JP2006039861A - Series regulator circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a series regulator circuit capable of achieving the enhancement of AC (Alternating Current) characteristics. <P>SOLUTION: The series regulator circuit comprises: a current source circuit 10 which generates a first operating current; an amplifier circuit 20 which operates after being supplied with the first operating current, compares a reference voltage with a feedback voltage after being supplied with them and outputs a comparison result voltage corresponding to the comparison result; an output circuit 30 having an output section which outputs an output current corresponding to the comparison result voltage after being supplied the comparison result voltage and a feedback voltage generation section which generates a feedback voltage corresponding to the output current and feeds it to the amplifier circuit 20; and an addition circuit 40 having an output extraction section which extracts part of the output current outputted by the output section and an addition section which adds a second operating current corresponding to part of the output current and feeds it to the amplifier circuit 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a series regulator circuit.

  In recent years, there has been an increasing demand for low power consumption for series regulator circuits in power supply devices such as portable electronic devices.

  When the operating current supplied to the amplifier in the series regulator circuit is reduced in order to reduce the power consumption of the series regulator circuit, the gm of the amplifier is lowered, so that the AC characteristics of the series regulator circuit are deteriorated.

  Here, the AC characteristic means an input voltage fluctuation response, a load transient fluctuation response, a regulator rise time, and the like.

  When the AC characteristics of the series regulator circuit deteriorate, there arises a problem that the characteristics of the entire system using the series regulator circuit as a power source are adversely affected.

The literature names disclosing the conventional series regulator circuit are described below.
JP 2002-343874 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a series regulator circuit capable of realizing improvement in AC characteristics.

A series regulator circuit according to an aspect of the present invention includes:
A current source circuit for generating a first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit that extracts a part of the output current output by the output unit; and an addition unit that adds a second operating current corresponding to the part of the output current to the amplifier circuit. An adder circuit;
It is characterized by providing.

A series regulator circuit according to an aspect of the present invention includes:
A current source circuit comprising: a current source that generates a first operating current; and an operating current corresponding voltage output unit that outputs an operating current corresponding voltage corresponding to the first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit for extracting a part of the output current output by the output unit; an addition unit for adding a second operating current corresponding to a part of the output current to the amplifier circuit; and An adder circuit having a limiter unit that limits the second operating current so as not to exceed a predetermined value based on the operating current corresponding voltage output by the operating current corresponding voltage output unit;
It is characterized by providing.

Furthermore, a series regulator circuit according to an aspect of the present invention includes:
A current source circuit for generating a first operating current;
An operating current corresponding voltage output circuit for outputting an operating current corresponding voltage corresponding to the first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit for extracting a part of the output current output by the output unit; an addition unit for adding a second operating current corresponding to a part of the output current to the amplifier circuit; and An adder circuit having a limiter unit that limits the second operating current so as not to exceed a predetermined value based on the operating current corresponding voltage output by the operating current corresponding voltage output circuit;
It is characterized by providing.

  According to the series regulator circuit of the present invention, the AC characteristics can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Embodiment 1
A series regulator circuit according to the first embodiment of the present invention will be described with reference to FIG.

  This series regulator circuit includes a current source circuit 10, an amplifier circuit 20, a reference voltage source Vref, an output circuit 30, and an adder circuit 40.

  The current source circuit 10 has a configuration in which a constant current source CS and an N-channel MOS transistor MN01 are connected in series.

The amplifier circuit 20 includes a differential amplifier including two P-channel MOS transistors MP01 and MP02, two N-channel MOS transistors MN03 and MN04, and an N-channel MOS transistor MN02 that drives the differential amplifier. Here, the transistor MN02 forms a current mirror circuit with the transistor MN01 of the current source circuit 10.

  The output circuit 30 includes a P-channel MOS transistor MP03 corresponding to a load driving output transistor, resistors R01 and R02 for resistance voltage division, and capacitors C01 and C02 for phase compensation.

  The adder circuit 40 includes a P-channel MOS transistor MP04 that captures part of the current flowing through the output transistor MP03, and N-channel MOS transistors MN05 and MN06. Here, the transistor MP04 forms a current mirror circuit with the transistor MP03 of the output circuit 30. The transistor MN05 and the transistor MN06 constitute a current mirror circuit.

  The operation of the first embodiment having such a configuration will be described.

  Since the transistor MN01 of the current source circuit 10 and the transistor MN02 of the amplifier circuit 20 form a current mirror circuit, a constant current determined by the ratio of the size W / L of these transistors flows to the transistor MN02. This is an operating current supplied to the amplifier circuit 20.

