CN109257023B - Power amplifier protection circuit and method - Google Patents
Power amplifier protection circuit and method Download PDFInfo
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- CN109257023B CN109257023B CN201810974722.5A CN201810974722A CN109257023B CN 109257023 B CN109257023 B CN 109257023B CN 201810974722 A CN201810974722 A CN 201810974722A CN 109257023 B CN109257023 B CN 109257023B
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- 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
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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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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
Abstract
The invention discloses a power amplifier protection circuit and a method, wherein the circuit comprises: the first-stage comparison circuit is connected with the second-stage comparison circuit in series; the first-stage comparison circuit comprises a first operational amplifier and is used for receiving an input power detection voltage value corresponding to the current moment and an input power detection voltage value at a preset moment before the current moment, comparing the input power detection voltage value and the input power detection voltage value to obtain a difference value between the input power detection voltage value and the input power detection voltage value, and outputting the difference value as one input path of the second-stage comparison circuit; the second-stage comparison circuit comprises a second comparator, and the second comparator is used for receiving the difference value output by the first-stage comparison circuit and receiving a preset difference value threshold, comparing the difference value with the difference value threshold, and outputting an alarm when the difference value is greater than the difference value threshold. Therefore, when the detection voltage difference value of a certain time period exceeds the preset difference value threshold, an alarm is given, fault protection measures are taken in advance, the power amplifier equipment is prevented from being damaged, and the problem of equipment damage which puzzles the power amplifier for a long time is solved.
Description
Technical Field
The invention relates to the technical field of circuits, in particular to a power amplifier protection circuit and a power amplifier protection method.
Background
As an important component device in communication and special communication systems, the stability and reliability of the work of a power amplifier (namely, a power amplifier) directly relate to the work effect of the whole system. However, since the power amplifier is a high power device, and has the inherent characteristics of the high power device, such as large current, high temperature, and sensitive load, the operation stability and reliability are affected by many external factors, such as temperature and frequency variation. Any abnormality of the devices connected to the front and back of the power amplifier and the environment may be "amplified" in the power amplifier to cause serious failure or even damage to the power amplifier. Therefore, all power amplifiers are designed without exception with a great deal of protection measures, such as overheat protection, open circuit protection, etc., and the protection is performed by acting immediately after the abnormality occurs.
However, in practical applications, it is found that although the power amplifier has been put into a protection state, irreversible damage still occurs, i.e. the desired protection effect is not achieved.
Disclosure of Invention
The invention provides a discharge protection circuit and a discharge protection method, which are used for solving the technical problems that the protection of the conventional protection circuit is lagged and the expected protection effect cannot be achieved.
In order to achieve the technical purpose, the technical scheme of the application is realized as follows:
according to an aspect of the present application, there is provided a power amplifier protection circuit, including: the first-stage comparison circuit and the second-stage comparison circuit are connected in series with the first-stage comparison circuit;
the first-stage comparison circuit comprises a first operational amplifier and a second-stage comparison circuit, wherein the first operational amplifier is used for receiving an input power detection voltage value corresponding to the current moment and an input power detection voltage value at a preset moment before the current moment, comparing the input power detection voltage value and the input power detection voltage value to obtain a difference value between the input power detection voltage value and the input power detection voltage value, and outputting the difference value as one input of the second-stage comparison circuit;
the second-stage comparison circuit comprises a second comparator and is used for receiving the difference value output by the first-stage comparison circuit and a preset difference threshold, comparing the difference value with the difference threshold, and outputting an alarm when the difference value is larger than the difference threshold.
Optionally, the first operational amplifier comprises a first input terminal, a second input terminal and a first output terminal;
the first input end is connected with a signal source and receives a power detection voltage corresponding to the current moment input by the signal source;
the second input end is connected with the output end of a first digital-to-analog converter, the input end of the first digital-to-analog converter is connected with a processor, the processor is connected with the output end of the analog-to-digital converter, the input end of the analog-to-digital converter is connected with a signal source, and the power detection voltage corresponding to the preset time before the current time input by the signal source is received;
the first output end is connected with the second comparator, and outputs a difference value obtained by comparing the power detection voltage corresponding to the current moment with the power detection voltage corresponding to the preset moment after the current moment by the first operational amplifier to the second comparator.
