High-precision pulse output current source

Abstract

The invention relates to the technical field of constant current sources, and discloses a high-precision pulse output current source, which comprises a feedback unit, a driving unit and an adjusting unit, and is characterized in that a first input end of the feedback unit inputs a control signal, and an output end of the feedback unit is connected with a control end of the driving unit; the feedback unit is used for outputting a driving signal after following and amplifying the control signal; the output end of the driving unit is connected with the control end of the adjusting unit, and the driving unit is used for switching the switch state based on the driving signal and then outputting an adjusting signal; the first output end of the adjusting unit is connected with the second input end of the feedback unit, the adjusting unit is connected with a load in series, and the adjusting unit is used for adjusting internal partial voltage based on an adjusting signal and outputting current flowing through the load and voltage at the two ends of the load as feedback signals; the feedback unit adjusts the driving signal based on the feedback signal. The current source can dynamically adjust the current flowing through the load and the voltage at the two ends of the load according to the feedback signal, and the precision of the current source is improved.

Description

Technical Field

[0001] The invention relates to the technical field of constant current sources, and in particular to a current source with high-precision pulse output. Background Art

[0002] During the development and post-processing testing of communication chips, the testing of chips requires the use of power supplies of various specifications as driving sources. Communication chips are generally LD laser chips, which are based on stimulated radiation luminescence. The characteristic of this luminescence principle is that the current drive directly generates lasers, so the light output power is linearly related to the current. Therefore, the driving source of the communication chip generally chooses a constant current source. However, according to the different manufacturing processes and application scenarios of different communication chips, the size of the driving current, the total power size and the heat generated by the chip are different, and the accuracy is mostly one thousandth. The low accuracy leads to inaccurate test results. Therefore, when testing communication chips, a high-precision, high-power, narrow-pulse constant current source is required. Summary of the invention

[0003] In view of this, the present invention provides a current source with high-precision pulse output to solve the problem of low precision of the existing current source.

[0004] The present invention provides a current source with high-precision pulse output, comprising: a feedback unit, a driving unit and an adjusting unit, wherein a control signal is input into a first input end of the feedback unit, an output end of the feedback unit is connected to a control end of the driving unit, and the feedback unit is used to follow and amplify the control signal and then output a driving signal; the output end of the driving unit is connected to the control end of the adjusting unit, and the driving unit is used to output an adjusting signal after switching a switch state based on the driving signal; the first output end of the adjusting unit is connected to a second input end of the feedback unit, and the adjusting unit is connected in series with a load, and the adjusting unit is used to adjust an internal voltage divider based on the adjusting signal, and output a current flowing through the load and a voltage across the load as a feedback signal, wherein the voltage divider is used to adjust the magnitude of the current flowing through the load; and the feedback unit adjusts the driving signal based on the feedback signal.

[0005] The high-precision pulse output current source provided by the present invention has a feedback unit that can adjust the drive signal according to the feedback signal output by the adjustment unit, so that the adjustment signal output by the drive unit changes, and then adjusts the voltage division in the adjustment unit, so that the voltage across the load and the current flowing through the load change, and the feedback signal changes, thereby forming an automatic closed-loop adjustment, which can accurately control the load current.

[0006] In an optional embodiment, the feedback unit includes: a first follower unit and a feedback amplifier unit, wherein a control signal is input into an input end of the first follower unit, an output end of the first follower unit is connected to a first input end of the feedback amplifier unit, and the first follower unit is used to follow the control signal; a second input end of the feedback amplifier unit is connected to a first output end of the adjustment unit, and the feedback amplifier unit is used to adjust and output a drive signal based on a deviation between the feedback signal and the control signal.

[0007] In an optional embodiment, the driving unit includes: a first resistor, a second resistor, a first diode, a second diode, a first controllable switch, a second controllable switch, a third controllable switch and a fourth controllable switch, wherein the first end of the first controllable switch is connected to the first end of the second controllable switch, the first end of the first resistor and an external power supply, the control end of the first controllable switch is connected to the control end of the second controllable switch, the second end of the first resistor and an anode of the first diode, the second end of the first controllable switch is connected to the second end of the second controllable switch, the first end of the third controllable switch, the first end of the fourth controllable switch and the control end of the adjustment unit; the control end of the third controllable switch is connected to the control end of the fourth controllable switch, the cathode of the second diode and the first end of the second resistor, the second end of the third controllable switch is connected to the second end of the fourth controllable switch and the second end of the second resistor and is grounded; the cathode of the first diode is connected to the anode of the second diode and the output end of the feedback unit.

