WO2019171674A1

WO2019171674A1 - Power supply stabilization circuit

Info

Publication number: WO2019171674A1
Application number: PCT/JP2018/043829
Authority: WO
Inventors: 山尾　隆
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2018-03-09
Filing date: 2018-11-28
Publication date: 2019-09-12

Abstract

This power supply stabilization circuit (1) is provided with: a ripple extraction unit (10) which is disposed in a first path (L1) and extracts a ripple voltage indicating a ripple component included in a constant voltage signal; a bias voltage generation unit (20) which is connected between the ripple extraction unit (10) and ground and adds a bias voltage to the ripple voltage; a transistor (30) disposed in a second path (L2); a reference voltage generation unit (40) which is connected between the transistor (30) and ground and generates a reference voltage corresponding to an output current of the transistor (30); and a differential amplifier unit (50) which inversely amplifies the difference between the reference voltage and the ripple voltage to which the bias voltage has been added and outputs a difference signal obtained by means of the inverse amplification to the transistor (30). The output current of the transistor (30) is a current that flows from the constant voltage signal to the reference voltage generation unit (40) through the transistor (30) in accordance with the difference signal.

Description

Power stabilization circuit

This disclosure relates to a power supply stabilization circuit that stabilizes the output of a constant voltage power supply.

Conventionally, a regulator circuit is used to stabilize the output of a constant voltage power supply (DC power supply) (specifically, to remove a ripple component contained in the output). The regulator circuit inserts a transistor in series in the output path of the constant voltage power supply, and feedback-controls the transistor so that the output of the constant voltage power supply becomes a target voltage value, so that the output including the ripple component is constant. It is intended to be a voltage of. For example, Patent Literature 1 discloses such a technique. By stabilizing the output of the constant voltage power supply, for example, it is possible to improve the sound quality of a device that reproduces sound.

JP 2002-157030 A

However, in Patent Document 1 described above, since a transistor inserted in series in the output path of the constant voltage power supply passes through the entire current output from the constant voltage power supply, a transistor with a large package corresponding to a large current is required. Become. In addition, since the heat generation of the transistor increases in proportion to the amount of current passing through the transistor, a large heat sink corresponding to a large current is required. As a result, the configuration for stabilizing the output of the constant voltage power supply becomes large.

Therefore, the present disclosure provides a power supply stabilization circuit capable of downsizing a configuration for stabilizing the output of a constant voltage power supply.

A power supply stabilization circuit in the present disclosure is a power supply stabilization circuit that stabilizes a constant voltage signal including a ripple component output from a constant voltage power supply and outputs the stabilized voltage signal from an output terminal, the constant voltage power supply, the output terminal, A ripple extracting unit that extracts a ripple voltage indicating a ripple component included in the constant voltage signal, and a ripple extracting unit and a ground in the first route. A bias voltage generator that adds a bias voltage to the ripple voltage, a transistor that connects the output path and the ground, and that is disposed in a second path different from the first path, and the second A reference voltage generator connected between the transistor and ground in the path and generating a reference voltage corresponding to the output current of the transistor; A power terminal and a negative input terminal, which inverts and amplifies the difference between the reference voltage input to the positive input terminal and the ripple voltage to which the bias voltage input to the negative input terminal is added, and A differential amplifier that outputs the amplified differential signal to the transistor, and an output current of the transistor flows from the constant voltage signal to the reference voltage generator through the transistor in accordance with the differential signal Current.

The power supply stabilization circuit in the present disclosure can reduce the size of the configuration for stabilizing the output of the constant voltage power supply.

FIG. 1 is a circuit configuration diagram showing an example of a power supply stabilization circuit according to the first embodiment. FIG. 2 is a diagram illustrating a waveform of a constant voltage signal including a ripple component output from a constant voltage power supply. FIG. 3 is a diagram showing a waveform of a ripple voltage to which a reference voltage and a bias voltage are added, which are input to the differential amplifier. FIG. 4 is a diagram illustrating a waveform of a differential signal output from the differential amplifier. FIG. 5 is a diagram illustrating a waveform of a voltage generated in the shunt resistor portion. FIG. 6 is a diagram for explaining that the ripple component is removed. FIG. 7 is a circuit configuration diagram showing an example of a power supply stabilization circuit according to the second embodiment. FIG. 8 is a circuit configuration diagram showing an example of a power supply stabilization circuit according to a modification of the second embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

In addition, the inventor provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and is not intended to limit the claimed subject matter. .