Optionally, the second comparator comprises a third input, a fourth input and a second output;
the third input end is connected with the first output end and receives a difference value between the power detection voltage output by the first operational amplifier and corresponding to the current moment and the power detection voltage corresponding to a preset moment before the current moment;
the fourth input end is connected with the output end of a second digital-to-analog converter, and the input end of the second digital-to-analog converter is connected with the processor and receives a preset difference threshold;
the second output end is connected with the processor and used for outputting an alarm signal which is compared by the first comparator with the difference threshold and is generated when the difference is greater than the difference threshold to the processor.
Optionally, the first input end is a positive input end of a first operational amplifier, one end of a first resistor and one end of a third resistor are connected to the positive input end, the other end of the first resistor is connected to a signal source, and the other end of the third resistor is grounded;
the second input end is an inverted input end of the first operational amplifier, the inverted input end is connected with one end of the second resistor and one end of the fourth resistor, the other end of the second resistor is connected with an output end of the first digital-to-analog converter, and the other end of the fourth resistor is connected with the first output end.
Optionally, the third input terminal is a positive input terminal of the second comparator, the fourth input terminal is a negative input terminal of the second comparator, and the negative input terminal is connected to the output terminal of the second digital-to-analog converter.
Optionally, the processor comprises a processor having a serial peripheral interface, SPI, and a direct memory access, DMA, controller.
According to another aspect of the present application, a power amplifier protection method is provided, including:
acquiring a power detection voltage value corresponding to the current moment and a power detection voltage value at a preset moment before the current moment,
comparing the power detection voltage value corresponding to the current moment with the power detection voltage value at the preset moment before the current moment to obtain a difference value between the power detection voltage value and the power detection voltage value;
and comparing the difference value with a preset difference value threshold, and outputting an alarm when the difference value is greater than the difference value threshold.
Optionally, the obtaining the power detection voltage value corresponding to the current time and the power detection voltage value at a preset time before the current time includes:
connecting a first input end of a first operational amplifier with a signal source, and receiving a power detection voltage corresponding to the current moment input by the signal source;
connecting a second input end of a first operational amplifier with an output end of a first digital-to-analog converter, wherein the input end of the first digital-to-analog converter is connected with a processor, the processor is connected with the output end of an analog-to-digital converter, and the input end of the analog-to-digital converter is connected with a signal source and receives power detection voltage corresponding to a preset moment before the current moment input by the signal source;
and connecting the first output end of the first operational amplifier with a second comparator, and outputting the difference to the second comparator.
Optionally, comparing the difference value with a preset difference threshold includes:
connecting a third input end of a second comparator with the first output end, and receiving a difference value between a power detection voltage corresponding to the current moment and a power detection voltage corresponding to a preset moment before the current moment, wherein the power detection voltage is output by the first operational amplifier;
connecting a fourth input end of the second comparator with an output end of a second digital-to-analog converter, wherein an input end of the second digital-to-analog converter is connected with the processor and receives a preset difference threshold;
and connecting a second output end of the second comparator with the processor, and outputting a warning signal generated when the difference is greater than the difference threshold to the processor.
Optionally, the connecting the first input terminal of the first operational amplifier to the signal source includes:
the first input end is used as a positive input end of a first operational amplifier, one end of a first resistor and one end of a third resistor of the positive input end are connected, the other end of the first resistor is connected with a signal source, and the other end of the third resistor is grounded;
and taking the second input end as an inverting input end of the first operational amplifier, connecting the inverting input end with one end of a second resistor and one end of a fourth resistor, connecting the other end of the second resistor with the output end of the first digital-to-analog converter, and connecting the other end of the fourth resistor with the first output end.
Has the advantages that: on the basis of analyzing a protection processing mechanism when the current power amplifier fails, the embodiment of the invention creatively provides trend measurement for judging that absolute value detection with inaccurate conversion is accurate, namely, real-time detection is carried out on a circuit, a signal change trend is obtained according to the difference between a voltage value corresponding to the current moment and a voltage value corresponding to a preset moment before the current moment, and when the difference value of a certain time period exceeds a preset difference value alarm threshold, a fault protection measure is taken in advance to avoid damage to equipment, so that the problem of long-term damage to the power amplifier equipment is successfully solved, and the invention has important application and reference values in the fields of communication, military industry and the like.