[0008] In an optional embodiment, the feedback signal includes a feedback current and a feedback voltage, and the adjustment unit includes: a sampling unit, a current output unit and a voltage output unit, wherein the input end of the sampling unit is connected to the output end of the driving unit, the first end of the sampling unit is connected to the first input end of the current output unit, the output end of the sampling unit is connected to the second input end of the current output unit and the first end of the load, and the sampling unit is used to divide the adjustment signal by adjusting the internal resistance to obtain a divided voltage of corresponding amplitude; the output end of the current output unit is connected to the output end of the voltage output unit and the second input end of the feedback unit, and the current output unit is used to output the current flowing through the load as a feedback current; the input end of the voltage output unit is connected to the second end of the load, and the voltage output unit is used to output the voltage across the load as a feedback voltage.

[0009] In an optional implementation, the sampling unit includes: a sampling circuit and a plurality of adjustable resistance circuits connected in parallel with the sampling circuit.

[0010] The current source provided by the present invention can control the sampling unit to achieve different degrees of voltage division by controlling the input of adjustable resistance circuits in different paths or adjusting the resistance value of the adjustable resistance circuit, thereby changing the current flowing through the load, switching the current source to different ranges, and expanding the scope of application.

[0011] In an optional embodiment, the current output unit includes: a second follower unit and a first amplifying unit, wherein the first input end of the second follower unit is connected to the input end of the sampling unit, the second input end of the second follower unit is connected to the output end of the sampling unit, the first output end of the second follower unit is connected to the first input end of the first amplifying unit, the second output end of the second follower unit is connected to the second input end of the first amplifying unit, and the second follower unit is used to follow and amplify the voltages at the input and output ends of the sampling unit; the output end of the first amplifying unit is connected to the second input end of the feedback unit, and the first amplifying unit is used to amplify the voltage difference between the input and output ends of the sampling unit and then output a feedback signal.

[0012] In an optional embodiment, the second follower unit includes: a second amplifying unit and a third amplifying unit, wherein the input end of the second amplifying unit is connected to the input end of the sampling unit, the output end of the second amplifying unit is connected to the first input end of the first amplifying unit, and the second amplifying unit is used to increase the input impedance of the first input end of the first amplifying unit; the input end of the third amplifying unit is connected to the output end of the sampling unit, the output end of the third amplifying unit is connected to the second input end of the first amplifying unit, and the third amplifying unit is used to increase the input impedance of the second input end of the first amplifying unit.

[0013] In an optional embodiment, the feedback signal includes: a feedback voltage, and the current source further includes: a current limiting unit, wherein the first input end of the current limiting unit is connected to the second output end of the regulating unit, and the output end of the current limiting unit is connected to the control end of the driving unit, and the current limiting unit is used to compare the feedback voltage with the internal reference voltage, and limit the current size of the driving signal when the feedback voltage is greater than the reference voltage.

[0014] In an optional embodiment, the reference voltage includes: a forward reference voltage and a reverse reference voltage, and the current limiting unit includes: a forward current limiting circuit and a reverse current limiting circuit, wherein the first input end of the forward current limiting circuit inputs the forward reference voltage, the second input end of the forward current limiting circuit is connected to the second input end of the reverse current limiting circuit and the second output end of the adjustment unit, the output end of the forward current limiting circuit is connected to the output end of the reverse current limiting circuit and the control end of the driving unit, the forward current limiting circuit is used to limit the current size of the current driving signal when the feedback voltage is greater than zero and the feedback voltage is greater than the forward reference voltage; the first input end of the reverse current limiting circuit inputs the reverse reference voltage, and the reverse current limiting circuit is used to limit the current size of the current driving signal when the feedback voltage is less than zero and the feedback voltage is less than the reverse reference voltage.

