WO2009145273A1 - Transimpedance amplifier, regulated type transimpedance amplifier, and optical receiver - Google Patents

Transimpedance amplifier, regulated type transimpedance amplifier, and optical receiver Download PDF

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Publication number
WO2009145273A1
WO2009145273A1 PCT/JP2009/059806 JP2009059806W WO2009145273A1 WO 2009145273 A1 WO2009145273 A1 WO 2009145273A1 JP 2009059806 W JP2009059806 W JP 2009059806W WO 2009145273 A1 WO2009145273 A1 WO 2009145273A1
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transimpedance amplifier
transistor
input
terminal
current source
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PCT/JP2009/059806
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French (fr)
Japanese (ja)
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久亮 金井
徳男 中條
雅巳 幕内
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株式会社日立製作所
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
    • H03F1/083—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements in transistor amplifiers
    • H03F1/086—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements in transistor amplifiers with FET's
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/72—Indexing scheme relating to amplifiers the amplifier stage being a common gate configuration MOSFET

Definitions

  • the present invention relates to a transimpedance amplifier that converts a current signal output from a light receiving element into a voltage signal in an optical receiver.
  • Transimpedance amplifier is an amplifier that converts current into voltage.
  • signals in the optical receiver for each information processing device or for each channel due to differences in performance of light receiving and emitting elements, differences in signal transmission distance, differences in coupling efficiency of lenses that collect optical signals, etc.
  • the current can vary greatly.
  • a transimpedance amplifier used in an optical receiver or the like is required to have a wide dynamic range in order to convert a current signal into a voltage signal without waveform distortion when the input current is large.
  • the transimpedance amplifier is required to have low input conversion noise so that no error occurs when the input current is small.
  • optical receivers are required to have a higher bandwidth for large-capacity data transmission.
  • FIG. 1 is a circuit configuration diagram showing an example of a conventional transimpedance amplifier.
  • the transistor 102 whose gate is connected to a constant voltage source, the resistance element 103 whose both terminals are connected to the drain terminal and the power source of the transistor 102, the constant current source 101 connected to the source terminal of the transistor 102, The constant voltage source 104 is connected to the gate terminal of the transistor.
  • An input signal is input from the input terminal 105, and an output signal is output from the output terminal 106.
  • this transimpedance amplifier when a current signal is input to the input terminal, the current flowing through the resistance element 103 changes, and a voltage signal proportional to the product of the element value of the resistance element 103 and the amount of fluctuation of the current is output to the output terminal. Is output.
  • This circuit configuration is suitable for higher bandwidth because of the grounded gate structure and low input impedance.
  • Patent Document 1 As a modification of this transimpedance amplifier, a technique described in Japanese Patent Laid-Open No. 11-205047 (Patent Document 1) can be mentioned.
  • Patent Document 1 by making the current value of the constant current source 101 variable, even if the input current increases, the current value of the variable current source increases following the input current. For this reason, a waveform can be output even at the time of a large input.
  • An object of the present invention is to provide a transimpedance amplifier that is compatible with a wide dynamic range and can reduce input conversion noise at the time of low input.
  • a transimpedance amplifier includes a first transistor, a variable current source and an input terminal are connected to a source terminal of the first transistor, and a drain terminal of the first transistor is connected to the drain terminal of the first transistor.
  • a resistance element for determining the potential of the output terminal and the drain terminal is connected, and the resistance element is a variable resistance.
  • the transimpedance amplifier may further include a control circuit, and the control circuit may control the variable current source and the variable resistance.
  • This control circuit may be characterized in that it detects the output signal of the output terminal and controls the variable current source and the variable resistor.
  • variable current source of this transimpedance amplifier may be composed of two or more transistors.
  • this transimpedance amplifier having a second transistor
  • the same variable current source and input terminal as the source terminal of the first transistor are connected to the source terminal of the second transistor,
  • the gate terminal of the transistor may be controlled by a control circuit.
  • a regulated transimpedance amplifier is composed of a variable current source, a transistor, and a resistance element, and a transimpedance adjustment circuit is connected to an input terminal, according to an output signal.
  • the transimpedance adjustment circuit may adjust the current value of the variable current source.
  • transimpedance amplifiers and regulated transimpedance amplifiers for optical receivers also falls within the scope of the present invention.
  • the transimpedance amplifier according to the representative embodiment of the present invention can convert a current signal to a voltage signal without waveform distortion by wide dynamic range when the input current is large.
