CN113809996A - Power amplifier bias protection circuit and circuit board using same - Google Patents
Power amplifier bias protection circuit and circuit board using same Download PDFInfo
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- CN113809996A CN113809996A CN202111114907.7A CN202111114907A CN113809996A CN 113809996 A CN113809996 A CN 113809996A CN 202111114907 A CN202111114907 A CN 202111114907A CN 113809996 A CN113809996 A CN 113809996A
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- 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
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Abstract
The invention provides a power amplifier bias protection circuit which comprises a voltage conversion module, a driving module, a voltage generation module and a signal generation module. The voltage conversion module converts a first voltage input by an external power supply into a second voltage. Based on the second voltage, the voltage generation module generates a driving voltage and outputs the driving voltage to the input end of the corresponding power amplifier, and the voltage generation module further comprises a delay energy storage unit for performing delay operation on the driving voltage. Based on the driving voltage and the first voltage, the driving module generates a control signal. Based on the control signal and the first voltage, the signal generation module generates a driving signal and outputs the driving signal to the control end of the corresponding power amplifier. When the power amplifier is started, the time for driving the control end by the driving signal is later than the time for driving the input end by the driving voltage. When the power amplifier is turned off, the driving signal stops driving the control terminal earlier than the driving voltage stops driving the input terminal. The invention also provides a corresponding circuit board.
Description
Technical Field
The invention relates to the field of circuits, in particular to a power amplifier bias protection circuit.
Background
In modern society, power amplifiers are used in the fields of wireless communication, microwave heating, and the like. The power amplifier can normally work through a specific power-on sequence and a specific power-off sequence. Otherwise, the internal current of the power amplifier is liable to increase instantaneously, and the power amplifier is liable to be damaged. There is a technical problem that the existing power amplifier is easily damaged.
Therefore, it is desirable to provide a power amplifier bias protection circuit and a circuit board using the same to solve the above problems.
Disclosure of Invention
The invention provides a power amplifier bias protection circuit and a circuit board using the same, which effectively solve the technical problem that the conventional power amplifier is easy to damage.
The invention provides a power amplifier bias protection circuit, which comprises:
the voltage conversion module is connected with an external power supply and used for converting a first voltage input by the external power supply into a second voltage;
the voltage generation module is used for generating the driving voltage based on the second voltage and outputting the driving voltage to the input end of the corresponding power amplifier, and the voltage generation module comprises a time delay energy storage unit for performing time delay operation on the driving voltage;
the driving module is used for generating a control signal based on the driving voltage and the first voltage;
the signal generation module generates a driving signal based on the control signal and the first voltage and outputs the driving signal to a control end of a corresponding power amplifier;
when the power amplifier is started, the external power supply outputs a first voltage, and the time for driving the control end by the driving signal is later than the time for driving the input end by the driving voltage based on the energy storage operation of the time-delay energy storage unit;
when the power amplifier is turned off, the external power supply stops outputting the first voltage, the driving voltage is maintained based on the energy release operation of the time-delay energy storage unit, and the time when the driving signal stops driving the control terminal is earlier than the time when the driving voltage stops driving the input terminal.
In the bias protection circuit of a power amplifier of the present invention, the driving module includes:
the LMV321 chip comprises an IN + pin, an IN-pin and an OUAT pin, wherein the IN + pin receives the second voltage, the IN-pin inputs the second voltage and the driving voltage, and the OUAT pin outputs a control signal;
and one end of the feedback unit is connected with the IN-pin, and the other end of the feedback unit is connected with the output end of the voltage generation module and is used for feeding back the driving voltage to the LMV321 chip.
In the bias protection circuit of the power amplifier, the voltage generation module comprises an LM2776 chip, the LM2776 chip comprises a VIN pin, a VOUT pin, a C1+ pin and a C1-pin, the VIN pin receives the second voltage, and the VOUT pin outputs the driving voltage to the input end of the power amplifier;
the time-delay energy storage unit comprises a first capacitor, one end of the first capacitor is connected with a pin C1+, and the other end of the first capacitor is connected with the pin C1-.