[0015] In the current source provided by the present invention, when the feedback voltage is large, the current limiting unit adjusts the voltage division in the regulating unit by limiting the current size of the driving signal, so that the current flowing through the load is reduced and the voltage across the load is reduced. The current limiting unit of the present invention can limit the voltage in the positive and negative directions respectively, improve the accuracy and reliability of the current source, and expand the application range of the current source.

[0016] In an optional embodiment, the forward current limiting circuit includes: a fourth amplifier unit and a comparison unit, wherein the input end of the fourth amplifier unit inputs a forward reference voltage, the output end of the fourth amplifier unit is connected to the first input end of the comparison unit, and the fourth amplifier unit is used to amplify the forward reference voltage; the second input end of the comparison unit inputs a feedback signal, the output end of the comparison unit is connected to the control end of the drive unit, and the comparison unit is used to limit the current size of the current limit drive signal when the feedback voltage is greater than zero and the feedback voltage is greater than the forward reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a composition diagram of a current source according to an embodiment of the present invention; Figure 2 is a specific circuit structure diagram of a feedback unit according to an embodiment of the present invention; Figure 3 is a specific circuit structure diagram of a driving unit according to an embodiment of the present invention; Figure 4 is another composition diagram of a current source according to an embodiment of the present invention; Figure 5 is a specific circuit structure diagram of a regulating unit according to an embodiment of the present invention; Figure 6 is another composition diagram of a current source according to an embodiment of the present invention; Figure 7 is a specific circuit structure diagram of a current limiting unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the current of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] This embodiment provides a current source with high-precision pulse output, such as Figure 1 As shown, it includes: a feedback unit 1, a driving unit 2 and an adjusting unit 3.

[0024] like Figure 1 As shown, a control signal is input to the first input terminal of the feedback unit 1, and the output terminal of the feedback unit 1 is connected to the control terminal of the drive unit 2; the output terminal of the drive unit 2 is connected to the control terminal of the adjustment unit 3; the first output terminal of the adjustment unit 3 is connected to the second input terminal of the feedback unit 1, and the adjustment unit 3 is connected in series with the load.

[0025] Figure 1In the figure, feedback unit 1 is used to follow and amplify the control signal and then output a driving signal, driving unit 2 is used to output a regulating signal after switching the switch state based on the driving signal, and regulating unit 3 is used to adjust the internal voltage division based on the regulating signal, and output the current flowing through the load and the voltage across the load as feedback signals, wherein the voltage division is used to adjust the current flowing through the load.

[0026] Specifically, Figure 1 In the embodiment, the feedback unit 1 adjusts the driving signal based on the feedback signal. When the control signal and the feedback signal are respectively input to the voltage of the first input terminal and the second input terminal of the feedback unit 1, resulting in the voltage of the first input terminal being different from the voltage of the second input terminal, the feedback unit 1 adjusts the current and voltage of the driving signal, so that the current of the adjustment signal output by the driving unit changes.

[0027] Specifically, Figure 1 In the embodiment, since the load is connected in series with the regulating unit, according to the principle that the current in the series circuit is equal everywhere, the current flowing through the load is adjusted by adjusting the voltage divider of the regulating unit 3, thereby changing the voltage across the load until the voltage across the load changes to the same as the voltage of the control signal, and the voltage of the first input terminal and the voltage of the second input terminal of the feedback unit 1 also tend to be consistent. When the voltage of the first input terminal and the voltage of the second input terminal of the feedback unit 1 are the same, at this time, the entire current source circuit returns to the initial stable state, and the current flowing through the load can be calculated by the voltage of the control signal and the equivalent resistance of the part in series with the load. The current source can switch the switch through the host computer program to control the output of DC or pulse.

[0028] The current source with high-precision pulse output provided in this embodiment has a feedback unit that can adjust the driving signal according to the feedback signal output by the regulating unit, so that the regulating signal output by the driving unit changes, and then adjusts the voltage divider in the regulating unit, so that the voltage across the load and the current flowing through the load change, and the feedback signal changes, thereby forming an automatic closed-loop regulation, which can accurately control the current on the load.

