JPH09298430A - IC amplifier circuit - Google Patents

Abstract

(57) [Abstract] [Problem] A conventional voice coil motor driver IC is
When the frequency characteristic of the current amplification factor in the inductive load (coil) is measured, the current gain has a peak of about 20 dB. The presence of this gain peak delays the phase of the output waveform of the voice coil motor driver in the frequency region higher than the gain peak, and cannot reproduce the waveform faithfully to the input. There is also a problem that noise is generated from the coil due to this distortion. In an integrated BTL type inductive load driving amplifier circuit, a ratio of an input resistance and a feedback resistance (R
2 / R1 and R3 / R4) are intentionally shifted by 1% or more and 10
The connection of the external capacitor of 0 nF order or more is omitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention occurs when an electric current is passed through an IC amplifier circuit having a semiconductor integrated circuit technology and further having an external terminal to which an inductive element is connected and for passing a current through the inductive element. The present invention relates to a technique effective for reducing noise, for example, a technique effectively used for a power amplifier circuit (voice coil motor driver) integrated into an IC that drives a voice coil motor used in a hard disk memory device.

[0002]

2. Description of the Related Art In a hard disk memory device, a magnetic disk is rotated by a spindle motor, and information recorded concentrically on the magnetic disk is read / written by a magnetic head at the tip of an arm called an actuator. . The actuator is mainly composed of a linear motor that performs parallel movement called a voice coil motor, and has a function of moving the magnetic head in the radial direction of the magnetic disk.

When positioning the magnetic head, there are the following two items required for a linear power amplifier called a voice coil motor driver. (1) The current can be faithfully amplified according to the input signal. (2) Minimize the phase delay in the region where the input frequency characteristic drops.

The applicant of the present invention has proposed an amplifier circuit suitable for the above voice coil motor driver, as shown in FIG.
We have developed a TL (Balanced Transformerless) type current feedback power amplifier. This voice coil motor driver is provided with a differential amplifier PA2 that inverts the output Vo of the differential amplifier PA1 to form an output −Vo whose phase is shifted by 180 ° with respect to Vo, as shown in FIG. 7B. These outputs Vo and -Vo are applied to both ends of the coil L to drive a current, and the current Io flowing through the current sensing resistor RS connected in series with the coil L is detected by the resistors R2 and R4 to obtain a difference. The feedback is made to the dynamic amplifier PA1. The current sensing resistor RS is provided to give a desired seek amount to the arm of the magnetic head by negatively feeding back the differential amplifier PA1. Since it is desirable that the resistance RS for current sensing has a resistance value as small as possible and high accuracy in order to reduce current loss, it is difficult to incorporate it in a semiconductor chip.

The voice coil motor driver of FIG. 7 can apply a large driving voltage to the coil L with a relatively small power supply voltage to drive it, and has frequency characteristics such that the ratio of the resistors R1 and R2 and the ratio of R3 and R4. It is suitable for semiconductor integrated circuit because it is determined by. This is because the resistance formed on the semiconductor chip has a relatively large variation, but the resistance ratio can be formed with relatively high accuracy. However, the accuracy of the pair of resistors formed on the semiconductor chip (the accuracy of the ratio of two resistors) is about 0.5% in the normal process, but the accuracy is 0% in the design stage. .

Conventionally, in a differential amplifier having symmetry such as the amplifier PA1 shown in FIG. 7, R1 / R2 = R3 /
R4 is a general configuration, and even in the voice coil motor driver IC previously developed by the applicant,
The configuration is 1 / R2 = R3 / R4. The operating characteristic of the voice coil motor driver of FIG. 7 can be expressed by the following equation in terms of DC. That is, Io = (Vctl-Vref) × (R2 / R1) / RS where, Io: current flowing in the voice coil motor Vctl: input voltage applied to the input terminal IN1 Vref: reference voltage applied to the input terminal IN2.

[0007]

However, in the voice coil motor driver IC of FIG. 7, when the frequency characteristic of the current amplification factor in the inductive load (coil) is measured, the gain of the current becomes 20 dB as shown in FIG. It has some peaks. The presence of this gain peak delays the phase of the output waveform of the voice coil motor driver in the frequency region higher than the gain peak, and cannot reproduce the waveform faithfully to the input.
Further, it has been revealed that there is a problem that noise is generated from the coil due to this distortion. Further, since the characteristics of the gain peak and the phase delay depend on the constant of the coil used, it is desirable that the frequency characteristics can be changed by an external element for each product series.

