JP2002032133A - Stabilized power supply circuit - Google Patents

Abstract

(57) [PROBLEMS] To provide a stabilized power supply circuit capable of using a low ESR capacitor as an output stabilizing capacitor without inserting a resistor equivalent to ESR. SOLUTION: There is provided a comparison amplifier means OP which compares a feedback signal representing an output voltage of the stabilized power supply circuit with a reference signal representing a reference voltage and outputs an error signal which is a difference between the two.
In a stabilized power supply circuit which supplies an output voltage controlled to a predetermined value via the output means Tr by controlling the output means with the error signal of the comparison and amplification means OP, the output terminal of the output means Tr Terminal T of the integrated power circuit
The phase compensation resistor R ₃ is provided between the _out, the phase compensation signal generated by the phase compensating resistor R ₃ to the back as the feedback signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage regulator capable of extracting a stabilized power supply from a battery.
For stabilized power supply circuits such as switching regulators, low ESR (equivalent series resistance)
It includes a phase compensation circuit that can use a capacitor.

[0002]

2. Description of the Related Art Conventionally, a stabilized power supply circuit has been used for a portable electronic device such as a mobile phone such as a portable telephone and a PHS, and a PDA such as an electronic organizer.

FIG. 6 shows an example of a conventional voltage regulator. This voltage regulator has an amplifier 1 and a driver transistor 2, and a reference voltage source 3 is connected to an inverting input terminal of the amplifier 1. The output terminal of the driver transistor 2 is an output terminal 4 of the voltage regulator, and the voltage of the output terminal 4 is fed back to the non-inverting input terminal of the amplifier 1 via the resistor 5. More specifically, as for the voltage of the output terminal 4, a voltage based on a division ratio determined by the resistance values R ₁ and R ₂ of the resistors 5 and 6 is fed back to the non-inverting input terminal of the amplifier 1. Further, a capacitor 7 is provided in parallel with the resistor 5, and an AC component having a certain frequency or higher is fed back to the non-inverting input terminal of the amplifier 1 via the capacitor 7.

[0004] In such a voltage regulator, a reference voltage V _ref of the reference voltage source 3 with respect to the output to the load 8 connected to the output V _out at the output terminal 4 of the following formula, always detects the output V _{o ut} The feedback is used to stabilize the output.

[0005]

V _out = V _ref {(R ₁ + R ₂ ) / R ₂ }

However, in this case, an external output stabilizing capacitor 9 must be provided to compensate for the phase of the feedback signal. That is, a tantalum capacitor or an electrolytic capacitor having a relatively large ESR is used as the output stabilizing capacitor 9, and the output stabilizing capacitor 9 is used.
In this case, the phase compensation is performed by using the zero point by the ESR to obtain a stabilized output.

FIG. 7 shows an example of a conventional switching regulator. This switching regulator
A booster 10 is provided in place of the driver transistor 2 in FIG. 6, and members having the same operation are denoted by the same reference numerals, and redundant description will be omitted.

Here, the booster 10 includes a switching controller 11, a switch 12 whose on / off is controlled by the switching controller 11, a coil 13, and a diode 14.
The switching controller 11 is controlled by the output signal of the amplifier 1, and the output voltage _Vout can be adjusted to a constant value based on the reference voltage _Vref .

[0009]

By the way, with the miniaturization and high performance of portable electronic devices, the size of the stabilized power supply unit has been reduced.
There has been a demand for high stabilization, and there has been an increasing demand for using a small multilayer ceramic capacitor having a low ESR as an output stabilizing capacitor.

However, when a low ESR capacitor is used as the output stabilizing capacitor, the phase shift is not sufficient to obtain sufficient feedback and stable operation cannot be achieved. Therefore, a resistor equivalent to ESR is inserted in series with the multilayer ceramic capacitor. Otherwise, there is a problem that a stabilized power supply cannot be obtained.

The present invention has been made in view of such circumstances, and
It is an object of the present invention to provide a stabilized power supply circuit which can use a low ESR capacitor as an output stabilizing capacitor without inserting a resistor equivalent to the above.

[0012]

According to a first aspect of the present invention, a feedback signal representing an output voltage of the stabilized power supply circuit is compared with a reference signal representing a reference voltage. A comparison and amplification unit that outputs an error signal that is a difference,
In a stabilized power supply circuit for supplying an output voltage controlled to a predetermined value through the output means by controlling the output means with an error signal of the comparison and amplification means, an output terminal of the output means and the stabilized power supply circuit A phase compensating resistor is provided between the output terminal and the stabilizing power supply circuit, and a phase compensating signal generated by the phase compensating resistor is returned as a feedback signal.

According to a second aspect of the present invention, there is provided the stabilized power supply circuit according to the first aspect, wherein the output means comprises a driver transistor.

