CN108923627B - Power supply following filter circuit - Google Patents
Power supply following filter circuit Download PDFInfo
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- CN108923627B CN108923627B CN201810896397.5A CN201810896397A CN108923627B CN 108923627 B CN108923627 B CN 108923627B CN 201810896397 A CN201810896397 A CN 201810896397A CN 108923627 B CN108923627 B CN 108923627B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from dc input or output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from dc input or output
- H02M1/143—Arrangements for reducing ripples from dc input or output using compensating arrangements
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Abstract
The invention provides a power supply following filter circuit, which comprises an input sampling filter circuit connected with a voltage input end, an output sampling circuit connected with a voltage output end, a following circuit, a filtering and feedback control circuit and a power loop, wherein the voltage input end is connected with the voltage output end through the power loop, the output end of the input sampling filter circuit and the output end of the output sampling circuit are respectively connected with the input end of the following circuit, and the output end of the following circuit is connected with the input end of the filtering and feedback control circuit. The invention has the beneficial effects that: the filter can effectively reserve the effective direct current component of power supply along with the change of an input power supply, can be widely applied to power supply filter circuits of various voltages, particularly circuits needing to adjust output voltage, only filters out ripples and noises, completely reserves the direct current component of the power supply, reduces the power consumption of the filter, and saves energy and reduces emission.
Description
Technical Field
The invention relates to a filter circuit, in particular to a power supply following filter circuit.
Background
Some dc power supply devices are sensitive to the ripple noise of the dc input Vin, so the power supply needs to be filtered to remove the ac component of the ripple noise to obtain the desired dc component.
At present, when a conventional scheme mainly utilizes a linear power supply rectified by a switching power supply or a transformer to supply power to a rear stage, the following scheme is generally adopted:
In the scheme 2, the low dropout linear regulator L DO (low dropout regulator) active filter circuit obtains a fixed direct current output by using a three-terminal regulator, and the principle is that an input power Vin passes through the linear regulator or L DO to obtain Vout 1.
The defects of the prior art are as follows:
with the two filtering methods of scheme 1, the method is useful for high-frequency ripple noise, and can effectively retain the effective components of the input voltage. But for low frequency ripple noise the cost is too large. For example, when the ripple noise of 100Hz and 200mV is low and filtered to be less than 10mV, the inductance and capacitance of the inductor and capacitor will be very large, 1.2mH is needed for the inductor, 6600 μ F is needed for the capacitor, if the output current increases, the size of the inductor with large current and large inductance will be very large, and the filter circuit causes the ripple phase change:
the active L DO filtering is carried out by adopting a mode of a scheme 2, so that the filtering is effective, but L DO is a fixed output, when the input voltage changes, the output is still a fixed voltage, namely, the L DO filters all ripple noise and effective components which exceed the fixed voltage, and in a power supply scene, only the ripple noise needs to be filtered, and the effective direct current components of the input voltage DO not need to be filtered.
In the filtering manners of the above schemes 1 and 2, the scheme 1 may only filter out the ripple noise, but is too costly or even ineffective for the low-frequency ripple noise. Scheme 2 is effective for ripple noise, but the effective dc component that would cut off the supply is particularly unsuitable for a scenario where Vin is not fixed, and results in large losses.
Therefore, a technical problem to be solved by those skilled in the art is how to provide an active filter circuit, which can effectively filter ripple noise and effectively retain the effective dc component of the power supply along with the variation of the input power.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a power supply following filter circuit which can follow the change of an input power supply and effectively reserve the effective direct current component of power supply.
The invention provides a power supply following filter circuit, which comprises an input sampling filter circuit connected with a voltage input end, an output sampling circuit connected with a voltage output end, a following circuit, a filtering and feedback control circuit and a power loop, wherein the voltage input end is connected with the voltage output end through the power loop, the output end of the input sampling filter circuit and the output end of the output sampling circuit are respectively connected with the input end of the following circuit, the output end of the following circuit is connected with the input end of the filtering and feedback control circuit, the output end of the filtering and feedback control circuit is connected with the power loop, the input sampling filter circuit performs input sampling on the voltage input end, the output sampling circuit performs feedback sampling on the voltage output end, the following circuit performs feedback sampling on the input sampling filter circuit and the output sampling circuit, and the following circuit performs feedback sampling on the input sampling filter circuit, And the differential voltage of the output sampling circuit is output to the filtering and feedback control circuit, and the filtering and feedback control circuit controls the working state of the power circuit according to the differential voltage output by the following circuit, so that the following filtering from a voltage input end to a voltage output end is realized.