  • the current-induced noise is reduced by reducing the current amount of the constant current source, and the influence of the circuit noise at the subsequent stage is reduced by increasing the gain. As a result, the occurrence of errors due to noise can be suppressed.
  • the input / output characteristics of this transimpedance amplifier when the control circuit operates when the input conversion noise is reduced are shown.
  • the input / output characteristics of this transimpedance amplifier when the control circuit operates in response to a wide dynamic range are shown.
  • It is a circuit block diagram of the transimpedance amplifier in connection with 3rd Embodiment. 1 shows an apparatus configuration to which an LSI equipped with a transimpedance amplifier according to the present invention is applied.
  • FIG. 2 is a circuit configuration diagram of the transimpedance amplifier according to the first embodiment of the present invention.
  • FIG. 3 is a block diagram showing the configuration of the control circuit 205.
  • This transimpedance amplifier includes a variable current source 201, a transistor 202, a variable resistor 203, a constant voltage source 204, a control circuit 205, and a memory 206. An input terminal 207 and an output terminal 208 are also included. Note that reference numerals 611, 612, and 613 in the figure are used in the description of FIG. 3 and will not be described here.
  • the variable current source 201 is a variable current source having one terminal connected to the source terminal of the transistor and the other grounded. Current amount of the variable current source 201 is controlled by a control signal S B.
  • the specific configuration of the variable current source 201 can achieve the effects of the present invention by either switching the number of parallel transistors or adjusting the gate voltage of the transistors.
  • Transistor 202 is an amplifier circuit in this circuit.
  • the transistor 202 operates in the same manner as a field effect transistor or a bipolar transistor.
  • the gate terminal of this transistor 202 is connected to a constant voltage source.
  • the source terminal of the transistor 202 is connected to the variable current source 201.
  • An input signal is input from the input terminal 207 to the connection point between the source terminal and the variable current source 201.
  • the drain terminal of the transistor 202 is connected to the power supply Vcc via the variable resistor 203.
  • a signal amplified by the transistor 202 is output from the connection point between the drain terminal of the transistor 202 and the variable resistor 203 to the output terminal 208.
  • the variable resistor 203 is a variable resistor for determining the potential of the drain terminal of the transistor 202.
  • a method for realizing the variable resistor 203 may be a method of switching the parallel number of resistance elements or a method of using a transistor as a load resistor and adjusting a gate voltage thereof.
  • the constant voltage source 204 is a constant voltage source that determines the potential of the gate terminal of the transistor 202.
  • the control circuit 205 is a control circuit that detects the signal of the output terminal 208 and controls the variable current source 201 and the variable resistor 203.
  • the control circuit 205 a control signal S B to the variable current source 201, and outputs the control signal S R to the variable resistor 203.
  • This control circuit 205 The operation of this control circuit 205 will be described.
  • the control circuit 205 increases the current amount of the variable current source 201, and outputs a control signal S B and the control signal S R in order to reduce the resistance of the variable resistor 203.
  • the control circuit 205 to reduce the current amount of the variable current source 201, and outputs a control signal S B and the control signal S R in order to increase the resistance value of the variable resistor 203.
  • the control circuit 205 includes a peak hold circuit 608 including a transistor 601, a transistor 602, and a capacitor 603, a comparator 604, a reset circuit 605, a multiplier 606, and a multiplier 607 (see FIG. 3).
  • reference numerals 611, 612, and 613 are indicators of the connection with FIG. 2 and do not have any effect on the circuit.
  • the reference voltage 610 is an input voltage serving as a threshold value of the comparator 604 and does not exist in FIG.
  • the peak hold circuit 608 includes a transistor 601 having a switch function, a transistor 602, and a capacitor 603 for exhibiting a peak hold function.
  • the ON / OFF operation of the transistor 601 is performed by the amplified signal (transimpedance) of the transistor 202.
  • the ON / OFF operation of the transistor 602 is performed by the output signal of the reset circuit 605.
  • the switch of the transistor 601 is ON, electric charge is accumulated in the capacitor 603.
  • the transistor 602 is ON, the electric charge accumulated in the capacitor 603 is removed.
  • the output voltage Vx input to the comparator 604 is determined by the electric charge accumulated in the capacitor 603. This output voltage Vx holds the maximum value of the output voltage at the output terminal 208.
  • the output of the transimpedance amplifier When the output of the transimpedance amplifier is input to the input terminal 613, it is input to the gate terminal of the transistor 601, and the transistor 601 operates as a switch. As a result, a charge proportional to the output of the transimpedance amplifier is accumulated in the capacitor 603. The charge accumulated in the capacitor 603 induces an output voltage Vx proportional to the output of the transimpedance amplifier at one end of the input of the comparator 604.