Therefore, it is conceivable to externally connect a capacitor and a resistor in parallel with the coil. However, in the BTL type power amplifier, the voltage applied to both ends of the coil becomes larger than the power supply voltage, and therefore, a high withstand voltage of several hundreds nF or more must be used as the capacitor connected in parallel with the coil. There is a problem in that the use of such a high withstand voltage increases the cost.

An object of the present invention is to drive an inductive load B
It is an object of the present invention to provide a technique for reducing a gain peak of a current flowing through an inductive load in a TL type amplifier circuit. Another object of the invention is a BTL driving an inductive load.
It is an object of the present invention to provide a technology that enables removal of noise generated by an inductive load and adjustment of phase delay in a type amplifier circuit by using a relatively inexpensive external element.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0011]

DISCLOSURE OF THE INVENTION The inventors of the present invention have studied in detail the cause of a gain peak in a BTL type amplifier circuit for driving an inductive load.
The phase delay in the L-type amplifier circuit includes a delay due to the pole of the amplifier and a phase delay due to the impedance of the inductive load, but the phase delay due to the impedance of the inductive load becomes more noticeable as the input signal becomes higher in frequency. I found that it was the cause.

Therefore, the present invention has two input pins, two output pins, and a sense pin for sensing current, and input resistors (R1, R3) are respectively provided between the input pin and the non-inverting input terminal and the inverting input terminal. Feedback resistors (R2, R4) are connected between the non-inverting input terminal and the inverting input terminal and both ends of the current sensing resistor (RS) externally attached to the sense pin, and a differential amplifier (PA1) is provided. And a differential amplifier (PA2) that inverts and amplifies the output voltage of the differential amplifier, and an inductive load (connectable between the two output pins to which the output terminals of these differential amplifiers are respectively connected ( The current flowing through the coil is detected by the current sensing resistor (RS), and the current is fed back to the differential amplifier. BTL type inductive load drive In the amplifier circuit, the first differential amplifier (PA1) the non-inverting input terminal and the ratio of the input resistor and the feedback resistor in the inverting input terminal of the (R2
/ R1 and R3 / R4) differ by 1% or more 100n
The connection of external capacitors of F order or more is omitted.

According to the above means, since the ratio of the input resistance and the feedback resistance (R2 / R1 and R3 / R4) is shifted by 1% or more, the phase delay due to the impedance of the inductive load can be reduced, Even if a signal containing a high frequency component is input to the differential amplifier from the input terminal, the gain of the current flowing through the inductive load (coil) will increase specifically at a certain frequency without connecting a large external capacitance. The peak can be suppressed to about 1 dB, and the noise generated due to this gain peak can be reduced.

A small resistor (R) is provided between the feedback resistor (R4) on the inverting input terminal side of the differential amplifier and the sense pin.
5) is inserted, a pin to which the coupling node of these resistors (R4 and R5) is connected is provided, and an external capacitor (Cf) for adjustment and an external resistor (Rf) are connected in series between this pin and the output pin. Connect to. In this case, the adjustment resistor (Rf) may be provided inside the semiconductor chip. In addition, as another method without providing a new pin, a small resistance (R
5) may be externally attached together with the external capacitance and resistance (Cf, Rf).

According to the above means, the gain peak can be suppressed to about 0.5 dB, and the external resistance (Rf) is several tens KΩ and the external capacitance (Cf) is several nF.
It is possible to reduce the size to some extent, and it is possible to suppress the generation of noise without using an expensive capacitor. Also, by setting the external capacitance and resistance (Cf, Rf) to appropriate values, it becomes possible to adjust the frequency characteristics of the phase from a steep change to a gentle change.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a voice coil motor driver comprising a BTL type current feedback power amplifier according to the present invention. The voice coil motor driver of this embodiment has substantially the same configuration as the voice coil motor driver shown in FIG. That is, two input pins Pi1 and Pi2 and two output pins Po1 and Po2
And a sense pin Ps for performing current sensing, and an input resistance R is respectively provided between the input pins Pi1 and Pi2 and the non-inverting input terminal (+ terminal) and the inverting input terminal (-terminal).
1, R3 are connected, and feedback resistors R2 and R4 are connected between the non-inverting input terminal and the inverting input terminal and both ends of the external current sensing resistor RS, respectively.
A differential amplifier PA1 whose current amplification factor is determined by the ratio of R3 and feedback resistors R2 and R4, and this differential amplifier PA1.
Differential amplifier PA2 that inverts and amplifies the output voltage of the differential amplifier PA2, and the output terminals of the differential amplifiers PA1 and PA2 are connected to the two output pins Po1 and Po2, respectively.

