部射频信号输入端连接，输出端与所述功率放大器的输入端连接，用于实现所述功率放大器和所述外部射频信号输入端之间的阻抗匹配；
    所述功率放大器用于对输入射频信号进行功率放大，其输出端与所述输出匹配模块的输入端连接；
    所述输出匹配模块的输出端与射频信号输出端连接，用于实现所述功率放大器和所述射频信号输出端之间的功率匹配；
    所述保护单元的输出端与所述功率放大器连接，通过所述保护单元产生的门限电压限制所述功率放大器的电流，实现电流保护。
  2. 如权利要求1所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元至少包括一个限流电阻和一个滤波电容；其中，
    所述限流电阻用于产生所述门限电压；所述滤波电容用于在射频频率及包络信号频率处呈现低阻状态，使所述门限电压不随射频信号及包络信号产生变化。
  3. 如权利要求2所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元还包括陷波支路，所述陷波支路与所述滤波电容并联连接。
  4. 如权利要求1所述的具有电流保护的射频前端模块，其特征在于：
    所述功率放大器包括至少一级功率放大单元，所述功率放大单元包括偏置电路和功率放大电路；所述保护单元至少与一级所述功率放大单元的所述偏置电路连接。
  5. 如权利要求4所述的具有电流保护的射频前端模块，其特征在于：
    所述偏置电路包括第一晶体管、第二晶体管、第三晶体管、第一偏置电阻和第一滤波电容；所述功率放大电路包括第四晶体管、第一 镇流电阻和第一电感；所述保护单元包括第一限流电阻和第二滤波电容；其中，
    所述第三晶体管的发射极与地电位端连接，所述第三晶体管的基极和集电极短接连接后与所述第二晶体管的发射极连接，所述第二晶体管的基极和集电极短接连接后一方面与所述第一偏置电阻连接，另一方面与所述第一晶体管的基极及所述第一滤波电容连接，所述第一偏置电阻的另一端接连偏置电源，所述第一滤波电容的另一端与地电位端连接，所述第一晶体管的集电极与所述第二滤波电容及所述第一限流电阻连接，所述第二滤波电容的另一端与地电位端连接，所述第一限流电阻的另一端与第二电源端连接；所述第一晶体管的发射极与所述第一镇流电阻连接，所述第一镇流电阻的另一端一方面与输入端连接，另一方面与所述第四晶体管的基极连接，所述第四晶体管的发射极与地电位端连接，所述第四晶体管的集电极一方面与输出端连接，另一方面与所述第一电感连接，所述第一电感的另一端与第一电源端连接。
  6. 如权利要求5所述的具有电流保护的射频前端模块，其特征在于：
    当所述偏置电路、所述功率放大电路和所述保护单元满足如下公式时，所述偏置电路和所述功率放大电路进入限流保护工作状态：
    V1C<V1b－Vth_bc
    V1C＝VDD－VR
    VR＝I1*R
    其中，V1C为第一晶体管的集电极电压，V1b为第一晶体管的基极电压，Vth_bc为第一晶体管的基极和集电极之间的阈值电压；VR为第一限流电阻上的电压降，I1为第一晶体管的集电极电流，R为第一限流电阻的电阻值，VDD为第二电源的电压。
  7. 如权利要求2所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元中的所述限流电阻采用带有温度系数的热敏电阻；对于低温下容易发生烧毁的所述功率放大器，所述限流电阻采用负温度系数的热敏电阻；对于高温下容易发生烧毁的所述功率放大器，所 述限流电阻采用正温度系数的热敏电阻。
  8. 如权利要求2所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元中的所述滤波电容采用多个不同大小的电容，用于滤除不同频率的射频信号和包络信号，实现宽带滤波。
  9. 如权利要求5所述的具有电流保护的射频前端模块，其特征在于：
    与所述保护单元中的所述第一限流电阻连接的电源采用带有温度系数的稳压源；对于低温下容易发生烧毁的所述功率放大器，所述电源采用正温度系数的稳压源；对于高温下容易发生烧毁的所述功率放大器，所述电源采用负温度系数的稳压源。
  10. 如权利要求5所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元还包括陷波支路；所述陷波支路由一个电感和一个电容串联构成，该陷波支路与所述第二滤波电容并联连接；其中，所述陷波支路的电感端与所述第一限流电阻和所述第二滤波电容的节点端连接，电容端与地电位端连接。
  11. 如权利要求2所述的具有电流保护的射频前端模块，其特征在于：
    所述保护单元还包括电感，与所述限流电阻和所述滤波电容构成RLC组合电路，进一步滤除射频信号和包络信号。
  12. 如权利要求11所述的具有电流保护的射频前端模块，其特征在于：
    所述RLC组合电路包括第十一电感、限流电阻、第十一电容和第十二电容；其中，
    所述限流电阻的一端一方面与偏置电路中的第一晶体管的集电极连接，另一方面与第十一电容连接；所述限流电阻的另一端一方面与所述第十一电感连接，另一方面与所述第十二电容连接；所述第十一电感的另一端与第二电源端连接；所述第十一电容和所述第十二电容的另一端分别与地电位端连接。
  13. 如权利要求1所述的具有电流保护的射频前端模块，其特征 在于还包括控制开关，所述控制开关并联在所述保护单元的两端，用于实现所述保护单元的投入或者退出；所述控制开关的控制信号端连接第一电源端或者功率检测电路的输出端。
  14. 一种电子设备，其特征在于包括权利要求1～13中任意一项所述的具有电流保护的射频前端模块。
PCT/CN2023/072885 2022-01-18 2023-01-18 一种具有电流保护的射频前端模块及电子设备 WO2023138615A1 (zh)

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