JP2002344253A - Semiconductor integrated circuit device and optical pickup apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost semiconductor integrated circuit device that is a light reception amplifier circuit being integrated monolithically, stably operates in a high-frequency region, and at the same time, has superior response properties. SOLUTION: This semiconductor integrated circuit device has a differential amplifier 2, that inputs a reference voltage Vref to a non-inverted input terminal via a resistor R1, inputs a current Ip sent by a photodiode 3 to a noninverted input terminal, and outputs a voltage Vout corresponding to the value of the current Ip to an output terminal; a resistor R2 that performs the negative feedback of the output voltage Vout , and an NPN type transistor Q1, where an emitter is connected to the connection point between the output terminal of the differential amplifier 2 and the resistor R2, a base is connected to the connection point between the inverted input terminal of the differential amplifier 2 and resistor R2; and a collector is connected to a terminal 5, where a specific voltage Vcc is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit device having an amplifier for inputting a current sent from a light receiving element and outputting a voltage corresponding to the current value, and an optical pickup device using the same. In particular, the present invention relates to a semiconductor integrated circuit device used in a high frequency region.

[0002]

2. Description of the Related Art An optical pickup device for irradiating a recording medium such as an optical disk with a light beam such as a semiconductor laser to perform recording and reproduction is provided with a photodiode which receives a laser beam reflected by the storage medium and outputs a current, and a photodiode. A light-receiving amplifier circuit that inputs a current sent by the photodiode and outputs a voltage corresponding to the current value. FIG. 5 shows a configuration of a conventional light receiving amplifier circuit.

A terminal 1 is connected to a non-inverting input terminal of a differential amplifier 2 via a resistor R1. Then, the cathode of the photodiode 3 is connected to the inverting input terminal of the differential amplifier 2. Incidentally, the anode of the photodiode 3 is connected to the ground. Further, the output terminal of the differential amplifier 2 is connected to the terminal 4, and one end of the resistor R2 and one end of the capacitor 6 are connected to a connection point between the output terminal of the differential amplifier 2 and the terminal 4. The other end of the resistor R2 and the other end of the capacitor 6 are connected to a connection point between the cathode of the photodiode 3 and the inverting input terminal of the differential amplifier 2.

Next, the operation of the light receiving amplifier circuit having such a configuration will be described. A reference voltage _Vref is applied to the terminal 1. Therefore, when the current input to the non-inverting input terminal of the differential amplifier 2 is I ₁ and the potential of the non-inverting input terminal of the differential amplifier 2 is V ₊ , the expression (1) is established. However, r ₁ is the resistance value of the resistor R1. V ₊ = V _ref -I ₁ × r ₁ (1)

When receiving light, the photodiode 3 outputs a current _Ip corresponding to the intensity of the light.

Here, the voltage output from the output terminal of the differential amplifier 2 (hereinafter referred to as the output voltage) is V _out , the current input to the inverting input terminal of the differential amplifier 2 is I ₂ , Assuming that the potential of the inverting input terminal is V ₋ , the output voltage V _out is negatively fed back to the differential amplifier 2 via the resistor R2. Therefore, when the photodiode 3 does not receive light, the equation (2) is used. Holds. However, r ₂ is the resistance value of the resistor R2. _{V out = V - + I 2} × r 2 ... (2)

Further, since the non-inverting input terminal and the inverting input terminal of the differential amplifier 2 are virtual ground points, the equation (3) holds. V ₊ −V ₋ = 0 (3) Assuming that the current input to the non-inverting input terminal of the differential amplifier 2 is equal to the current input to the inverting input terminal, Expression (4) holds. I ₁ = I ₂ (4)

Then, the output voltage V _out is expressed by the following equation (5) according to the equations (1) to (4). _{V out = V - + I 2} × r 2 = V + + I 1 × r 2 = (V ref -I 1 × r 1) + I 1 × r 2 = V ref + I 1 (r 2 -r 1) ... (5)

Therefore, the resistance value r ₁ of the resistor R1 and the resistance R2
The resistance value by equal r _2, it is possible to resistor R2 to correct the offset voltage (= I ₂ × r ₂₎ caused by the negative feedback output voltage V _out. As a result, the value of the output voltage _Vout when the photodiode 3 does not receive light matches the reference voltage _Vref .

