Power amplifier over-temperature protection circuit

Abstract

According to the power amplifier over-temperature protection circuit provided by the utility model, an input voltage and a reference voltage are provided for the voltage comparison module through the resistance voltage division module; comparing the input voltage with the reference voltage through a voltage comparison module; controlling the input voltage through an MOS tube switch module according to the comparison result; according to the utility model, the positive feedback circuit is added, so that the damage of thermal oscillation to the power amplifier chip can be effectively avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, and particularly relates to an over-temperature protection circuit for a power amplifier. Background Art

[0002] During the operation of the power amplifier, power loss will inevitably occur, and most of these power losses will be converted into heat and dissipated. In the case of too high ambient temperature, the heat inside the power amplifier cannot be dissipated in time, which will inevitably cause the operating temperature of the power amplifier to rise. Too high operating temperature has a great impact on the operating performance, reliability and safety of the power amplifier. Research shows that for every 1°C increase in temperature, the driving ability of the MOS transistor will decrease by about 4%, the wiring delay will increase by 5%, and the failure rate of the integrated circuit will double. Therefore, the power amplifier must have an over-temperature protection circuit to ensure the safety of the power amplifier.

[0003] However, the existing over-temperature protection circuit will generate thermal oscillation and damage the power amplifier chip.

[0004] In summary, the problems existing in the prior art need to be solved urgently. Content of the Utility Model

[0005] The utility model provides an over-temperature protection circuit for a power amplifier to solve the defects in the prior art and avoid the loss of the power amplifier chip caused by thermal oscillation.

[0006] The utility model provides an over-temperature protection circuit for a power amplifier, including: a power supply module, a resistor voltage division module, a voltage comparison module, a reverse module, and a MOS transistor switch module;

[0007] The resistor voltage division module is used to provide an input voltage and a reference voltage for the voltage comparison module;

[0008] The voltage comparison module is used to compare the input voltage and the reference voltage;

[0009] The MOS transistor switch module is used to control the input voltage according to the comparison result;

[0010] The power supply module is connected to the resistor voltage division module, the resistor voltage division module is connected to the reverse module, the reverse module is connected to the MOS transistor switch module, and the MOS transistor switch module is connected to the resistor voltage division module.

[0011] According to an over-temperature protection circuit for a power amplifier provided by the utility model, the voltage comparison module includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a thermistor;

[0012] The power supply module is connected to the first end of the second resistor through a first resistor and a thermistor. The second end of the second resistor is grounded, and the first end of the second resistor is connected to the inverting input terminal of the voltage comparison module;

[0013] The power supply module is connected to the first end of the fourth resistor through a third resistor. The second end of the fourth resistor is grounded, and the first end of the fourth resistor is connected to the non-inverting input terminal of the voltage comparison module.

[0014] According to an over-temperature protection circuit for a power amplifier provided by the present invention, the voltage comparison module includes a comparator;

[0015] The inverting input terminal of the comparator is connected to the first end of the second resistor;

[0016] The non-inverting input terminal of the comparator is connected to the first end of the fourth resistor;

[0017] The output terminal of the comparator is connected to the input terminal of the inverting module.

[0018] According to an over-temperature protection circuit for a power amplifier provided by the present invention, the inverting module includes an inverter;

[0019] The input terminal of the inverter is connected to the output terminal of the comparator;

[0020] The output terminal of the inverter is connected to the MOS transistor switch module;

[0021] The output terminal of the inverter serves as the output terminal of the over-temperature protection circuit for the power amplifier.

[0022] According to an over-temperature protection circuit for a power amplifier provided by the present invention, the MOS transistor switch module includes a MOS transistor;

[0023] The gate of the MOS transistor is connected to the output terminal of the inverter;

[0024] The drain of the MOS transistor is connected to the power supply module;

[0025] The source of the MOS transistor is connected to the inverting input terminal of the comparator.

[0026] The over-temperature protection circuit for a power amplifier provided by the present invention provides an input voltage and a reference voltage to the voltage comparison module through a resistor voltage division module; compares the input voltage and the reference voltage through the voltage comparison module; controls the input voltage according to the comparison result through the MOS transistor switch module; by adding a positive feedback circuit, the present invention can effectively avoid damage to the power amplifier chip caused by thermal oscillation. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic diagram of the modules of the over-temperature protection circuit provided by the present utility model;

[0029] Figure 2 It is a circuit connection diagram of the over-temperature protection circuit provided by the present utility model. Specific embodiments

[0030] To make the objectives, technical solutions, and advantages of the present utility model clearer, the following will clearly and completely describe the technical solutions in the present utility model in conjunction with the drawings in the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0031] During the operation of the power amplifier, power loss will inevitably occur, and most of these losses will be dissipated in the form of heat. When the ambient temperature is high, the heat inside the power amplifier is difficult to dissipate in time, resulting in an increase in its operating temperature. Excessive operating temperature will have an adverse impact on the performance, reliability, and safety of the power amplifier. Research shows that for every 1°C increase in temperature, the driving ability of the MOS transistor will decrease by about 4%, the wiring delay will increase by 5%, and the failure rate of the integrated circuit will double. Therefore, the power amplifier must be equipped with an over-temperature protection circuit to ensure its safe operation.