As a further improvement of the present invention, the follower circuit includes an operational amplifier X1, the filter and feedback control circuit includes a reference source Vref, an operational amplifier X2 and a resistor R2, the power loop includes a MOS transistor Q1, a positive input terminal of the operational amplifier X1 is connected to an output terminal of the input sampling filter circuit, a negative input terminal of the operational amplifier X1 is connected to an output terminal of the output sampling circuit, an output terminal of the operational amplifier X1 is connected to a negative input terminal of the operational amplifier X2, a positive input terminal of the operational amplifier X2 is connected to the reference source Vref, an output terminal of the operational amplifier X2 is connected to a gate of the MOS transistor Q1 through the resistor R2, a source of the MOS transistor Q1 is connected to the voltage input terminal, a drain of the MOS transistor Q1 is connected to the voltage output terminal, and the operational amplifier X1 connects the input sampling circuit to the voltage output terminal, The differential voltage of the output sampling circuit is output to the operational amplifier X2, the operational amplifier X2 adjusts the output according to the differential voltage output by the operational amplifier X1 and a reference source Vref, and the working state of the MOS transistor Q1 is controlled through the resistor R2, so that the following filtering from a voltage input end to a voltage output end is realized.
As a further improvement of the present invention, the input sampling filter circuit includes a resistor R3, a resistor R5, and a capacitor C2, one end of the resistor R3 is connected between the voltage input terminal and the power circuit, the other end of the resistor R3 is connected to the resistor R5 and the capacitor C2, respectively, and then grounded, and the positive input terminal of the operational amplifier X1 is connected between the resistor R3 and the resistor R5.
As a further improvement of the present invention, the power supply following filter circuit further includes a zener diode D3, an anode of the zener diode D3 is connected to the capacitor C2 and then to ground, and a cathode of the zener diode D3 is connected between the voltage input terminal and the power loop.
As a further improvement of the present invention, the output sampling circuit includes a resistor R4, a capacitor C3, and a resistor R6, the voltage output terminal is connected to the negative input terminal of the operational amplifier X1 through the resistor R4 and the capacitor C3, a compensation circuit is connected in series between the output terminal of the operational amplifier X2 and the resistor R6, and the other end of the resistor R6 is connected to the negative input terminals of the resistor R4 and the operational amplifier X2.
As a further improvement of the present invention, the compensation circuit includes a resistor R8 and a capacitor C1 connected in series, the resistor R8 is connected to the resistor R6, and the capacitor C1 is connected to the output terminal of the computation comparator X2.
As a further improvement of the present invention, a diode D4 is connected between the source and the drain of the MOS transistor Q1, the anode of the diode D4 is connected between the source of the MOS transistor Q1 and the voltage input terminal, and the cathode of the diode D4 is connected between the drain of the MOS transistor Q1 and the voltage output terminal.
As a further improvement of the present invention, the reference source Vref includes a resistor R9 and a zener diode D2, an anode of the zener diode D2 is grounded, a cathode of the zener diode D2 is connected to the resistor R9 and then connected between the voltage input end and the power loop, and an anode input end of the operational amplifier X2 is connected between the resistor R9 and the cathode of the zener diode D2.