Next, a case where the photodiode 3 is receiving light will be described. At this time, since the current I _p is withdrawn from the connection point between the inverting input terminal of a resistor R2 and a differential amplifier 2 to the photodiode 3 side, the current flowing through the resistor R2 (I ₂ + I _P), and the (6) Holds. _{V out = V - + (I} p + I 2) × r 2 ... (6)

Further, the above equations (1), (3),
Using equation (4), the output voltage V _out can be expressed as equation (7). Note that r ₁ = r ₂ as described above. V _out = V _ref + I _p × r ₂ (7)

The capacitor 6 connected in parallel to the resistor R2
Compensates for the phase of the negative feedback. Thereby, the operation of the light receiving amplifier circuit in the high frequency region is stabilized.

On the other hand, the light receiving amplifier circuit provided in the optical pickup device is generally constituted by a monolithic integrated circuit for miniaturization and cost reduction. When the light receiving amplifier circuit of FIG. 5 is a monolithic integrated circuit, the capacitor 6 must be formed of an insulating film such as a silicon nitride film. For this reason, it is necessary to add a process for forming an insulating film, which has led to an increase in manufacturing cost.

Therefore, a light receiving amplifier circuit as shown in FIG. 6 has been proposed. 6 is a monolithic semiconductor integrated circuit device, to which a photodiode 3 is connected. In FIG. 6, the same portions as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. 6 differs from the light receiving amplifier circuit of FIG. 5 in that an NPN transistor Q8 is provided instead of the capacitor 6. The emitter of the transistor Q8 is connected to the connection point between the output terminal of the differential amplifier 2 and the resistor R2.
The base and collector of the differential amplifier 8 are connected to a connection point between the inverting input terminal of the differential amplifier 2 and the resistor R2. The silicon chip substrate on which the light receiving amplifier circuit is formed (hereinafter referred to as the substrate) is at ground potential, and the photodiode 3 is at P
It consists of a PN junction of a mold substrate and an N-type epitaxial layer,
The anode of the photodiode 3 has the potential of the substrate, that is,
It becomes the ground potential.

With such a configuration, the transistor Q
8 can be used as the phase compensation capacitance. Further, since the transistor Q8 can be formed simultaneously with the process of forming the transistor included in the differential amplifier 2, the manufacturing cost does not increase.

The cutoff frequency f _{c of the} light receiving amplifier circuit
When the response speed of the photodiode 3 is sufficiently fast,
It is expressed as in equation (8). However, the resistance value of r ₂ are the resistance R2, C _BE is the base of the transistor Q8 - a emitter capacitance. f _c = 1 / (2π × r ₂ × C _BE ) (8)

A light receiving amplifier used in an optical pickup device
Resistance r of the resistor R2 provided in the loop circuit _TwoIs Photodaio
30 kΩ to 5 depending on the amount of laser light received by
It is set to 0 kΩ. Also, for optical pickup devices
The light receiving amplifier circuit used has a cutoff frequency of about 150 MHz.
Since it is required to have a wave number, the above (8)
From the equation, the base-emitter capacitance C of the transistor Q8 is obtained._BE
Needs to be 21 fF to 35 fF. In addition, equation (8)
As is clear from FIG.
Capacitance C_BEThe smaller the is, the cutoff frequency of the light receiving amplifier circuit
Will be higher.

When the light receiving amplifier circuit is constituted by a monolithic integrated circuit, the capacitance between the base and the emitter of the transistor provided in the differential amplifier 2 is about 10 to 20 fF, which is close to the capacitance between the base and the emitter of the transistor Q8. Therefore, the transistor Q8 can have the same structure as the transistor provided in the differential amplifier 2.