The internal reference voltage Vrefint is applied to the non-inverting input terminal of the differential amplifier PA2, and the output of the differential amplifier PA1 is input to the inverting input terminal via the resistor R and the inverting input terminal and the output are also provided. The resistance R ′ connected between the terminal and the terminal has the same resistance value as R, so that a gain of −1 is obtained. Then, VC as an inductive load connected between the output pins Po1 and Po2
The current Io that drives the M coil L and flows therein is detected by the current sensing resistor RS, and the differential amplifier PA
1, PA2 is configured to feed back a current.
Further, in this embodiment, a minute resistor R5 for reducing the gain peak is inserted between the feedback resistor R4 and the sense pin Ps. A voltage such as Vcc / 2 is selected as the internal reference voltage Vrefint.

In the circuit of FIG. 1, input pins Pi1 and P1
The voltage of i2 is Vin and Vref, respectively, and R3 = R
When 1, R4 = R2, the voltage at the non-inverting input terminal of the differential amplifier PA1 is Vp, the voltage at the inverting input terminal is Vm, and the minute resistor R5 is ignored on the non-inverting input terminal side and the inverting input terminal side, respectively. When the formula is established, -Vo = (Vin-Vp) R2 / R1 (+ side) -Vo = (Vref-Vm) R2 / R1 + Io.Rs (-side).

From this, the following equation (Vin-Vp) R2 / R1 = (Vref-Vm) R2 / R1 + Io
・ Rs is obtained. Here, considering that the non-inverting input terminal side and the inverting input terminal of the differential amplifier are imaginary short and have the same voltage, that is, Vp = Vm, it can be expressed as (Vin-Vref) R2 / R1 = Io.Rs. From this, it is understood that Io = (R2 / R1). (Vin-Vref) / Rs ... (1), and the current Io flowing through the coil does not depend on the impedance of the coil. That is, in the voice coil motor driver of this embodiment, even if the coil L is changed, the flowing current is the same.

On the other hand, when the output Vo of the differential amplifier PA1 is calculated with the equivalent resistance of the coil L as RL and the current flowing through the coil L as Io, Vo = (RL + Rs) Io is obtained. Substituting the above (1) into Io of this equation gives Vo = (R2 / R1). (RL + Rs). (Vin-Vref) / Rs ... (2). Further, the gain Gv of the differential amplifier is Gv =
Since it is Vo / (Vin-Vref), Gv = (R2 / R1). (RL + Rs) / Rs from the above equation (2). From this, it can be seen that the gain Gv is proportional to R2 / R1. Therefore, the accuracy of the resistance ratio is important in the voice coil motor driver.

In the voice coil motor driver of this embodiment as well, it is necessary to adopt a process in which the accuracy of the ratio of the resistors R1 and R2 and the ratio of R3 and R4 is 0.5% or more, and ideally 0%. Is desirable.

In the embodiment of FIG. 1, the small resistor R5 inserted to reduce the gain peak is R1 and R2.
R1 = R3 = 40KΩ, R2 = R, depending on the ratio value of
When 4 = 20 KΩ, it may be set to about 500Ω. According to the simulation, 1% to 4% of the resistance R4
Good results can be obtained with moderate resistance values. R5 = 5
In case of 00Ω (2.5% of R4), (R4 + R5) / R
3 ÷ R2 / R1 = 20.5 / 40 ÷ 20/40 = 1.0
25, and the balance between the ratio of the resistors R1 and R2 and the ratio of R3 and R4 is 2.5%.