(Embodiment 1)
The first embodiment will be described below with reference to FIGS.

FIG. 1 is a circuit configuration diagram showing an example of a power supply stabilization circuit 1 according to the first embodiment. In FIG. 1, in addition to the power supply stabilization circuit 1, processing is performed by a constant voltage power supply 100 that outputs a signal input to the power supply stabilization circuit 1 and the power supply stabilization circuit 1 (details will be described later, but ripple removal processing). The load 120 connected to the output terminal 110 and the output terminal 110 which output the signal which was) is shown.

The constant voltage power source 100 is a power source that generates and outputs a constant voltage signal from an AC power source or a DC power source. The constant voltage signal output from the constant voltage power supply 100 includes noise such as a ripple component.

The load 120 is connected to the output terminal 110 in order to supply power output from the constant voltage power supply 100. The load 120 is, for example, a device that reproduces sound, and it is necessary to supply power from which the ripple component has been removed in order to achieve high sound quality.

The power supply stabilization circuit 1 is a circuit that stabilizes a constant voltage signal including a ripple component output from the constant voltage power supply 100 and outputs it from the output terminal 110. Hereinafter, a component that does not include a ripple component in the constant voltage signal is also referred to as a DC (Direct Current) component. The constant voltage signal output from the constant voltage power supply 100 has a ripple component superimposed on a DC component. The power supply stabilization circuit 1 includes a ripple extraction unit 10, a bias voltage generation unit 20, a transistor 30, a reference voltage generation unit 40, and a differential amplification unit 50.

The ripple extracting unit 10 is arranged in an output path L0 connecting the constant voltage power supply 100 and the output terminal 110 and a first path L1 connecting the ground, and extracts a ripple voltage indicating a ripple component included in the constant voltage signal. As shown in FIG. 1, the first path L1 is a path connecting the node x1 on the output path L0 and the ground. A node is a point where two or more wirings are connected in an electronic circuit, and is represented by a black circle in the circuit diagram shown in FIG. The ripple component is a noise component superimposed on a constant voltage (DC component) generated by the constant voltage power supply 100, and is generated, for example, corresponding to the switching frequency when generating the constant voltage. The ripple extraction unit 10 is, for example, a capacitor connected in series between the output path L0 (node x1) and a negative input terminal included in the differential amplification unit 50 described later, and only a ripple voltage corresponding to the switching frequency is included. Can be taken out. The constant voltage signal including the ripple component fluctuates around the DC component, and the ripple extraction unit 10 extracts this fluctuation as a ripple voltage that fluctuates on the plus side and the minus side around 0V.

The bias voltage generation unit 20 is connected between the ripple extraction unit 10 and the ground in the first path L1, and adds a bias voltage to the ripple voltage. The ripple extracting unit 10 and the bias voltage generating unit 20 are connected in series between the node x1 and the ground. Since the ripple voltage extracted by the ripple extraction unit 10 fluctuates around 0 V as described above, the bias voltage is biased so that the ripple voltage when the differential amplification unit 50 described later is fluctuating to the negative side can also be detected. The voltage generator 20 generates a bias voltage and adds it to the ripple voltage. As a result, the ripple voltage that fluctuates to the negative side also becomes a positive voltage, and the differential amplifier 50 can always detect the ripple voltage. For example, the bias voltage generation unit 20 generates a bias voltage using a reverse voltage of a diode.

The transistor 30 is disposed on a second path L2 that is different from the first path L1 and connects the output path L0 that connects the constant voltage power supply 100 and the output terminal 110 to the ground. As shown in FIG. 1, the second path L2 is a path connecting the node x2 on the output path L0 and the ground. Note that the node x1 and the node x2 are provided at positions separated from each other on the circuit diagram, but may be provided at the same position on an actual substrate or the like. The transistor 30 is, for example, a PNP bipolar transistor, an emitter is connected to the node x2, a collector is connected to a reference voltage generation unit 40 described later, and a base is connected to a differential amplification unit 50 described later. A voltage is applied to the base of the transistor 30 so that a small amount of current always flows between the emitter and the collector. The current flowing between the emitter and collector is also referred to as the output current of the transistor 30.