In the bias protection circuit of the power amplifier, the voltage generation module includes a voltage stabilization unit, one end of the voltage stabilization unit is connected to the VOUT pin, the other end of the voltage stabilization unit is connected to the input end of the power amplifier, and the voltage stabilization unit is configured to perform voltage stabilization operation on the output driving voltage.
In the bias protection circuit of the power amplifier, the signal generating module includes a first triode and a first MOS transistor, a base of the first third connecting pipe is connected to the OUAT pin, a collector of the first triode is connected to a gate of the first MOS transistor, an emitter of the first triode is grounded, a drain of the first MOS transistor is connected to the external power supply, and a source of the first MOS transistor is connected to an input terminal of the power amplifier.
IN the power amplifier bias protection circuit of the present invention, when the voltage input by the IN + pin is greater than the voltage input by the IN-pin, the OUAT pin outputs the control signal of high level to the signal generating module, so that the first triode and the first MOS transistor are IN a conducting state, and the control end of the power amplifier receives a driving signal; when the voltage input by the IN + pin is less than or equal to the voltage input by the IN-pin, the OUAT pin outputs the control signal with low level to the signal generating module, so that the first triode and the first MOS tube are IN a closed state.
In the bias protection circuit of the power amplifier, the voltage conversion module includes a filter network unit, the filter network unit is used for filtering out noise waves of the second voltage, the filter network unit includes an inductor and a first filter capacitor and a second filter capacitor which are connected in parallel, the inductor is connected in series with an output end of the voltage conversion module, and the first filter capacitor and the second filter capacitor are connected in parallel with an output end of the voltage conversion module.
In the bias protection circuit of the power amplifier, the voltage generation module comprises an indication circuit unit, one end of the indication circuit unit is connected with the VOUT pin, and the other end of the indication circuit is grounded and used for indicating whether the driving voltage is a preset voltage or not.
IN the bias protection circuit of the power amplifier, the voltage generation module includes a filtering unit, the filtering unit is configured to filter the driving voltage, the filtering unit includes a third filtering capacitor and a first resistor, the first resistor is connected IN series with the IN-pin, and the third filtering capacitor is connected IN parallel with the IN-pin.
A circuit board comprises any one of the power amplifier bias protection circuits.
Compared with the prior art, the invention has the beneficial effects that: when the power amplifier is started, the voltage conversion module converts a first voltage input by an external power supply into a second voltage. The voltage generation module generates a driving voltage through the second voltage, the voltage generation module outputs the driving voltage to the delay energy storage unit and the input end of the corresponding power amplifier, and the delay energy storage unit stores the driving voltage. And then the driving module generates a control signal through the driving voltage and the second voltage, and the driving module transmits the control signal to the signal generating module. The signal generation module generates a driving signal through the control signal and the first voltage, and the signal generation module outputs the driving signal to the control end of the corresponding power amplifier. Therefore, the driving signal drives the control terminal later than the driving voltage drives the input terminal. When the power amplifier is turned off, the delayed energy storage unit may perform an energy release operation, so that the delayed energy storage unit may maintain the driving voltage. Therefore, the driving signal stops driving the control terminal earlier than the driving voltage stops driving the input terminal. The sequence of the power amplifier receiving the driving signal and the driving voltage accords with the power-on sequence and the power-off sequence of the normal work of the power amplifier, so the circuit can protect the power amplifier. The technical problem that the existing power amplifier is easy to damage is effectively solved.
Drawings
Fig. 1 is a block diagram of a power amplifier bias protection circuit of the present invention.
Fig. 2 is a circuit diagram of the power amplifier bias protection circuit of the present invention.
Fig. 3 is a circuit diagram of a voltage conversion module of the power amplifier bias protection circuit of the present invention.
In the figure, 10, a power amplifier bias protection circuit; 11. a voltage conversion module; 111. a filter network unit; 12. a drive module; 121. a feedback unit; 122. a filtering unit; 13. a voltage generation module; 131. a time-delayed energy storage unit; 132. a voltage stabilization unit; 133. an indication circuit unit; 14. and a signal generation module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the present invention, directional terms such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", "top" and "bottom" are used only with reference to the orientation of the drawings, and the directional terms are used for illustration and understanding of the present invention, and are not intended to limit the present invention.
The terms "first," "second," and the like in the terms of the invention are used for descriptive purposes only and not for purposes of indication or implication relative importance, nor as a limitation on the order of precedence.