Drawings
Fig. 1 is a schematic diagram of a power amplifier protection circuit according to an embodiment of the present invention;
fig. 2 is a flowchart of a power amplifier protection method according to an embodiment of the present invention.
Detailed Description
The design concept of the invention is as follows: aiming at the problem that the protection effect of the current power amplifier protection measures cannot achieve the expected protection effect in practical application, the main reason that the protection expectation cannot be achieved is that all current protection circuit designs are based on after-the-fact judgment is known through analysis. That is, after the power amplifier has a serious failure state, the power amplifier can detect the failure and take corresponding measures, which brings hysteresis, so that the power amplifier can continuously operate for a period of time in the serious failure state, thereby causing damage.
A large standing wave fault condition is exemplified. The fault condition that the power amplifier is most damaged is that the reflected power is too large (large standing wave) caused by poor contact of matching or output cables and the like. At present, two major standing wave protection circuits are designed, one is to judge the absolute value of reflected power, and when the reflected power exceeds a certain degree, the protection circuit enters a protection state; the other is to compare the relative values of the reverse power and the forward power and enter a protection state when the reverse power exceeds a certain proportion of the forward power. The former protection mode has accurate detection, but because of lack of comparison of forward power, the standing wave coefficient cannot be reflected, and error protection can be brought; the latter method is commonly used and can reflect the standing wave coefficient, but false alarm often occurs due to forward and reverse detection errors. Most importantly, in any mode, the large standing wave is detected after serious standing wave reflection occurs, and then various processing measures are taken by a circuit, so that the hysteresis is realized. The time taken for the whole link from the fault condition to the final stop or derated output is usually between ten microseconds and tens of microseconds (depending on the specific circuit design), i.e. the power amplifier needs to continue working for tens of microseconds in the fault condition. The power transistor of the core device of the power amplifier is very sensitive to large-amplitude reflected power, the endurance time of certain types of power amplifiers to large standing waves under total reflection is even only 3-5 microseconds, and irreversible damage can be caused when the endurance time is exceeded, which is difficult to solve by the existing power amplifier protection technology based on a post judgment method. The power amplifier can prompt the fault state but cannot protect the equipment fundamentally.
In order to solve the problem that the power amplifier cannot normally work due to equipment damage or error protection caused by the hysteresis of fault protection processing, which is common in important equipment in the communication and special communication fields, in a power amplifier, a power amplifier fault protection processing method based on trend judgment is provided. The fault judgment is realized by adopting a two-stage series comparator, wherein the first stage is a difference value circuit comprising an operational amplifier and is used for comparing voltage signals at the beginning and the end in each time period in real time to obtain a difference value; and the second-stage comparator is used for comparing the difference value with a preset alarm threshold so as to obtain a final alarm signal and make a protection action according to the final alarm signal. The following description focuses on the circuit of the embodiments of the present application with reference to the drawings.
Referring to fig. 1, the power amplifier protection circuit of the present embodiment includes: the first-stage comparison circuit is connected with the second-stage comparison circuit in series; the first-stage comparison circuit comprises a first operational amplifier (see a power amplifier illustrated in fig. 1) and is used for receiving an input power detection voltage value corresponding to the current moment and an input power detection voltage value at a preset moment before the current moment, comparing the input power detection voltage value and the input power detection voltage value to obtain a difference value between the input power detection voltage value and the input power detection voltage value, and outputting the difference value as one input of the second-stage comparison circuit; the second stage comparator circuit includes a second comparator (see the schematic comparator in fig. 1) for receiving the difference value output by the first stage comparator circuit and receiving a preset difference threshold, comparing the difference value with the difference threshold, and outputting an alarm when the difference value is greater than the difference threshold.
In this embodiment, the voltage value at the present time and the voltage value before the present time are compared. As shown in fig. 1, the signal reaching the "+" terminal (i.e., the non-inverting input terminal) of the first operational amplifier through the resistor R1 is the detection voltage corresponding to the present moment, while the voltage appearing at the "-" terminal (i.e., the inverting input terminal) of the first operational amplifier at the same moment is the signal subjected to the AD-DA conversion delay, and the signal appearing at the "-" terminal of the first operational amplifier at the same moment is known to be generated before the "+" terminal signal (e.g., before 5 microseconds) after the conversion (at the signal source).