  • the comparator 604 compares the output voltage Vx of the peak hold circuit 608 with the reference voltage 610. When the output voltage Vx of the peak hold circuit 608 is larger than the reference voltage 610, the comparator 604 outputs a control signal. After the output signal of the comparator 604 is multiplied by the adjustment coefficient C R and the adjustment period count C B , the control circuit 205 outputs the control signal S R and the control signal S B to the variable resistor 203 and the variable current source 201. Further, the output signal of the comparator 604 is also output to the reset circuit 605.
  • the reset circuit 605 In response to the output signal of the comparator 604, the reset circuit 605 outputs a signal to the gate terminal of the transistor 602. Thereby, the electric charge accumulated in the capacitor 603 is removed.
  • the reference voltage 610 is a voltage for comparison with the transimpedance output voltage Vx.
  • a threshold value for detecting noise contained in the output signal is set. The reference voltage 610 determines this threshold value.
  • the comparator 604 compares the reference voltage 610 with the output voltage Vx of the peak hold circuit 608. When the output voltage Vx of the peak hold circuit 608 exceeds a certain value, it corresponds to a wide dynamic range.
  • Memory 206 is a circuit for output adjustment factor for adjusting the variation in the individual control circuit 205 C R, the adjustment period count C B to the control circuit 205. By changing this setting, fine adjustment of the control circuit 205 of each optical receiver is performed.
  • FIG. 4 is a graph showing the input / output characteristics of this transimpedance amplifier when the wide dynamic range is supported by increasing the current value of the variable current source 201 and decreasing the resistance value of the variable resistor 203.
  • FIG. 5 is a graph showing the frequency characteristics of the input conversion noise of this transimpedance amplifier under the conditions of FIG.
  • the input conversion noise is 2.0E-11 A / ⁇ Hz at least, which is relatively high.
  • FIG. 6 is a graph showing the input / output characteristics of this transimpedance amplifier when the input equivalent noise is reduced by decreasing the current value of the variable current source 201 and increasing the resistance value of the variable resistor 203.
  • FIG. 7 shows the frequency characteristics of the input conversion noise of this transimpedance amplifier under the conditions of FIG. Compared to the case where this transimpedance amplifier is compatible with a wide dynamic range, the effective range that can be converted from a current signal to a voltage signal without distortion is not wide (0 mA to 0.3 mA). On the other hand, input conversion noise is reduced in the entire frequency range.
  • FIG. 8 shows the input / output characteristics of this transimpedance amplifier when the control circuit 205 operates when the input conversion noise is reduced.
  • FIG. 9 shows the input / output characteristics of the transimpedance amplifier when the control circuit 205 is operated when the wide dynamic range is supported.
  • FIG. 8 has a short period in which the output voltage rises in proportion to the input current (up to 3.0E-04A).
  • this section extends to about 6.0E-04A.
  • the initial state is assumed to be when the input conversion noise in FIG. 8 is reduced.
  • the reference voltage 610 is set so that the maximum value becomes equal to or lower than the reference voltage 610.
  • the comparator 604 of the control circuit 205 issues a control signal, and the reset circuit 605 outputs a signal to the gate terminal of the transistor 602 so that the charge accumulated in the capacitor 603 is removed.
  • the output voltage Vx of the peak hold circuit 608 returns to the reference voltage 610 or lower.
  • variable resistor 203 and the variable current source 201 can shift to the characteristics corresponding to the wide dynamic range shown in FIG.
  • FIG. 10 is a circuit configuration diagram of a transimpedance amplifier according to the second embodiment of the present invention. The second embodiment will be described using this.
  • the transimpedance amplifier includes a variable current source including transistors 301 and 306, a gate-grounded transistor 302, a transistor 307, resistance elements 303 and 308, a control circuit 309, and a memory 310.
  • a variable current source including transistors 301 and 306, a gate-grounded transistor 302, a transistor 307, resistance elements 303 and 308, a control circuit 309, and a memory 310.
  • an input terminal 311 and an output terminal 312 are provided as input / output terminals.
  • the variable current source including the transistor 301 and the transistor 306 corresponds to the variable current source 201 of the first embodiment.
  • the transistor 306 is used as a circuit for adjusting the current amount of the variable current source. In this figure, two transistors are used in parallel, but the same effect can be obtained by paralleling three or more transistors.