[0029] In some optional embodiments, such as Figure 2 As shown, the feedback unit 1 includes: a first follower unit 11 and a feedback amplifier unit 12, wherein the input end of the first follower unit 11 inputs a control signal, and the output end of the first follower unit 11 is connected to the first input end of the feedback amplifier unit 12; the second input end of the feedback amplifier unit 12 (i.e., one end for inputting the feedback signal) is connected to the first output end of the adjustment unit 3.

[0030] Specifically, Figure 2 In the embodiment, the first follower unit 11 is used to follow the control signal and synchronously amplify the control signal; the feedback amplification unit 12 is used to amplify the deviation between the feedback signal and the control signal, and adjust and output the drive signal.

[0031] Specifically, Figure 2 In the embodiment, the first follower unit 11 includes: a resistor R42 for current limiting, an RC filter circuit composed of a resistor R40 and a capacitor C14, and an operational amplifier IOP8; the feedback amplifier unit 12 includes: a resistor R38 and R39 for current limiting, an RC filter circuit composed of capacitors C12, C13 and a resistor R37, an operational amplifier IOP1 and an adjustable resistor P4. The positive input terminal of IOP1 inputs a control signal, the reverse input terminal inputs a feedback signal, and the output terminal outputs a driving signal with adjustable current through the adjustable resistor P4. The switch state of the switch K can be switched by the host computer program, so that the in-phase input terminal of IOP1 is grounded, or the in-phase input terminal of IOP1 is connected to the output terminal of IOP8, thereby controlling IOP1 to output a direct current or a pulse.

[0032] In some optional embodiments, such as Figure 3 As shown, the driving unit 2 includes: a first resistor R2, a second resistor R18, a first diode D1, a second diode D2, a first controllable switch T1, a second controllable switch T2, a third controllable switch T3 and a fourth controllable switch T4, wherein a first end of the first controllable switch T1 is connected to a first end of the second controllable switch T2, a first end of the first resistor R2 and an external power supply, a control end of the first controllable switch T1 is connected to a control end of the second controllable switch T2, a second end of the first resistor R2 and an anode of the first diode D1, and a second end of the first controllable switch T1 is connected to a second controllable switch T2. 2, a first end of the third controllable switch T3 (i.e., an end outputting the adjustment signal), a first end of the fourth controllable switch T4 and a control end of the adjustment unit are connected; the control end of the third controllable switch T3 is connected to the control end of the fourth controllable switch T4, the cathode of the second diode D2 and the first end of the second resistor R18, the second end of the third controllable switch T3 is connected to the second end of the fourth controllable switch T4 and the second end of the second resistor R18 and is grounded; the cathode of the first diode D1 is connected to the anode of the second diode D2 and the output end of the feedback unit 1 (i.e., an end receiving the driving signal).

[0033] Specifically, Figure 3 In the embodiment, the driving signal is a DC signal or a pulse signal, and the regulating signal is outputted after the on-off state is alternately switched by controlling the first controllable switch T1, the second controllable switch T2, the third controllable switch T3 and the fourth controllable switch T4, and the current of the regulating signal changes with the current of the driving signal.

[0034] Optionally, Figure 3In the embodiment, the first controllable switch T1, the second controllable switch T2, the third controllable switch T3 and the fourth controllable switch T4 are all MOS tubes, and the drain of the MOS tube is connected to the power supply. The parallel connection of multiple MOS tubes in the driving unit 2 can disperse the heat and dissipate the heat better. The driving unit 2 uses a MOS tube as a switch, which has the advantages of fast driving speed and large current generation. The MOS tube can drive a large current and has a fast startup time. It can output a pulse current with a narrower pulse width. The rising edge of the current pulse can be controlled at 50uS, and the current size can reach twelve amperes.

