Positive temperature coefficient current source

Abstract

The utility model relates to a positive temperature coefficient current source, which relates to the field of power supply equipment, and comprises a band-gap reference device, an offset device, a conversion device, a current mirror device and an output device, the counteracting device is connected with the band-gap reference device to receive a reference temperature signal and output a counteracting temperature signal, the conversion device is connected with the counteracting device to receive the counteracting temperature signal and output a conversion signal, and the current mirror device is connected with the conversion device to receive the conversion signal and output a positive temperature signal. And the output device is used for outputting the positive temperature signal to the outside. The positive temperature coefficient current source has the advantages that the compensation effect of the positive temperature coefficient current source is improved, and the situation that the positive temperature coefficient current fluctuates along with batches of poly resistors is reduced.

Description

Technical Field

[0001] The utility model relates to the field of power supply equipment, in particular to a positive temperature coefficient current source. Background Art

[0002] A current source is an idealized circuit element that can provide a constant current to a circuit regardless of changes in the voltage of the external circuit.

[0003] In existing technologies, in RF transceiver chips, each module in the signal chain usually requires a current with a positive temperature coefficient for biasing. The purpose is to compensate for the reduced gain of the circuit at high temperatures through the positive temperature coefficient current, so as to achieve stable gain over the entire temperature range. Currently, the most common solution to generate a positive temperature coefficient current is to mirror the positive temperature coefficient current from a bandgap reference module. Poly resistors are generally used in bandgap reference modules. Poly resistors vary little with temperature, but fluctuate greatly with process.

[0004] When a poly resistor with large process fluctuations is used to generate a positive temperature coefficient current, it is easy to cause large fluctuations in the positive temperature coefficient current, resulting in a decrease in the compensation effect of the positive temperature coefficient current. Utility Model Content

[0005] In order to improve the compensation effect of the positive temperature coefficient current source and reduce the fluctuation of the positive temperature coefficient current with the batch of poly resistors, the utility model provides a positive temperature coefficient current source.

[0006] The present invention provides a positive temperature coefficient current source that adopts the following technical solution:

[0007] A positive temperature coefficient current source includes a bandgap reference device, a compensation device, a conversion device, a current mirror device and an output device. The bandgap reference device is used to detect an external temperature physical quantity and provide a reference temperature signal. The compensation device is connected to the bandgap reference device to receive the reference temperature signal and output a compensation temperature signal. The conversion device is connected to the compensation device to receive the compensation temperature signal and output a conversion signal. The current mirror device is connected to the conversion device to receive the conversion signal and output a positive temperature signal. The output device is used to output the positive temperature signal to the outside world.

[0008] By adopting the above technical solution, the fluctuation of the temperature signal generated by the bandgap reference device is offset by the offset device, and the temperature signal that offsets the fluctuation is scaled and transmitted to the output device by the conversion device and the current mirror device, thereby reducing the batch fluctuation of the positive temperature coefficient current with the poly resistor and improving the compensation effect of the positive temperature coefficient current source.

[0009] Optionally, the bandgap reference device includes a current transfer module and a current generation module, the current generation module is used to generate a reference temperature signal, and the current transfer module is used to transmit the reference temperature signal to the compensation device.

[0010] Optionally, the current generating module and the compensation device use resistors made of the same process.

[0011] By adopting the above technical solution, when the current generating module and the compensation device use resistors produced by the same process, the compensation temperature signal output by the compensation device depends on the ratio of the poly resistors in the current generating module and the compensation device, thereby reducing the situation where the compensation temperature signal fluctuates with the batches of poly resistors.

[0012] Optionally, the conversion device includes an operational amplifier module and a scaling module, the operational amplifier module is connected to the cancellation device to receive the offset temperature signal and output the operational amplifier signal, and the scaling module is connected to the operational amplifier module to receive the operational amplifier signal and output the conversion signal to the current mirror device.

[0013] By adopting the above technical solution, the scaling module is adjusted to adjust the size of the conversion signal output by the conversion device, thereby obtaining the required positive temperature coefficient signal, thereby improving the convenience of using the positive temperature coefficient current source.

[0014] Optionally, the scaling module uses off-chip high-precision resistors.