[0019]

However, in the light receiving amplifier circuit of FIG. 6, a parasitic capacitance C _CG between the collector and the substrate of the transistor Q8 is formed between the inverting input terminal of the differential amplifier 2 and the substrate, and The configuration is such that the capacitance C _CG is connected in parallel to the photodiode 3.

In the light receiving amplifier circuit shown in FIG. 5, when the response speed of the differential amplifier 2 is sufficiently high, the response speed of the light receiving amplifier circuit is determined by the junction capacitance C _jpd of the photodiode 3 and the internal resistance of the photodiode 3 (which constitutes the photodiode). to be determined by the integration circuit caused by the semiconductor resistor) R _pd, the cutoff frequency f _c of the light receiving amplifier circuit is expressed by equation (9). f _c = 1 / (2π × C _jpd × R _pd ) (9)

On the other hand, in the light receiving amplifier circuit of FIG. 6, the parasitic capacitance C _CG is connected in parallel to the photodiode 3 as described above, which is equivalent to an increase in the junction capacitance C _{jpd of the} photodiode 3. Thus, (9) cut-off frequency f _c is reduced in the light receiving amplifier circuit as is clear from FIG. 6 from expression, the response speed has fallen into drops.

In view of the above problems, the present invention is a monolithically integrated light receiving amplifier circuit, which operates stably in a high frequency region, is inexpensive and has excellent responsiveness, and uses the same. It is an object of the present invention to provide a conventional optical pickup device.

[0023]

In order to achieve the above object, in a semiconductor integrated circuit device according to the present invention, an amplifier for inputting a current sent from a light receiving element and outputting a voltage,
A resistance means for negatively feeding back the output voltage of the amplifier, an emitter is connected to a connection point between the output terminal of the amplifier and the resistance means, and a base is connected to a connection point between the input terminal of the amplifier and the resistance means. , An NPN transistor having a collector connected to a terminal to which a predetermined voltage is applied.

Further, as another configuration, an amplifier for inputting a current sent from the light receiving element and outputting a voltage, a resistance means for negatively feeding back the output voltage of the amplifier, an output terminal of the amplifier and the resistance means, An NPN transistor having a base connected to a connection point of the above, an emitter connected to a connection point between the input terminal of the amplifier and the resistance means, and a collector connected to a terminal to which a predetermined voltage is applied. To

In the semiconductor integrated circuit device having any one of the above structures, the transistor may be plural, and the base-emitter junction area of the transistor may be larger than the base-emitter junction area of the transistor included in the amplifier. .

Further, as still another configuration, an amplifier for inputting a current sent from the light receiving element and outputting a voltage, a resistance means for negatively feeding back the output voltage of the amplifier, an output terminal of the amplifier and the resistance means A first transistor of an NPN type having a base connected to a connection point between the first transistor and the N-type transistor having a base connected to a connection point between the input terminal of the amplifier and the resistance means.
A second transistor of a PN type;
And the emitters of the second transistor are connected to each other, and the collectors are connected to a terminal to which a predetermined voltage is applied.

According to another aspect of the present invention, there is provided an optical pickup device for irradiating a light beam to a storage medium, a light receiving element for receiving light reflected from the storage medium, and a light receiving element. And a semiconductor integrated circuit device having any one of the above configurations connected to the element.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a light receiving amplifier circuit according to a first embodiment of the present invention. The light receiving amplifier circuit of the first embodiment is a monolithic semiconductor integrated circuit device, and has a photodiode 3 connected thereto. The structure of the NPN transistor Q1 is the same as that of the NPN transistor Q1 provided in the differential amplifier 2.
It has the same structure as a PN transistor. In FIG. 1, the same portions as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

The emitter of the transistor Q1 is connected to a connection point between the output terminal of the differential amplifier 2 and the resistor R2, and the base of the transistor Q1 is connected to a connection point between the inverting input terminal of the differential amplifier 2 and the resistor R2. The collector of the transistor Q1 is connected to a terminal 5 to which a predetermined voltage _Vcc is applied. Further, the substrate is set to the ground potential, and the anode of the photodiode 3 is formed of a P-type substrate and has the ground potential.