  • the resistance element 303 takes a fixed resistance value.
  • the transistor 307 and the resistance element 308 are arranged as a circuit for adjusting the transimpedance. Note that the same effect can be obtained even when a plurality of transistors 306 and resistor elements 308 are arranged in parallel as a circuit for switching the transimpedance.
  • the control circuit 309 is a circuit that adjusts the current amount and transimpedance of the variable current source by controlling (ON / OFF) the gate terminals of the transistor 306 and the transistor 307 in accordance with the output voltage of the output terminal 312.
  • FIG. 11 is a circuit configuration diagram of a transimpedance amplifier according to the third embodiment of the present invention. The third embodiment will be described using this.
  • the transimpedance amplifier includes a variable current source 401, a transistor 402, a resistor element 403, a transistor 404, a resistor element 405, a transistor 406, a resistor element 407, a transistor 408, a resistor element 409, a transistor 410, a control circuit 411, and a memory 412.
  • the transimpedance amplifier has an input terminal 413 and an output terminal 414 as input / output terminals.
  • variable current source 401 has the same function as the variable current source 201 of the first embodiment.
  • Transistor 402, resistance element 403, transistor 404, and resistance element 405 constitute a regulated transimpedance amplifier.
  • the transistor 406, the resistance element 407, the transistor 408, the resistance element 409, and the transistor 410 constitute a transimpedance adjustment circuit 420.
  • the transimpedance adjustment circuit 420 switches the characteristics of the transimpedance amplifier by controlling ON / OFF of the transistor 410 by the control circuit 411.
  • the frequency band can be widened as compared with the transimpedance amplifier according to the first embodiment.
  • the transimpedance amplifier according to the present embodiment is more suitable for large-capacity data transfer than the first embodiment.
  • FIG. 12 shows an apparatus configuration to which an LSI equipped with the transimpedance amplifier of the present invention is applied.
  • a control signal monitor 901 capable of observing the output signal of the control circuit of the transimpedance amplifier of the present invention in real time on the apparatus, it is possible to confirm the secular change and temperature fluctuation of the apparatus, and to improve the reliability of the apparatus. It becomes possible to improve.
  • the transimpedance amplifier according to the present invention is assumed to be used in an optical receiver, but is not necessarily limited thereto. There is room for application in fields where transimpedance amplifiers require linearity.

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Abstract

Provided is a transimpedance amplifier capable of corresponding to a wide dynamic range and reducing input conversion noises at the time of a low input.  Specifically, a variable current source (201), a variable resistor (203) and a control circuit (205) thereof are applied to the transimpedance amplifier.  The magnitude of an input current of the transimpedance amplifier is estimated with an output voltage, and a transition is made from a state of corresponding to a wide dynamic range to a state of reducing the input conversion noises.  As a result, the linearity of an output signal can be maintained irrespective of the magnitude of the input current.

Description

トランスインピーダンスアンプ、レギュレイテッド型トランスインピーダンスアンプ及び光受信器Transimpedance amplifier, regulated transimpedance amplifier and optical receiver
　本発明は、光受信器において受光素子から出力される電流信号を電圧信号に変換するトランスインピーダンスアンプに係わる。 The present invention relates to a transimpedance amplifier that converts a current signal output from a light receiving element into a voltage signal in an optical receiver.
　トランスインピーダンスアンプとは電流を電圧に変換するアンプのことである。 Transimpedance amplifier is an amplifier that converts current into voltage.
　光信号を扱う光受信器において、受発光素子の性能ばらつきや信号伝送距離の違い、光信号を集光するレンズの結合効率の違いなどにより、情報処理装置毎あるいはチャネル毎に光受信器における信号電流が大きく異なることがある。 In optical receivers that handle optical signals, signals in the optical receiver for each information processing device or for each channel due to differences in performance of light receiving and emitting elements, differences in signal transmission distance, differences in coupling efficiency of lenses that collect optical signals, etc. The current can vary greatly.
　そのため、光受信器などに用いられるトランスインピーダンスアンプは、入力電流が大きい場合に波形歪み無く電流信号を電圧信号に変換するために広ダイナミックレンジを持つことが求められる。また、トランスインピーダンスアンプには、入力電流が小さい場合にエラーが発生しないよう入力換算ノイズが小さいことが要求される。 Therefore, a transimpedance amplifier used in an optical receiver or the like is required to have a wide dynamic range in order to convert a current signal into a voltage signal without waveform distortion when the input current is large. In addition, the transimpedance amplifier is required to have low input conversion noise so that no error occurs when the input current is small.