In the above case, the order of the resistors R4 and R5 may be reversed, or R4 and R5 may be formed as one integrated resistor. As another method, a minute resistor R5 may be inserted between the input pin Pi1 and the resistor R1. Also in this case, the order of the resistors R1 and R5 may be reversed or integrated. As the resistors R1 to R4, specifically, resistors having a resistance value of about 1 KΩ to 100 KΩ are used. The current sensing resistor RS varies depending on the VCM coil, but is set to 0.
A resistor having a small resistance value of about 1 to 10Ω is used.

With these methods, R1 / R2 = R3 / R4
In case of, the amplifier of FIG.
If the current gain peak which was 0 dB is set to about 2% of the resistance R5 of the resistor R4, it is 1 dB as shown by the dotted line in FIG.
It was confirmed by simulation that the size could be reduced to a certain degree.

It is possible to make the gain peak smaller as the ratio of the resistors R1 and R2 and the ratio of R3 and R4 become smaller, but in this case, when the input is 0, the offset current flowing in the power amplifier is small. It becomes a problem. The offset current is generated by the difference between the input reference voltage and the internal reference voltage. Offset current (Ioff) is input reference voltage (Vr
ef) and the internal reference voltage (Vrefint), the following formula is obtained.

Ioff = ((Vref-Vrefint). ((R1 + R2) / R
1- (R3 + R4 + R5) / R3)) / RS In this formula, RS = 1Ω, R1 = R3 = 40KΩ, R2 = R4 = 20KΩ, R5 = 5
Setting 00Ω, Vref = 6V, Vrefint = 6V, Ioff = ((6-4) ・ ((40 + 20) / 40- (40 + 20 + 0.5) / 40)) / 1 = 25 (mA) Become. The voice coil motor driver is normally controlled by the DA converter, but if this offset increases, the control range of the DA converter is narrowed.
It is necessary to make it about 10 mA or less.

FIG. 2 shows an embodiment in which the current gain peak can be further lowered. In this embodiment, means for adjusting the phase delay is added to the embodiment of FIG. That is, the minute resistor R5 is inserted between the resistor R4 and the sense pin Ps, and a new pin Ps ′ is provided.
Connect the connection node of resistors R4 and R5 to pin Ps',
An external capacitance C is provided between this pin Ps' and the output pin Po1.
f and an external resistor Rf are connected in series. Cf and Rf operate as a high-pass filter and can reduce the apparent impedance of the coil in the high frequency region and reduce the gain peak. In this embodiment, the feedback amount can be adjusted by the ratio of the resistors R5 and Rf. Incidentally, as shown in FIG. 3, the resistor Rf may be formed on the semiconductor chip and incorporated in the semiconductor device. As another method without providing the pin Ps ′, as shown in FIG.
5 is also an output pin Po as an external element like Cf and Rf.
1, Po2 may be connected.

In the embodiment shown in FIGS. 2, 3 and 4, the external resistance Rf is 30 KΩ and the capacitance Cf is 4.7 nF.
By setting to, the gain peak can be suppressed to about 0.5 dB. In addition, the power amplifier of FIG. 7 required an external capacitance of the order of several 100 nF, but the external capacitance Cf used in this embodiment can be reduced to about several nF, resulting in an expensive high breakdown voltage. It is possible to suppress the generation of noise without using a capacitor. Further, by changing Cf and Rf to appropriate values, it becomes possible to adjust the frequency characteristic of the phase from a steep change to a gentle change. However, in the embodiment of FIG. 1, the phase delay is about 2 ° at a frequency of 1 KHz, whereas in the embodiment of FIGS.
The phase delay is about 5 ° at KHz, and the phase delay is slightly larger than that in the embodiment of FIG. That is, when the frequency characteristics of the phase are smoothed, the gain peak is 0d.
It is possible to lower the value to B, but the phase delay at a frequency of 1 KHz increases, which may affect the control of the head position in the hard disk memory device. Therefore, when it is desired to suppress the phase delay more than the gain peak, the embodiment of FIG. 1 may be applied.

FIG. 5 shows the configuration of another embodiment of the present invention.