[0035] In some optional embodiments, such as Figure 4 As shown, the feedback signal includes a feedback current and a feedback voltage, and the regulating unit 3 includes: a sampling unit 31, a current output unit 32 and a voltage output unit 33, wherein the input end of the sampling unit 31 is connected to the output end of the driving unit 2, the first end of the sampling unit 31 is connected to the first input end of the current output unit 32, the output end of the sampling unit 31 is connected to the second input end of the current output unit 32 and the first end of the load; the output end of the current output unit 32 is connected to the output end of the voltage output unit 33 and the second input end of the feedback unit 1; the input end of the voltage output unit 33 is connected to the second end of the load.

[0036] Optionally, Figure 4 In the embodiment, the sampling unit 31 may include a plurality of adjustable resistors, and the current flowing through the sampling unit 31 and the load is adjusted by adjusting the resistance value of the adjustable resistor. The load is connected in series with the sampling unit 31. According to the principle that the current is equal everywhere in the series circuit, the current and voltage on the load are controlled and fed back by controlling the voltage across the adjustable resistor.

[0037] Specifically, Figure 4 In the example, the sampling unit 31 is used to divide the voltage of the adjustment signal by adjusting the internal resistance to obtain the voltage of the corresponding amplitude; since the sampling unit 31 is connected in series with the load, the current output unit 32 is used to equate the current flowing through the sampling unit 31 with the current flowing through the load, and output it as the feedback current; the voltage output unit 33 is used to output the voltage across the load as the feedback voltage. After that, the feedback unit 1 adjusts the drive signal according to the difference between the feedback voltage and the voltage of the control signal, or the difference between the feedback current and the current of the control signal, and then adjusts the signal until the feedback unit 1 determines that the feedback signal is consistent with the control signal, indicating that the entire current source circuit has returned to the initial stable state, and the current source precision is dynamically adjustable by closed-loop regulation.

[0038] In some optional embodiments, such as Figure 5As shown, the current output unit includes: a second follower unit 321 and a first amplifying unit 322, wherein the first input end of the second follower unit 321 (i.e., one end of the input adjustment signal) is connected to the input end of the sampling unit 31, the second input end of the second follower unit 321 is connected to the output end of the sampling unit 31, the first output end of the second follower unit 321 is connected to the first input end of the first amplifying unit 322, and the second output end of the second follower unit 321 is connected to the second input end of the first amplifying unit 322; the output end of the first amplifying unit 322 (i.e., one end of the output feedback current) is connected to the second input end of the feedback unit 1.

[0039] Specifically, Figure 5 In the embodiment, the second follower unit 321 is used to follow and amplify the voltages at the input and output ends of the sampling unit 31, and the first amplifying unit 322 is used to amplify the voltage difference between the input and output ends of the sampling unit 31 and then output a feedback current.

[0040] Specifically, Figure 5 In the embodiment, the second follower unit 321 includes: a second amplifying unit 3211 and a third amplifying unit 3212, wherein the input end of the second amplifying unit 3211 (i.e., one end of the input adjustment signal) is connected to the input end of the sampling unit 31, and the output end of the second amplifying unit 3211 is connected to the first input end of the first amplifying unit 322; the input end of the third amplifying unit 3212 is connected to the output end of the sampling unit 31, and the output end of the third amplifying unit 3212 is connected to the second input end of the first amplifying unit 322.

[0041] Specifically, Figure 5 In the embodiment, the second amplifying unit 3211 is used to improve the input impedance of the first input end of the first amplifying unit 322 , and the third amplifying unit 3212 is used to improve the input impedance of the second input end of the first amplifying unit 322 .

[0042] Optionally, Figure 5 In the invention, the sampling unit includes: a sampling circuit and a plurality of adjustable resistance circuits connected in parallel with the sampling circuit. The sampling circuit includes a sampling resistor R1, and each adjustable resistance circuit includes a sampling resistor (R21, R22, R23, R24) and an adjustable resistor (R36, R37, R38, R39) connected in series. The corresponding adjustable resistance circuit can be controlled to be put into or out of operation by controlling the on and off of switches (K5B, K6B, K7B, K8B) connected in series with each adjustable resistance circuit. The adjustable resistance circuits with different resistance values ​​are connected in parallel with the sampling resistor R1 and then connected in series with the load DUT, that is, the current on the load DUT is controlled by adjusting the voltage across the sampling resistor R1. By controlling the resistance value of each adjustable resistance circuit, the ammeter can switch to different current ranges, thereby improving the accuracy of the ammeter, which is about one thousandth to five ten-thousandths.