Fig. 1 is a block diagram of a power amplifier bias protection circuit of the present invention; FIG. 2 is a circuit diagram of a power amplifier bias protection circuit of the present invention; fig. 3 is a circuit diagram of a voltage conversion module of the power amplifier bias protection circuit of the present invention.
In the drawings, elements having similar structures are denoted by the same reference numerals.
Referring to fig. 1, the present invention provides a power amplifier bias protection circuit 10. The power amplifier bias protection circuit 10 is applied to a circuit board. The power amplifier bias protection circuit 10 includes a voltage conversion module 11, a driving module 12, a voltage generation module 13, and a signal generation module 14. The voltage conversion module 11 is connected to an external power source, and the voltage conversion module 11 can convert a first voltage input by the external power source into a second voltage. The first voltage is 50V, and the second voltage is 5V. Since the first voltage is a positive voltage, the first voltage may be represented as + 50V. Since the second voltage is a positive voltage, the second voltage may be represented as + 5V.
Referring to fig. 3, the voltage conversion module 11 further includes an SCT2a10 chip, and the SCT2a10 chip can be used for voltage conversion. The SCT2A10 chip comprises a GND pin, a VIN pin, an EN pin, an RT pin, an SW pin, a BST pin, an NC pin and an FB pin. The VIN pin is connected with an external power supply, so that the VIN pin can input a first voltage, the SW pin is connected, and the VIN pin can input the first voltage. The GND pin, the EN pin and the RT pin are all grounded, and the NC pin is suspended. The FB pin is connected with the SW pin, and the SW pin can be used for outputting a second voltage.
Referring to fig. 3, the voltage conversion module 11 includes a second capacitor C1 and a third capacitor C2, wherein the capacitance reactance of the second capacitor C1 is 2.2 μ F, the capacitance reactance of the third capacitor C2 is 0.1 μ F, and the highest working voltages of the second capacitor C1 and the third capacitor C2 are both 100V. One end of the second capacitor C1 is connected to the VIN pin, and the other end of the second capacitor C1 is grounded. One end of the third capacitor C2 is connected to the VIN pin, the other end of the third capacitor C2 is grounded, and the second capacitor C1 and the third capacitor C2 can be used for filtering noise of the first voltage. The voltage conversion module 11 includes a second resistor R3, a third resistor R8, and a fourth resistor R7, and the resistance of the second resistor R3 is 180k Ω. The third resistor R8 has a resistance of 42.2k Ω, and the fourth resistor R7 has a resistance of 510k Ω. One end of the second resistor R3 is connected to the VIN pin, and the other end of the second resistor R3 is connected to the EN pin. One end of the third resistor R8 is connected to the EN pin, and the other end of the third resistor R8 is grounded. One end of the fourth resistor R7 is connected to the RT pin, and the other end of the fourth resistor R7 is grounded. The voltage conversion module 11 further includes a fourth capacitor C3 and a fifth capacitor C6, wherein the capacitive reactance of the fourth capacitor C3 is 0.1 μ F, the capacitive reactance of the fifth capacitor C6 is 100pF, and the highest working voltages of the fourth capacitor C3 and the fifth capacitor C6 are both 10V. One end of the fourth capacitor C3 is connected to the SW pin, and the other end of the fourth capacitor C3 is connected to the BST pin. One end of the fifth capacitor C6 is connected to the SW pin, and the other end of the fifth capacitor C6 is connected to the FB pin.
Referring to fig. 3, the voltage conversion module 11 further includes a fifth resistor R2, a sixth resistor R1, and a seventh resistor R4. The resistance of the fifth resistor R2 is 2k Ω. The sixth resistor R1 has a resistance of 120k Ω, and the seventh resistor R4 has a resistance of 21k Ω. The fifth resistor R2 is connected between the FB pin and the fourth capacitor C3, and the sixth resistor R1 is connected between the FB pin and the SW pin. One end of the seventh resistor R4 is connected to the sixth resistor, and the other end of the seventh resistor R4 is grounded.