The reference voltage generation unit 40 is connected between the transistor 30 and the ground in the second path L2, and generates a reference voltage according to the output current of the transistor 30. That is, the reference voltage generation unit 40 generates a reference voltage corresponding to the current between the emitter and collector of the transistor 30. The reference voltage generator 40 includes a shunt resistor 41 that is disposed between the transistor 30 and the ground in the second path L2, a path that connects the transistor 30 and the shunt resistor 41, and a differential amplifier 50 that will be described later. A low-pass filter (LPF) 42 disposed in a path connecting to the positive electrode input terminal. For example, the shunt resistor unit 41 includes only the first resistor R1 connected between the transistor 30 and the ground, and the voltage that is the product of the output current of the transistor 30 and the resistance value of the first resistor R1 is the shunt resistor unit. Occurs at 41. The configuration of the shunt resistor 41 is not limited to the configuration including only the first resistor R1 connected between the transistor 30 and the ground, and other examples will be described in a second embodiment to be described later. The LPF 42 is configured by, for example, an RC filter composed of a resistor and a capacitor, and uses a frequency lower than the frequency of the ripple component as a pass band. The configuration of the LPF 42 is not limited to an RC filter or the like, and is not particularly limited as long as it is a configuration that can realize a low-pass filter. As described above, the reference voltage generated by the reference voltage generation unit 40 is a voltage having a component corresponding to the pass band of the LPF 42 in the voltage generated in the shunt resistor unit 41 according to the output current of the transistor 30.

The differential amplifier 50 is a differential amplifier circuit having a positive input terminal (+) and a negative input terminal (−), for example, an operational amplifier. A reference voltage generator 40 (specifically, LPF 42) is connected to the positive input terminal, and the reference voltage generated by the reference voltage generator 40 is input to the positive input terminal. The negative input terminal is connected between the ripple extracting unit 10 and the bias voltage generating unit 20 in the first path L1, and a ripple voltage to which a bias voltage is added is input. The output terminal (out) of the differential amplifier 50 is connected to the base of the transistor 30. The differential amplifying unit 50 inverts and amplifies the difference between the reference voltage input to the positive input terminal and the ripple voltage to which the bias voltage input to the negative input terminal is added. Output to base. The output current of the transistor 30 is a current that flows from the constant voltage signal output from the constant voltage power supply 100 to the reference voltage generation unit 40 via the transistor 30 in accordance with the difference signal. In other words, the transistor 30 outputs, as an output current, a current that flows from the constant voltage signal output from the voltage power supply 100 to the reference voltage generation unit 40 via the transistor 30 according to the difference signal. For example, as the difference between the reference voltage and the ripple voltage to which the bias voltage is added is smaller, the difference signal is smaller, that is, the voltage applied to the base of the transistor 30 that is a PNP bipolar transistor is smaller. The current drawn is increased.

The ripple component is often a minute component compared to the DC component, and in the present disclosure, the power supply stabilization circuit 1 performs an operation that gives the constant voltage signal a current fluctuation enough to remove the minute component. Therefore, the current drawn from the constant voltage signal by the transistor 30 is also minute according to the ripple component.

Next, the detailed operation of the power supply stabilization circuit 1 will be described with reference to FIGS. In the graphs of FIGS. 2 to 5, the horizontal axis (time) scale is unified. That is, the same position on the time axis in each graph is the same timing. Actually, a slight deviation occurs depending on the responsiveness of each component constituting the power supply stabilization circuit 1. In the graphs in FIGS. 2 to 5, the scale of the vertical axis (voltage) is not unified. That is, the same position on the voltage axis in each graph is not necessarily the same voltage value.

FIG. 2 is a diagram showing a waveform of a constant voltage signal including a ripple component output from the constant voltage power supply 100. In FIG. 2, as a constant voltage signal output from the constant voltage power supply 100, a waveform (solid line in FIG. 2) in which a ripple component is superimposed on a DC component (broken line in FIG. 2) is shown. In the description with reference to FIGS. 2 to 5, the waveform related to the ripple component is schematically shown as a sine wave.

FIG. 3 is a diagram showing a waveform of a ripple voltage to which a reference voltage and a bias voltage are added, which are input to the differential amplifying unit 50. The waveform of the reference voltage in FIG. 3 is the voltage waveform at the positive input terminal of the differential amplifier 50, and the waveform of the ripple voltage with the bias voltage added in FIG. 3 is the negative input terminal of the differential amplifier 50. Is a voltage waveform at.

As shown in FIG. 3, the ripple voltage is higher than 0 V even when the ripple voltage fluctuates on the negative side due to the addition of the bias voltage by the bias voltage generation unit 20. Further, as shown in FIG. 3, the reference voltage generation unit 40 generates a reference voltage that is higher than the ripple voltage to which the bias voltage is added. For example, by adjusting the resistance value of the shunt resistor 41, a reference voltage that is always higher than the ripple voltage to which the bias voltage is added is generated. However, as will be described later, if the difference between the bias voltage and the reference voltage becomes too large, the output current of the transistor 30 becomes large. Therefore, the output current of the transistor 30 does not become too large for the bias voltage and the reference voltage. To be adjusted.