As a further improvement of the present invention, the follower circuit, the filter and feedback control circuit constitute a follower, filter and feedback control unit, the follower, filter and feedback control unit includes an operational amplifier X1 and a resistor R2, the power loop includes a MOS transistor Q1, a positive input terminal of the operational amplifier X1 is connected to an output terminal of the output sampling circuit, a negative input terminal of the operational amplifier X1 is connected to an output terminal of the input sampling filter circuit, an output terminal of the operational amplifier X1 is connected to a gate of the MOS transistor Q1 through the resistor R2, a source of the MOS transistor Q1 is connected to the voltage input terminal, a drain of the MOS transistor Q1 is connected to the voltage output terminal, the operational amplifier X1 adjusts its own output according to a differential voltage of the input sampling filter circuit and the output sampling circuit, and controls an operating state of the MOS transistor Q1 through the resistor R2, thereby realizing following filtering from the voltage input end to the voltage output end
As a further improvement of the present invention, the following, filtering and feedback control unit further includes a resistor R8 and a capacitor C1 connected in series, the output terminal of the operational amplifier X1 is connected to the resistor R8, and the negative input terminal of the operational amplifier X1 is connected to the capacitor C1.
The invention has the beneficial effects that: through the scheme, the power supply following filter circuit can follow the change of an input power supply, effectively reserve the effective direct current component of power supply, can be widely applied to power supply filter circuits of various voltages, particularly circuits needing to adjust output voltage, only filters out ripples and noises, completely reserves the direct current component of the power supply, reduces the power consumption of a filter, and saves energy and reduces emission.
Drawings
Fig. 1 is a schematic block diagram of a power supply following filter circuit of the present invention.
Fig. 2 is a circuit diagram of a first embodiment of a power supply follower filter circuit according to the present invention.
FIG. 3 is a waveform diagram of the filtering effect of a first embodiment of the power supply follow filter circuit according to the present invention.
Fig. 4 is a circuit diagram of a second embodiment of a power supply follower filter circuit according to the present invention.
FIG. 5 is a waveform diagram of the filtering effect of the second embodiment of the power-supply-follower filter circuit according to the present invention.
Fig. 6 is a circuit diagram of a third embodiment of a power supply following filter circuit according to the present invention.
Fig. 7 is a circuit diagram of a third embodiment of a power supply following filter circuit according to the present invention.
Detailed Description
The invention is further described with reference to the following description and embodiments in conjunction with the accompanying drawings.
As shown in fig. 1, a power supply following filter circuit includes an input sampling filter circuit 3 connected to a voltage input terminal (i.e. input Vin)1, an output sampling circuit 4 connected to a voltage output terminal (i.e. output Vout)2, a following circuit 5, a filtering and feedback control circuit 6, and a power loop 7, wherein the voltage input terminal 1 is connected to the voltage output terminal 2 through the power loop 7, an output terminal of the input sampling filter circuit 3 and an output terminal of the output sampling circuit 4 are respectively connected to an input terminal of the following circuit 5, an output terminal of the following circuit 5 is connected to an input terminal of the filtering and feedback control circuit 6, an output terminal of the filtering and feedback control circuit 6 is connected to the power loop 7, the input sampling filter circuit 3 performs input sampling on the voltage input terminal 1, and the output sampling circuit 4 performs feedback sampling on the voltage output terminal 2, the following circuit 5 outputs the differential voltage of the input sampling filter circuit 3 and the output sampling circuit 4 to the filtering and feedback control circuit 6, and the filtering and feedback control circuit 6 controls the working state of the power loop 7 according to the differential voltage output by the following circuit 5, so that the following filtering from the voltage input end 1 to the voltage output end 2 is realized.
The invention adopts an input sampling filter circuit 3 as input sampling and an output sampling circuit 4 as feedback sampling, and utilizes an operational amplifier to carry out following, filtering and feedback, and control the device of a power loop 7, thereby achieving the purpose of active filtering, and the schematic block diagram of the circuit is shown in figure 1.
Example one
As shown in fig. 2, the basic implementation of the present invention is a differential active follower filter, and the circuit is shown in fig. 2, V1 and V2 form an "input sampling Vin", a resistor R3, a resistor R5 and a capacitor C2 form an input sampling filter circuit 3, a resistor R4, a capacitor C3 and a resistor R6 form an output sampling circuit 4, the output of an operational amplifier X1 follows the difference between the input and output sampling filter circuits 3 and 4 to serve as a follower circuit 5, and the difference is output to an operational amplifier X2, the resistor R9 and a zener diode D2 serve as reference sources, and the resistor R9, the zener diode D2, the operational amplifier X2, the resistor R8 and the capacitor C1 form a filter and feedback control circuit 6. The operational amplifier X2 adjusts the output of the operational amplifier X2 according to the output of the operational amplifier X1 and the reference source Vref, and controls the working state of the MOS transistor Q1 of the power loop 7 through the resistor R2, thereby realizing the following filtering from Vin to Vout.