Referring to fig. 2, the voltage conversion module 11 includes a filter network unit 111, the filter network unit 111 is connected to the output end of the voltage conversion module 11, and the filter network unit 111 is used for filtering noise of the second voltage. The filter network unit 111 includes an inductor L1 and two first filter capacitors C4 and second filter capacitors C5 connected in parallel, the inductor L1 is connected in series to the output terminal of the voltage conversion module 11, and the first filter capacitors C4 and the second filter capacitors C5 are connected in parallel to the output terminal of the voltage conversion module 11. The inductance of the inductor L1 is 47 μ H, the capacitance of the first filter capacitor C4 is 0.1 μ F, and the capacitance of the second filter capacitor C5 is 22 μ F. The highest working voltage of the first filter capacitor C4 and the second filter capacitor C5 is 10V. Since high frequency components or noise may exist in the second voltage, the filter network unit 111 may be provided to suppress interference of the high frequency components and noise with the second voltage.
Referring to fig. 2, the driving module 12 includes an LMV321 chip. The LMV321 chip comprises an IN + pin, an IN-pin, a VCACA + pin and an OUAT pin, wherein the IN + pin and the IN-pin are both connected with the SW pin of the SCT2A10 chip, and the IN + pin and the IN-pin both receive a second voltage. The VCACA + pin is used for inputting a second voltage, so that the second voltage can provide power for the LMV321 chip. The driving module 12 further includes an eighth resistor R11 and a ninth resistor R13, wherein the resistance of the eighth resistor R11 is 1.5k Ω, and the resistance of the ninth resistor R13 is 1.1k Ω. One end of the eighth resistor R11 is connected to the SW pin, the other end of the eighth resistor R11 is connected between the ninth resistor R13 and the filter unit 111, and the ninth resistor R13 is connected to the IN-pin. The driving module 12 further includes a sixth capacitor C9, a seventh capacitor C10, and a tenth capacitor C14, wherein the sixth capacitor C9 and the seventh capacitor C10 are both connected in parallel to one end of the eighth resistor R11, and the tenth capacitor C14 is connected in parallel to the VCACA + pin. The driving module 12 includes a tenth resistor R15, an eleventh resistor R16, and a twelfth resistor R19, wherein the impedance of the tenth resistor R15 is 2k Ω. The impedance of the eleventh resistor R16 is 1.1k Ω, and the impedance of the twelfth resistor R19 is 1.5k Ω. The tenth resistor R15 and the eleventh resistor R16 are connected IN series with the IN + pin. One end of the twelfth resistor R19 is connected between the tenth resistor R15 and the eleventh resistor R16, and the other end of the twelfth resistor R19 is grounded. The driving module 12 further includes a zener diode D1 and a twenty-fourth resistor R14, wherein the resistance of the twenty-fourth resistor R14 is 5.1k Ω. The twenty-fourth resistor R14 is connected to the VCACA + pin, and the zener diode D1 is connected in parallel with the twenty-fourth resistor R14.
Referring to fig. 2, based on the second voltage, the voltage generating module 13 may generate a driving voltage, and the voltage generating module 13 outputs the driving voltage to the input terminal of the corresponding power amplifier. The voltage generation module 13 comprises an LM2776 chip, wherein the LM2776 chip comprises an EN pin, a VIN pin and a VOUT pin, and the EN pin is connected with a VCACA + pin. The VIN pin is connected with the SW pin, so that the VIN pin receives a second voltage, and the VOUT pin outputs a driving voltage to the input end of the power amplifier.
Referring to fig. 2, the voltage generating module 13 includes a thirteenth resistor R22, an eighth capacitor C15, and a ninth capacitor C17, wherein the resistance of the thirteenth resistor is 1k Ω, and the thirteenth resistor R22 is connected between the EN pin and the VCACA + pin. The eighth capacitor C15 is connected in parallel with the VIN pin, the reactance of the eighth capacitor C15 is 2.2 muF, and the maximum working voltage of the eighth capacitor C15 is 16V. The capacitance reactance of the ninth capacitor C17 is 2.2 muF, and the maximum working voltage of the ninth capacitor C17 is 16V. The ninth capacitor C17 can be used for filtering noise, so that the ripple of the driving voltage is less than 2mV, and the purity of the power supplied by the input end of the power amplifier is ensured.