[0015] By adopting the above technical solution, high-precision resistors are used to scale the op amp signal to obtain a conversion signal, thereby reducing the fluctuation of the conversion signal with the batch of the scaling module, thereby reducing the fluctuation of the positive temperature coefficient current and improving the compensation effect of the positive temperature coefficient current source.

[0016] Optionally, the system further includes a load device, a temperature reference device, a temperature comparison device, a control device, and a heat dissipation device, wherein the load device is connected to the output device to receive a positive temperature signal in the form of current and convert it into a positive temperature signal in the form of voltage, the temperature reference device is used to provide a temperature reference signal, the temperature comparison device is connected to the load device and the temperature reference device to receive the positive temperature signal and the temperature reference signal and output a temperature comparison signal, the control device is connected to the temperature comparison device to receive the temperature comparison signal and output a control signal, and the heat dissipation device is connected to the control device to receive the control signal and respond to the control signal to control the opening and closing of the fan;

[0017] When the temperature is high, the load device outputs a high-level positive temperature signal, the temperature comparison device receives the temperature reference signal and the high-level positive temperature signal and outputs a high-level temperature comparison signal, the control device receives the high-level temperature comparison signal and outputs a high-level control signal, and the heat dissipation device receives the high-level control signal and controls the fan to start;

[0018] When the temperature is low, the load device outputs a low-level positive temperature signal, the temperature comparison device receives the temperature reference signal and the low-level positive temperature signal and outputs a low-level temperature comparison signal, the control device receives the low-level temperature comparison signal and outputs a low-level control signal, and the heat dissipation device receives the low-level control signal and controls the fan to turn off.

[0019] By adopting the above technical solution, a comparison device is used to detect the size of the positive temperature coefficient current in real time, so that when the positive temperature coefficient current is too large, that is, when the ambient temperature is too high, the heat dissipation performance of the positive temperature coefficient current source is improved by a fan, thereby improving the working stability of the positive temperature coefficient current source.

[0020] Optionally, a lighting device is also included, and the lighting device is used to display the working status of the heat dissipation device.

[0021] By adopting the above technical solution, a lighting device is used to display the working status of the heat dissipation circuit. When the prompt light is turned on, it means that the heat dissipation circuit is energized. When the prompt light is off, it means that the heat dissipation circuit is energized, which makes it easier for staff to make judgments.

[0022] Optionally, a brightening device is further included, wherein the brightening device is connected to the control device to receive a control signal and output a brightening signal to the lighting device;

[0023] When the control device outputs a high-level control signal, the brightness increasing device outputs a high-level brightness increasing signal to the lighting device;

[0024] When the control device outputs a low-level control signal, the brightness increasing device outputs a low-level brightness increasing signal to the lighting device.

[0025] By adopting the above technical solution, a lighting device is used to further display the working status of the heat dissipation circuit. When the prompt light is illuminated at a lower brightness, it means that the fan is not started at this time. When the prompt light is illuminated at a higher brightness, it means that the fan is started at this time.

[0026] Optionally, the brightness enhancement device includes a relay module and a resistance enhancement module, and the relay module is used to control the connection state between the resistance enhancement module and the lighting device.

[0027] By adopting the above technical solution, when the fan is started, the relay module short-circuits the resistance increasing module, thereby increasing the control signal received by the lighting device, and then increasing the intensity of the light emitted by the lighting device. When the fan is not started, the resistance increasing module is controlled to be connected to the lighting device to reduce the control signal received by the lighting device.

[0028] Optionally, the heat dissipation device includes an optocoupler module and a fan module, the optocoupler module is connected to the control device to receive a control signal and output an optocoupler signal, and the fan module is connected to the optocoupler module to receive the optocoupler signal and respond to the optocoupler signal to control the opening and closing of the fan;

[0029] When the control device outputs a high-level control signal, the optical coupling module receives the high-level control signal and outputs a high-level optical coupling signal, and the fan module receives the high-level optical coupling signal and controls the fan to start;

[0030] When the control device outputs a low-level control signal, the optocoupler module receives the low-level control signal and outputs a low-level optocoupler signal, and the fan module receives the low-level optocoupler signal and controls the fan to be turned off.