FIG. 4 is a diagram illustrating a waveform of a differential signal output from the differential amplifier unit 50. The waveform in FIG. 4 is a voltage waveform at the output terminal of the differential amplifier 50.

As shown in FIG. 3, the reference voltage input to the positive input terminal of the differential amplifier 50 is always higher than the ripple voltage to which the bias voltage input to the negative input terminal of the differential amplifier 50 is added. Therefore, as shown in FIG. 4, the differential amplifier 50 always outputs a differential signal having a voltage higher than 0 from the output terminal. Thereby, since a differential signal having a voltage higher than 0 is always input (applied) to the base of the transistor 30, the transistor 30 extracts current from the constant voltage signal according to the magnitude of the differential signal. Can do. At this time, if the difference signal is too large, the current is greatly extracted from the constant voltage signal, and the DC component of the constant voltage signal is greatly reduced, so that a current that can cancel out a minute ripple component is pulled out from the constant voltage signal. As described above, the magnitude of the difference signal is adjusted. Specifically, by adjusting the magnitudes of the bias voltage generated by the bias voltage generation unit 20 and the reference voltage generated by the reference voltage generation unit 40, a current enough to cancel the ripple component is extracted from the constant voltage signal. .

FIG. 5 is a diagram illustrating a waveform of a voltage generated in the shunt resistor portion 41. A voltage waveform (solid line) generated in the shunt resistor 41 in FIG. 5 is a voltage waveform between the transistor 30 and the shunt resistor 41, and a reference voltage waveform (broken line) is the LPF 42 and the differential amplifier 50. It is a voltage waveform between. The reference voltage is a voltage having a component corresponding to the pass band of the LPF 42 in the voltage generated in the shunt resistor portion 41 according to the output current of the transistor 30. That is, the reference voltage is obtained by cutting the high frequency component of the voltage generated in the shunt resistor 41 by the LPF 42.

2, 4, and 5, it can be seen that the amount of current drawn from the constant voltage signal is larger when the ripple component is larger than when the ripple component is small. For example, when the ripple component is large as in the A portion in FIG. 2, the difference signal becomes small as in the A portion in FIG. 4, so that the output current of the transistor 30 that is a PNP bipolar transistor (that is, from the constant voltage signal). The current drawn) increases. The fact that the current drawn from the constant voltage signal is large when the ripple component is large can also be seen from the fact that the voltage generated in the shunt resistor portion 41 is large like the portion A in FIG. Further, for example, when the ripple component is small as in the B portion in FIG. 2, the differential signal becomes large as in the B portion in FIG. 4, so that the output current (that is, constant voltage) of the transistor 30 that is a PNP bipolar transistor. The current drawn from the signal is small. The fact that the current drawn from the constant voltage signal is small when the ripple component is small can also be seen from the fact that the voltage generated in the shunt resistor portion 41 is small like the portion B in FIG.

Next, the fact that the ripple component has been removed from the constant voltage signal output from the constant voltage power supply 100 by the power supply stabilization circuit 1 will be described with reference to FIG.

FIG. 6 is a diagram for explaining that the ripple component is removed. A solid line in FIG. 6 is a waveform of a constant voltage signal including a ripple component output from the constant voltage power supply 100, and shows a waveform in which the ripple component is superimposed on the DC component. The broken line in FIG. 6 is the waveform of the signal output from the output terminal 110, and shows the waveform of the DC component after ripple component removal.

2 to 5, when the ripple component is large, the amount of current drawn from the constant voltage signal is large, and when the ripple component is small, the amount of current drawn from the constant voltage signal is small. For this reason, when the ripple component is large as in the portion A in FIG. 6, the amount of current drawn is large and the voltage drop amount is large, and when the ripple component is small as in the portion B in FIG. The amount of current is small and the amount of voltage drop is small. As a result, the ripple component is removed and only a constant DC component is output from the output terminal 110. In FIG. 6, the ripple component portion of the constant voltage signal is shown in an enlarged manner for easy understanding, but in reality, the magnitude of the fluctuation of the ripple component is larger than the magnitude of the DC component. Is small. That is, since the amount of current drawn from the constant voltage signal by the transistor 30 is small, the voltage drop amount of the DC component before and after the ripple component removal is smaller than the magnitude of the DC component itself. Since the amount of current drawn from the constant voltage signal by the transistor 30 is small, the transistor 30 does not have to be a large package transistor corresponding to a large current, and a large radiator corresponding to the large current is not necessary.