Referring to fig. 2, the voltage generating module 13 includes an indicating circuit unit 133, one end of the indicating circuit unit 133 is connected to the VOUT pin, and the other end of the indicating circuit unit 133 is grounded. The indicating circuit unit 133 includes a fourteenth resistor R25 and a light emitting diode D2, and the resistance of the fourteenth resistor R25 is 2k Ω. When the driving voltage output from the VOUT pin is a negative voltage, the light emitting diode D2 will emit light, so that the indicating circuit unit 133 can indicate whether the driving voltage is a negative preset voltage.
Referring to fig. 2, the voltage generating module 13 includes a voltage stabilizing unit 132, one end of the voltage stabilizing unit 132 is connected to the VOUT pin, the other end of the voltage stabilizing unit 132 is connected to the input terminal of the power amplifier, and the voltage stabilizing unit 132 is configured to perform a voltage stabilizing operation on the output driving voltage. The voltage stabilizing unit 132 includes a potentiometer RP2, an LMV321 chip, a fifteenth resistor R18, a sixteenth resistor R26, a seventeenth resistor R24, an eighteenth resistor R23, and a nineteenth resistor R20. The resistance of the fifteenth resistor R18 is 2k Ω, and the resistance of the sixteenth resistor R26 is 2k Ω. The seventeenth resistor R24 has a resistance of 10k Ω, and the nineteenth resistor R20 has a resistance of 10k Ω. The potentiometer RP2, the fifteenth resistor R18 and the sixteenth resistor R26 may be used to regulate voltage, the LMV321 chip of the voltage stabilizing unit 132 may be used as a voltage follower, and the potentiometer RP2 and the LMV321 chip of the voltage stabilizing unit 132 may perform voltage stabilizing operation on the driving voltage. Therefore, the driving voltage input by the input end of the power amplifier is stable.
Referring to fig. 2, the driving module 12 further includes a feedback unit 121, one end of the feedback unit 121 is connected to the IN-pin, and the other end of the feedback unit 121 is connected to the output end of the voltage generating module 13. The feedback unit 121 may feed back the driving voltage to the LMV321 chip.
Referring to fig. 2, the voltage generating module 13 includes a filtering unit 132, and the filtering unit 132 can filter the driving voltage fed back by the feedback unit. The filter unit 132 includes a third filter capacitor C13 and a first resistor R12, the resistance of the first resistor R12 is 3k Ω, the first resistor R12 is connected IN series with the IN-pin, and the third filter capacitor C13 is connected IN parallel with the IN-pin. The IN-pin inputs a driving voltage which is a negative voltage. The driving voltage is 5V, and since the driving voltage is a negative voltage, the driving voltage can be represented as-5V.
Referring to FIG. 2, the LMV321 chip can compare the input voltages of the IN + pin and the IN-pin, and based on the comparison result, the OUAT pin outputs a control signal. When the voltage input by the IN + pin is greater than the voltage input by the IN-pin, the OUAT pin outputs a high-level control signal to the signal generating module 14. Therefore, the first transistor Q2 and the first MOS transistor Q1 are in a conducting state, and the control terminal of the power amplifier receives the driving signal. When the voltage input to the IN + pin is less than or equal to the voltage input to the IN-pin, the OUAT pin outputs a low-level control signal to the signal generating module 14. Therefore, the first transistor Q2 and the first MOS transistor Q1 are in an off state, and the control terminal of the power amplifier fails to receive the driving signal.
Referring to fig. 2, the signal generating module 14 includes a first transistor Q2 and a first MOS transistor Q1, a base of the first three-connection pipe Q2 is connected to the OUAT pin, a collector of the first transistor Q2 is connected to a gate of the first MOS transistor Q1, and an emitter of the first transistor Q2 is grounded. The drain of the first MOS transistor Q1 is connected to an external power source, and the source of the first MOS transistor Q1 is connected to the input of the power amplifier. The signal generating module 14 may receive the first voltage through a drain of the first MOS transistor, and the signal generating module 14 may receive the control signal through a base of the first triple pipe Q2. Based on the control signal and the first voltage, the signal generation module 14 may generate a driving signal. And the signal generating module 14 may output the driving signal to the control terminal of the corresponding power amplifier through the source of the first MOS transistor Q1.