[0043] Specifically, Figure 5 In the embodiment, the first amplifying unit 322 includes resistors R6, R7, R8 and R9, an operational amplifier IOP5 and a capacitor C2. The second amplifying unit 3211 includes resistors R3, R4 and R5, an operational amplifier IOP3 and a capacitor C1. The third amplifying unit 3212 includes resistors R10, R11 and R12, an operational amplifier IOP4 and a capacitor C3. The voltage output unit includes resistors R13, R14 and R15, an operational amplifier IOP2 and a capacitor C4. IOP3, IOP4 and IOP5 are current feedback devices, and IOP2 is a voltage feedback device. All of them pass through the switch SW-SPDT1 to input the feedback signal to the feedback unit 1. IOP3 and IOP4 are voltage followers, which can improve the input impedance of the subtractor. IOP5 is a subtractor. IOP3 and IOP4 can improve the input impedance of IOP5. After the voltage across the sampling resistor R1 is fed back to IOP5, it is output as the feedback signal of the load DUT, reducing the shunt and ensuring the accuracy of the current value of the load DUT.

[0044] In some optional implementations, the feedback signal includes: a feedback voltage, such as Figure 6 As shown, the current source also includes: a current limiting unit 4, wherein the first input end of the current limiting unit 4 is connected to the second output end of the regulating unit 3, the output end of the current limiting unit 4 is connected to the control end of the driving unit 2, and the current limiting unit 4 is used to compare the feedback voltage with the internal reference voltage, and limit the current size of the driving signal when the feedback voltage is greater than the reference voltage.

[0045] Specifically, the reference voltage includes: a forward reference voltage and a reverse reference voltage, such as Figure 7 As shown, the current limiting unit 4 includes: a forward current limiting circuit 41 and a reverse current limiting circuit 42, wherein the first input end of the forward current limiting circuit 41 inputs a forward reference voltage, and the second input end of the forward current limiting circuit 41 (i.e., an end for inputting a feedback signal) is connected to the second input end of the reverse current limiting circuit 42 and the second output end of the regulating unit 3 (i.e., Figure 5 The output end of the forward current limiting circuit 41 is connected to the output end of the reverse current limiting circuit 42 and the control end of the driving unit 2; the first input end of the reverse current limiting circuit 42 inputs the reverse reference voltage.

[0046] Specifically, Figure 7 In the figure, the forward current limiting circuit 41 is used to limit the current size of the current driving signal when the feedback voltage is greater than zero and the feedback voltage is greater than the forward reference voltage, and the reverse current limiting circuit is used to limit the current size of the current driving signal when the feedback voltage is less than zero and the feedback voltage is less than the reverse reference voltage.

[0047] Specifically, Figure 7In the figure, the forward current limiting circuit 41 includes: a fourth amplifier unit 411 and a comparison unit 412, wherein the input end of the fourth amplifier unit 411 inputs a forward reference voltage, and the output end of the fourth amplifier unit 411 is connected to the first input end of the comparison unit 412; the second input end of the comparison unit 412 inputs a feedback signal, and the output end of the comparison unit 412 is connected to the control end of the driving unit 2.

[0048] Specifically, Figure 7 In the embodiment, the fourth amplifying unit 411 includes an operational amplifier IOP9, and the fourth amplifying unit 411 is used to amplify the positive reference voltage; the comparing unit 412 includes an operational amplifier IOP6, and the comparing unit 412 is used to limit the current of the current-limiting driving signal when the feedback voltage is greater than zero and the feedback voltage is greater than the positive reference voltage. The positive feedback voltage or the positive feedback current is input to the reverse input terminal of IOP6, and the positive reference voltage is input to the non-inverting input terminal of IOP6 after being reversely amplified by IOP9, and the positive reference voltage is the maximum voltage limit of the current source. When the feedback voltage is positive and greater than the positive reference voltage, the current source output exceeds the limit value, and the IOP6 outputs a level signal to limit the current size in the driving signal, so that the regulating current output by the driving unit is reduced, thereby adjusting the gate voltage of the MOS tube, controlling the current flowing through the load, and then controlling the voltage value at both ends of the sampling resistor to below the limit, so as to achieve the purpose of limiting the load current and the voltage at both ends of the load. When the feedback voltage is positive and less than or equal to the positive reference voltage, the current source output is within the normal range, and IOP6 does not adjust the driving signal.