　併せて、光受信器は大容量データ伝送に向けた高帯域化が要求される。 In addition, optical receivers are required to have a higher bandwidth for large-capacity data transmission.
　図１は、従来のトランスインピーダンスアンプの一例を示す回路構成図である。 FIG. 1 is a circuit configuration diagram showing an example of a conventional transimpedance amplifier.
　従来のトランスインピーダンスアンプでは、ゲートを定電圧源に接続したトランジスタ１０２と、トランジスタ１０２のドレイン端子および電源に両端子を接続した抵抗素子１０３、トランジスタ１０２のソース端子に接続された定電流源１０１、トランジスタのゲート端子に接続した定電圧源１０４で構成される。また入力信号は入力端子１０５より入力され、出力信号は出力端子１０６より出力される。 In the conventional transimpedance amplifier, the transistor 102 whose gate is connected to a constant voltage source, the resistance element 103 whose both terminals are connected to the drain terminal and the power source of the transistor 102, the constant current source 101 connected to the source terminal of the transistor 102, The constant voltage source 104 is connected to the gate terminal of the transistor. An input signal is input from the input terminal 105, and an output signal is output from the output terminal 106.
　このトランスインピーダンスアンプは、入力端子に電流信号が入力されると、抵抗素子１０３に流れる電流が変化して、抵抗素子１０３の素子値と電流の変動量との積に比例した電圧信号が出力端子に出力される。 In this transimpedance amplifier, when a current signal is input to the input terminal, the current flowing through the resistance element 103 changes, and a voltage signal proportional to the product of the element value of the resistance element 103 and the amount of fluctuation of the current is output to the output terminal. Is output.
　この回路構成は、ゲート接地の構造であり入力インピーダンスが低いことから、高帯域化に向いている。 This circuit configuration is suitable for higher bandwidth because of the grounded gate structure and low input impedance.
　このトランスインピーダンスアンプの変形として、特開平１１－２０５０４７号公報（特許文献１）記載の技術が上げられる。この特許文献では、定電流源１０１の電流値を可変とすることで、入力電流が増加しても可変電流源の電流値が入力電流に追従して増加する。このため、大入力時にも波形を出力することができるというものである。 As a modification of this transimpedance amplifier, a technique described in Japanese Patent Laid-Open No. 11-205047 (Patent Document 1) can be mentioned. In this patent document, by making the current value of the constant current source 101 variable, even if the input current increases, the current value of the variable current source increases following the input current. For this reason, a waveform can be output even at the time of a large input.
特開平１１－２０５０４７号公報JP-A-11-205047
　しかし、従来の回路で、広ダイナミックレンジを実現するには、定電流源の電流値を最大入力電流以上に設定する必要がある。このため、トランジスタにおける電流起因のノイズを低減することが困難である。 However, in order to realize a wide dynamic range with the conventional circuit, it is necessary to set the current value of the constant current source to be greater than the maximum input current. For this reason, it is difficult to reduce current-induced noise in the transistor.
　また、トランジスタの微細化により電源電圧を低電圧化してトランジスタを動作させる必要がある。このため、トランジスタを飽和領域で動作させるには、抵抗値を大きくすることが出来ず、トランスインピーダンスアンプの利得を大きくすることが出来ない。このことから、後段の回路ノイズが入力換算ノイズとして大きく影響する。 Also, it is necessary to operate the transistor by lowering the power supply voltage by miniaturizing the transistor. For this reason, in order to operate the transistor in the saturation region, the resistance value cannot be increased and the gain of the transimpedance amplifier cannot be increased. For this reason, the circuit noise at the subsequent stage greatly affects the input conversion noise.
　一方、入力換算ノイズを小さくするには、定電流源１０１の電流値を小さくし、且つ、抵抗素子１０３の素子値を大きくする必要があるため、広ダイナミックレンジ化が困難となる。このため、従来回路では、入力電流が異なる場合でも、波形歪み無く電流信号から電圧信号に変換し、且つ、入力換算ノイズを小さくすることが困難であった。 On the other hand, in order to reduce the input conversion noise, it is necessary to reduce the current value of the constant current source 101 and increase the element value of the resistance element 103, so that it is difficult to widen the dynamic range. For this reason, in the conventional circuit, even when the input current is different, it is difficult to convert the current signal to the voltage signal without waveform distortion and to reduce the input conversion noise.