A third aspect of the present invention is the stabilized power supply circuit according to the first aspect, wherein the output means includes an inductance, a rectifying element, and a switching circuit.

A fourth aspect of the present invention is a comparison / amplification means for comparing a feedback signal representing an output voltage of the stabilized power supply circuit with a reference signal representing a reference voltage and outputting an error signal representing a difference between the two. In a stabilized power supply circuit that supplies an output voltage controlled to a predetermined value via the output means by controlling the output means with an error signal of the comparison and amplification means, the output side of the comparison and amplification means Providing a sub-output means in parallel with the output means and connecting the output terminals of these output means and the sub-output means via a phase compensation resistor,
An output terminal of the output means is used as an output terminal of the stabilized power supply circuit, and a phase compensation signal generated by the phase compensation resistor is returned as a feedback signal. .

A fifth aspect of the present invention is the stabilized power supply circuit according to the fourth aspect, wherein each of the output means and the sub-output means is constituted by a driver transistor.

According to a sixth aspect of the present invention, in the fifth aspect, the output means and the sub-output means are transistors having different current capacity ratios, so that a relatively small current flows through the sub-output means. And a stabilized power supply circuit.

In the stabilized power supply circuit according to the present invention, ES
Even if a low ESR capacitor is used as an output stabilizing capacitor without inserting a resistor equivalent to R, phase compensation can be performed and the output power supply can be stabilized.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the phase compensation signal generated by the phase compensation resistor is returned as a feedback signal to a stage before or after the comparison amplification means. A stabilized power supply circuit characterized in that:

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the phase compensation signal generated by the phase compensation resistor is returned via a capacitor. It is in the stabilized power supply circuit.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the phase compensation signal generated by the phase compensation resistor is returned via an amplification or attenuation circuit and a capacitor. And a stabilized power supply circuit.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments, but the present invention is not limited to these embodiments.

Embodiment 1 FIG. 1 shows a schematic configuration of a voltage regulator which is a stabilized power supply circuit according to Embodiment 1.

This voltage regulator is used for comparison amplification.
An amplifier OP as a means, and as an output means, for example,
With driver transistor Tr composed of MOSFET
The inverting input terminal of the amplifier OP has a reference voltage source V_refBut
It is connected. Here, the output terminal of the amplifier OP is dry.
Connected to the gate of transistor Tr, and V
_ccAnd the drain is used as the output terminal 20.
0 is the output terminal T of the voltage regulator_outConnected to
Have been. The output terminal T_outOf the resistor R ₁as well as
Resistance R_TwoVoltage based on the division ratio determined by the resistance of the amplifier
So that it is fed back to the non-inverting input terminal of the OP.
Has been established.

The phase compensation resistor R ₃ is connected between the output terminal 20 of the driver transistor Tr and the output terminal T _out.
Is provided, the output terminal 20 via a capacitor C, is connected to the middle of the feedback circuit to the amplifier OP resistors R _1. That it is configured to phase compensating resistor R ₃ by generating a phase compensation signal returning the phase compensation signal to the amplifier OP as a feedback signal via the capacitor C.

The stabilized power supply circuit described above is manufactured as a semiconductor integrated circuit (IC). Further, such a stabilized power supply circuit to the output terminal T _out, is used in the capacitor C _L and the load R _L is a low-ESR capacitors are connected. Here, examples of the low ESR capacitor include a multilayer ceramic capacitor and an OS capacitor.

In such a configuration, the amplifier OP compares the feedback signal representing the output voltage _Vout with the reference signal representing the reference voltage _Vref and outputs an error signal. The error signal is output from the gate of the driver transistor Tr. And the output voltage V _out of the driver transistor Tr is controlled to a predetermined value.

Here, considering the case where a phase delay occurs in the feedback signal, since the capacitor C _L has a low ESR, it is not possible to perform the phase compensation using the zero point by the ESR as described in the prior art. . However, in this embodiment, to generate a phase compensation signal in phase compensating resistor R _3, are configured to return to the amplifier OP as a feedback signal to the phase compensation signal via the capacitor C as a transmission element Therefore, phase compensation can be performed as in the related art, and a stabilized output can be obtained. Incidentally, so as to operate in this manner, it is of course appropriately designing the capacitance value of the resistance value and the capacitor C of the phase compensation resistor R _3.

As described above, the use of the stabilized power supply circuit of the present invention has an effect that a stable voltage can be obtained by performing phase compensation even if a small low-ESR capacitor is used as an external capacitor.

The driver transistor Tr includes n-MOS, p-MOS and bipolar NPN.
And a transistor such as PNP.