With such a configuration, the photo diode
3 receives the light and the current I_pOutput
From the equation (7), the output voltage V_outIs V_out= V_ref+ I_p× r
_TwoAnd the differential increase from the above equations (1) and (3).
The potential V of the inverting input terminal of the width unit 2 _-Is V_-= V_ref-I₁× r
₁And the current I_pIs the current I₁Large enough compared to
Resistance value r₁And r_TwoIs equal to the threshold voltage of the transistor Q1,
Voltage V to the source-emitter capacitance_B(= R_Two× I_p) Is reverse
It will be applied as the bias voltage. That is,
When photodiode 3 receives light and outputs current
However, the transistor Q1 is reverse-biased. this
As a result, the base-emitter capacitance of the transistor Q1 is
It can be used as a phase compensation capacitor. This allows
The light receiving amplifier circuit of the first embodiment is stable in a high frequency region.
Operate.

The NPN provided in the differential amplifier 2
Since the transistor Q1 can be formed at the same time in the process of forming the transistor, the manufacturing cost does not increase. Thereby, the light receiving amplifier circuit of the first embodiment is a low-cost circuit.

Since the collector of the transistor Q1 is connected to the terminal 5 to which a predetermined voltage _Vcc is applied, a parasitic capacitance Q _CG generated between the collector of the transistor Q1 and the substrate.
Are connected to the terminal 5. Further, a transistor Q is provided between the cathode of the photodiode 3 and the terminal 5.
One base-collector capacitance C _BC is formed. That is, the capacitance C _BC between the base and the collector is
And the terminal 5 which is the _Vcc potential. This is equivalent to adding the base-collector capacitance C _BC between the cathode of the photodiode 3 and the ground. Since the base-collector capacitance C _BC is smaller than the parasitic capacitance Q _CG , the cutoff frequency of the light receiving amplifier circuit of the first embodiment is higher than the cutoff frequency of the conventional light receiving amplifier circuit shown in FIG. That is, the response speed of the light receiving amplifier circuit of the first embodiment is faster than the response speed of the conventional light receiving amplifier circuit of FIG.

Next, the configuration of a light receiving amplifier circuit according to a second embodiment of the present invention is shown in FIG. The light receiving amplifier circuit of the second embodiment is a monolithic semiconductor integrated circuit device, and has a photodiode 3 connected thereto. The structure of the NPN transistor Q2 is the same as that of the NPN transistor Q2 provided in the differential amplifier 2.
It has the same structure as the N-type transistor. In FIG. 2, the same portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The base of the transistor Q2 is the differential amplifier 2
Is connected to the connection point between the output terminal of the differential amplifier 2 and the resistor R2, the emitter of the transistor Q2 is connected to the connection point between the inverting input terminal of the differential amplifier 2 and the resistor R2, and the predetermined voltage _Vcc is applied to the collector of the transistor Q2. Connected to the terminal 5. Further, the substrate is set to the ground potential, and the anode of the photodiode 3 is formed of a P-type substrate and has the ground potential.

[0035] With such a configuration, when the photodiode 3 outputs a current I _p receives light, the output voltage V _out from the aforementioned equation (7) _{V out = V ref + I p} × r 2
From the above equations (1) and (3), the potential V ₋ of the inverting input terminal of the differential amplifier 2 is V ₋ = V _ref −I ₁ × r ₁
Further, since the current I _p is sufficiently larger than the current I ₁ and the resistance values r ₁ and r ₂ are equal to each other, the voltage V _B (= r ₂ × I _p ) is sequentially added to the base-emitter capacitance of the transistor Q2. It will be applied as a bias voltage. That is, when the photodiode 3 receives light and outputs a current, the transistor Q2 is forward-biased.