Referring to fig. 2, the signal generating module 14 further includes a tenth capacitor C7, an eleventh capacitor C8, a twelfth capacitor C11, and a thirteenth capacitor C12. The capacitive reactance of the tenth capacitor C7 is 22 μ F, the maximum operating voltage of the tenth capacitor C7 is 65V, and the tenth capacitor C7 is connected in parallel to the drain of the first MOS transistor Q1. The capacitive reactance of the twelfth capacitor C11 is 2.2 μ F, the maximum operating voltage of the twelfth capacitor C11 is 100V, and the tenth capacitor C7 is connected in parallel to the source of the first MOS transistor Q1.
Referring to fig. 2, the signal generating module 14 further includes a twentieth resistor R9, a twenty-first resistor R10, a twenty-second resistor R5, and a twenty-third resistor R6. The twentieth resistor R9 has a resistance of 5.1k omega, the twenty-first resistor R10 has a resistance of 10k omega, and the twentieth resistor R9 and the twenty-first resistor R10 are connected in series between an external power supply and the collector of the first triode Q2. The resistance of the twenty-second resistor R5 is 18k Ω, the resistance of the twenty-third resistor R6 is 18k Ω, and the twenty-second resistor R5 and the twenty-third resistor R6 are both connected in parallel to the source of the first MOS transistor Q1.
Referring to fig. 3, the LM2776 chip further includes a C1+ pin and a C1-pin, the voltage generating module 13 includes a delay energy storage unit 131, the delay energy storage unit 131 includes a first capacitor C16, one end of the first capacitor C16 is connected to the C1+ pin, and the other end of the first capacitor C16 is connected to the C1-pin. The time-delay energy storage unit 131 can perform time-delay operation on the driving voltage through the first capacitor C16.
Referring to fig. 2 and 3, the power amplifier may be a GaN power amplifier, and when the power amplifier is used, a user should apply a negative voltage to an input terminal of the power amplifier and then apply a positive voltage to a control terminal of the power amplifier. If the user power-on sequence is wrong, the power amplifier is easily damaged. When the power amplifier is started, the external power supply outputs a first voltage. The voltage generation module 13 generates a driving voltage by the second voltage, the voltage generation module 13 outputs the driving voltage to the delay energy storage unit 131 and the input terminal of the corresponding power amplifier, and the delay energy storage unit 131 performs a storage operation on the driving voltage. Subsequently, the driving module 12 generates a control signal by the driving voltage and the second voltage, and the driving module 12 transmits the control signal to the signal generating module 14. The signal generating module 14 generates a driving signal through the control signal and the first voltage, and the signal generating module 14 outputs the driving signal to a control terminal of the corresponding power amplifier. Therefore, the driving signal drives the control terminal of the power amplifier later than the driving voltage drives the input terminal of the power amplifier. When the power amplifier is turned off, the external power supply stops outputting the first voltage. Based on the energy release operation of the delay energy storage unit 131, the delay energy storage unit 131 can maintain the driving voltage, and therefore, the driving signal stops driving the control terminal of the power amplifier earlier than the driving voltage stops driving the input terminal of the power amplifier. Since the power amplifier bias protection circuit is provided with the delay energy storage unit 131, the driving voltage is turned off after lagging the driving signal, thereby preventing the power amplifier from being damaged.
In a classical circuit, a circuit needs two power supplies to supply power to a power amplifier, and the power-on sequence of a user is easy to be wrong, so that the power amplifier is easy to be damaged. The power amplifier bias protection circuit only needs to be powered on all the way, namely, a user supplies power to the power amplifier bias circuit through an external power supply, and the power amplifier can normally work after receiving driving voltage and driving. Moreover, the charge pump chip LTC1261CS8-4 and the operational amplifier LM7321MF of the voltage follower of the classical circuit are high in cost, the load carrying capacity of the charge pump chip LTC1261CS8-4 is poor, the negative voltage output by the charge pump chip LTC1261CS8-4 is only-4.0V, and the current output by the charge pump chip LTC1261CS8-4 is 15 mA. The negative driving voltage of the power amplifier bias protection circuit is generated by the LM2776 chip, the LM2776 chip can output-5.5V voltage at minimum, and the current output by the LM2776 chip can reach 200mA at maximum. Compared with a classical circuit, the power amplifier bias protection circuit LM2776 chip has better effect of outputting voltage and current and better meets the requirements of actually required voltage and current.
