JP2008283316A - Light receiving amplifier and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light receiving amplifier for preventing the focus deviation of a laser beam or the tracking incapability of a disc from being generated even when the high speed reading of a disc or the like is necessary. <P>SOLUTION: This light receiving amplifier is provided with: a light receiving element PD4; a first current amplification part 4 for amplifying currents from the light receiving element PD4; and a current generation circuit 6 for generating currents Ico for offsetting output offset currents Iao to be outputted from the first current amplification part 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light receiving amplification device incorporating a light receiving element.

  In recent years, high-speed data rotation is required when reading data from an optical disk device represented by a DVD-R drive device or a Blu-ray disk device, and there is a demand for data writing to various types of optical disks. There is a demand for a light receiving and amplifying device capable of handling signals.

  Furthermore, since a large amount of information is recorded on one disc, multi-layer recording is becoming mainstream, and the light receiving and amplifying device corresponding to such an application has a weak light reflected from the inner layer of the disc. In order to amplify the signal, a relatively high sensitivity is required.

  FIG. 1 shows a circuit diagram of a light receiving and amplifying device in the prior art (for example, Patent Document 1). The light receiving and amplifying device of FIG. 1 includes a current-voltage converter 1 and a light receiving element PD1. The inverting input terminal of the amplifier 1a constituting the current / voltage converter 1 is connected to the cathode of the light receiving element PD1. The anode of the light receiving element PD1 is grounded. A plurality of feedback resistors Rg-a1, Rg-b1, and a switch SW1 for selecting a feedback resistor are connected between the inverting input terminal and the output terminal of the amplifier 1a. Here, if the photocurrent generated in PD1 is Iin and the output voltage of the amplifier 1a is Vout, the conversion efficiency from the photocurrent Iin to the output voltage Vout (hereinafter referred to as photoelectric conversion efficiency) is proportional to the value of the feedback resistance. Therefore, the output voltage Vout is expressed by Vout = Iin × Rg-a1 or Vout = Iin × (Rg-a1 // Rg-b1) (Rg-a1 // Rg-b1 is Rg-a1 and Rg-b1 Shows the combined resistance of

  For example, in a DVD disc, when reading a signal from an inner layer having a lower reflectivity, a high photoelectric conversion efficiency can be obtained by turning off the switch SW1 and selecting only Rg-a1 as a feedback resistor. It is done. Also, when reading the signal of the outer layer having a relatively high reflectivity, the photoelectric conversion efficiency may be relatively low, so that SW1 is turned on and the feedback resistor is connected in parallel with Rg-a1 and Rg-b1. It is used to lower the photoelectric conversion efficiency.

  According to this prior art, the photoelectric conversion efficiency of the light receiving and amplifying device can be changed even if the power of the signal light reflected from the disk and incident on the light receiving element is different due to the difference in the standard of the optical disk or the difference in writing / reading. Therefore, a constant output voltage can be obtained.

  However, in order to obtain high photoelectric conversion efficiency, the feedback resistance value connected to the amplifier must be increased. When the feedback resistance value increases, in an amplifier that performs current-voltage conversion, for example, the parasitic capacitance between the feedback resistor and the semiconductor substrate increases. When the capacity increases, the response speed of the amplifier decreases, in other words, the high-frequency response performance decreases.

For this reason, when trying to read a signal of an inner layer having a lower reflectivity in a DVD disc, the signal reading speed must be lowered in order to avoid a decrease in the high-frequency response performance of the amplifier due to selection of a large feedback resistance value.
Japanese Patent No. 3142214

  In order to improve the signal reading speed decrease due to the decrease in the high frequency response performance of the amplifier, a method of amplifying the output current of the light receiving element once as it is and converting the output current into a current voltage can be considered.

  FIG. 2 is a circuit diagram of a light receiving and amplifying device that realizes this method. The light receiving and amplifying device includes a light receiving element PD2, a current amplifying unit 2, and a current-voltage converting unit 3. The photocurrent of the light receiving element PD2 is once amplified by the current amplification unit 2 as it is, and the output current is converted into an output voltage by the current-voltage conversion unit 3.