On the other hand, in order for transistor Q2 to be in an active state, the voltage between the base and the emitter needs to exceed about 0.7V. In the optical pickup device, the maximum current output from the photodiode 3 is set to about 20 μA. Accordingly, the resistance value r ₂ of the resistor R2 35kΩ (=
0.7 V / 20 μA) or less, the transistor Q2
Are forward biased but do not become active.

[0037] Therefore, in the light receiving amplifier circuit of the second embodiment sets the resistance value r ₂ of the resistors R2 below 35Keiomega. As a result, the base-emitter capacitance of the transistor Q2 can be used as a phase compensation amount, so that the light receiving amplifier circuit of the second embodiment operates stably in a high frequency region.

The NP provided in the differential amplifier 2
Since the transistor Q2 can be formed simultaneously in the process of forming the N-type transistor, the manufacturing cost does not increase. Thus, the light receiving amplifier circuit of the second embodiment is a low-cost circuit.

The collector of the transistor Q2 is
Voltage V_ccIs connected to the terminal 5 to which
The parasitic capacitance Q generated between the collector of the transistor Q2 and the substrate
_CGAre connected to the terminal 5. Therefore, the parasitic capacitance
Q_CGAre not connected to the photodiode 3 in parallel. Further
The cathode of the photodiode 3 has a transistor Q
2 are connected, the transistor Q2
Source-collector capacitance C _BCAlso in parallel with photodiode 3
Not connected. Thereby, the light receiving amplifier of the second embodiment
The cutoff frequency of the circuit is the same as that of the first embodiment shown in FIG.
It becomes higher than the cutoff frequency of the amplifier circuit. That is,
The response speed of the light receiving amplifier circuit of the second embodiment is shown in FIG.
Faster than the response speed of the light receiving amplifier circuit of the first embodiment.
You.

Next, FIG. 3 shows a configuration of a light receiving amplifier circuit according to a third embodiment of the present invention. The light receiving amplifier circuit according to the third embodiment is a monolithic semiconductor integrated circuit device, to which a photodiode 3 is connected. The structures of the NPN transistors Q3 and Q4 are the same as those of the NPN transistors provided in the differential amplifier 2. In FIG. 3, the same parts as those in FIG.
Description is omitted.

The base of the transistor Q3 is the differential amplifier 2
And the base of the transistor Q4 is connected to a connection point between the inverting input terminal of the differential amplifier 2 and the resistor R2. And the transistor Q
3 and Q4 are connected to each other to form a transistor Q
The collectors of 3 and Q4 are both connected to a terminal 5 to which a predetermined voltage _Vcc is applied. Further, the substrate is set to the ground potential, and the anode of the photodiode 3 is formed of a P-type substrate and has the ground potential.

[0042] With such a configuration, when the photodiode 3 outputs a current I _p receives light, the output voltage V _out from the aforementioned equation (7) _{V out = V ref + I p} × r 2
From the above equations (1) and (3), the potential V ₋ of the inverting input terminal of the differential amplifier 2 is V ₋ = V _ref −I ₁ × r ₁
Further, since the current I _p is sufficiently larger than the current I ₁ and the resistance values r ₁ and r ₂ are equal, the bias voltage applied between the base and the emitter of the transistor Q 3 and the transistor Q 3
4 and the bias voltage applied between the base and the emitter becomes the voltage V _B (= r ₂ × I _p ).

For this reason, in the light receiving amplifier circuit of the third embodiment, since the transistor Q3 is not forward biased by the action of the transistor Q4, the resistance R2
Possible setting maximum resistance r ₂ be greater than 35kΩ is set maximum value of the light receiving amplifier circuit of the second embodiment.

Since the phase compensation capacitance connected in parallel to the resistor R2 is a combined capacitance in which the base-emitter capacitances of the transistors Q3 and Q4 are connected in series, the phase compensation capacitance is higher than that of the light receiving amplifier circuits of the first and second embodiments. The compensation capacity can be reduced.