The specific embodiment is as follows:
as shown in fig. 2, the follower circuit 5 includes an operational amplifier X1, the filter and feedback control circuit 6 includes a reference source Vref, an operational amplifier X2 and a resistor R2, the power circuit 7 includes a MOS transistor Q1, a positive input terminal of the operational amplifier X1 is connected to an output terminal of the input sampling filter circuit 3, a negative input terminal of the operational amplifier X1 is connected to an output terminal of the output sampling circuit 4, an output terminal of the operational amplifier X1 is connected to a negative input terminal of the operational amplifier X2, a positive input terminal of the operational amplifier X2 is connected to the reference source Vref, an output terminal of the operational amplifier X2 is connected to a gate of the MOS transistor Q1 through the resistor R2, a source of the MOS transistor Q1 is connected to the voltage input terminal 1, a drain of the MOS transistor Q1 is connected to the voltage output terminal 2, and the operational amplifier X1 connects the input sampling filter circuit 3, the output terminal of the output, The differential voltage of the output sampling circuit 4 is output to the operational amplifier X2, the operational amplifier X2 adjusts the output according to the differential voltage output by the operational amplifier X1 and the reference source Vref, and the working state of the MOS transistor Q1 is controlled by the resistor R2, so that the following filtering from the voltage input end 1 to the voltage output end 2 is realized.
As shown in fig. 2, the input sampling filter circuit 3 includes a resistor R3, a resistor R5, and a capacitor C2, one end of the resistor R3 is connected between the voltage input terminal 1 and the power circuit 7, the other end of the resistor R3 is connected to the resistor R5 and the capacitor C2, and then grounded, and the positive input terminal of the operational amplifier X1 is connected between the resistor R3 and the resistor R5.
As shown in fig. 2, the output sampling circuit 4 includes a resistor R4, a capacitor C3, and a resistor R6, the voltage output terminal is connected to the negative input terminal of the operational amplifier X1 through the resistor R4 and the capacitor C3, a compensation circuit (also called a compensation network) is connected in series between the output terminal of the operational amplifier X2 and the resistor R6, and the other end of the resistor R6 is connected to the negative input terminals of the resistor R4 and the operational amplifier X2.
As shown in fig. 2, the compensation circuit includes a resistor R8 and a capacitor C1 connected in series, the resistor R8 is connected to the resistor R6, and the capacitor C1 is connected to the output terminal of the computation comparator X2.
As shown in fig. 2, a diode D4 is connected between the source and the drain of the MOS transistor Q1, the anode of the diode D4 is connected between the source of the MOS transistor Q1 and the voltage input terminal 1, and the cathode of the diode D4 is connected between the drain of the MOS transistor Q1 and the voltage output terminal 2.
As shown in fig. 2, the reference source Vref includes a resistor R9 and a zener diode D2, an anode of the zener diode D2 is grounded, a cathode of the zener diode D2 is connected to the resistor R9 and then connected between the voltage input terminal 1 and the power loop 7, and an anode input terminal of the operational amplifier X2 is connected between the resistor R9 and the cathode of the zener diode D2.
As shown in fig. 2, the principle of the basic implementation circuit is illustrated: the input power Vin is composed of a dc component and an ac component of ripple noise, where V1 represents the dc component of Vin and V2 represents the ac component of the ripple noise of Vin. The resistor R3, the resistor R4, the resistor R5, the resistor R6, the capacitor C2, the capacitor C3 and the operational amplifier X1 form a filtered differential amplifier, detect the DC component V1 of Vin, and perform differential amplification with the output Vout to obtain a differential voltage.