Specifically, referring to fig. 1, the first operational amplifier includes a first input terminal, a second input terminal, and a first output terminal; the first input end is connected with a signal source (see a detection signal input end illustrated in fig. 1) and receives a power detection voltage corresponding to the current moment input by the signal source; the second input end is connected with the output end of a first digital-to-analog converter (see a first D/a converter illustrated in fig. 1), the input end of the first digital-to-analog converter is connected with the processor, the processor is connected with the output end of an analog-to-digital converter (see an a/D converter illustrated in fig. 1), the input end of the analog-to-digital converter (i.e., the a/D converter in fig. 1) is connected with a signal source (see a detection signal input end illustrated in fig. 1), and the input end of the analog-to-digital converter receives a power detection voltage corresponding to a preset time before the current time of the signal source input; the first output end is connected with the second comparator and outputs the difference value to the second comparator. The first operational amplifier is used for receiving the power detection voltage, and real-time comparison of voltage values from the same signal source at two different moments is achieved.
Referring to fig. 1, the second comparator includes a third input terminal, a fourth input terminal, and a second output terminal; the third input end is connected with the first output end and receives the difference value of the power detection voltage output by the first operational amplifier and corresponding to the current moment and the power detection voltage corresponding to the preset moment before the current moment; the fourth input end is connected with the output end of the second digital-to-analog converter, and the input end of the second digital-to-analog converter is connected with the processor and receives a preset difference threshold; the second output end is connected with the processor and used for outputting the alarm signal generated when the difference value is greater than the difference value threshold to the processor.
As shown in fig. 1, the first input terminal is a positive input terminal of the first operational amplifier, one end of a first resistor (see R1 in fig. 1) and one end of a third resistor (see R3 in fig. 1) are connected to the positive input terminal, the other end of the first resistor is connected to the signal source, and the other end of the third resistor is grounded; the second input end is an inverting input end of the first operational amplifier, the inverting input end is connected with one end of a second resistor (see R2 in fig. 1) and one end of a fourth resistor (see R4 in fig. 1), the other end of the second resistor is connected with the output end of the first digital-to-analog converter, and the other end of the fourth resistor is connected with the first output end. In this embodiment, referring to fig. 1, the third input terminal is a positive input terminal of the second comparator, the fourth input terminal is an inverting input terminal of the second comparator, and the inverting input terminal is connected to the output terminal of the second digital-to-analog converter.
As described above, the embodiment of the present invention provides a specific implementation circuit and method for power amplifier fault detection, in which trend judgment is used to replace post judgment. In view of the generality of various fault protection principles of the power amplifier, for simplicity and convenience of discussion, the operation of the protection circuit is described in the embodiment of the present invention by taking the standing wave condition with the greatest harm to the power amplifier as an example.
For the protection of the standing wave fault of the power amplifier, the circuit is divided into two parts of detection and judgment processing. The detection part mainly adopts a coupling detection device to realize high-speed real-time power-voltage conversion, and the voltage values with different amplitudes are used for representing power values. The circuit is consistent with the protection processing circuit in the prior art, and the forward power and the reflected power are detected simultaneously in two paths, and the power detection voltage is output to the control board.
The improvement of the embodiment of the invention mainly aims at the judgment processing part on the control panel to realize the trend judgment circuit to replace the traditional circuit based on the after judgment. The principle of the fault trend judgment is as follows: the large absolute detection value of the correlation signal does not necessarily determine that a failure state has occurred, but the large amount of change in the detection value in a short time is inevitably a failure tendency. Considering that the power detection voltage is an analog continuous variable, and a sudden change from 0 to 1 does not occur, it is possible to predict the abnormal condition that may occur completely based on the curvature of the change of the variable. The inaccurate absolute value measurement is a relative difference measurement, and an early warning is provided by continuously calculating the variable curvature. The difficulty is how to quickly obtain the difference between the real-time value of the detection voltage and the previous time value.
In one embodiment of the invention, the fixed time delay of the voltage signal is realized by means of an AD-DA process, and the difficulty is solved. Specifically, referring to fig. 1, the working process of the power amplifier protection circuit of this embodiment is as follows:
the real-time reflected power detection voltage (detection signal input) is divided into two paths after reaching the control board, wherein one path is a real-time detection signal and directly goes to the positive input end of a subtraction circuit consisting of a high-speed operational amplifier (model number is AD 8056) and four resistors R1-R4, and the other path goes to a high-speed AD-DA loop controlled by a processor (ARM processor). The signal enters from the analog signal input end of the AD device, the processor reads the AD result through the SPI interface, and then the DMA channel of the processor directly sends the AD result to the first DA device, the analog voltage output end of the DA device is directly connected to the negative input end of the subtraction circuit, the output of the subtraction circuit composed of the power amplifier is directly connected to the positive end of the high-speed comparator, and the negative end of the comparator is from the preset comparison reference (namely the preset difference threshold) output by the other DA.