Furthermore, since the combined capacitance C _CG ′ in which the collector-substrate capacitances of the transistors Q 3 and Q 4 are connected in parallel is not connected in parallel to the photodiode 3, the cutoff frequency of the light receiving amplifier circuit of the third embodiment is The cutoff frequency of the conventional light receiving amplifier circuit shown in FIG. 6 can be made higher. That is, the response speed of the light receiving amplifier circuit of the third embodiment is faster than the response speed of the conventional light receiving amplifier circuit shown in FIG.

Next, the configuration of a light receiving amplifier circuit according to a fourth embodiment of the present invention is shown in FIG. The light receiving amplifier circuit according to the fourth embodiment is a monolithic semiconductor integrated circuit device, to which a photodiode 3 is connected. The structures of the NPN transistors Q5, Q6, and Q7 are the same as those of the NPN transistors provided in the differential amplifier 2. In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The emitters of the transistors Q5, Q6, and Q7 are connected to the connection point between the output terminal of the differential amplifier 2 and the resistor R2, and the bases of the transistors Q5, Q6, and Q7 are connected to the inverting input terminal of the differential amplifier 2. It is connected to a connection point with the resistor R2. Then, the transistors Q5, Q6, and Q
The collector of 7 is connected to a terminal 5 to which a predetermined voltage _Vcc is applied. Further, the substrate is set to the ground potential, and the anode of the photodiode 3 is formed of a P-type substrate and has the ground potential.

Transistors Q5 and Q5 are connected across resistor R2.
6 and Q7 connected in parallel, the phase compensation capacitance connected in parallel to the resistor R2 becomes a combined capacitance in which the base-emitter capacitances of the transistors Q5, Q6 and Q7 are connected in parallel, and thus the capacitance of the phase compensation capacitance The value can be increased by an integral multiple of the base-emitter capacitance of the transistor in the differential amplifier circuit 2.

Further, transistors Q5, Q6, and Q
7 of the collector - because the combined capacitance C _CG connected in parallel between the substrates capacity '' is not be connected in parallel to the photodiode 3, the conventional cut-off frequency of the light receiving amplifier circuit of the fourth embodiment shown in FIG. 6 It can be higher than the cutoff frequency of the light receiving amplifier circuit. That is, the response speed of the light receiving amplifier circuit of the fourth embodiment is faster than the response speed of the conventional light receiving amplifier circuit shown in FIG.

In the light receiving amplifier circuits of the first and fourth embodiments, since the transistor connected to the resistor R2 has the same structure as the transistor in the differential amplifier circuit 2, the light receiving amplifier circuit of the fourth embodiment is used as described above. The value of the phase compensation capacitance of the amplifier circuit could only be an integral multiple of the value of the phase compensation capacitance of the light receiving amplifier circuit of the first embodiment. Therefore, the base-emitter junction area of the transistor Q1 included in the light receiving amplifier circuit of the first embodiment may be made larger than the base-emitter junction area of the transistor provided in the differential amplifier circuit 2. Since the base-emitter capacitance is proportional to the base-emitter junction area, such a configuration allows the value of the phase compensation capacitance to be an integral multiple of the base-emitter capacitance of the transistor provided in the differential amplifier circuit 2. It can be set to a value other than.

Next, an embodiment of the optical pickup device according to the present invention will be described. The optical pickup device according to the present invention includes the photodiode 3 shown in FIG. 1 and the light receiving amplifier circuit of the first embodiment. FIG. 7 shows the configuration of the optical system of the optical pickup device according to the present invention.

The laser light emitted from the semiconductor laser 7 becomes parallel light by the collimator lens 8, passes through the beam splitter 9, passes through the 波長 wavelength plate 10, and is focused by the objective lens 11. The condensed light is reflected by the optical disc 12, becomes parallel light by the objective lens, is reflected by the beam splitter 9 via the quarter-wave plate 10, is condensed by the condensing lens 13, and reaches the photodiode 3. . Then, the light receiving amplifier circuit (not shown in FIG. 7) of the first embodiment outputs a voltage _Vout according to the output current of the photodiode 3. This output voltage V
It is possible to detect a reproduction signal, a focusing error signal, and a tracking error signal based on _out . Thereby, the information stored in the optical disk can be reproduced.