[0032] However, the existing over-temperature protection circuits may cause thermal oscillation problems in actual applications, which will damage the power amplifier chip. Thermal oscillation refers to the fact that during the triggering and resetting processes of the temperature protection circuit, the power amplifier chip frequently experiences temperature changes, causing stress and damage. To solve this problem, it is necessary to optimize the design of the over-temperature protection circuit to ensure that while providing effective protection, thermal oscillation is avoided.

[0033] As Figure 1 shown, an over-temperature protection circuit for a power amplifier includes but is not limited to the following modules:

[0034] Power supply module, resistor voltage division module, voltage comparison module, reverse module, MOS transistor switch module;

[0035] The resistor voltage division module is used to provide an input voltage and a reference voltage for the voltage comparison module;

[0036] The voltage comparison module is used to compare the input voltage and the reference voltage;

[0037] The MOS transistor switch module is used to control the input voltage according to the comparison result;

[0038] The power supply module is connected to the resistor voltage division module, the resistor voltage division module is connected to the reverse module, the reverse module is connected to the MOS transistor switch module, and the MOS transistor switch module is connected to the resistor voltage division module.

[0039] The power supply module is responsible for providing the operating voltage required for the entire circuit. This module can be a linear voltage regulator or a switching power supply to ensure a stable DC voltage output. The output voltage of the power supply module is connected to the resistor voltage division module to provide a voltage source for it.

[0040] The resistor voltage division module consists of a series of precise resistors and is used to divide the voltage output by the power supply module to generate a signal suitable for input to the voltage comparison module. The resistor voltage division module has two main functions:

[0041] Provide an input voltage signal that reflects the current operating temperature.

[0042] Provide a reference voltage signal that is used to set the trigger temperature threshold of the protection circuit.

[0043] The voltage signals after voltage division are respectively sent to the input terminal and the reference terminal of the voltage comparison module.

[0044] The voltage comparison module is a high-precision operational amplifier with two input terminals. One receives the input voltage signal provided by the resistor voltage division module, and the other receives the reference voltage signal. This module is responsible for comparing the input voltage and the reference voltage. When the input voltage exceeds the reference voltage, the voltage comparison module outputs a high-level signal; otherwise, it outputs a low-level signal.

[0045] The reverse module is a simple inverter circuit, and its function is to invert the signal output by the voltage comparison module. For example, when the voltage comparison module outputs a high-level signal, the reverse module converts it into a low-level signal, and vice versa. This is to ensure that the MOS transistor switch module can correctly receive the control signal under different states.

[0046] The MOS transistor switching module consists of one or more MOSFETs and is responsible for switching the operating state of the power amplifier according to the control signal output by the reverse module. When the reverse module outputs a low-level signal, the MOS transistor is in the conducting state, allowing current to pass through, and the power amplifier operates normally; when the reverse module outputs a high-level signal, the MOS transistor is in the cut-off state, cutting off the current to protect the power amplifier from overheating.

[0047] As a further optional embodiment, the voltage comparison module includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a thermistor;

[0048] The power supply module is connected to the first end of the second resistor through the first resistor and the thermistor. The second end of the second resistor is grounded, and the first end of the second resistor is connected to the inverting input terminal of the voltage comparison module;

[0049] The power supply module is connected to the first end of the fourth resistor through the third resistor. The second end of the fourth resistor is grounded, and the first end of the fourth resistor is connected to the non-inverting input terminal of the voltage comparison module.

[0050] Specifically, referring to Figure 2 , the power supply module VCC is connected to the first end of the second resistor R2 through the first resistor R1 and the thermistor NTC1. The second end of the second resistor R2 is grounded, and the first end of the second resistor R2 is connected to the inverting input terminal of the voltage comparison module;

[0051] The power supply module VCC is connected to the first end of the fourth resistor R4 through the third resistor R3. The second end of the fourth resistor R4 is grounded, and the first end of the fourth resistor R4 is connected to the non-inverting input terminal of the voltage comparison module.

[0052] As a further optional embodiment, the voltage comparison module includes a comparator;

[0053] The inverting input terminal of the comparator is connected to the first end of the second resistor;

[0054] The non-inverting input terminal of the comparator is connected to the first end of the fourth resistor;

[0055] The output terminal of the comparator is connected to the input terminal of the reverse module.