　本発明の目的は、広ダイナミックレンジに対応し、かつ低入力時の入力変換ノイズの低減も可能なトランスインピーダンスアンプを提供することにある。 An object of the present invention is to provide a transimpedance amplifier that is compatible with a wide dynamic range and can reduce input conversion noise at the time of low input.
　本発明の前記並びにその他の目的と新規な特徴は、本明細書の記述及び添付図面から明らかになるであろう。 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.
　本願において開示される発明のうち、代表的なものの概要を簡単に説明すれば、次の通りである。 The outline of a representative one of the inventions disclosed in the present application will be briefly described as follows.
　本発明の代表的な実施の形態に関わるトランスインピーダンスアンプは、第１のトランジスタを有し、第１のトランジスタのソース端子に可変電流源及び入力端子が接続され、第１のトランジスタのドレイン端子に出力端子及びドレイン端子の電位を決定する抵抗素子が接続され、この抵抗素子が可変抵抗であることを特徴とする。 A transimpedance amplifier according to a typical embodiment of the present invention includes a first transistor, a variable current source and an input terminal are connected to a source terminal of the first transistor, and a drain terminal of the first transistor is connected to the drain terminal of the first transistor. A resistance element for determining the potential of the output terminal and the drain terminal is connected, and the resistance element is a variable resistance.
　また、このトランスインピーダンスアンプは、更に制御回路を有し、この制御回路が可変電流源及び可変抵抗を制御することを特徴としても良い。この制御回路は、出力端子の出力信号を検出して可変電流源及び可変抵抗を制御することを特徴としても良い。 The transimpedance amplifier may further include a control circuit, and the control circuit may control the variable current source and the variable resistance. This control circuit may be characterized in that it detects the output signal of the output terminal and controls the variable current source and the variable resistor.
　このトランスインピーダンスアンプの可変電流源は、２以上のトランジスタより構成されることを特徴としても良い。 The variable current source of this transimpedance amplifier may be composed of two or more transistors.
　さらに、第２のトランジスタを有する、このトランスインピーダンスアンプの場合には、第２のトランジスタのソース端子には、第１のトランジスタのソース端子と同じ可変電流源及び入力端子が接続され、第２のトランジスタのゲート端子は制御回路によって制御されることを特徴としても良い。 Furthermore, in the case of this transimpedance amplifier having a second transistor, the same variable current source and input terminal as the source terminal of the first transistor are connected to the source terminal of the second transistor, The gate terminal of the transistor may be controlled by a control circuit.
　本発明の代表的な実施の形態に関わるレギュレイテッド型トランスインピーダンスアンプは、可変電流源と、トランジスタと、抵抗素子とで構成され、入力端子にトランスインピーダンス調整回路が接続され、出力信号に応じてトランスインピーダンス調整回路が可変電流源の電流値を調整することを特徴としても良い。 A regulated transimpedance amplifier according to a representative embodiment of the present invention is composed of a variable current source, a transistor, and a resistance element, and a transimpedance adjustment circuit is connected to an input terminal, according to an output signal. The transimpedance adjustment circuit may adjust the current value of the variable current source.
　これらのトランスインピーダンスアンプ及びレギュレイテッド型トランスインピーダンスアンプを光受信器に用いることも本発明の射程に入る。 The use of these transimpedance amplifiers and regulated transimpedance amplifiers for optical receivers also falls within the scope of the present invention.
　本願において開示される発明のうち、代表的なものによって得られる効果を簡単に説明すれば以下の通りである。 Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.
　本発明の代表的な実施の形態に関わるトランスインピーダンスアンプにより、入力電流が大きい場合、広ダイナミックレンジ化により波形歪み無く電流信号から電圧信号に変換することが可能となる。 The transimpedance amplifier according to the representative embodiment of the present invention can convert a current signal to a voltage signal without waveform distortion by wide dynamic range when the input current is large.
　また、入力電圧が小さい場合には、定電流源の電流量を小さくすることで電流起因ノイズを小さくし、かつ利得を大きくすることで後段の回路ノイズの影響を低減する。これによりノイズによるエラーの発生を抑えることが可能となる。 Also, when the input voltage is small, the current-induced noise is reduced by reducing the current amount of the constant current source, and the influence of the circuit noise at the subsequent stage is reduced by increasing the gain. As a result, the occurrence of errors due to noise can be suppressed.