[0031] By adopting the above technical solution, the electromagnetic interference caused by the positive temperature coefficient current source itself is reduced through the optical coupling module, thereby reducing the situation where the positive temperature coefficient current source interferes with the fan device and causes the fan device to malfunction.

[0032] In summary, the present invention has at least one of the following beneficial technical effects:

[0033] 1. The fluctuation of the temperature signal generated by the bandgap reference device is offset by the offset device, and the temperature signal that offsets the fluctuation is scaled and transmitted to the output device by the conversion device and the current mirror device, thereby reducing the fluctuation of the positive temperature coefficient current due to the batch fluctuation of the poly resistor and improving the compensation effect of the positive temperature coefficient current source;

[0034] 2. When the current generation module and the compensation device use resistors produced using the same process, the compensation temperature signal output by the compensation device depends on the ratio of the poly resistors in the current generation module and the compensation device, thereby reducing the fluctuation of the compensation temperature signal due to batch fluctuations of the poly resistors;

[0035] 3. Use high-precision resistors to scale the op amp signal to obtain the conversion signal, thereby reducing the fluctuation of the conversion signal with the batch of scaling modules, thereby reducing the fluctuation of the positive temperature coefficient current and improving the compensation effect of the positive temperature coefficient current source. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a circuit diagram of a positive temperature coefficient current source;

[0037] Figure 2 This is the circuit schematic of the heat sink.

[0038] The names of the parts indicated by the numerical labels in the above drawings are as follows: 1. Bandgap reference device; 2. Compensation device; 3. Conversion device; 4. Current mirror device; 5. Output device; 6. Current transfer module; 7. Current generation module; 8. Operational amplifier module; 9. Scaling module; 10. Load device; 11. Temperature reference device; 12. Temperature comparison device; 13. Control device; 14. Heat dissipation device; 15. Lighting device; 16. Brightening device; 17. Relay module; 18. Resistance increasing module; 19. Optocoupler module; 20. Fan module. DETAILED DESCRIPTION

[0039] The present invention is described in further detail below with reference to the accompanying drawings and embodiments.

[0040] The present invention discloses a positive temperature coefficient current source. Figure 1 A positive temperature coefficient current source includes a bandgap reference device 1, a compensation device 2, a conversion device 3, a current mirror device 4, and an output device 5. The bandgap reference device 1 is used to detect an external temperature physical quantity and provide a reference temperature signal. The compensation device 2 is connected to the bandgap reference device 1 to receive the reference temperature signal and output a compensation temperature signal. The conversion device 3 is connected to the compensation device 2 to receive the compensation temperature signal and output a conversion signal. The current mirror device 4 is connected to the conversion device 3 to receive the conversion signal and output a positive temperature signal. The output device 5 is used to output the positive temperature signal to the outside.

[0041] The bandgap reference device 1 includes a current transfer module 6 and a current generating module 7. The current generating module 7 is used to generate a reference temperature signal. The current transfer module 6 is used to transmit the reference temperature signal to the compensation device 2. The current transfer module 6 includes a transistor MP0, a transistor MP1, a transistor MP2, a transistor MP3, an operational amplifier N1, a bipolar junction transistor BJ0, a bipolar junction transistor BJ1, a bipolar junction transistor BJ2, and a resistor R2. The current generating module 7 includes a resistor R1. MP0, a transistor MP1, a transistor MP2, a transistor MP3, an operational amplifier N1, a bipolar junction transistor BJ0, a bipolar junction transistor BJ1, a bipolar junction transistor BJ2, a resistor R1 and a resistor R2 are used to form a bandgap reference circuit. The bandgap reference circuit is common knowledge among people in this field. The model used is selected by the staff according to actual conditions and will not be elaborated here.

[0042] The compensation device 2 includes a resistor R3. Resistor R3 and resistor R1 are single poly resistors of the same size but different quantities. In the CMOS process, the resistance value of the poly resistor will fluctuate with the process, so it is impossible to produce a precise resistance. However, by allowing the errors of the two poly resistors to offset each other, a precise resistance ratio can be generated. This resistance ratio, namely R1 / R3, is precise and does not fluctuate with the process.