(Embodiment 2) FIG. 2 shows a schematic configuration of a voltage regulator which is a stabilized power supply circuit according to Embodiment 2. In the voltage regulator shown in FIG. 2, a sub-driver transistor is provided in parallel with the driver transistor of the first embodiment.

That is, a driver transistor Tr ₁ and a sub-driver transistor Tr ₂ are connected in parallel to the output side of the amplifier OP, and the output terminal 20 A of the driver transistor Tr _{1 and} the output terminal 20 B of the sub-driver transistor Tr ₂ are connected. in the provided phase compensating resistor R _3, together with so as to directly connect to the driver transistor Tr ₁ of the output terminal 20A of the output terminal T _out, the sub-driver transistor Tr ₂ of the output end 20B to connect the capacitor C feedback signal Is configured to return.

Preferably, the driver transistor T
It is preferable that the current capacity ratio between r ₁ and the sub-driver transistor Tr ₂ is set to, for example, about 100: 1 so that most of the current from the external power supply flows through the driver transistor Tr ₁ . For example, it is possible to suitably differently designed ratio of the channel width and channel length of both the driver transistor Tr ₁ and the sub-driver transistor Tr ₂ as MOS transistors.

In such a configuration, the phase compensation resistor R ₃
To generate a phase compensation signal and return the phase compensation signal to the amplifier OP as a feedback signal via the capacitor C as a transmission element. And a stabilized output can be obtained.

On the other hand, most of the output voltage is an effect that it is possible to take out not through the phase compensating resistor R ₃ from the output end 20A of the driver transistor Tr _1, it is possible to minimize the loss.

The driver transistors Tr ₁ , Tr ₂
In addition to n-MOS and p-MOS, transistors such as bipolar NPN and PNP can be used.

Third Embodiment FIG. 3 shows a schematic configuration of a switching regulator which is a stabilized power supply circuit according to a third embodiment. The switching regulator shown in FIG. 3 is the same as that of the first embodiment except that a booster unit S is provided instead of the driver transistor of the first embodiment. .

As shown in FIG. 3, the boosting section S includes an amplifier O
A switching controller SC and a switch SW controlled by this switching signal are provided as a switching circuit connected to the output side of P. Further, a coil L connected in series with the switch SW and supplied with current from an input power supply _Vcc And a diode D that rectifies the output from the coil L and outputs it to the output terminal _Tout .

In this case, the switching controller SW
When the switch SW is turned on by the switching signal of (1), a current is supplied from the input power supply _Vcc.
Stores energy. Next, when the switch SW is turned off by the switching signal of the switching controller SW, the energy stored in the coil L is released via the diode D.

Here, the amplifier OP outputs an error signal which is a deviation between a feedback signal representing the output voltage _Vout and a reference signal representing the reference voltage _Vref , and controls the switching controller SC with the error signal. Therefore, the output voltage _Vout can be adjusted to a constant value based on the reference voltage _Vref .

Further, the phase compensation signal is generated by the phase compensating resistor R _3, which is configured to return to the amplifier OP as a feedback signal via the capacitor C of the phase compensation signal as a transfer element, Phase compensation can be performed as in the first embodiment, and a stabilized output can be obtained.

With the switching regulator described above,
Are, for example, coils L, diodes D, switches SW and
And resistor R for phase compensation_ThreeExcept for semiconductor integrated circuit (IC)
Coil L, diode D, switch SW and
And resistor R for phase compensation_ThreeMay be external or
And the resistor R₁And resistance R_TwoOr an external device.
The configuration of the switching regulator is optional.
You. Of course, capacitor C _LThe switching regulator
May be included.

In the present embodiment, a step-up switching regulator has been described as an example, but it goes without saying that a step-down switching regulator or an inverting switching regulator may be used.

[0044] (Other embodiments) Each embodiment described above, it is the non-inverting input terminal of the amplifier OP is a comparative amplifying means for controlling the output means to the phase compensation signal generated by the phase compensating resistor R ₃ Although it was made to return, before or after the amplification means, or the output side of the circuit of the output means,
It goes without saying that the phase can be compensated in the same manner no matter which way it is returned.

When returning to the comparison and amplification means, the signal may be returned to the inverting input terminal side instead of the non-inverting input terminal, or the phase compensation signal itself may be amplified, attenuated, or divided back. The divided signal may be returned to a plurality of locations, or may be returned to the output side of the output means via another circuit, and the way of feedback is not particularly limited.

[0046] Further, there is no particular limitation how extraction of the phase compensation signal generated by the phase compensating resistor R _3.

A plurality of phase compensation resistors may be provided, and the phase compensation resistors generated by the respective phase compensation resistors may be returned together or separately.