従来のトランスインピーダンスアンプの一例を示す回路構成図である。It is a circuit block diagram which shows an example of the conventional transimpedance amplifier. 第１の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。It is a circuit block diagram of the transimpedance amplifier in connection with 1st Embodiment. 第１の実施の形態に関わる制御回路の構成を示すブロック図である。It is a block diagram which shows the structure of the control circuit in connection with 1st Embodiment. 広ダイナミックレンジ対応時の、第１の実施の形態に関わるトランスインピーダンスアンプの入出力特性を表すグラフである。It is a graph showing the input-output characteristic of the transimpedance amplifier concerning 1st Embodiment at the time of a wide dynamic range correspondence. 広ダイナミックレンジ対応時の、第１の実施の形態に関わるトランスインピーダンスアンプの入力換算ノイズの周波数特性を表すグラフである。It is a graph showing the frequency characteristic of the input conversion noise of the transimpedance amplifier in connection with 1st Embodiment at the time of a wide dynamic range correspondence. 入力換算ノイズを低減時の、第１の実施の形態に関わるトランスインピーダンスアンプの入出力特性を表すグラフである。It is a graph showing the input-output characteristic of the transimpedance amplifier concerning 1st Embodiment at the time of reducing input conversion noise. 入力換算ノイズを低減時の、第１の実施の形態に関わるトランスインピーダンスアンプの入力換算ノイズの周波数特性を表すグラフである。It is a graph showing the frequency characteristic of the input conversion noise of the transimpedance amplifier concerning 1st Embodiment at the time of reducing input conversion noise. 入力換算ノイズ低減時に、制御回路が動作した場合の、このトランスインピーダンスアンプの入出力特性を示す。The input / output characteristics of this transimpedance amplifier when the control circuit operates when the input conversion noise is reduced are shown. 広ダイナミックレンジ対応時に、制御回路が動作した場合の、このトランスインピーダンスアンプの入出力特性を示す。The input / output characteristics of this transimpedance amplifier when the control circuit operates in response to a wide dynamic range are shown. 第２の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。It is a circuit block diagram of the transimpedance amplifier in connection with 2nd Embodiment. 第３の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。It is a circuit block diagram of the transimpedance amplifier in connection with 3rd Embodiment. 本発明に関わるトランスインピーダンスアンプを搭載したＬＳＩを適用した装置形態を示す。1 shows an apparatus configuration to which an LSI equipped with a transimpedance amplifier according to the present invention is applied.
　以下、図を用いて本発明の実施の形態を説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　（第１の実施の形態）
　本発明の第１の実施の形態に関わるトランスインピーダンスアンプについて説明する。図２は本発明の第１の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。また、図３は、制御回路２０５の構成を示すブロック図である。 (First embodiment)
The transimpedance amplifier according to the first embodiment of the present invention will be described. FIG. 2 is a circuit configuration diagram of the transimpedance amplifier according to the first embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the control circuit 205.
　このトランスインピーダンスアンプは可変電流源２０１、トランジスタ２０２、可変抵抗２０３、定電圧源２０４、制御回路２０５、メモリ２０６を備える。また入力端子２０７及び出力端子２０８も含む。なお、図中の６１１、６１２、６１３は図３の説明で用いるものであり、ここでは説明を省く。 This transimpedance amplifier includes a variable current source 201, a transistor 202, a variable resistor 203, a constant voltage source 204, a control circuit 205, and a memory 206. An input terminal 207 and an output terminal 208 are also included. Note that reference numerals 611, 612, and 613 in the figure are used in the description of FIG. 3 and will not be described here.
　可変電流源２０１は、一方の端子をトランジスタのソース端子に接続され、他方が接地される可変電流源である。この可変電流源２０１の電流量は制御信号ＳＢによって制御される。この可変電流源２０１の具体的な構成は、トランジスタの並列数を切り替える方法でも、トランジスタのゲート電圧を調整する方法でも本発明の効果は得られる。 The variable current source 201 is a variable current source having one terminal connected to the source terminal of the transistor and the other grounded. Current amount of the variable current source 201 is controlled by a control signal S B. The specific configuration of the variable current source 201 can achieve the effects of the present invention by either switching the number of parallel transistors or adjusting the gate voltage of the transistors.
　トランジスタ２０２は本回路における増幅回路である。このトランジスタ２０２は電界効果型トランジスタでもバイポーラトランジスタでも同様に動作する。 Transistor 202 is an amplifier circuit in this circuit. The transistor 202 operates in the same manner as a field effect transistor or a bipolar transistor.