[0043] The conversion device 3 includes an operational amplifier module 8 and a scaling module 9. The operational amplifier module 8 is connected to the cancellation device 2 to receive the cancellation temperature signal and output the operational amplifier signal. The scaling module 9 is connected to the operational amplifier module 8 to receive the operational amplifier signal and output the conversion signal to the current mirror device 4. The operational amplifier module 8 includes the operational amplifier N2, and the scaling module 9 includes the resistor R4. The resistor R4 is an off-chip high-precision resistor, and its resistance value is accurate and does not fluctuate with the process.

[0044] The current mirror device 4 includes a transistor MP4 and a transistor MP5, wherein the transistors MP4, MP5, an operational amplifier N2 and a resistor R4 are used to form a current mirror circuit. The current mirror circuit is common knowledge in this field. The model used is selected by the staff according to actual conditions and will not be described in detail here.

[0045] The output device 5 includes a port A. The port A can be changed according to the docking device. The port A is selected by the staff according to the actual situation and will not be described in detail here.

[0046] The source of transistor MP0 is connected to the power supply VDD, and then to the source of transistor MP1, and then to the source of transistor MP2, and then to the source of transistor MP3, and then to the source of transistor MP4, and then to the source of transistor MP5. The gate of transistor MP0 is connected to the output terminal of operational amplifier N1, and then to the gate of transistor MP1, and then to the gate of transistor MP2, and then to the gate of transistor MP3. The drain of transistor MP0 is connected to the positive input terminal of operational amplifier N1, and then to the collector of bipolar junction transistor BJ0. The drain of transistor MP1 is connected to the negative input terminal of operational amplifier N1, and then to one end of resistor R1. The other end of resistor R1 is connected to the collector of bipolar junction transistor BJ1. The base of bipolar junction transistor BJ0 is connected to the emitter of bipolar junction transistor BJ0. Then connected to the base of bipolar junction transistor BJ1, then to the emitter of bipolar junction transistor BJ1, then to the base of bipolar junction transistor BJ2, then to the emitter of bipolar junction transistor BJ2, and then to ground GND. The drain of transistor MP2 is connected to one end of resistor R2, and the other end of resistor R2 is connected to the collector of bipolar junction transistor BJ2. The drain of transistor MP3 is connected to one end of resistor R3 and then to the negative input terminal of operational amplifier N2, and the other end of resistor R3 is connected to ground GND. The positive input terminal of operational amplifier N2 is connected to one end of resistor R4 and then to the drain of transistor MP4. The output terminal of operational amplifier N2 is connected to the gate of transistor MP4 and then to the gate of transistor MP5. The other end of resistor R9 is connected to ground GND. The drain of transistor MP5 is connected to port A.

[0047] Reference Figure 2, also includes a load device 10, a temperature reference device 11, a temperature comparison device 12, a control device 13, a heat dissipation device 14, a brightening device 16 and a lighting device 15. The load device 10 is connected to the output device 5 to receive a positive temperature signal in the form of current and convert it into a positive temperature signal in the form of voltage. The temperature reference device 11 is used to provide a temperature reference signal. The temperature comparison device 12 is connected to the load device and the temperature reference device 11 to receive a positive temperature signal and a temperature reference signal and output a temperature comparison signal. The control device 13 is connected to the temperature comparison device 12 to receive the temperature comparison signal and output a control signal. The heat dissipation device 14 is connected to the control device 13 to receive a control signal and respond to the control signal to control the start and stop of the fan. The brightening device 16 is connected to the control device 13 to receive a control signal and output a brightening signal. The lighting device 15 is connected to the brightening device 16 to receive the brightening signal and respond to the brightening signal to adjust the brightness of the prompt light.

[0048] The load device 10 includes a resistor R8 , the temperature reference device 11 includes resistors R5 , R6 and R7 , and the temperature comparison device 12 includes a comparator N2 . The comparator N2 may be a comparator chip of model TLV1701AIDCLKR.