  Here, the current amplification factor of the current amplification unit 2 is determined by Rgn2 / Rgp2. By adding the current amplifying unit 2, the value of the feedback resistance of the amplifier 3a is reduced to 1 / (Rgn2 / Rgp2) times, and the parasitic capacitance is reduced. Therefore, the high frequency response performance of the amplifier 3a is improved. Further, by setting the values of the feedback resistors Rgn2 and Rgp2 of the amplifier 2a to be relatively small, the high frequency response performance of the current amplifying unit 2 is further improved.

  However, in this system, the input offset current generated at the input terminal of the amplifier 2a is amplified by the amplifier 2a and an offset output current is generated at the terminal A. Further, the offset output current becomes an input current of the current-voltage conversion unit 3, and is converted into a voltage to generate an offset output voltage Vout at the output terminal. That is, a phenomenon occurs in which an output is generated even if the photocurrent generated in the light receiving element PD2 is not present.

  Therefore, even if the two-stage amplification method of the current amplification unit and the current-voltage conversion unit as shown in FIG. 2 is adopted and the high-speed response of the current amplification device is improved, the laser beam irradiated to the disk due to the occurrence of the offset output This causes problems such as frequent focus shifts and inability to track the disc. As a result, high-speed reading from a disc that maintains high image quality and high sound quality is not realized.

  In view of the foregoing, the present invention provides a light receiving and amplifying device that does not cause laser beam defocusing or disc tracking inability when performing high-speed readout of a multilayer Blu-ray disc or DVD disc with a small amount of reflected light by an optical pickup. The purpose is to provide.

  In order to achieve the above object, a light receiving and amplifying device according to the present invention is a light receiving and amplifying device comprising a light receiving element and a first current amplifying circuit for amplifying a current from the light receiving element. A current generation circuit that generates an offset current that cancels out the output offset current output from the current amplification circuit is provided.

  According to this configuration, the output offset current output from the current amplifying circuit is canceled by the canceling current generated by the current generating circuit. Therefore, even when high-speed reading of a disk or the like is required, the laser beam is not defocused, and the disk cannot be tracked. As a result, high-speed reading from a disc maintaining high image quality and high sound quality is realized.

  Here, the current generation circuit includes a second current amplification circuit and a current mirror, and the current mirror outputs a current corresponding to the current output from the second current amplification circuit as the cancellation current. You may do it.

  Here, the first current amplification circuit is a differential input type including a first inverting input terminal, a first non-inverting input terminal, and a first output terminal, and the light receiving element is connected to the first inverting input terminal. The first current amplification circuit is connected, the first resistor inserted between the first inverting input terminal and the first output terminal, the first non-inverting input terminal and the first output terminal And a second resistor inserted between the first current amplification circuit and the first current amplification circuit for outputting a current from the first output terminal via the second resistance, and the second current amplification circuit comprising: A differential input type comprising a second inverting input terminal, a second non-inverting input terminal and a second output terminal, wherein the current mirror comprises a third input terminal and a third output terminal; The current amplifier circuit includes a third resistor inserted between the second inverting input terminal and the second output terminal. , A fourth resistor inserted between the second non-inverting input terminal and the second output terminal, the third input terminal being connected to the second non-inverting input terminal, The output terminal may be connected to the first non-inverting input terminal.

  Thereby, the offset of the output offset current is realized by simple circuit components such as a current mirror, an amplifier, and a resistor.

  Here, the first current amplifier circuit includes a first transistor connected to the first inverting input terminal and a second transistor connected to the first non-inverting input terminal. The current amplifier circuit includes a third transistor connected to the second inverting input terminal and a fourth transistor connected to the second non-inverting input terminal, and the first to fourth transistors are the same. A joining type is preferred.

  As a result, the magnitudes of the input offset currents of the amplifier of the current amplifying unit and the amplifier of the current generation circuit are accurately matched, and the manufacturing process is simplified and the area is reduced.

  Here, it is preferable that a resistance value ratio between the first resistor and the second resistor is equal to a resistance value ratio between the third resistor and the fourth resistor.