[0049] Specifically, Figure 7 In the embodiment, the reverse current limiting circuit 42 includes operational amplifiers IOP7 and IOP10, the reverse feedback voltage or the reverse feedback current is input to the reverse input terminal of IOP7, the reverse reference voltage is input to the non-inverting input terminal of IOP7 after being amplified in the same direction by IOP10, and the reverse reference voltage is the lowest voltage limit of the current source. When the feedback voltage is negative and less than the reverse reference voltage, the current source output exceeds the limit value, and the IOP7 outputs a level signal to limit the current size in the drive signal, so that the regulated current output by the drive unit is reduced, thereby adjusting the gate voltage of the MOS tube, controlling the current flowing through the load, and then controlling the voltage value at both ends of the sampling resistor to below the limit, so as to achieve the purpose of limiting the load current and the voltage at both ends of the load. When the feedback voltage is negative and less than or equal to the reverse reference voltage, the current source output is in the normal range, and IOP7 does not adjust the drive signal.

[0050] Optionally, the operator can freely set the magnitude of the forward reference voltage and the reverse reference voltage according to the limit value of the ammeter.

[0051] It should be noted that the method of using the feedback unit to control the current in the sampling unit adopted in this embodiment can accurately control the current on the load, and the accuracy of the current can reach 0.5%. The requirements for the operational amplifier are more extensive, and the above functions can be achieved without using a rail-to-rail operational amplifier.

[0052] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A current source with high-precision pulse output, characterized in that: include: Feedback unit, drive unit and adjustment unit, wherein: The first input terminal of the feedback unit inputs a control signal, the output terminal of the feedback unit is connected to the control terminal of the driving unit, and the feedback unit is used to follow and amplify the control signal and then output a driving signal; The output end of the driving unit is connected to the control end of the regulating unit, and the driving unit is used to output a regulating signal after switching a switch state based on the driving signal; The first output end of the regulating unit is connected to the second input end of the feedback unit, the regulating unit is connected in series with the load, the regulating unit is used to adjust the internal voltage division based on the regulating signal, and output the current flowing through the load and the voltage across the load as the feedback signal, wherein the voltage division is used to adjust the magnitude of the current flowing through the load; The feedback unit adjusts the driving signal based on the feedback signal.

2. The current source according to claim 1, characterized in that The feedback unit includes: a first follower unit and a feedback amplifier unit, wherein: The input end of the first follower unit inputs a control signal, the output end of the first follower unit is connected to the first input end of the feedback amplification unit, and the first follower unit is used to follow the control signal; The second input end of the feedback amplifying unit is connected to the first output end of the regulating unit, and the feedback amplifying unit is used to adjust and output the driving signal based on the deviation between the feedback signal and the control signal.

3. The current source according to claim 1, characterized in that The driving unit includes: a first resistor, a second resistor, a first diode, a second diode, a first controllable switch, a second controllable switch, a third controllable switch and a fourth controllable switch, wherein: The first end of the first controllable switch is connected to the first end of the second controllable switch, the first end of the first resistor and an external power supply, the control end of the first controllable switch is connected to the control end of the second controllable switch, the second end of the first resistor and the anode of the first diode, and the second end of the first controllable switch is connected to the second end of the second controllable switch, the first end of the third controllable switch, the first end of the fourth controllable switch and the control end of the regulating unit; The control end of the third controllable switch is connected to the control end of the fourth controllable switch, the cathode of the second diode and the first end of the second resistor, and the second end of the third controllable switch is connected to the second end of the fourth controllable switch and the second end of the second resistor and is grounded; The cathode of the first diode is connected to the anode of the second diode and the output end of the feedback unit.