[0049] The control device 13 includes a transistor Q1, which adopts an NPN transistor with a model number of 9013. The heat dissipation device 14 includes an optocoupler module 19 and a fan module 20. The optocoupler module 19 is connected to the control device 13 to receive a control signal and output an optocoupler signal. The fan module 20 is connected to the optocoupler module 19 to receive the optocoupler signal and respond to the optocoupler signal to control the opening and closing of the fan. The optocoupler module 19 includes an optocoupler U1, which adopts an optocoupler chip with a model number of HCPL-6431. The fan module 20 includes a fan M, which refers to a blowing device used to improve the heat dissipation performance of the positive temperature coefficient current source. The fan module 20 is selected by the staff according to actual conditions and will not be elaborated here.

[0050] The brightness enhancement device 16 includes a relay module 17 and a resistance enhancement module 18. The relay module 17 is used to control the connection status of the resistance enhancement module 18 and the lighting device 15. The relay module 17 includes a relay KM1 and a relay normally open contact KM1-1. The relay KM1 adopts an electromagnetic relay model JQX-13F. The resistance enhancement module 18 includes a resistor R9.

[0051] The lighting device 15 includes a resistor R10 and a light emitting diode LED1 , wherein the resistor R9 and the resistor R10 can be relatively high and have the same resistance value so that the brightness of the light emitting diode LED1 changes significantly.

[0052] Port A is connected to one end of resistor R8 and then to the positive input terminal of comparator N2. The other end of resistor R8 is connected to ground GND. One end of resistor R5 is connected to power supply VCC. The other end of resistor R5 is connected to one end of resistor R6 and then to one end of resistor R7. The other end of resistor R7 is connected to ground GND. The other end of resistor R6 is connected to the negative input terminal of comparator N2. The output terminal of comparator N2 is connected to the base of transistor Q1. The emitter of transistor Q1 is connected to ground GND. The collector of transistor Q1 is connected to the negative input terminal of optocoupler U1. The positive input terminal of optocoupler U1 is connected to The output end of the relay KM1 is connected, the input end of the relay KM1 is connected to the power supply VCC, the positive output end of the optocoupler U1 is connected to one end of the relay normally open contact KM1-1, then to the power supply VCC, and then to one end of the resistor R9, the negative output end of the optocoupler U1 is connected to the input end of the fan M, the output end of the fan M is connected to the ground GND, the other end of the relay normally open contact KM1-1 is connected to the other end of the resistor R9, and then to one end of the resistor R10, the other end of the resistor R10 is connected to the anode of the light-emitting diode LED1, and the cathode of the light-emitting diode LED1 is connected to the ground GND.

[0053] The implementation principle of a positive temperature coefficient current source in this embodiment of the utility model is to generate a positive temperature coefficient current that is independent of process fluctuations by using an external off-chip resistor. First, a bandgap reference device 1 generates reference temperature information in the form of a current, ΔVBE / R1. Resistor R3 converts this reference temperature information into a voltage, Vptat = ΔVBE * (R1 / R3). In CMOS processes, the resistance of poly resistors fluctuates with the process, making it difficult to produce a precise resistance. However, by offsetting the errors of two poly resistors, a precise resistance ratio can be generated. Thus, the resistance ratio R1 / R3 is precise and independent of process fluctuations. Consequently, the offset temperature information Vptat is also independent of process fluctuations. Because op amp N2 has the characteristics of virtual short and virtual open, the voltage at the upper end of resistor R4 is also the offset temperature information Vptat. R1 is a high-precision off-chip resistor with a precise resistance value that is independent of process fluctuations. This generates a positive temperature coefficient current across resistor R4, with a value of Vptat / R4. Since Vptat and R1 are both batch-invariant, the positive temperature coefficient current generated by R1 is also batch-invariant. This batch-invariant current flows through MP4 and is mirrored by MP5 to provide bias for other modules.

[0054] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, certain improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A positive temperature coefficient current source, characterized in that: The invention comprises a bandgap reference device (1), a compensation device (2), a conversion device (3), a current mirror device (4) and an output device (5), wherein the bandgap reference device (1) is used to detect an external temperature physical quantity and provide a reference temperature signal, the compensation device (2) is connected to the bandgap reference device (1) to receive the reference temperature signal and output a compensation temperature signal, the conversion device (3) is connected to the compensation device (2) to receive the compensation temperature signal and output a conversion signal, the current mirror device (4) is connected to the conversion device (3) to receive the conversion signal and output a positive temperature signal, and the output device (5) is used to output the positive temperature signal to the outside.