It should be noted that the processor in one embodiment of the present invention includes a processor having an SPI interface and a DMA controller, for example, STM32F107. The STM32F107 processor was chosen primarily for its DMA capability over the SPI interface. The AD device and the DA device selected by the circuit are high-speed serial SPI interface devices, can be hung on the same SPI interface of the processor, and are 16-bit in data format, so that the processing is convenient. Therefore, the AD-DA processing process of the detected voltage is automatically and continuously realized under the DMA control of the processor, and the influence on the detection accuracy caused by different detection time intervals due to the fact that the processor needs to process other work is avoided. And because the DMA flow is not interfered by other work of the processor, the time delay of the processor link is basically fixed, and the data conversion time of the AD device and the DA device is relatively fixed in the same circuit, thereby the time delay of the whole AD-DA link is basically fixed. Through measurement and calculation, the fixed time delay of the AD-DA processing branch circuit of the actually measured detection voltage signal is about 5 microseconds. Thus, the first stage of the comparison circuit (i.e., the comparison circuit with the first operational amplifier as the comparator) in fig. 1 actually compares the difference between the present detected voltage value of the reflected power and the detected voltage value about 5 microseconds ago.
The magnitude of this difference around 5 microseconds directly reflects the failure trend. When the power amplifier equipment normally works, in each 5 microsecond time period, the voltage difference value is inevitably in a certain range and cannot be changed greatly, and if the load condition is abnormal, the voltage difference value suddenly begins to increase sharply in a certain time period, so that a possible fault trend is judged. The comparison is accomplished by the comparison circuit of the second comparator in fig. 1, which compares the real-time difference with a predetermined maximum difference output from the second dac to obtain the alarm signal. The alarm signal informs the processor in an interruption mode, and the processor adopts modes of cutting off receiving and sending or derating output and the like to timely take protection action, so that the power amplifier equipment enters a protection state before entering a serious fault state.
It should be noted that the processing method for other power amplifier failures such as overheating and overcurrent is similar to the protection circuit for large standing wave failure, that is, the circuit shown in fig. 1 is completely suitable for the judgment and protection of different failure states. Specifically, when protection of other power amplifier faults is applied, a plurality of basic unit circuits shown in fig. 1 are overlapped, in other words, the circuit in fig. 1 is copied to protect other power amplifier faults, and only the detection signal input source in fig. 1 needs to be changed. If the processor in fig. 1 adopts a process with 3 independent SPI interfaces, a plurality of processors similar to the power amplifier protection circuit can be shared.
Through tests, the functional protection circuit realized by the technical scheme is successfully applied to a certain type of power amplifier equipment, the protection time (which refers to the time for completing the action of cutting off power output by the power amplifier) under the condition of open circuit and large standing wave is greatly improved to 2-3 microseconds after the power amplifier enters a total reflection state from ten microseconds to tens of microseconds after the original fault occurs, the reliability of the equipment is greatly improved, and the phenomenon of power amplifier damage does not occur any more.
In addition, the model of the electronic device in fig. 1 is only illustrative, and is not limited to this, for example, other types of processors may be used to implement the present function instead of the processor STM32F107 in the AD-DA branch of fig. 1, but this circuit form cannot be bypassed no matter what processor is used, and is essentially the same as the present technical solution. Similarly, if the operational amplifier or the comparator of other types is used, the scheme can be realized, but the circuit form and the structure are still the same as the scheme. That is, model changes of the device do not affect the reference to the present circuit form.
An inventive concept is the same as that of the foregoing embodiment, and an embodiment of the present application further provides a power amplifier protection method, referring to fig. 2, the method includes:
step S201, obtaining a power detection voltage value corresponding to the current time and a power detection voltage value at a preset time before the current time,
step S202, comparing the power detection voltage value corresponding to the current moment with the power detection voltage value at the preset moment before the current moment to obtain a difference value between the power detection voltage value and the power detection voltage value;
step S203, comparing the difference value with a preset difference threshold, and outputting an alarm when the difference value is greater than the difference threshold.