△ V is input to the negative input port of the operational amplifier X2, the voltage stabilizing diode D2 and the resistor R9 form a reference source Vref and are input to the positive input port of the operational amplifier X2, and the operational amplifier X2 forms a complete closed-loop feedback according to the positive input port and the negative input port of the operational amplifier, a compensation network formed by the resistor R8 and the capacitor C1, and controls the working state of the MOS transistor Q1, so that the expected output power Vout is obtained.
Here, for convenience of expression, the present invention sets R3 to R4 and R5 to R6, and the following equations are obtained:
therefore, it is
Since V1 is the dc effective component of Vin of the input power, and the resistors R4, R6 and Vref are constants, Vout can follow V1, so as to effectively filter out the ac part of the ripple and noise of Vin, and retain the dc component, thereby achieving the purpose of following filtering. The loss between Vout and V1 can be conveniently adjusted by changing the times of differential amplification, and the power consumption of the filter is saved. Fig. 3 is a graph showing the effect of the input Vin of the active follower filter after passing through the active filter of the present invention, wherein the upper curve is the waveform of the input Vin of the power supply, and the lower straight line is the waveform of the output Vout of the power supply.
Example two
As shown in fig. 4, on the basis of the first embodiment, the follower circuit 5 and the filter and feedback control circuit 6 constitute a follower, filter and feedback control unit, which includes an operational amplifier X1 and a resistor R2, the power loop 7 includes a MOS transistor Q1, a positive input terminal of the operational amplifier X1 is connected to an output terminal of the output sampling circuit 2, a negative input terminal of the operational amplifier X1 is connected to an output terminal of the input sampling filter circuit 1, an output terminal of the operational amplifier X1 is connected to a gate of the MOS transistor Q1 through the resistor R2, a source of the MOS transistor Q1 is connected to the voltage input terminal 1, a drain of the MOS transistor Q1 is connected to the voltage output terminal 2, the operational amplifier X1 adjusts its output according to a differential voltage of the input sampling filter circuit 3 and the output sampling circuit 4, the working state of the MOS transistor Q1 is controlled by the resistor R2, so that the following filtering from the voltage input end 1 to the voltage output end 2 is realized
As shown in fig. 4, the following, filtering and feedback control unit further includes a resistor R8 and a capacitor C1 connected in series, an output terminal of the operational amplifier X1 is connected to the resistor R8, and a negative input terminal of the operational amplifier X1 is connected to the capacitor C1.
As shown in fig. 4, in the second embodiment, another implementation circuit is an error active filter, the differential amplifier portion of the differential active filter in the first embodiment is simplified, and the cost is reduced, V1 and V2 form an "input sampling Vin", a resistor R3, a resistor R5, and a capacitor C2 form an input sampling filter circuit 3, a resistor R4, a capacitor C3, and a resistor R6 form an output sampling circuit 4, the input sampling filter circuit 3 and the output sampling circuit 4 are input to an operational amplifier X1, and the operational amplifier X1, the resistor R8, and the capacitor C1 form a "follower, filter, and feedback control" circuit. The operational amplifier X1 adjusts the output of the operational amplifier X1 according to the input of V3 and V4, and controls the working state of the MOS transistor Q1 of the power loop 7 through the resistor R2, thereby realizing the following filtering from Vin to Vout.
The operation principle diagram is shown in fig. 4, wherein V1 represents the dc component of Vin, V2 represents the ripple noise part of Vin, the input sampling filter circuit 1 is composed of a resistor R3, a resistor R5, and a capacitor C2, the sampled and filtered voltage is sent to the negative input port of the operational amplifier X1, the output sampling circuit 4 is composed of a resistor R4, a resistor R6, and a capacitor C3, the sampled voltage is sent to the positive input port of the operational amplifier X1, the capacitor C3, a capacitor C1, and a resistor R8 constitute a compensation circuit, the operational amplifier X1 performs error amplification according to the error between the positive input port and the negative input port, so as to control the operating state of the MOS transistor Q1 of the control power circuit 7 through the resistor R2, and finally achieve the purpose of following filtering.