  As a result, the current amplification factors of the current amplification circuits included in the current amplification unit and the current generation circuit are equal to each other, the output offset current and the cancellation current are precisely matched, and the output offset current is accurately canceled. .

  Here, it is preferable that the circuit configuration of the second current amplification circuit is the same as the circuit configuration of the first current amplification circuit.

  As a result, the manufacturing processes of the current amplification circuits included in the current amplification unit and the current generation circuit are matched, the manufacturing process of the current generation circuit is simplified, and the magnitudes of the output offset current and the cancellation current are matched accurately. The output offset current is canceled with high accuracy.

  Here, the first current amplification circuit further includes a fifth resistor and a first switch element, and the fifth resistor and the first switch element connected in series with each other include the first resistor. The second current amplification circuit further includes a sixth resistor and a second switch element, and the sixth resistor and the second resistor connected in series to each other. It is preferable that a switch element is connected in parallel to the third resistor, and the first switch element and the second switch element are linked to turn on and off.

  According to this configuration, even when the feedback resistor of the current amplification unit and the feedback resistor of the current generation circuit are switched, the output offset current is accurately canceled as in the case of no switching, and the multilayer Blu with a small amount of reflected light is obtained. -High-quality high-speed reading is realized even on a ray disk or the like.

  Here, the light receiving and amplifying device further includes at least one amplifying unit including a light receiving element and a current amplifier, and the current generation circuit is further provided corresponding to the at least one amplifying unit, You may provide at least one current mirror part equivalent to a mirror.

  According to this configuration, when there is a light receiving amplification device having a plurality of light receiving elements and a plurality of light receiving amplification circuits, a plurality of output offset currents are generated, and a plurality of output offset currents are generated by one current generation circuit. Since they are canceled out, for example, when the light receiving and amplifying device is used for multi-drive, a reduction in area is realized.

  Here, the second current amplification circuit may further include a light-shielding light-receiving element, and the light-shielded light-receiving element may be connected to the second inverting input terminal.

  As a result, the output offset current is accurately canceled regardless of the characteristics of the light receiving element.

Here, the light receiving and amplifying device is preferably fabricated on the same semiconductor substrate.
As a result, the canceling current and the output offset current have the same characteristics, so that the output offset current can be canceled with high accuracy and the manufacturing process can be simplified.

  The present invention can be realized not only as a light receiving and amplifying device having the above-described characteristics, but also as an optical pickup provided with such a light receiving and amplifying device, has the same configuration and effect as described above.

  According to the present invention, even in a DVD-R drive device or a Blu-ray disc device, even when a high-speed reading such as a multi-layer disc with a small amount of reflected light is required, the optical pickup has no laser beam defocus, and the disc cannot be tracked. Does not occur. As a result, high-speed reading from a disc maintaining high image quality and high sound quality is realized.

  Hereinafter, a light receiving and amplifying device according to an embodiment of the present invention and an optical pickup using the same will be described with reference to the drawings.

  The light receiving and amplifying device in the present embodiment includes a current generation circuit that generates a current that cancels an offset current output from the current amplification unit.

  FIG. 3 is a block diagram of the light receiving and amplifying device in the embodiment of the present invention. The light receiving and amplifying device in the figure includes a light receiving element PD4, a current amplifying unit 4, and a current-voltage converting unit 5. The current amplifying unit 4 includes a differential input type amplifier 4a and two feedback resistors Rgn4 and Rgp4. The cathode of the light receiving element PD4 is connected to the inverting input terminal of the amplifier 4a. The anode of PD4 is grounded. Rgn4 is connected between the inverting input terminal and the output terminal B of the amplifier 4a, and Rgp4 is connected between the non-inverting input terminal and the output terminal of the amplifier 4a.

  Here, the current amplification factor of the current amplifying unit 4 is determined by Rgn4 / Rgp4, and the signal current generated in the light receiving element is amplified by Rgn4 / Rgp4 times. The amplified signal current is output from the output terminal B to the terminal A via the resistor Rgp4 and input to the current-voltage converter 5. The conversion efficiency of the current-voltage converter 5 is determined by the feedback resistance Rg-a5 or Rg-a5 // Rg-b5, which is selected by turning on / off the switch SW5.