The optical pickup device according to the present invention has the structure shown in FIG.
Since the light receiving amplifier circuit of the first embodiment shown in FIG.
An optical pickup device which operates stably in a high frequency region and is inexpensive and has a high response speed is obtained.

[0054]

According to the present invention, an amplifier for inputting a current sent by a light receiving element and outputting a voltage, a resistor for negatively feeding back the output voltage of the amplifier, and a connection point between the output terminal of the amplifier and the resistor are provided. An NPN transistor having an emitter connected thereto, a base connected to a connection point between the input terminal of the amplifier and the resistance means, and a collector connected to a terminal to which a predetermined voltage is applied, so that the base-emitter of the transistor is provided. The inter-capacitance can be used as the phase compensation capacitance. This stabilizes the operation in the high frequency range. Further, since it is not necessary to add a manufacturing process to form the phase compensation capacitance, a low-cost semiconductor integrated circuit device is realized. Furthermore, since the collector of the transistor used as the phase compensation capacitor is connected to the terminal to which a predetermined voltage is applied, the collector-substrate capacitance of the transistor is not connected in parallel to the light receiving element. Thereby, the response speed of the semiconductor integrated circuit device can be increased.

Further, according to the present invention, an amplifier for inputting a current sent from a light receiving element and outputting a voltage, a resistance means for negatively feeding back the output voltage of the amplifier, and a connection point between the output terminal of the amplifier and the resistance means. An NPN transistor whose base is connected, whose emitter is connected to the connection point between the input terminal of the amplifier and the resistance means, and whose collector is connected to the terminal to which a predetermined voltage is applied, the resistance value of the resistance means Is set to a value that does not activate the transistor, the capacitance between the base and the emitter of the transistor can be used as the phase compensation capacitance. This stabilizes the operation in the high frequency range. Further, since it is not necessary to add a manufacturing process to form the phase compensation capacitance, a low-cost semiconductor integrated circuit device can be realized. Furthermore, since the collector of the transistor used as the phase compensation capacitor is connected to the terminal to which a predetermined voltage is applied, the collector-substrate capacitance of the transistor is not connected in parallel to the light receiving element. Thereby, the response speed of the semiconductor integrated circuit device can be increased.

Further, according to the present invention, an amplifier for inputting a current sent from a light receiving element and outputting a voltage, a resistance means for negatively feeding back the output voltage of the amplifier, and a connection point between the output terminal of the amplifier and the resistance means. A first transistor having an NPN type having a base connected thereto, and a second transistor having an NPN type having a base connected to a connection point between an input terminal of the amplifier and the resistor means; And the emitters of the second transistor are connected to each other, and the collectors are connected to a terminal to which a predetermined voltage is applied. Therefore, the capacitance values of the phase compensation capacitors connected in parallel to the resistance means are the first and second values. The capacitance value is obtained by connecting the base-emitter capacitance of the transistor in series. As a result, the capacitance value of the phase compensation capacitor can be made smaller than the capacitance value of the base-emitter capacitance of one transistor, and the selection range for designing the capacitance value of the phase compensation capacitor is expanded.

Further, according to the present invention, since there are a plurality of transistors connected in parallel to the resistance means, the capacitance value of the phase compensation capacitance connected in parallel to the resistance means is obtained by connecting the base-emitter capacitances of the plurality of transistors in parallel. It becomes the capacitance value that was obtained. As a result, the capacitance value of the phase compensation capacitor can be made larger than the capacitance value of the base-emitter capacitance of one transistor, and the selection range for designing the capacitance value of the phase compensation capacitor is expanded.