  A feedback voltage at the node N14 obtained by resistance-dividing the output voltage at the drain of the output transistor MP03 in the output circuit 30 by the resistors R01 and R02 constituting the feedback voltage generator is input to the gate of the transistor MN04. On the other hand, the reference voltage Vref is input to the gate of the transistor MN03. As a result, a comparison result voltage obtained by comparing the potential of the node N14 with the reference voltage Vref is output from the node N11 to which the drain of the transistor MN03 is connected.

  In the output circuit 30, the voltage output from the node N <b> 11 is input to the gate of the output transistor MP <b> 03 and also input to the gate of the transistor MP <b> 04 constituting the output extraction unit in the adder circuit 40.

  Here, the transistors MP03 and MP04 form a current mirror circuit as described above, and the relative sizes are set so that the current supplied to the transistor MP04 is negligibly small. For example, transistor MP03: transistor MP04 = 100: 1 may be set.

  As a result, a current of about 1% of the output current flowing through the transistor MP03 and supplied to a load not shown is mirrored in the transistor MP04.

  In the adder circuit 40, a current flowing through the node N15 connected to the drain of the transistor MP04 flows through the transistor MN06, and this current is mirrored to the transistor MN05 that forms a current mirror circuit with the transistor MN06. The transistors MN06 and MN05 constitute an adding unit. That is, the current corresponding to the ratio of the sizes of the transistors MN06 and MN05 flows to the node N13 connected to the drain of the transistor MN05 with respect to the current flowing to the node N15.

  As a result, the operating current supplied to the differential amplifier composed of the transistors MP01 and MP02, MN03 and MN04 in the amplifier circuit 20 is not only a constant current flowing through the transistor MN02 whose drain is connected to the node N12, but also the drain at the node N13. The current flowing through the transistor MN05 connected to is added. Even if the size of the transistor MN02 is not increased, the operating current flowing through the amplifier circuit 20 can be increased and the performance of the series regulator circuit can be improved.

  As described above, in the first embodiment, the node N11 corresponding to the output of the amplifier circuit 20 is connected to the gate of the output transistor MP03 and to the gate of the transistor MP04 constituting the current mirror circuit together with the transistor MP03. A part of the output current flowing from the transistor MP03 to the load is mirrored. Then, a current corresponding to a part of the output current is passed through the transistor MN06 connected in series with the transistor MP04, so that this current is mirrored on the transistor MN06 and the transistor MN06 constituting the current mirror circuit.

  Thereby, a current corresponding to the magnitude of the output current flowing through the load is added to the operating current of the amplifier circuit 20 by drawing a current from the node N13 of the amplifier circuit 20 by the transistor NM06.

  As a result, when the output current flowing through the load is small, the current mirrored by the transistor MP04 is also small, so that the overall current consumption is suppressed.

  On the other hand, when the output current flowing through the load is large, a sufficiently small current that is negligible in this output current is mirrored in the transistor MP04, and the current corresponding to this current is added as the operating current of the amplifier circuit 20, It is possible to suppress the current consumption at the time of loading with little influence.

  Since the operating current added to the amplifier circuit 20 can be increased according to the size of the load, it is possible to improve the AC characteristics of the series regulator circuit, and AC power fluctuations adversely affect the system. Can be prevented.

(2) Embodiment 2
A series regulator circuit according to the second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, when the output current applied from the output transistor MP03 to the load increases, the current flowing from the transistor MP04 to the node N15 increases accordingly, and the current flowing from the transistor MN05 mirroring this current to the node N13 increases. To do. For this reason, when the current supplied to the load exceeds a certain level, the operating currents flowing in the transistors MP01 and MP02, MN03 and MN04 included in the amplifier circuit 20 become too large and operate in the linear region. There is a risk of malfunction.

  Therefore, in the second embodiment, a predetermined limit value is provided for the current supplied to the amplifier circuit 20, and current exceeding this value is not supplied to the amplifier circuit 20.

  In the second embodiment, the configurations of the current source circuit 11 and the adder circuit 41 are different from those of the first embodiment, and description of other common configurations is omitted.

  The current source circuit 11 includes a constant current source CS and a transistor MN01 that operate as a current source that supplies an operating current to the amplifier circuit 20, and a transistor MN07 that operates as an operating current corresponding voltage output unit that outputs a voltage corresponding to the operating current. And have.

  The adder circuit 41 includes transistors MP04, MN05, and MN06 that operate as the adder circuit 40 described in the first embodiment, and a transistor MN08 that operates as a limiter unit.