For example, FIG. 4 shows an example in which the phase compensation signal generated by the phase compensation resistor R ₃ is returned to the amplifier OP via the amplifier OP ₁ and the capacitor C. In this case, it is possible to easily change the amount of return of the phase compensation signal generated by the phase compensating resistor R _3. The position of the amplifier OP ₁ and the capacitor C may be reversed.

In FIG. 5, a sub-driver transistor Tr ₃ is provided in addition to the configuration of the second embodiment, and a phase compensation resistor R _{4 is provided} between the output terminal of the sub-driver transistor Tr _{3 and} the output terminal of the driver transistor Tr _1. the provided, in which then returned to the amplifier OP a phase compensation signal generated by the phase compensating resistor R ₄ via the capacitor C _2. By providing the plurality of sub-driver transistors Tr ₂ and Tr ₃ and the plurality of phase compensating resistors R ₃ and R ₄ corresponding to the respective sub-driver transistors Tr ₂ and Tr ₃ , the phase compensating signals generated by the respective sub-driver transistors Tr ₂ and Tr ₃ are supplied to the capacitor C ₁
And by the back to the amplifier OP at C _2, it is possible to change the frequency band of the phase compensation signal is taken out, an effect that can be readily produced the desired frequency characteristics. Of course, in addition to it it is needless to say that may be returned to the phase compensation signal generated by each provided with a phase compensation resistor R ₄ via the amplifier circuit or attenuation circuit of the phase compensation resistor R _3. Further, a plurality of three or more sub-driver transistors may be provided, and a plurality of phase compensation resistors corresponding to each or a part of these sub-driver transistors may be provided.

[0050]

As described above, in the stabilized power supply circuit of the present invention, phase compensation can be performed even if a low ESR capacitor is used as an output stabilizing capacitor without inserting a resistor equivalent to ESR. Thus, the output power can be stabilized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a voltage regulator that is a stabilized power supply circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a voltage regulator that is a stabilized power supply circuit according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a schematic configuration of a switching regulator that is a stabilized power supply circuit according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a schematic configuration of a voltage regulator that is a stabilized power supply circuit according to another embodiment of the present invention.

FIG. 5 is a diagram illustrating a schematic configuration of a voltage regulator that is a stabilized power supply circuit according to another embodiment of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a voltage regulator according to the related art.

FIG. 7 is a diagram illustrating a schematic configuration of a switching regulator according to a conventional technique.

[Explanation of symbols]

OP, OP ₁ amplifier Tr driver transistor R ₁ , R ₂ resistor R ₃ , R ₄ Phase compensation resistor C, C ₁ , C ₂ capacitor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Naka 5-1-1, Bakurocho, Nihonbashi, Chuo-ku, Tokyo Bakurocho Yuraku Bldg. 5th floor F.E. GG08 HH03 LB05

Claims (9)

[Claims] 1. A comparison amplification means for comparing a feedback signal representing an output voltage of the stabilized power supply circuit with a reference signal representing a reference voltage and outputting an error signal representing a difference between the two. In a stabilized power supply circuit for supplying an output voltage controlled to a predetermined value via the output means by controlling the output means with an error signal of the means, an output terminal of the output means and an output terminal of the stabilized power supply circuit And a phase compensation signal generated by the phase compensation resistor and returning the phase compensation signal as a feedback signal. 2. The stabilized power supply circuit according to claim 1, wherein said output means comprises a driver transistor. 3. The stabilized power supply circuit according to claim 1, wherein said output means includes an inductance, a rectifying element, and a switching circuit. 4. A comparison amplification means for comparing a feedback signal representing an output voltage of the stabilized power supply circuit with a reference signal representing a reference voltage and outputting an error signal representing a difference between the feedback signal and the reference signal. A stabilized power supply circuit that supplies an output voltage controlled to a predetermined value through the output means by controlling the output means with an error signal of the means; Output means are provided, and the output terminals of the output means and the sub-output means are connected to each other via a resistor for phase compensation. The output end of the output means is used as the output end of the stabilized power supply circuit and A stabilized power supply circuit wherein a phase compensation signal generated by a resistor is returned as a feedback signal. 5. The stabilized power supply circuit according to claim 4, wherein said output means and said sub-output means are each constituted by a driver transistor. 6. The stabilization method according to claim 5, wherein said output means and said sub-output means are transistors having different current capacity ratios, and a relatively small current flows through said sub-output means. Power circuit. 7. The stability according to claim 1, wherein the phase compensation signal generated by the phase compensation resistor is returned as a feedback signal to a stage before or after the comparison and amplification means. Power circuit. 8. The stabilized power supply circuit according to claim 1, wherein a phase compensation signal generated by the phase compensation resistor is returned via a capacitor. 9. The stabilization method according to claim 1, wherein the phase compensation signal generated by the phase compensation resistor is returned via an amplification or attenuation circuit and a capacitor. Power circuit.