As described above, the power supply stabilization circuit 1 can make the DC component after removing the ripple component constant by adjusting the amount of current drawn from the constant voltage signal according to the magnitude of the ripple component. A constant voltage signal can be stabilized and output from the terminal 110.

As described above, the power supply stabilization circuit 1 is a circuit that stabilizes a constant voltage signal including a ripple component output from the constant voltage power supply 100 and outputs it from the output terminal 110. The power supply stabilization circuit 1 is arranged in an output path L0 connecting the constant voltage power supply 100 and the output terminal 110 and a first path L1 connecting the ground, and extracts a ripple voltage indicating a ripple component included in the constant voltage signal. The ripple extracting unit 10 includes a bias voltage generating unit 20 that is connected between the ripple extracting unit 10 and the ground in the first path L1 and adds a bias voltage to the ripple voltage. In addition, the power supply stabilization circuit 1 includes a transistor 30 that is disposed on a second path L2 that connects the output path L0 and the ground, and is different from the first path L1, and between the transistor 30 and the ground in the second path L2. And a reference voltage generation unit 40 that generates a reference voltage corresponding to the output current of the transistor 30. The power supply stabilization circuit 1 has a positive input terminal and a negative input terminal, and calculates a difference between a reference voltage input to the positive input terminal and a ripple voltage to which a bias voltage input to the negative input terminal is added. A differential amplifying unit 50 that performs inverting amplification and outputs the inverted and amplified differential signal to the transistor 30 is provided. The output current of the transistor 30 is a current that flows from the constant voltage signal to the reference voltage generation unit 40 via the transistor 30 according to the difference signal.

According to this, the ripple voltage extracted by the ripple extracting unit 10 is inverted and amplified in the differential amplifying unit 50, and the transistor 30 is driven by the inverted and amplified differential signal. That is, since the differential signal is a reverse-phase signal of the ripple component, the current can be extracted from the constant voltage signal so as to reduce the ripple component by controlling the transistor 30 using the negative-phase signal. In addition, the transistor 30 is not provided in the output path L0 through which all the current output from the constant voltage power supply 100 flows, and performs current driving to reduce only a ripple component that is a small signal. The transistor in the package is not required, and a large heat sink that can handle a large current is also unnecessary. Therefore, the power supply stabilization circuit 1 can reduce the size of the configuration for stabilizing the output of the constant voltage power supply 100.

Further, the ripple extraction unit 10 may be a capacitor connected in series between the output path L0 and the negative input terminal.

According to this, the ripple extraction unit 10 can be realized with a simple configuration.

In addition, the reference voltage generation unit 40 includes a shunt resistor unit 41 disposed between the transistor 30 and the ground in the second path L2, a path connecting the transistor 30 and the shunt resistor unit 41 in the second path L2, and a positive electrode And an LPF 42 disposed in a path connecting the input terminals. The reference voltage may be a voltage having a component corresponding to the pass band of the LPF 42 in the voltage generated in the shunt resistor portion 41 according to the output current of the transistor 30.

According to this, the reference voltage can be adjusted by the resistance value of the shunt resistor portion 41, and the magnitude of the differential signal for driving the transistor 30 can be determined according to the magnitude of the reference voltage. For this reason, the amount of current drawn from the constant voltage signal can be easily adjusted by the resistance value of the shunt resistor portion 41.

(Embodiment 2)
Next, Embodiment 2 will be described with reference to FIGS.

FIG. 7 is a circuit configuration diagram showing an example of the power supply stabilization circuit 1a according to the second embodiment. In FIG. 7, in addition to the power supply stabilization circuit 1a, a constant voltage power supply 100 that outputs a signal input to the power supply stabilization circuit 1a, and an output terminal 110 that outputs a signal processed by the power supply stabilization circuit 1a. The load 120 connected to the output terminal 110 is shown.

The power supply stabilization circuit 1a according to the second embodiment further includes a control unit 60, and includes a reference voltage generation unit 40a instead of the reference voltage generation unit 40, in that the power supply stabilization circuit 1 according to the first embodiment is different from the power supply stabilization circuit 1 according to the first embodiment. Different. The reference voltage generation unit 40 a is different from the reference voltage generation unit 40 in that the reference voltage generation unit 40 a includes a shunt resistance unit 41 a instead of the shunt resistance unit 41. Since the other points are the same as those in the power supply stabilization circuit 1, the description thereof is omitted.