  Here, the transistors MN07 and MN08 constitute a current mirror circuit.

  As in the first embodiment, a current of, for example, about 1% of the output current flowing through the transistor MP03 and supplied to the load is mirrored by the transistor MP04.

  In the adder circuit 41, the current flowing through the node N15 connected to the drain of the transistor MP04 flows through the transistors MN08 and MN0606 connected in series, and this current is mirrored to the transistor MN06 and the transistor MN05 constituting the current mirror circuit. It flows to the node N13.

  As a result, in the amplifier circuit 20, the current flowing through the transistor MN05 is added to the constant current flowing through the transistor MN02 as the operating current supplied to the differential amplifier.

  However, the transistor MN08 of the adder circuit 41 flows only to the current mirrored from the current flowing through the transistor MN07 in the current source circuit 11, that is, the current corresponding to the operating current supplied from the current source circuit 11 to the amplifier circuit 20. . Therefore, the current more than the predetermined current is limited so as not to flow through the transistors MN08 and MN06.

  As a result, since the limited current flowing through the transistor MN06 is mirrored by the transistor MN05, only the limited current flows as the operation current added to the node N13 of the amplifier circuit 20.

  For example, the ratio of the sizes of the transistors MN07 and MN08 is set so that MN07: MN08 = 1: 1000. Thus, if the current flowing through the transistor MN07 in the current source circuit 11 is 1 μA, for example, the current flowing through the transistors MN08 and MN06 in the adder circuit 41 is 1 mA, and this current is determined by the ratio of the sizes of the transistors MN06 and MN05. Thus, the operation current is added to the amplifier circuit 20 by being mirrored by the transistor MN05.

  That is, according to the second embodiment, when the output current flowing through the output transistor MP03 and supplied to the load is small, the transistor MN08 does not act as a limiter and operates in the same manner as in the first embodiment.

  When the output current supplied to the load becomes excessive, the operating current exceeding the current determined by the size ratio of the transistors MN08 and MN07 and the size ratio of the transistors MN06 and MN05 is added to the amplifier circuit 20 Therefore, the operation current of the amplifier circuit 20 becomes excessive and the malfunction is prevented.

  Similarly to the first embodiment, when the output current supplied from the output transistor MP03 to the load is small, the current mirrored by the transistor MP04 for extracting a part of the output current is also small, so that the consumption at no load is achieved. An increase in current is prevented.

  Further, when the load is loaded, the size of the transistors MP03 and MP04 is determined so that the transistor MP04 mirrors a sufficiently small current that is negligible with respect to the output current flowing through the load. Almost no effect on current.

  The operating current flowing through the amplifier circuit 20 when there is a load can be increased in accordance with the size of the load within a range of a predetermined value or less, so that the AC characteristics as a series regulator circuit are improved and AC power fluctuations Can be prevented from adversely affecting the system.

(3) Embodiment 3
A series regulator circuit according to a third embodiment of the present invention will be described with reference to FIG. 3 showing its circuit configuration.

  In the second embodiment, the function as the current source supplied to the amplifier circuit 20 and the function as the operating current corresponding voltage output unit are realized by one current source circuit 11.

  In contrast, in the third embodiment, the function as the current source of the amplifier circuit 20 is provided in the current source circuit 10 and the function as the operating current corresponding voltage output unit is provided in the operating current corresponding voltage output circuit 12, respectively. Both are made independent.

  The current source circuit 10 has the same configuration as that of the current source circuit 10 in the first embodiment shown in FIG. 1, and includes a constant current source CS1 and an N-channel MOS transistor MN01a.

  Similarly to the current source circuit 11 in the second embodiment shown in FIG. 2, the operating current corresponding voltage output circuit 12 includes a constant current source CS2 and N-channel MOS transistors MN07 and MN01b.

  In the second embodiment, as described above, one current source circuit 11 needs to have a function as a current source supplied to the amplifier circuit 20 and a function as a limiter circuit. For this reason, the current value to be supplied to the amplifier circuit 20 becomes a restriction, and there is a restriction on the size ratio of the transistors MN01 and MN07. For this reason, the setting of the size of the transistor MN08 constituting the current mirror circuit with the transistor MN07 is also restricted, and the size of the transistor MN08 has to be set large, which may increase the element area.

  On the other hand, according to the third embodiment, the function as the current source for the amplifier circuit 20 and the function as the operating current corresponding voltage output unit are provided in independent circuits, respectively, so that the operating current corresponding voltage output is obtained. The constant current source CS2 included in the circuit 12 and the size of the transistor MN07 can be set freely. As a result, the size of the transistor MN08 in the adder circuit 41 can be kept small, and an increase in element area can be prevented.