The working principle of the second embodiment is as follows: the input sampling filter circuit 1 performs proportional sampling on the input, and filters the input to obtain a proportional average voltage of Vin:
Similarly, the output sampling filter circuit 2 performs proportional sampling on the output to obtain a proportional average voltage of Vout:
v4 ═ b × Vout, wherein
After error feedback control is performed by the operational amplifier X1, according to the characteristics of the operational amplifier, V3 is virtually equal to V4, which is denoted as V3 being V4, so that:
by changing the values of a and b, Vout with the ripple and noise of Vin filtered out can be obtained.
In the active-follower filter circuit of fig. 4, Vin is V1+ V2, and V1 is a dc component, the average value is:
v2 is the ac component of ripple noise, the average value of V2:
thus, the average value of the input voltage Vin is:
therefore, the method comprises the following steps:
after the circuit design is finished, the values of the resistor R3, the resistor R4, the resistor R5 and the resistor R6 are set, Vout can follow the direct current component V1 of the power input Vin, and the purpose of filtering the alternating current component of ripple noise is achieved.
The filtered waveform is schematically shown in fig. 5.
EXAMPLE III
As shown in fig. 6 and 7, based on the first embodiment, a zener diode D3 is added, specifically, the power follower filter circuit 6 further includes a zener diode D3, an anode of the zener diode D3 is connected to the capacitor C2 and then grounded, and a cathode of the zener diode D3 is connected between the voltage input terminal 1 and the power loop 7.
The zener diode D3 is used to improve the response speed of the filter circuit during the on/off operation, and in some specific scenarios, to further improve the on/off response speed of the active filter and the response speed of the short-circuit protection, a diode D4 is added, as shown in fig. 6 and 7.
The power circuit 7 can adopt a P-MOSFET tube, an N-MOSFET tube or a triode as a main device of the power circuit, and the diode D1 is used for protecting the power circuit.
The power supply following filter circuit provided by the invention can follow the change of an input power supply, effectively reserve the effective direct current component of power supply, can be widely applied to power supply filter circuits with various voltages, particularly circuits needing to adjust output voltage, only filters out ripples and noises, completely reserves the direct current component of the power supply, reduces the power consumption of a filter, and saves energy and reduces emission.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (9)
1. A power supply following filter circuit, comprising: the voltage sampling circuit comprises an input sampling filter circuit connected with a voltage input end, an output sampling circuit connected with a voltage output end, a follower circuit, a filtering and feedback control circuit and a power loop, wherein the voltage input end is connected with the voltage output end through the power loop, the output end of the input sampling filter circuit and the output end of the output sampling circuit are respectively connected with the input end of the follower circuit, the output end of the follower circuit is connected with the input end of the filtering and feedback control circuit, the output end of the filtering and feedback control circuit is connected with the power loop, the input sampling filter circuit performs input sampling on the voltage input end, the output sampling circuit performs feedback sampling on the voltage output end, the follower circuit outputs the differential voltage of the input sampling filter circuit and the output sampling circuit to the filtering and feedback control circuit, the filtering and feedback control circuit controls the working state of the power loop according to the differential voltage output by the following circuit, so that following filtering from a voltage input end to a voltage output end is realized; the follower circuit comprises an operational amplifier X1, the filtering and feedback control circuit comprises a reference source Vref, an operational amplifier X2 and a resistor R2, the power loop comprises a MOS transistor Q1, the positive input end of the operational amplifier X1 is connected with the output end of the input sampling filter circuit, the negative input end of the operational amplifier X1 is connected with the output end of the output sampling circuit, the output end of the operational amplifier X1 is connected with the negative input end of the operational amplifier X2, the positive input end of the operational amplifier X2 is connected with the reference source Vref, the output end of the operational amplifier X2 is connected with the gate of the MOS transistor Q1 through the resistor R2, the source of the MOS transistor Q1 is connected with the voltage input end, the drain of the MOS transistor Q1 is connected with the voltage output end, the operational amplifier X1 outputs the differential voltage of the input sampling filter circuit and the output sampling circuit to the operational amplifier X2, the operational amplifier X2 adjusts output according to the differential voltage output by the operational amplifier X1 and a reference source Vref, and controls the working state of the MOS transistor Q1 through the resistor R2, thereby realizing follow-up filtering from a voltage input end to a voltage output end.