4. The current source according to claim 1, characterized in that The feedback signal includes a feedback current and a feedback voltage, and the regulating unit includes: a sampling unit, a current output unit and a voltage output unit, wherein: The input end of the sampling unit is connected to the output end of the driving unit, the first end of the sampling unit is connected to the first input end of the current output unit, the output end of the sampling unit is connected to the second input end of the current output unit and the first end of the load, and the sampling unit is used to divide the voltage of the adjustment signal by adjusting the internal resistance to obtain the divided voltage of the corresponding amplitude; The output end of the current output unit is connected to the output end of the voltage output unit and the second input end of the feedback unit, and the current output unit is used to output the current flowing through the load as the feedback current; The input end of the voltage output unit is connected to the second end of the load, and the voltage output unit is used to output the voltage across the load as a feedback voltage.

5. The current source according to claim 4, characterized in that The sampling unit includes: a sampling circuit and a plurality of adjustable resistance circuits connected in parallel with the sampling circuit.

6. The current source according to claim 4, characterized in that The current output unit includes: a second follower unit and a first amplification unit, wherein: The first input end of the second follower unit is connected to the input end of the sampling unit, the second input end of the second follower unit is connected to the output end of the sampling unit, the first output end of the second follower unit is connected to the first input end of the first amplifying unit, the second output end of the second follower unit is connected to the second input end of the first amplifying unit, and the second follower unit is used to follow and amplify the voltages of the input end and the output end of the sampling unit; The output end of the first amplifying unit is connected to the second input end of the feedback unit, and the first amplifying unit is used to amplify the voltage difference between the input end and the output end of the sampling unit and then output the feedback signal.

7. The current source according to claim 6, characterized in that The second following unit includes: a second amplifying unit and a third amplifying unit, wherein: The input end of the second amplifying unit is connected to the input end of the sampling unit, the output end of the second amplifying unit is connected to the first input end of the first amplifying unit, and the second amplifying unit is used to increase the input impedance of the first input end of the first amplifying unit; The input end of the third amplifying unit is connected to the output end of the sampling unit, the output end of the third amplifying unit is connected to the second input end of the first amplifying unit, and the third amplifying unit is used to increase the input impedance of the second input end of the first amplifying unit.

8. The current source according to claim 1, characterized in that The feedback signal includes: a feedback voltage, and the current source further includes: a current limiting unit, wherein: The first input end of the current limiting unit is connected to the second output end of the regulating unit, and the output end of the current limiting unit is connected to the control end of the driving unit. The current limiting unit is used to compare the feedback voltage with the internal reference voltage, and limit the current of the driving signal when the feedback voltage is greater than the reference voltage.

9. The current source according to claim 8, characterized in that The reference voltage includes: a forward reference voltage and a reverse reference voltage, and the current limiting unit includes: a forward current limiting circuit and a reverse current limiting circuit, wherein: The first input end of the forward current limiting circuit inputs a forward reference voltage, the second input end of the forward current limiting circuit is connected to the second input end of the reverse current limiting circuit and the second output end of the regulating unit, the output end of the forward current limiting circuit is connected to the output end of the reverse current limiting circuit and the control end of the driving unit, and the forward current limiting circuit is used to limit the current of the driving signal when the feedback voltage is greater than zero and the feedback voltage is greater than the forward reference voltage; A reverse reference voltage is input to the first input terminal of the reverse current limiting circuit, and the reverse current limiting circuit is used to limit the current of the driving signal when the feedback voltage is less than zero and the feedback voltage is less than the reverse reference voltage.

10. The current source according to claim 9, characterized in that The forward current limiting circuit comprises: a fourth amplifying unit and a comparing unit, wherein: The input end of the fourth amplifying unit inputs a positive reference voltage, the output end of the fourth amplifying unit is connected to the first input end of the comparing unit, and the fourth amplifying unit is used to amplify the positive reference voltage; The feedback signal is input to the second input terminal of the comparison unit, and the output terminal of the comparison unit is connected to the control terminal of the drive unit. The comparison unit is used to limit the current of the drive signal when the feedback voltage is greater than zero and the feedback voltage is greater than the forward reference voltage.

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