2. The positive temperature coefficient current source according to claim 1, characterized in that: The bandgap reference device (1) comprises a current transfer module (6) and a current generation module (7), wherein the current generation module (7) is used to generate a reference temperature signal, and the current transfer module (6) is used to transmit the reference temperature signal to the compensation device (2).

3. The positive temperature coefficient current source according to claim 2, characterized in that: The current generating module (7) and the offset device (2) use resistors made of the same process.

4. The positive temperature coefficient current source according to claim 1, wherein: The conversion device (3) includes an operational amplifier module (8) and a scaling module (9), wherein the operational amplifier module (8) is connected to the cancellation device (2) to receive the offset temperature signal and output the operational amplifier signal, and the scaling module (9) is connected to the operational amplifier module (8) to receive the operational amplifier signal and output the conversion signal to the current mirror device (4).

5. The positive temperature coefficient current source according to claim 4, characterized in that: The scaling module (9) uses off-chip high-precision resistors.

6. The positive temperature coefficient current source according to claim 1, characterized in that: The invention also includes a load device (10), a temperature reference device (11), a temperature comparison device (12), a control device (13) and a heat dissipation device (14), wherein the load device (10) is connected to the output device (5) to receive a positive temperature signal in the form of current and convert it into a positive temperature signal in the form of voltage, the temperature reference device (11) is used to provide a temperature reference signal, the temperature comparison device (12) is connected to the load device and the temperature reference device (11) to receive the positive temperature signal and the temperature reference signal and output a temperature comparison signal, the control device (13) is connected to the temperature comparison device (12) to receive the temperature comparison signal and output a control signal, and the heat dissipation device (14) is connected to the control device (13) to receive the control signal and respond to the control signal to control the opening and closing of the fan; When the temperature is high, the load device (10) outputs a high-level positive temperature signal, the temperature comparison device (12) receives the temperature reference signal and the high-level positive temperature signal and outputs a high-level temperature comparison signal, the control device (13) receives the high-level temperature comparison signal and outputs a high-level control signal, and the heat dissipation device (14) receives the high-level control signal and controls the fan to start; When the temperature is low, the load device (10) outputs a low-level positive temperature signal, the temperature comparison device (12) receives the temperature reference signal and the low-level positive temperature signal and outputs a low-level temperature comparison signal, the control device (13) receives the low-level temperature comparison signal and outputs a low-level control signal, and the heat dissipation device (14) receives the low-level control signal and controls the fan to be turned off.

7. The positive temperature coefficient current source according to claim 6, characterized in that: It also includes a lighting device (15), which is used to display the working status of the heat dissipation device (14).

8. The positive temperature coefficient current source according to claim 7, characterized in that: It also includes a brightening device (16), wherein the brightening device (16) is connected to the control device (13) to receive a control signal and output a brightening signal to the lighting device (15); When the control device (13) outputs a high-level control signal, the brightness increasing device (16) outputs a high-level brightness increasing signal to the lighting device (15); When the control device (13) outputs a low-level control signal, the brightening device (16) outputs a low-level brightening signal to the lighting device (15).

9. The positive temperature coefficient current source according to claim 8, characterized in that: The brightness increasing device (16) comprises a relay module (17) and a resistance increasing module (18), and the relay module (17) is used to control the connection state between the resistance increasing module (18) and the lighting device (15).

10. The positive temperature coefficient current source according to claim 6, characterized in that: The heat dissipation device (14) comprises an optical coupling module (19) and a fan module (20), wherein the optical coupling module (19) is connected to the control device (13) to receive a control signal and output an optical coupling signal, and the fan module (20) is connected to the optical coupling module (19) to receive the optical coupling signal and respond to the optical coupling signal to control the opening and closing of the fan; When the control device (13) outputs a high-level control signal, the optical coupling module (19) receives the high-level control signal and outputs a high-level optical coupling signal, and the fan module (20) receives the high-level optical coupling signal and controls the fan to start; When the control device (13) outputs a low-level control signal, the optical coupling module (19) receives the low-level control signal and outputs a low-level optical coupling signal, and the fan module (20) receives the low-level optical coupling signal and controls the fan to be turned off.

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