In an embodiment of the present invention, step S201 specifically includes: connecting a first input end of a first operational amplifier with a signal source, and receiving a power detection voltage corresponding to the current moment input by the signal source; connecting a second input end of a first operational amplifier with an output end of a first digital-to-analog converter, wherein the input end of the first digital-to-analog converter is connected with a processor, the processor is connected with the output end of an analog-to-digital converter, and the input end of the analog-to-digital converter is connected with a signal source and receives power detection voltage corresponding to a preset moment before the current moment input by the signal source; and connecting a first output end of the first operational amplifier with a second comparator, and outputting a difference value to the second comparator.
In an embodiment of the present invention, step S202 specifically includes: connecting a third input end of a second comparator with the first output end, and receiving a difference value between the power detection voltage corresponding to the current moment and the power detection voltage corresponding to a preset moment before the current moment, which are output by the first operational amplifier; connecting a fourth input end of the second comparator with an output end of a second digital-to-analog converter, wherein an input end of the second digital-to-analog converter is connected with the processor, and receives a preset difference threshold; and connecting a second output end of the second comparator with the processor, and outputting an alarm signal generated when the difference value is greater than the difference value threshold to the processor.
In one embodiment of the present invention, connecting the first input terminal of the first operational amplifier to a signal source comprises: the first input end is used as a positive input end of a first operational amplifier, one end of a first resistor and one end of a third resistor of the positive input end are connected, the other end of the first resistor is connected with a signal source, and the other end of the third resistor is grounded; and taking the second input end as an inverting input end of the first operational amplifier, connecting the inverting input end with one end of a second resistor and one end of a fourth resistor, connecting the other end of the second resistor with the output end of the first digital-to-analog converter, and connecting the other end of the fourth resistor with the first output end.
It should be noted that the power amplifier protection method shown in fig. 2 is implemented based on the circuit shown in fig. 1, and therefore for further description on implementation steps of the power amplifier protection method shown in fig. 2, reference may be made to the description of the working process of the circuit shown in fig. 1 in the foregoing embodiment, and details are not repeated here.
While the foregoing is directed to embodiments of the present invention, other modifications and variations of the present invention may be devised by those skilled in the art in light of the above teachings. It should be understood by those skilled in the art that the foregoing detailed description is for the purpose of illustrating the invention rather than the foregoing detailed description, and that the scope of the invention is defined by the claims.
Claims (7)
1. A power amplifier protection circuit, comprising: the first-stage comparison circuit and the second-stage comparison circuit are connected in series with the first-stage comparison circuit;
the first-stage comparison circuit comprises a first operational amplifier and a second-stage comparison circuit, wherein the first operational amplifier is used for receiving an input power detection voltage value corresponding to the current moment and an input power detection voltage value at a preset moment before the current moment, comparing the input power detection voltage value and the input power detection voltage value to obtain a difference value between the input power detection voltage value and the input power detection voltage value, and outputting the difference value as one path of input of the second-stage comparison circuit, wherein the power detection voltage is a continuous variable;
the second-stage comparison circuit comprises a second comparator, a first comparator and a second comparator, wherein the second comparator is used for receiving the difference value output by the first-stage comparison circuit and receiving a preset difference threshold, comparing the difference value with the difference threshold, and outputting an alarm when the difference value is greater than the difference threshold;
the first operational amplifier comprises a first input end, a second input end and a first output end;
the first input end is connected with a signal source and receives a power detection voltage corresponding to the current moment input by the signal source;
the second input end is connected with the output end of a first digital-to-analog converter, the input end of the first digital-to-analog converter is connected with a processor, the processor is connected with the output end of the analog-to-digital converter, the input end of the analog-to-digital converter is connected with a signal source, and the power detection voltage corresponding to the preset moment before the current moment input by the signal source is received; the processor comprises a Serial Peripheral Interface (SPI) and a Direct Memory Access (DMA) controller, a first digital-to-analog converter and an analog-to-digital converter are SPI devices, and the processor reads the result of the analog-to-digital converter through the SPI and then directly sends the result to the first digital-to-analog converter through a DMA controller channel;
the first output end is connected with the second comparator and outputs the difference value to the second comparator.