  Therefore, if the signal current generated by the light receiving element PD4 is Ipd, the output voltage Vout is Vout = Ipd × Rgn4 / Rgp4 × Rg-a5 or Vout = Ipd × Rgn4 / Rgp4 × (Rg-a5 // Rg-b5) expressed. Further, a current generation circuit 6 is connected to the terminal A, and functions to cancel the output offset current generated in the current amplifying unit 4 by the current generated therefrom.

Here, the principle that an output offset current is generated in the current amplifying unit 4 will be described.
FIG. 4 is a diagram illustrating a circuit example of the amplifier 4a in the current amplifying unit of FIG. As shown in the figure, the amplifier 4a includes differential transistors Q1 and Q2, transistors Q3 and Q4 forming a current mirror, a transistor Q5 operating as an emitter follower, a power supply voltage Vcc, and constant current sources I1 and I2. . An input offset current Ioff flows through the inverting input terminal and the non-inverting input terminal which are the input portions of the differential transistors Q1 and Q2. This input offset current Ioff becomes the base current of the differential transistor.

  Ioff flowing through the inverting input terminal is multiplied by Rgn4 / Rgp4 by the amplifier 4a in FIG. Further, Ioff flowing to the non-inverting input terminal flows to terminal A as it is. Therefore, the current flowing through the terminal A, that is, the output offset current Iao is the sum of the two currents, and Iao = Rgn4 / Rgp4 × Ioff + Ioff.

  The power supply voltage Vcc shown in FIG. 4 is omitted in FIG. 3 for simplicity. The amplifier 5a may have a circuit configuration equivalent to that shown in FIG.

  FIG. 4 shows a case where the differential transistors Q1 and Q2 are formed of bipolar transistors. This is because Q1 and Q2 are more excellent in high frequency characteristics than the case where Q1 and Q2 are constituted by junction FETs, and are suitable for high-speed signal reading of the multilayer optical disc as described above.

  Next, the function of the current generation circuit 6 canceling out the output offset current generated in the current amplification unit 4 will be described.

  FIG. 5 is a diagram showing a circuit example of the current generation circuit of FIG. As shown in the figure, the current generation circuit 7 includes an amplifier 7a, a feedback resistor Rgn7 connected between the inverting input terminal and the output terminal, Rgp7 connected between the non-inverting input terminal and the output terminal, Transistors Q6 and Q7 constituting a mirror and a power supply voltage Vcc are provided.

  The input side of the current mirror is connected to the non-inverting input terminal of the amplifier 7a, and the output side is connected to the terminal A.

  As the best mode, the amplifier 7a is a circuit equivalent to the amplifier 4a of the current amplifying unit 4 in FIG. 3, and the resistance values of Rgn7 and Rgp7 are equivalent to Rgn4 and Rgp4, respectively, so that the non-inversion of the amplifier 7a is achieved. An output offset current having the same magnitude as the output offset current of the amplifier 4a is generated from the input terminal. The direction of the generated current is reversed through the current mirror and flows to the terminal A, so that the output offset current generated in the amplifier 4a is canceled out.

  The optimum value of the current Ico generated from the current generation circuit 6 is Ico = − (Rgn4 / Rgp4 × Ioff + Ioff). As a result, the output offset current is canceled, and the occurrence of the output offset from the photoreceiver / amplifier is solved.

  The above-described resistance values are preferably within 10% in consideration of general semiconductor manufacturing variations.

  If the amplifier 4a and the amplifier 7a have the same circuit configuration as shown in FIG. 4, the change in the output offset current due to the power supply voltage fluctuation and the change in the output offset current due to the temperature are equivalent in the amplifier 4a and the amplifier 7a. The effect of being well offset is obtained.

  Here, the fact that the amplifier 4a and the amplifier 7a have the same circuit configuration will be described with reference to the circuit of FIG. 4. The junction type (DJ) of the differential transistors Q1 and Q2 constituting the differential input section of both amplifiers ( (PNP type / NPN type) is the same between both amplifiers, the junction type (PNP type / NPN type) of transistors Q3 and Q4 constituting the current mirror is the same between both amplifiers, differential transistor The Q5 junction type (PNP type / NPN type) that operates as an emitter follower with the same output is the same between the two amplifiers, and the difference in current value between the two amplifiers of the constant current sources I1 and I2 is a general semiconductor. It is within 10% in consideration of manufacturing variations.