  Here, comparing Embodiments 1 to 3, since Embodiments 1 and 2 have one constant current source, it is possible to achieve further reduction in current consumption.

  However, also in the third embodiment, as in the first or second embodiment, the current consumption when the load is small does not increase, and a part of the output current that flows to the load when the load is large is extracted. By adding the current corresponding to the size of the load as the operating current of the amplifier circuit, it is possible to improve the AC characteristics while suppressing the influence on the overall current consumption. An adverse effect on the system can be prevented.

  Each of the above-described embodiments is an example, and the present invention is not limited thereto, and various modifications can be made as necessary. For example, the polarity of each transistor shown in FIGS. 1 to 3 can be reversed. Further, the size ratio in the current mirror circuit formed by the transistors MN01 and MN02, MP03 and MP04, MN05 and MN06, MN07 and MN08 can be freely set to a desired value.

1 is a circuit diagram showing a configuration of a series regulator circuit according to a first embodiment of the present invention. The circuit diagram which shows the structure of the series regulator circuit by Embodiment 2 of this invention. The circuit diagram which shows the structure of the series regulator circuit by Embodiment 3 of this invention.

Explanation of symbols

10, 11 Current source circuit 12 Operating current corresponding voltage output circuit 20 Amplifier circuit 30 Output circuit 40, 41 Adder circuits CS, CS1, CS2 Constant current sources MP01-MP04 P-channel MOS transistors MN01-MN08 N-channel MOS transistor R01, R02 resistance

Claims (5)

A current source circuit for generating a first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit that extracts a part of the output current output by the output unit; and an addition unit that adds a second operating current corresponding to the part of the output current to the amplifier circuit. An adder circuit;
A series regulator circuit comprising: The output unit has a source connected to a first power supply terminal, a drain connected to a first output terminal that outputs the output current, and a gate connected to a second output terminal that outputs the comparison result voltage. A first P-channel MOS transistor,
A second P-channel MOS transistor having a source connected to the first power supply terminal, a drain connected to the input side of the adder, and a gate connected to the second output terminal; The series regulator circuit according to claim 1, comprising: A current source circuit comprising: a current source that generates a first operating current; and an operating current corresponding voltage output unit that outputs an operating current corresponding voltage corresponding to the first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit for extracting a part of the output current output by the output unit; an addition unit for adding a second operating current corresponding to a part of the output current to the amplifier circuit; and An adder circuit having a limiter unit that limits the second operating current so as not to exceed a predetermined value based on the operating current corresponding voltage output by the operating current corresponding voltage output unit;
A series regulator circuit comprising: The current source circuit includes the current source having an input side connected to a first power supply terminal;
A first N-channel MOS transistor having a drain and a gate connected to a first output terminal that outputs the first operating current, and a source connected to a second power supply terminal;
A second N-channel type included in the operating current corresponding voltage output unit, having a drain and a gate connected to an output side of the current source, and a source connected to a drain and a gate of the first N-channel MOS transistor; A MOS transistor,
The output unit has a source connected to the first power supply terminal, a drain connected to a second output terminal that outputs the output current, and a gate connected to a third output terminal that outputs the comparison result voltage. A first P-channel MOS transistor,
The output extraction unit includes a second P-channel MOS transistor having a source connected to the first power supply terminal and a gate connected to the third output terminal.
The limiter has a gate connected to the gate of the second N-channel MOS transistor, a drain connected to the drain of the second P-channel MOS transistor, and a source connected to the input side of the adder. 4. The series regulator circuit according to claim 3, further comprising a third N-channel MOS transistor. A current source circuit for generating a first operating current;
An operating current corresponding voltage output circuit for outputting an operating current corresponding voltage corresponding to the first operating current;
An amplifier circuit which operates by being supplied with the first operating current, compares a reference voltage and a feedback voltage, and outputs a comparison result voltage corresponding to the comparison result;
An output section that is supplied with the comparison result voltage and outputs an output current corresponding to the comparison result voltage; and a feedback voltage generation section that generates the feedback voltage corresponding to the output current and supplies the feedback voltage to the amplifier circuit. An output circuit having
An output extraction unit for extracting a part of the output current output by the output unit; an addition unit for adding a second operating current corresponding to a part of the output current to the amplifier circuit; and An adder circuit having a limiter unit that limits the second operating current so as not to exceed a predetermined value based on the operating current corresponding voltage output by the operating current corresponding voltage output circuit;
A series regulator circuit comprising:

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