According to the present invention, since the base-mitter junction area of the transistor connected in parallel to the resistance means is larger than the base-emitter junction area of the transistor provided in the amplifier, the phase compensation connected in parallel to the resistance means is provided. The capacitance value of the capacitance can be set to a value that is not an integral multiple of the capacitance between the base and the emitter of the transistor provided in the amplifier, and the selection range for designing the capacitance value of the phase compensation capacitance is expanded.

According to the optical pickup device of the present invention, the means for irradiating the storage medium with a light beam, the light receiving element for receiving the reflected light from the storage medium, and the semiconductor integrated circuit connected to the light receiving element Device, it is possible to realize an optical pickup device that operates stably in a high-frequency region, is inexpensive, and has a high response speed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a light receiving amplifier circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a light receiving amplifier circuit according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a light receiving amplifier circuit according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a light receiving amplifier circuit according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional light receiving amplifier circuit.

FIG. 6 is a diagram showing another configuration of a conventional light receiving amplifier circuit.

FIG. 7 is a diagram showing a configuration of an optical system of the optical pickup device according to the present invention.

[Explanation of symbols]

1, 4, 5 terminals 2 Differential amplifier 3 Photodiode 6 Capacitor 7 Semiconductor laser 8 Collimator lens 9 Beam splitter 10 Quarter-wave plate 11 Objective lens 12 Optical disk C _CG parasitic capacitance R1, R2 Resistance Q1-Q8 NPN transistor

Continued on the front page F-term (reference) 5D119 AA01 AA10 AA40 BA01 KA02 KA43 5J066 AA01 AA47 AA56 CA18 CA65 CA87 CA91 FA17 FA19 HA02 HA25 HA31 HA44 KA01 KA02 KA12 KA16 KA25 KA27 KA47 MA13 MA21 PD01 SA01 CA01 A01CA01 DN01 FA17 FA19 HA02 HA25 HA31 HA44 HN06 KA01 KA02 KA16 KA25 KA27 KA47 MA13 MA21 MN02 NN14 SA01 TA01 5J092 AA01 AA47 AA56 CA18 CA65 CA87 CA91 FA17 FA19 HA02 HA25 HA31 HA44 KA01 KA02 KA16 MA01 KA25 KA25

Claims (6)

[Claims] An amplifier for inputting a current sent from a light receiving element and outputting a voltage; a resistor for negatively feeding back an output voltage of the amplifier; an emitter connected to a connection point between an output terminal of the amplifier and the resistor. An NPN transistor having a base connected to a connection point between the input terminal of the amplifier and the resistance means, and a collector connected to a terminal to which a predetermined voltage is applied. Circuit device. 2. An amplifier for inputting a current sent by a light receiving element and outputting a voltage, a resistance means for negatively feeding back an output voltage of the amplifier, and a base at a connection point between an output terminal of the amplifier and the resistance means. An NPN transistor having an emitter connected to a connection point between the input terminal of the amplifier and the resistance means, and a collector connected to a terminal to which a predetermined voltage is applied. Circuit device. 3. An amplifier for inputting a current sent from a light receiving element and outputting a voltage, a resistance means for negatively feeding back an output voltage of the amplifier, and a base at a connection point between an output terminal of the amplifier and the resistance means. A first transistor of an NPN type to be connected, and a second transistor of an NPN type having a base connected to a connection point between the input terminal of the amplifier and the resistance means, wherein the first transistor And an emitter of the second transistor are connected to each other, and collectors are connected to terminals to which a predetermined voltage is applied. 4. The semiconductor integrated circuit device according to claim 1, wherein said plurality of transistors are provided. 5. The semiconductor integrated circuit device according to claim 1, wherein a base-emitter junction area of the transistor is larger than a base-emitter junction area of a transistor provided in the amplifier. 6. A semiconductor integrated circuit according to claim 1, wherein said means for irradiating said storage medium with a light beam, a light receiving element for receiving reflected light from said storage medium, and said light receiving element are connected to said light receiving element. An optical pickup device comprising: a circuit device.