In the embodiment shown in FIGS. 1 to 4, since the minute resistor R5 is inserted, the voltage drop thereof lowers the potential of the inverting input terminal of the differential amplifier PA1 and increases the offset current. Therefore, in the present embodiment, a level-shifting differential amplifier OP is provided in front of the differential amplifier PA1 to which the current is fed back, and the output voltage of the differential amplifier OP is provided by the resistor R14 provided on the non-inverting input terminal side thereof. To offset the voltage drop due to the resistor R5 and reduce the offset current. In addition,
In this embodiment, since the input signal is inverted by the differential amplifier OP, the output of the differential amplifier OP is input to the inverting input terminal side of the differential amplifier PA1 and internally output to the non-inverting input terminal side of the differential amplifier PA1. The reference voltage Vrefint is input.

FIG. 6 shows the configuration of still another embodiment of the present invention.

The configuration of the power amplifier of this embodiment is different from the above-described embodiments of FIGS. 1 to 5 in the coil connecting method.
Operationally, they are the same. In the embodiment of FIG. 6, a current sensing resistor Rs is connected between the output pin Po1 and the sense pin Ps, and the sense pin Ps and the output pin Po2 are connected.
And a coil L is connected between and. In the embodiment shown in FIG. 6, the input pin P1 receives the reference voltage and the input pin P1 receives the reference voltage.
An AC signal is input to i2. In this example,
By inserting the small resistor R5 between the resistor R4 and the output pin Po1, it becomes possible to suppress the peak of the current gain.

As described above, the above embodiment has two input pins, two output pins, and a sense pin for current sensing, and the input resistance is provided between the input pin and the non-inverting input terminal and the inverting input terminal, respectively. (R1, R
3) is connected and feedback resistors (R2, R4) are respectively connected between the non-inverting input terminal and the inverting input terminal and both ends of the current sensing resistor (RS).
1) and a differential amplifier (PA2) that inverts and amplifies the output voltage of this differential amplifier, and the inductive property connected between the two output pins to which the output terminals of these differential amplifiers are respectively connected. In the BTL type inductive load driving amplifier circuit configured to detect the current flowing in the load (coil) by the current sensing resistor (RS) and feed the current back to the differential amplifier, the first difference The ratio of the input resistance to the feedback resistance (R2 / R1 and R3 / R4) at the non-inverting input terminal and the inverting input terminal of the dynamic amplifier (PA1) is made different by 1% or more, and an external capacitance of 100 nF order or more is connected. Since I omitted it,
The phase delay due to the impedance of the inductive load can be reduced, and even if a signal containing high frequency components is input to the differential amplifier from the input terminal, the inductive load (coil) can be connected without connecting a large external capacitance. The gain peak of the current flowing in the loop becomes 1 at a certain frequency.
It can be suppressed to about dB. As a result, it is possible to reduce the noise generated due to this gain peak.

In the above embodiment, a small resistor (R5) is inserted between the feedback resistor (R4) on the inverting input terminal side of the amplifier and the sense pin, and the connection node of these resistors (R4 and R5) is connected. Is provided, and an external capacitance (Cf) for adjustment and an external resistor (R) are provided between this pin and the output pin.
Since f) is connected in series, the gain peak can be further suppressed to about 0.5 dB, and the external resistance (Rf) is reduced to several tens KΩ and the external capacitance (Cf) is reduced to several nF. It is possible to suppress the generation of noise without using an expensive capacitor. Further, by setting the external capacitance and resistance (Cf, Rf) to appropriate values, it becomes possible to adjust the frequency characteristic of the phase from a steep change to a gentle change.

Further, in the prior art, it took a long time for the current value to converge because the output waveform of the amplifier had an excessive response called ringing. However, in the above embodiment, the amount of the excessive response becomes small. Thus, the convergence time can be shortened, and the seek time can be shortened in the hard disk memory device.

In order to perform high-speed access in the hard disk memory device, it is necessary to increase the input frequency, but according to the present invention, it is possible to input a frequency that could be uncontrollable in the past. Therefore, the control circuit can be simplified.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say. For example, in the above-described embodiment, the resistor R5 is inserted in series with the feedback resistor R4 on the inverting terminal side of the differential amplifier PA1 or in series with the input resistor R1 on the non-inverting terminal side of the differential amplifier PA1 to break the balance. However, the resistor R5 is inserted in parallel with the feedback resistor R2 on the non-inverting terminal side of the differential amplifier PA1 or in parallel with the input resistor R2 on the inverting terminal side of the differential amplifier PA1 so as to reduce the combined resistance and break the balance. May be.