2. The power supply following filter circuit according to claim 1, wherein: the input sampling filter circuit comprises a resistor R3, a resistor R5 and a capacitor C2, one end of the resistor R3 is connected between the voltage input end and the power loop, the other end of the resistor R3 is respectively connected with the resistor R5 and the capacitor C2 and then grounded, and the positive electrode input end of the operational amplifier X1 is connected between the resistor R3 and the resistor R5.
3. The power supply following filter circuit according to claim 2, wherein: the power supply following filter circuit further comprises a voltage stabilizing diode D3, the anode of the voltage stabilizing diode D3 is connected with the capacitor C2 and then is grounded, and the cathode of the voltage stabilizing diode D3 is connected between the voltage input end and the power loop.
4. The power supply following filter circuit according to claim 1, wherein: the output sampling circuit comprises a resistor R4, a capacitor C3 and a resistor R6, the voltage output end is connected with the negative input end of the operational amplifier X1 through the resistor R4 and the capacitor C3 respectively, a compensation circuit is connected in series between the output end of the operational amplifier X2 and the resistor R6, and the other end of the resistor R6 is connected with the negative input ends of the resistor R4 and the operational amplifier X2 respectively.
5. The power supply following filter circuit according to claim 4, wherein: the compensation circuit comprises a resistor R8 and a capacitor C1 which are connected in series, wherein the resistor R8 is connected with the resistor R6, and the capacitor C1 is connected with the output end of the operational amplifier X2.
6. The power supply following filter circuit according to claim 1, wherein: a diode D4 is connected between the source and the drain of the MOS transistor Q1, the anode of the diode D4 is connected between the source of the MOS transistor Q1 and the voltage input end, and the cathode of the diode D4 is connected between the drain of the MOS transistor Q1 and the voltage output end.
7. The power supply following filter circuit according to claim 1, wherein: the reference source Vref comprises a resistor R9 and a zener diode D2, the anode of the zener diode D2 is grounded, the cathode of the zener diode D2 is connected with the resistor R9 and then connected between the voltage input end and the power loop, and the anode input end of the operational amplifier X2 is connected between the resistor R9 and the cathode of the zener diode D2.
8. The power supply following filter circuit according to claim 1, wherein: the follower circuit, the filter and the feedback control circuit form a follower, filter and feedback control unit, the follower, filter and feedback control unit comprises an operational amplifier X1 and a resistor R2, the power loop comprises a MOS transistor Q1, the positive input end of the operational amplifier X1 is connected with the output end of the output sampling circuit, the negative input end of the operational amplifier X1 is connected with the output end of the input sampling filter circuit, the output end of the operational amplifier X1 is connected with the grid of the MOS transistor Q1 through the resistor R2, the source of the MOS transistor Q1 is connected with the voltage input end, the drain of the MOS transistor Q1 is connected with the voltage output end, the operational amplifier X1 adjusts the output of the operational amplifier according to the differential voltage of the input sampling filter circuit and the output sampling circuit, and controls the working state of the MOS transistor Q1 through the resistor R2, therefore, follow-up filtering from the voltage input end to the voltage output end is realized.
9. The power supply following filter circuit according to claim 8, wherein: the following, filtering and feedback control unit further comprises a resistor R8 and a capacitor C1 which are connected in series, the output end of the operational amplifier X1 is connected with the resistor R8, and the negative input end of the operational amplifier X1 is connected with the capacitor C1.
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|---|---|---|---|---|
| CN111431377B (en) * | 2018-12-24 | 2024-02-23 | 东南大学 | Voltage differential sampling circuit and control circuit of switching converter |
| CN110401431B (en) * | 2019-07-18 | 2020-11-10 | 江苏康众数字医疗科技股份有限公司 | Frequency following digital discrete filter, implementation method and application thereof |
| CN111682744B (en) * | 2020-06-30 | 2022-03-22 | 上海杰瑞兆新信息科技有限公司 | Ripple attenuation circuit with load slope compensation function |
| CN117498689B (en) * | 2023-12-27 | 2024-04-02 | 四川中久大光科技有限公司 | Low-ripple efficient laser driving power supply, power supply system and generation method thereof |
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| CN108923627A (en) | 2018-11-30 |
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