The control unit 60 is a processor or the like, for example, a microcomputer. The control unit 60 acquires a signal corresponding to the size (power consumption) of the load 120, and controls the shunt resistor unit 41a according to the signal. The control unit 60 may have a function of detecting the size of the load 120, or may acquire a signal indicating the size of the load 120 from another detection device. The power supply stabilization circuit 1a may not include the control unit 60. In this case, the power supply stabilization circuit 1a (shunt resistor unit 41a) receives a control signal based on a signal corresponding to the size of the load 120 from the control unit 60 provided outside.

The resistance value of the shunt resistor portion 41a is controlled to the first resistance value when the size of the load 120 connected to the output terminal 110 is larger than a predetermined value, and when the size of the load 120 is equal to or smaller than the predetermined value. The second resistance value is controlled to be smaller than the first resistance value. A specific example of the control will be described below.

The shunt resistor 41a includes, for example, a first resistor R1 connected between the transistor 30 and the ground in the second path L2, and a second resistor R2 connected in parallel to the first resistor R1 and the switch SW. A series circuit. The resistance value of the shunt resistor portion 41a is controlled to the resistance value of the first resistor R1 as the first resistance value when the load 120 is larger than the predetermined value by turning off the switch SW. When the magnitude of 120 is equal to or smaller than a predetermined value, the switch SW is turned on and the combined resistance value of the first resistance R1 and the second resistance R2 is controlled as the second resistance value. For example, the control unit 60 determines whether or not the size of the load 120 is larger than a predetermined value based on a signal indicating the size of the load 120, and on / off control of the switch SW according to the determination result. I do. The switch SW may be a switch (such as a relay) that is turned on and off mechanically or a switch (such as a transistor) that is electrically turned on and off.

The predetermined value is, for example, the size of the load 120 at which the constant voltage power supply 100 performs an idling operation, and is appropriately determined depending on the type of the load 120 and the like.

For example, when the size of the load 120 is less than or equal to a predetermined value, the constant voltage power supply 100 (for example, a switching power supply) is in an idling operation (specifically, the output is off for a long time and then the output is on for a short time. To repeat the process). That is, when the load 120 is small, the output suddenly rises repeatedly, and the ripple component becomes large. Therefore, the resistance value of the shunt resistor portion 41a is smaller than the resistance value (first resistance value) of the first resistor R1, which is the resistance value when the switch SW is off, and is the resistance value when the switch SW is on. The combined resistance value (second resistance value) of the first resistor R1 and the second resistor R2 is controlled. Thus, the amount of current that can be passed through the transistor 30 can be increased while the reference voltage remains constant. Therefore, by increasing the amount of current drawn from the constant voltage signal by the transistor 30 according to the magnitude of the ripple component while maintaining a state where differential amplification is possible, the idling operation of the constant voltage power supply 100 increases. Ripple components can be removed. An RC circuit composed of a resistor and a capacitor may be provided instead of the second resistor R2. Since the RC circuit has a time constant, when the switch SW is turned on / off, the resistance value of the shunt resistor portion 41a is suddenly changed, so that the occurrence of noise can be suppressed. .

On the other hand, as the amount of current drawn from the constant voltage signal increases, power loss occurs. Therefore, when the size of the load 120 is larger than a predetermined value, that is, for example, when the constant voltage power supply 100 does not perform an idling operation. The resistance value of the shunt resistor portion 41a is controlled to the resistance value (first resistance value) of the first resistor R1, which is the resistance value when the switch SW is off.

Thus, by controlling the resistance value of the shunt resistor 41a according to the size of the load 120, the ripple component can be effectively removed according to the size of the generated ripple component. The method for controlling the resistance value of the shunt resistor 41a is not limited to this.

FIG. 8 is a circuit configuration diagram showing an example of a power supply stabilization circuit 1b according to a modification of the second embodiment. In FIG. 8, in addition to the power supply stabilization circuit 1b, a constant voltage power supply 100 that outputs a signal input to the power supply stabilization circuit 1b, and an output terminal 110 that outputs a signal processed by the power supply stabilization circuit 1b. The load 120 connected to the output terminal 110 is shown.