In the above description, the case where the invention made by the present inventor is mainly applied to the voice coil motor driver used in the hard disk memory device which is the field of application of the invention has been described, but the invention is limited thereto. FDD, ZIP, JAZ
It can be used for a magnetic disk device such as Z, a driver for a magneto-optical disk device such as MOD or DVD, and other BTL type power amplifier circuits integrated into an IC.

[0040]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, in the BTL type amplifier circuit for driving an inductive load, the gain peak of the current flowing in the inductive load can be reduced, and noise generated in the inductive load can be removed and the phase delay can be adjusted. This can be done by a relatively inexpensive external element.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a voice coil motor driver including a BTL type current feedback power amplifier according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of a voice coil motor driver according to the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of a voice coil motor driver according to the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of a voice coil motor driver according to the present invention.

FIG. 5 is a circuit diagram showing a fifth embodiment of a voice coil motor driver according to the present invention.

FIG. 6 is a circuit diagram showing a sixth embodiment of a voice coil motor driver according to the present invention.

FIG. 7 is a circuit diagram showing an example of a conventional voice coil motor driver.

FIG. 8 is a diagram showing output current characteristics of a conventional voice coil motor driver.

[Explanation of symbols]

 PA1, PA2 Differential amplifier Pi1, Pi2 Input pin Po1, Po2 Output pin Ps Sense pin Rs Current sense resistor L Inductive load (coil)

Front Page Continuation (72) Inventor Kunio Seki 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Hitachi, Ltd. Semiconductor Division

Claims (6)

[Claims] 1. A control device comprising two control input terminals, two external output terminals and an external sense terminal for performing current sensing, wherein an inductive element is externally provided between one of the two external output terminals and the external sense terminal. A current sense resistor is externally connected between the external sense terminal and the other of the two external output terminals, and between the control input terminal and the non-inverting input terminal and the other of the two control input terminals. An input resistance connected to each of the inverting input terminals, and a feedback resistance connected to each of the non-inverting input terminal and the inverting input terminal and both ends of the current sense resistance; A second differential amplifier that inverts and amplifies the output voltage of the first differential amplifier, detects a current flowing through the inductive load by the current sense resistor, and outputs the detection signal to the upper side of the first differential amplifier. In an amplifier circuit formed on a semiconductor chip configured to perform negative feedback to the inverting input terminal, a ratio of the input resistance connected to the non-inverting input terminal of the first differential amplifier to the feedback resistance is An IC amplifier characterized in that the ratio of the input resistance connected to the inverting input terminal and the ratio of the feedback resistance are made different by 1% or more so that the connection of the external capacitance of 100 nF or more is omitted. circuit. 2. The input resistance at the non-inverting input terminal and the inverting input terminal of the first differential amplifier, in which a minute resistor is connected in series with a feedback resistor on the inverting input terminal side of the first differential amplifier. 2. The I according to claim 1, wherein the ratio of the feedback resistance to the feedback resistance is made different by 1% or more, and the connection of the external capacitance of 100 nF order or more is omitted.
C amplifier circuit. 3. The input at the non-inverting input terminal and the inverting input terminal of the first differential amplifier by connecting a minute resistor in series with the input resistance on the non-inverting input terminal side of the first differential amplifier. 2. The I according to claim 1, wherein the ratio of the resistance and the feedback resistance is made different by 1% or more so that the connection of the external capacitance of 100 nF order or more is omitted.
C amplifier circuit. 4. An external terminal to which a coupling node of the minute resistor and the feedback resistor is connected is added, and a capacitor or a capacitor and a resistor can be connected between the external terminal and the external output terminal. The integrated amplifier circuit according to claim 2. 5. A resistor is connected between a coupling node of the minute resistor and the feedback resistor and the external terminal, and a capacitor can be connected between the external terminal and the external output terminal. The integrated amplifier circuit according to claim 4, wherein. 6. A disk memory using the IC amplifier circuit according to claim 1 as a voice coil motor driver for driving a voice coil motor for moving an arm having a magnetic head at its tip. apparatus.