The working principle of the invention is as follows: when the power amplifier is enabled, the user turns on the external power supply, which outputs a first voltage that the SCT2a10 chip receives. Then, the SCT2a10 chip converts the first voltage into a second voltage, which the SCT2a10 chip outputs through the SW pin. In order to filter out the noise of the first voltage, the output terminal of the voltage conversion module 11 is connected to a filter network unit 111. The LM2776 chip of the voltage generation module 13 receives the second voltage, the LM2776 chip converts the received second voltage into a driving voltage, and the LM2776 chip outputs the driving voltage to the input terminals of the delay energy storage unit 131 and the power amplifier bias protection circuit. In order to filter out noise of the driving voltage, the output end of the voltage generating module 13 is provided with a filtering unit 122. In order to indicate whether the driving voltage is a preset voltage, the output terminal of the voltage generation module 13 is provided with an indication circuit unit 133.
Meanwhile, the IN + pin and the IN-pin of the LMV321 chip of the driving module 12 receive the second voltage, and the LM2776 chip feeds back the driving voltage to the IN-pin through the feedback unit 121. The LMV321 chip compares the input voltages of the IN + pin and the IN-pin, and when the input voltage of the IN-pin is less than that of the IN + pin, the LMV321 chip outputs a high-level control signal to the base of the first triode Q2. Therefore, the first transistor Q2 is turned on, and the first MOS transistor Q1 is turned on. Since the gate of the first MOS transistor Q1 receives the first voltage, at this time, the signal generating module 14 generates a driving signal based on the control signal and the first voltage, and the signal generating module 14 outputs the driving signal to the control terminal of the corresponding power amplifier. Therefore, the time for driving the control end of the power amplifier by the driving signal is later than the time for driving the input end of the power amplifier by the driving voltage, the influence of the fluctuation of the driving voltage on the power amplifier is avoided, and the effect of protecting the power amplifier is achieved.
When the power amplifier is turned off, the user turns off the external power supply, so that the external power supply stops outputting the first voltage. Therefore, the signal generation module 14 cannot generate the driving signal based on the control signal and the first voltage. At this time, the time-delay energy storage unit 131 may perform an energy release operation, the time-delay energy storage unit 131 may maintain a driving voltage, and the time-delay energy storage unit 131 outputs the driving voltage to the input terminal. Therefore, the time for the driving signal to stop driving the control end of the power amplifier is earlier than the time for the driving voltage to stop driving the input end of the power amplifier, so that the influence of the fluctuation of the driving voltage on the power amplifier is avoided, and the effect of protecting the power amplifier is achieved.
The invention provides a power amplifier bias protection circuit 10, when a power amplifier is started, a voltage conversion module 11 converts a first voltage input by an external power supply into a second voltage. The voltage generation module 13 generates a driving voltage by the second voltage, the voltage generation module 13 outputs the driving voltage to the input terminal of the delay energy storage unit 131 and the corresponding power amplifier, and the delay energy storage unit 13 performs a storage operation on the driving voltage. The driving module then generates a control signal by the driving voltage and the second voltage, and the driving module 12 transmits the control signal to the signal generating module 14. The signal generating module 14 generates a driving signal through the control signal and the first voltage, and the signal generating module 14 outputs the driving signal to a control terminal of the corresponding power amplifier. Therefore, the driving signal drives the control terminal later than the driving voltage drives the input terminal. When the power amplifier is turned off, the delayed energy storage unit 131 may perform an energy release operation, so that the delayed energy storage unit 131 may maintain the driving voltage. Therefore, the driving signal stops driving the control terminal earlier than the driving voltage stops driving the input terminal. The sequence of the power amplifier receiving the driving signal and the driving voltage accords with the power-on sequence and the power-off sequence of the normal work of the power amplifier, so the circuit can protect the power amplifier. The technical problem that the existing power amplifier is easy to damage is effectively solved.
In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.