[0056] Specifically, referring to Figure 2 , the inverting input terminal of the comparator U1 is connected to the first end of the second resistor R2 to receive the input voltage, which is used to reflect the temperature;

[0057] The non-inverting input terminal of the comparator U1 is connected to the first end of the fourth resistor R4;

[0058] The output terminal of the comparator U1 is connected to the input terminal of the reverse module.

[0059] As a further optional embodiment, the reverse module includes an inverter;

[0060] The input terminal of the inverter is connected to the output terminal of the comparator;

[0061] The output terminal of the inverter is connected to the MOS transistor switch module;

[0062] The output terminal of the inverter serves as the output terminal of the power amplifier over-temperature protection circuit.

[0063] Specifically, referring to Figure 2 , the input terminal of the inverter U2 is connected to the output terminal of the comparator U1;

[0064] The output terminal of the inverter U2 is connected to the MOS transistor switch module;

[0065] The output terminal of the inverter U2 serves as the output terminal of the power amplifier over-temperature protection circuit.

[0066] As a further optional embodiment, the MOS transistor switch module includes a MOS transistor;

[0067] The gate of the MOS transistor is connected to the output terminal of the inverter;

[0068] The drain of the MOS transistor is connected to the power supply module;

[0069] The source of the MOS transistor is connected to the inverting input terminal of the comparator.

[0070] Specifically, referring to Figure 2 , the gate of the MOS transistor Q1 is connected to the output terminal of the inverter;

[0071] The drain of the MOS transistor Q1 is connected to the power supply module VCC;

[0072] The source of the MOS transistor Q1 is connected to the inverting input terminal of the comparator U1.

[0073] Based on the above embodiments, the principle of the present invention is further described:

[0074] The input voltage and the reference voltage generated by the resistor voltage division module are respectively input into the voltage comparison module. When NTC1 detects that the temperature of the radiator increases, its resistance decreases, causing the input voltage to increase. When the input voltage exceeds the reference voltage, the voltage comparison module outputs a low level, which is converted into a high-level signal by the reverse module and acts on the power amplifier chip to make it stop working. At the same time, the high-level signal turns on the MOS transistor, increasing the current on resistor R2, forming positive feedback to increase the system hysteresis effect and avoid thermal oscillation. When the temperature drops, the input voltage is lower than the reference voltage, the voltage comparison module outputs a high level, which is converted into a low-level signal by the reverse module and acts on the power amplifier chip to make it work again. At the same time, the MOS transistor is turned off, reducing the current on resistor R2 to further protect the power amplifier chip.

[0075] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An over-temperature protection circuit for an amplifier, characterized in that, It includes: a power supply module, a resistor voltage division module, a voltage comparison module, an inverter module, and a MOS transistor switch module; The resistor voltage division module is used to provide an input voltage and a reference voltage for the voltage comparison module; The voltage comparison module is used to compare the input voltage and the reference voltage; The MOS transistor switch module is used to control the input voltage according to the comparison result; The power supply module is connected to the resistor voltage division module, the resistor voltage division module is connected to the inverter module, the inverter module is connected to the MOS transistor switch module, and the MOS transistor switch module is connected to the resistor voltage division module.

2. The over-temperature protection circuit for the power amplifier according to claim 1, characterized in that, The voltage comparison module includes a first resistor, a second resistor, a third resistor, a fourth resistor, and a thermistor; The power supply module is connected to the first end of the second resistor through the first resistor and the thermistor, the second end of the second resistor is grounded, and the first end of the second resistor is connected to the inverting input terminal of the voltage comparison module; The power supply module is connected to the first end of the fourth resistor through the third resistor, the second end of the fourth resistor is grounded, and the first end of the fourth resistor is connected to the non-inverting input terminal of the voltage comparison module.

3. The over-temperature protection circuit for an amplifier according to claim 2, characterized in that, The voltage comparison module includes a comparator; The inverting input terminal of the comparator is connected to the first end of the second resistor; The non-inverting input terminal of the comparator is connected to the first end of the fourth resistor; The output terminal of the comparator is connected to the input terminal of the inverter module.

4. The over-temperature protection circuit of the power amplifier according to claim 3, characterized in that, The inverter module includes an inverter; The input terminal of the inverter is connected to the output terminal of the comparator; The output terminal of the inverter is connected to the MOS transistor switch module; The output terminal of the inverter serves as the output terminal of the power amplifier over-temperature protection circuit.

5. The power amplifier over-temperature protection circuit according to claim 4, wherein, The MOS transistor switch module includes a MOS transistor; The gate of the MOS transistor is connected to the output terminal of the inverter; The drain of the MOS transistor is connected to the power supply module; The source of the MOS transistor is connected to the inverting input terminal of the comparator.

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