  In FIG. 4, Ioff is the base current of the differential transistors Q1 and Q2, but this base current is often different for each semiconductor substrate even in the same semiconductor production lot. Therefore, by providing the current generation circuit 6 and the current amplification amplifier 4a on the same semiconductor substrate and generating a cancellation current based on the base current of a transistor having equivalent characteristics, the cancellation current and the output offset current have the same characteristics. This is preferable because it is not affected by variations in the output offset current.

  FIG. 6 is a block diagram showing a first modification of the photoreceiver / amplifier. The light receiving and amplifying device in the figure includes a light receiving element PD4, a current amplifying unit 8, a current-voltage converting unit 10, a current generating circuit 9, and a switch circuit 11.

  Compared with the current amplifying unit 4 in FIG. 3, the current amplifying unit 8 includes a feedback resistor Rgn4-1 and a switch SW7 connected between the inverting input terminal and the output terminal of the amplifier 8a. The difference is that the resistance value is selected. Similarly to the current amplifier 8, the current generation circuit 9 has a feedback resistor Rgn7-1 and a switch SW8 connected thereto, and is different in that a feedback resistance value is selected by turning on and off SW8.

  Further, a switch circuit is connected so that SW7 and SW8 are turned on and off in conjunction with each other. The description of the same points will be omitted, and different points will be described below.

  When this photoreceiver / amplifier is used for an optical pickup, the switch circuit 11 receives a signal from the outside of the photoreceiver / amplifier so as to select a feedback resistor that can provide photoelectric conversion efficiency suitable for the type of disk and recording / reproducing conditions. And the current amplification factor of the current amplification unit 8 is switched. The current amplification factor is Rgn4 / Rgp4 when SW7 is off, and (Rgn4 // Rgn4-1) / Rgp4 when SW7 is on. Therefore, the output offset current output from the current amplifying unit 8 is changed by switching SW7.

  In order to cope with this change in the output offset current, the current generation circuit 9 has a feedback resistance switching function, like the current amplification unit 8. Moreover, the on / off operation of the switch SW8 and the switch SW7 is interlocked by the switch circuit 11.

  As a result, a canceling current corresponding to the change in the output offset current is generated. Needless to say, the output offset current is canceled more accurately by making the circuits of the amplifier 8a and the amplifier 9a equivalent, and making the values of Rgn4, Rgn4-1, and Rgp4 equivalent to those of Rgn7, Rgn7-1, and Rgp7, respectively. Is done.

  FIG. 7 is a circuit diagram showing a second modification of the light receiving and amplifying device. The light receiving and amplifying device in the figure includes a plurality of light receiving elements PD4, a plurality of current amplifying units 12, a plurality of current-voltage converting units 13, and a current generating circuit 14.

  The light receiving element PD4, the current amplifying unit 12 and the current / voltage converting unit 13 are different from the light receiving element PD4, the current amplifying unit 4 and the current / voltage converting unit 5 in FIG. The current generation circuit 14 is different from the current generation circuit 7 in FIG. 5 in that a plurality of current mirror outputs exist. The description of the same points will be omitted, and different points will be described below.

  In this circuit diagram, when there are a plurality of current amplifying units, a plurality of output offset currents generated from the respective current amplifying units are represented by a plurality of canceling currents generated from one current generating circuit composed of minimum elements. The offset configuration is shown. In the current generation circuit 14, Q8 is added to increase the number of outputs of the current mirror, and the outputs of Q7 and Q8 are connected to the output terminal A of each current amplifying unit 12 to cancel each output offset current.

  As a result, compared to the case where a current generation circuit is provided for each current amplification unit, the output from one current generation circuit is duplicated to cancel each output offset current, so fewer elements are required, Space saving is achieved.