Claims (10)
1. A power amplifier bias protection circuit, comprising:
the voltage conversion module is connected with an external power supply and used for converting a first voltage input by the external power supply into a second voltage;
the voltage generation module is used for generating the driving voltage based on the second voltage and outputting the driving voltage to the input end of the corresponding power amplifier, and the voltage generation module comprises a time delay energy storage unit for performing time delay operation on the driving voltage;
the driving module is used for generating a control signal based on the driving voltage and the first voltage;
the signal generation module generates a driving signal based on the control signal and the first voltage and outputs the driving signal to a control end of a corresponding power amplifier;
when the power amplifier is started, the external power supply outputs a first voltage, and the time for driving the control end by the driving signal is later than the time for driving the input end by the driving voltage based on the energy storage operation of the time-delay energy storage unit;
when the power amplifier is turned off, the external power supply stops outputting the first voltage, the driving voltage is maintained based on the energy release operation of the time-delay energy storage unit, and the time when the driving signal stops driving the control terminal is earlier than the time when the driving voltage stops driving the input terminal.
2. The power amplifier bias protection circuit of claim 1, wherein the driver module comprises:
the LMV321 chip comprises an IN + pin, an IN-pin and an OUAT pin, wherein the IN + pin receives the second voltage, the IN-pin inputs the second voltage and the driving voltage, and the OUAT pin outputs a control signal;
and one end of the feedback unit is connected with the IN-pin, and the other end of the feedback unit is connected with the output end of the voltage generation module and is used for feeding back the driving voltage to the LMV321 chip.
3. The power amplifier bias protection circuit of claim 2, wherein the voltage generation module comprises an LM2776 chip, the LM2776 chip comprising a VIN pin, a VOUT pin, a C1+ pin, a C1-pin, the VIN pin receiving the second voltage, the VOUT pin outputting the driving voltage at the input of the power amplifier;
the time-delay energy storage unit comprises a first capacitor, one end of the first capacitor is connected with a pin C1+, and the other end of the first capacitor is connected with the pin C1-.
4. The power amplifier bias protection circuit of claim 3, wherein the voltage generating module comprises a voltage stabilizing unit, one end of the voltage stabilizing unit is connected to the VOUT pin, the other end of the voltage stabilizing unit is connected to the input end of the power amplifier, and the voltage stabilizing unit is configured to perform a voltage stabilizing operation on the output driving voltage.
5. The power amplifier bias protection circuit according to claim 2, wherein the signal generating module comprises a first transistor and a first MOS transistor, a base of the first three connection pipe is connected to the OUAT pin, a collector of the first transistor is connected to a gate of the first MOS transistor, an emitter of the first transistor is grounded, a drain of the first MOS transistor is connected to the external power supply, and a source of the first MOS transistor is connected to the input terminal of the power amplifier.
6. The power amplifier bias protection circuit of claim 5, wherein when the voltage at the input of the IN + pin is greater than the voltage at the input of the IN-pin, the OUAT pin outputs the control signal with a high level to the signal generating module, so that the first transistor and the first MOS transistor are IN a conducting state, and the control terminal of the power amplifier receives a driving signal; when the voltage input by the IN + pin is less than or equal to the voltage input by the IN-pin, the OUAT pin outputs the control signal with low level to the signal generating module, so that the first triode and the first MOS tube are IN a closed state.
7. The power amplifier bias protection circuit of claim 1, wherein the voltage conversion module comprises a filter network unit for filtering noise of the second voltage, the filter network unit comprises an inductor and two first and second filter capacitors connected in parallel, the inductor is connected in series with an output of the voltage conversion module, and the first and second filter capacitors are connected in parallel with an output of the voltage conversion module.
8. The power amplifier bias protection circuit of claim 3, wherein the voltage generation module comprises an indication circuit unit, one end of the indication circuit unit is connected to the VOUT pin, and the other end of the indication circuit is grounded for indicating whether the driving voltage is a preset voltage.
9. The power amplifier bias protection circuit of claim 2, wherein the voltage generation module comprises a filtering unit for filtering the driving voltage, the filtering unit comprising a third filtering capacitor and a first resistor, the first resistor being connected IN series with the IN-pin, the third filtering capacitor being connected IN parallel with the IN-pin.
10. A circuit board comprising the power amplifier bias protection circuit of any of claims 1-9.
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| CN113809996B (en) | 2024-01-23 |
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