The power supply stabilization circuit 1b according to the modification of the second embodiment is different from the power supply stabilization circuit 1a according to the second embodiment in that a reference voltage generation unit 40b is provided instead of the reference voltage generation unit 40a. The reference voltage generation unit 40b is different from the reference voltage generation unit 40a in that the reference voltage generation unit 40b includes a shunt resistance unit 41b instead of the shunt resistance unit 41a. Since the other points are the same as those in the power supply stabilization circuit 1a, description thereof is omitted.

The resistance value of the shunt resistor 41b is controlled to be smaller as the size of the load 120 connected to the output terminal 110 is smaller. A specific example of the control will be described below.

The shunt resistor 41b has a variable resistor R3 connected between the transistor 30 and the ground in the second path L2. The smaller the load 120 is, the smaller the resistance value of the variable resistor R3 is controlled as the resistance value of the shunt resistor portion 41b. For example, the control unit 60 controls the resistance value of the variable resistor R3 based on a signal indicating the size of the load 120. For example, the control unit 60 controls the resistance value of the variable resistor R3 by referring to a table or the like indicating a correspondence relationship between the size of the load 120 and the resistance value of the variable resistor R3.

For example, as the size of the load 120 is smaller, the constant voltage power supply 100 (for example, the switching power supply) is in an idling operation (specifically, after the output is turned off for a long time, the output is turned on for a short time). It is easier to repeat the action). Therefore, the resistance value of the shunt resistor 41b is controlled to be smaller as the size of the load 120 is smaller. Thus, the amount of current that can be passed through the transistor 30 can be increased while the reference voltage remains constant. Therefore, by increasing the amount of current drawn from the constant voltage signal by the transistor 30 according to the magnitude of the ripple component while maintaining a state where differential amplification is possible, the idling operation of the constant voltage power supply 100 increases. Ripple components can be removed.

As described above, the resistance value of the shunt resistor portion 41a is controlled to the first resistance value when the size of the load 120 connected to the output terminal 110 is larger than a predetermined value, and the size of the load 120 is determined. May be controlled to a second resistance value smaller than the first resistance value. Specifically, the shunt resistor 41a includes a first resistor R1 connected between the transistor 30 and the ground in the second path L2, and a second resistor R2 and a switch connected in parallel to the first resistor R1. And a series circuit with SW. When the size of the load 120 is larger than a predetermined value, the resistance value of the shunt resistor 41a is controlled by turning off the switch SW and controlling the resistance value of the first resistor R1 as the first resistance value. When the magnitude is less than or equal to a predetermined value, the switch SW may be turned on and controlled to a combined resistance value of the first resistance R1 and the second resistance R2 as the second resistance value.

According to this, when the size of the load 120 is equal to or less than a predetermined value at which the constant voltage power supply 100 performs an idling operation, the resistance value of the shunt resistor 41a is controlled to be small, and the transistor 30 flows. The amount of current that can be increased. Therefore, by increasing the amount of current drawn from the constant voltage signal by the transistor 30 according to the magnitude of the ripple component, the ripple component that has become large due to the idling operation of the constant voltage power supply 100 can be removed.

Further, the resistance value of the shunt resistor portion 41b may be controlled to be smaller as the load 120 connected to the output terminal 110 is smaller. Specifically, the shunt resistor portion 41b may have a variable resistor R3 connected between the transistor 30 and the ground in the second path L2. The smaller the load 120 is, the smaller the resistance value of the variable resistor R3 may be controlled as the resistance value of the shunt resistor portion 41b.

According to this, as the size of the load 120 is smaller, the constant voltage power supply 100 becomes easier to perform the idling operation. Therefore, the resistance value of the shunt resistor 41b is controlled to be smaller as the size of the load 120 is smaller, and the amount of current that can be passed through the transistor 30 can be increased. Therefore, by increasing the amount of current drawn from the constant voltage signal by the transistor 30 according to the magnitude of the ripple component, the ripple component that has become large due to the idling operation of the constant voltage power supply 100 can be removed.

(Other embodiments)
As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, and the like are appropriately performed. Moreover, it is also possible to combine each component demonstrated in the said embodiment and it can also be set as a new embodiment.

For example, in the above embodiment, the ripple extraction unit 10 is a capacitor connected in series between the output path L0 and the negative input terminal of the differential amplification unit 50. However, only the ripple voltage can be extracted. Any configuration that can be used is not limited to such a configuration.

For example, in the above embodiment, the transistor 30 is a PNP bipolar transistor, but is not limited thereto. For example, the transistor 30 is an NPN bipolar transistor or a transistor such as an N-channel or P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) as long as it has a function of controlling the current flowing through the second path L2. Also good.