  6 and 7, the effect of interlocking switching of the current amplification factor by the switch circuit and the effect of the generation of a plurality of canceling currents by one current generation circuit have been described separately. However, the current amplification unit having a variable current amplification factor Of course, there is an effect even in a combination in which the output from one current generation circuit is duplicated by a current mirror to cancel each output offset current.

  FIG. 8 is a circuit diagram showing a modification of the current generation circuit. The current generation circuit 15 in the figure includes a light receiving element PD5, an amplifier 15a which is a current amplification unit, feedback resistors Rgn7 and Rgp7, Q6 and Q7 constituting a current mirror, and a power supply voltage Vcc.

  The current generation circuit 15 is different from the current generation circuit 7 in FIG. 5 in that the light receiving element PD5 is connected to the inverting input terminal of the amplifier 15a. The description of the same points will be omitted, and different points will be described below.

  Since a light receiving element PD5 having an area equivalent to that of the light receiving element PD4 connected to the current amplification unit 4 in FIG. 3 is added to the current generation circuit 15, an output offset due to dark current flowing in the light receiving element PD4 in FIG. The generation of current is further canceled out, making it more suitable. At this time, by covering the upper surface of the light receiving element PD5 with aluminum or the like used for circuit wiring, the photocurrent generated when the current generation circuit 15 is irradiated with stray light is suppressed, and as a result, the output offset current is accurately obtained. Offset.

  FIG. 9 is an example of a configuration diagram when the present invention is applied as an optical pickup built in a DVD-R drive device.

  The DVD-R drive apparatus 100 in FIG. The optical pickup 101 includes an objective lens 102, a mirror 103, a light receiving and amplifying device 104 of the present invention, a collimator lens 105, a red laser 106, a three-beam grating 107, an infrared laser 108, and a beam splitter 109. Prepare. The light emitted from the red laser 106 or the infrared laser 108 is irradiated onto the optical disc 110 through the collimator lens 105 and the like, and the reflected light is collected on a light receiving element built in the light receiving amplification device 104. The optical signal is converted into an electric signal by the light receiving and amplifying device 104, and reading / writing of information and position control of the light spot irradiated on the optical disc 110 are performed.

  As described above, according to the light receiving and amplifying device in the present embodiment, it is possible to provide a light receiving and amplifying device that has a small output offset and achieves both a high photoelectric signal conversion efficiency and a high-speed response. High-speed recording / reproduction of a multilayer Blu-ray disc / DVD disc or the like can be supported.

  Although the embodiment of the light receiving and amplifying device according to the present invention has been described above, the present invention is not limited to this embodiment.

  For example, in this embodiment, as shown in FIG. 3, the output current of the current amplifying unit is converted into a voltage by the current-voltage converting unit, and the voltage is output from the light receiving amplifier. However, the current-voltage converting unit is used. Instead, the output current of the current amplification unit may be output as is from the light receiving amplification device.

  As described above, the present invention is particularly useful for a light receiving and amplifying device for an optical pickup having a built-in light receiving element, and is particularly suitable for use in a light receiving and amplifying device for an optical pickup that is compatible with a multilayer optical disk. .

It is an equivalent circuit diagram in a conventional light receiving and amplifying device. It is an equivalent circuit diagram in a light receiving and amplifying device including a light receiving element, a current amplifying unit, and a current / voltage converting unit. It is a block diagram of the light reception amplifying device in the embodiment of the present invention. FIG. 4 is an example of an equivalent circuit diagram of an amplifier in the light receiving amplification device of FIG. 3. FIG. 4 is an example of an equivalent circuit diagram of the current generation circuit of FIG. 3. It is a block diagram which shows the 1st modification of the light reception amplifying device in embodiment of this invention. It is a circuit diagram which shows the 2nd modification of the light reception amplifying device in embodiment of this invention. It is a circuit diagram which shows the modification of the electric current generation circuit in embodiment of this invention. It is a figure which shows an example of the system configuration | structure of the optical pick-up containing the light reception amplifying device of this invention.