2. The power amplifier protection circuit of claim 1, wherein the second comparator comprises a third input terminal, a fourth input terminal and a second output terminal;
the third input end is connected with the first output end and receives a difference value between the power detection voltage output by the first operational amplifier and corresponding to the current moment and the power detection voltage corresponding to a preset moment before the current moment;
the fourth input end is connected with the output end of a second digital-to-analog converter, the input end of the second digital-to-analog converter is connected with the processor, and the preset difference threshold is received;
and the second output end is connected with the processor and used for outputting an alarm signal generated when the difference value is greater than the difference value threshold to the processor.
3. The power amplifier protection circuit of claim 1, wherein the first input terminal is a positive input terminal of a first operational amplifier, one end of a first resistor and one end of a third resistor are connected to the positive input terminal, the other end of the first resistor is connected to a signal source, and the other end of the third resistor is grounded;
the second input end is an inverted input end of the first operational amplifier, the inverted input end is connected with one end of the second resistor and one end of the fourth resistor, the other end of the second resistor is connected with an output end of the first digital-to-analog converter, and the other end of the fourth resistor is connected with the first output end.
4. The power amplifier protection circuit of claim 2, wherein the power amplifier protection circuit is configured to be connected to a power supply line of a power amplifier
The third input end is a positive input end of the second comparator, the fourth input end is a negative input end of the second comparator, and the negative input end is connected with the output end of the second digital-to-analog converter.
5. A power amplifier protection method is characterized by comprising the following steps:
acquiring a power detection voltage value corresponding to the current moment and a power detection voltage value at a preset moment before the current moment, wherein the power detection voltage is a continuous variable,
comparing the power detection voltage value corresponding to the current moment with the power detection voltage value at the preset moment before the current moment to obtain a difference value of the power detection voltage value and the power detection voltage value;
comparing the difference value with a preset difference value threshold, and outputting an alarm when the difference value is greater than the difference value threshold;
the step of obtaining the power detection voltage value corresponding to the current moment and the power detection voltage value at the preset moment before the current moment comprises the following steps:
connecting a first input end of a first operational amplifier with a signal source, and receiving a power detection voltage corresponding to the current moment input by the signal source;
connecting a second input end of a first operational amplifier with an output end of a first digital-to-analog converter, connecting an input end of the first digital-to-analog converter with a processor, connecting the processor with an output end of the analog-to-digital converter, connecting an input end of the analog-to-digital converter with a signal source, and receiving a power detection voltage corresponding to a preset moment before the current moment input by the signal source; the processor comprises a Serial Peripheral Interface (SPI) and a Direct Memory Access (DMA) controller, a first digital-to-analog converter and an analog-to-digital converter are SPI devices, and the processor reads the result of the analog-to-digital converter through the SPI and directly sends the result to the first digital-to-analog converter through a DMA controller channel;
and connecting the first output end of the first operational amplifier with a second comparator, and outputting the difference to the second comparator.
6. The power amplifier protection method of claim 5, wherein comparing the difference value to a preset difference threshold comprises:
connecting a third input end of a second comparator with the first output end, and receiving a difference value between a power detection voltage corresponding to the current moment and a power detection voltage corresponding to a preset moment before the current moment, wherein the power detection voltage is output by the first operational amplifier;
connecting a fourth input end of the second comparator with an output end of a second digital-to-analog converter, wherein an input end of the second digital-to-analog converter is connected with the processor, and receives a preset difference threshold;
and connecting a second output end of the second comparator with the processor, and outputting a warning signal generated when the difference is greater than the difference threshold to the processor.
7. The method of claim 5, wherein the connecting the first input terminal of the first operational amplifier to the signal source comprises:
the first input end is used as a positive input end of a first operational amplifier, one end of a first resistor and one end of a third resistor of the positive input end are connected, the other end of the first resistor is connected with a signal source, and the other end of the third resistor is grounded;
and taking the second input end as an inverting input end of the first operational amplifier, connecting the inverting input end with one end of a second resistor and one end of a fourth resistor, connecting the other end of the second resistor with the output end of the first digital-to-analog converter, and connecting the other end of the fourth resistor with the first output end.
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| US8620225B2 (en) * | 2008-12-15 | 2013-12-31 | Nec Corporation | Power detection circuit, transmitter, and power detection method |
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