For example, in the second embodiment, the shunt resistor 41a has one series circuit of the second resistor R2 and the switch SW connected in parallel to the first resistor R1, but the present invention is not limited to this. Absent. For example, the shunt resistor portion 41a may have a configuration in which a plurality of such series circuits are connected in parallel to the first resistor R1. Thereby, the resistance value of the shunt resistor portion 41a can be controlled more flexibly.

As described above, the embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description are provided.

Therefore, the constituent elements described in the accompanying drawings and the detailed description may include not only constituent elements essential for solving the problem but also constituent elements not essential for solving the problem. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

In addition, since the above-described embodiment is for illustrating the technique in the present disclosure, various modifications, replacements, additions, omissions, and the like can be performed within the scope of the claims or an equivalent scope thereof.

The present disclosure is applicable to a device that requires a stabilized constant voltage power source. Specifically, the present disclosure can be applied to a device that reproduces sound, such as an audio device, a television, a PC (Personal Computer), and a portable device.

DESCRIPTION OF

SYMBOLS

1, 1a, 1b Power supply stabilization circuit 10 Ripple extraction part 20 Bias voltage generation part 30

Transistor

40, 40a, 40b Reference

voltage generation part

41, 41a, 41b Shunt resistance part 42 Low-pass filter (LPF)
50 Differential Amplifier 60 Control Unit 100 Constant Voltage Power Supply 110 Output Terminal 120 Load L0 Output Path L1 First Path L2 Second Path R1 First Resistance R2 Second Resistance R3 Variable Resistance SW Switch x1, x2 Node

Claims

A power supply stabilization circuit that stabilizes a constant voltage signal including a ripple component output from a constant voltage power supply and outputs it from an output terminal.
A ripple extracting unit that is arranged in an output path connecting the constant voltage power supply and the output terminal and a first path connecting the ground, and extracts a ripple voltage indicating a ripple component included in the constant voltage signal;
A bias voltage generation unit connected between the ripple extraction unit and the ground in the first path and adding a bias voltage to the ripple voltage;
A transistor arranged in a second path different from the first path connecting the output path and the ground;
A reference voltage generation unit that is connected between the transistor and the ground in the second path and generates a reference voltage according to an output current of the transistor;
Having a positive input terminal and a negative input terminal, inverting and amplifying a difference between the reference voltage input to the positive input terminal and the ripple voltage to which the bias voltage input to the negative input terminal is added, and A differential amplifier that outputs the inverted and amplified differential signal to the transistor, and
The output current of the transistor is a current that flows from the constant voltage signal to the reference voltage generation unit via the transistor according to the difference signal.
Power stabilization circuit.
The ripple extraction unit is a capacitor connected in series between the output path and the negative input terminal.
The power supply stabilization circuit according to claim 1.
The reference voltage generator is
A shunt resistor portion disposed between the transistor and the ground in the second path;
A path connecting the transistor and the shunt resistor in the second path, and a low-pass filter disposed in a path connecting the positive input terminal,
The reference voltage is a voltage having a component corresponding to a pass band of the low-pass filter in a voltage generated in the shunt resistor unit according to an output current of the transistor.
The power supply stabilization circuit according to claim 1 or 2.
The resistance value of the shunt resistor is
When the load connected to the output terminal is larger than a predetermined value, the first resistance value is controlled.
When the magnitude of the load is a predetermined value or less, the second resistance value is controlled to be smaller than the first resistance value.
The power supply stabilization circuit according to claim 3.
The shunt resistor unit includes a first resistor connected between the transistor and the ground in the second path, and a series circuit of a second resistor and a switch connected in parallel to the first resistor. Have
The resistance value of the shunt resistor is
When the magnitude of the load is larger than a predetermined value, the switch is turned off and the resistance value of the first resistor is controlled as the first resistance value.
When the magnitude of the load is less than or equal to a predetermined value, the switch is turned on and controlled as a combined resistance value of the first resistor and the second resistor as the second resistance value.
The power supply stabilization circuit according to claim 4.
The resistance value of the shunt resistor portion is controlled to be smaller as the load connected to the output terminal is smaller.
The power supply stabilization circuit according to claim 3.
The shunt resistor unit has a variable resistor connected between the transistor and the ground in the second path,
The smaller the load size, the smaller the resistance value of the variable resistor is controlled as the resistance value of the shunt resistor portion.
The power supply stabilization circuit according to claim 6.