Explanation of symbols

1, 3, 5, 10, 13 Current-voltage converter 1a, 2a, 3a, 4a, 5a, 7a, 8a, 9a, 10a, 12a, 13a, 14a, 15a Amplifier 2, 4, 8, 12 Current amplifier 6 , 7, 9, 14, 15 Current generation circuit 11 Switch circuit 100 DVD-R drive device 101 Optical pickup 102 Objective lens 103 Mirror 104 Light receiving amplification device 105 Collimator lens 106 Red laser 107 Three beam grating 108 Infrared laser 109 Beam splitter 110 optical disk
PD1, PD2, PD4, PD5 Photo detector
Rg-a1, Rg-b1, Rg-a3, Rg-b3, Rg-a5, Rg-b5, Rgn2, Rgn4, Rgn4-1, Rgn7, Rgn7-1, Rref-a1, Rref-b1, Rref-a3, Rref-b3, Rref-a5, Rref-b5, Rgp2, Rgp4, Rgp7 resistance
SW1 to SW12 switch
A, B output terminals
Ioff Input offset current
Iao output offset current
Ico current
Q1-Q8 transistors

Claims (11)

A light receiving and amplifying device comprising a light receiving element and a first current amplification circuit for amplifying a current from the light receiving element,
A light receiving amplification apparatus comprising: a current generation circuit that generates an offset current that cancels an output offset current output from the first current amplification circuit. The current generation circuit includes a second current amplification circuit and a current mirror,
The light receiving and amplifying apparatus according to claim 1, wherein the current mirror outputs a current corresponding to a current output from the second current amplifier circuit as the canceling current. The first current amplifier circuit is a differential input type including a first inverting input terminal, a first non-inverting input terminal, and a first output terminal,
The light receiving element is connected to a first inverting input terminal;
The first current amplifier circuit includes a first resistor inserted between the first inverting input terminal and the first output terminal;
A second resistor inserted between the first non-inverting input terminal and the first output terminal;
The first current amplifier circuit outputs a current from the first output terminal via the second resistor,
The second current amplification circuit is a differential input type including a second inverting input terminal, a second non-inverting input terminal, and a second output terminal,
The current mirror is
A third input terminal and a third output terminal;
The second current amplification circuit includes:
A third resistor inserted between the second inverting input terminal and the second output terminal;
A fourth resistor inserted between the second non-inverting input terminal and the second output terminal;
The third input terminal is connected to the second non-inverting input terminal;
The photoreceiver / amplifier according to claim 2, wherein the third output terminal is connected to the first non-inverting input terminal. The first current amplification circuit includes a first transistor connected to the first inverting input terminal, and a second transistor connected to the first non-inverting input terminal,
The second current amplifier circuit includes a third transistor connected to the second inverting input terminal, and a fourth transistor connected to the second non-inverting input terminal,
The photoreceiver / amplifier according to claim 3, wherein the first to fourth transistors are of the same junction type. The resistance value ratio between the first resistor and the second resistor and the resistance value ratio between the third resistor and the fourth resistor are equivalent to each other. Light receiving amplification device. 6. The light receiving and amplifying device according to claim 3, wherein a circuit configuration of the second current amplification circuit is the same as a circuit configuration of the first current amplification circuit. The first current amplifier circuit further includes a fifth resistor and a first switch element,
The fifth resistor and the first switch element connected in series with each other are connected in parallel to the first resistor,
The second current amplifier circuit further includes a sixth resistor and a second switch element,
The sixth resistor and the second switch element connected in series with each other are connected in parallel to the third resistor,
The light receiving and amplifying device according to any one of claims 3 to 6, wherein the first switch element and the second switch element are interlocked with each other. The photoreceiver / amplifier further comprises:
At least one amplifying unit including a light receiving element and a current amplifier;
The current generation circuit further includes:
The light receiving and amplifying device according to any one of claims 2 to 7, further comprising at least one current mirror unit provided corresponding to the at least one amplifying unit and equivalent to the current mirror. The second current amplification circuit further includes a light-shielding light-receiving element, and the light-shielded light-receiving element is connected to the second inverting input terminal. The light receiving and amplifying device described in 1.   The light receiving and amplifying device according to claim 1, wherein the light receiving and amplifying device is manufactured on the same semiconductor substrate.   An optical pickup device comprising the light receiving and amplifying device according to claim 1.

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