　このトランジスタ２０２のゲート端子は定電圧源に接続される。このトランジスタ２０２のソース端子は可変電流源２０１と接続される。このソース端子と可変電流源２０１との接続点に対して、入力端子２０７から入力信号が入力される。またトランジスタ２０２のドレイン端子は可変抵抗２０３を介して電源Ｖｃｃに接続される。このトランジスタ２０２のドレイン端子と可変抵抗２０３の接続点から出力端子２０８に対し、トランジスタ２０２によって増幅された信号が出力される。 The gate terminal of this transistor 202 is connected to a constant voltage source. The source terminal of the transistor 202 is connected to the variable current source 201. An input signal is input from the input terminal 207 to the connection point between the source terminal and the variable current source 201. The drain terminal of the transistor 202 is connected to the power supply Vcc via the variable resistor 203. A signal amplified by the transistor 202 is output from the connection point between the drain terminal of the transistor 202 and the variable resistor 203 to the output terminal 208.
　可変抵抗２０３は、トランジスタ２０２のドレイン端子の電位を定めるための可変抵抗である。可変抵抗２０３の実現方法は抵抗素子の並列数を切り替える方法でも、トランジスタを負荷抵抗として用い、そのゲート電圧を調整する方法でも良い。 The variable resistor 203 is a variable resistor for determining the potential of the drain terminal of the transistor 202. A method for realizing the variable resistor 203 may be a method of switching the parallel number of resistance elements or a method of using a transistor as a load resistor and adjusting a gate voltage thereof.
　定電圧源２０４は、トランジスタ２０２のゲート端子の電位を定める定電圧源である。 The constant voltage source 204 is a constant voltage source that determines the potential of the gate terminal of the transistor 202.
　制御回路２０５は出力端子２０８の信号を検出して可変電流源２０１及び可変抵抗２０３の制御を行う制御回路である。制御回路２０５は可変電流源２０１に対して制御信号ＳＢを、可変抵抗２０３に対して制御信号ＳＲを出力する。 The control circuit 205 is a control circuit that detects the signal of the output terminal 208 and controls the variable current source 201 and the variable resistor 203. The control circuit 205 a control signal S B to the variable current source 201, and outputs the control signal S R to the variable resistor 203.
　この制御回路２０５の動作について説明する。 The operation of this control circuit 205 will be described.
　入力端子２０７から入力される入力電流が大きい場合、比例して出力端子２０８に流れる出力電流も大きくなる。このとき、制御回路２０５は可変電流源２０１の電流量を大きくし、かつ、可変抵抗２０３の抵抗値を小さくすべく制御信号ＳＢおよび制御信号ＳＲを出力する。 When the input current input from the input terminal 207 is large, the output current flowing through the output terminal 208 is proportionally increased. At this time, the control circuit 205 increases the current amount of the variable current source 201, and outputs a control signal S B and the control signal S R in order to reduce the resistance of the variable resistor 203.
　一方、入力端子２０７から入力される入力電流が小さい場合、比例して出力電流２０８も小さくなる。このとき、制御回路２０５は可変電流源２０１の電流量を小さくし、かつ、可変抵抗２０３の抵抗値を大きくすべく制御信号ＳＢおよび制御信号ＳＲを出力する。 On the other hand, when the input current inputted from the input terminal 207 is small, the output current 208 is also reduced proportionally. At this time, the control circuit 205 to reduce the current amount of the variable current source 201, and outputs a control signal S B and the control signal S R in order to increase the resistance value of the variable resistor 203.
　この制御回路２０５は、トランジスタ６０１、トランジスタ６０２及びコンデンサ６０３よりなるピークホールド回路６０８、比較器６０４、リセット回路６０５、乗算器６０６、乗算器６０７より構成される（図３参照）。 The control circuit 205 includes a peak hold circuit 608 including a transistor 601, a transistor 602, and a capacitor 603, a comparator 604, a reset circuit 605, a multiplier 606, and a multiplier 607 (see FIG. 3).
　なお、６１１、６１２、６１３は図２とのつながりの指標であり、回路的に何がしかの効果を奏する点ではない。一方、リファレンス電圧６１０は比較器６０４の閾値となる入力電圧であり、図２中には存在しない。 Note that reference numerals 611, 612, and 613 are indicators of the connection with FIG. 2 and do not have any effect on the circuit. On the other hand, the reference voltage 610 is an input voltage serving as a threshold value of the comparator 604 and does not exist in FIG.
　ピークホールド回路６０８は、スイッチの機能を有するトランジスタ６０１、トランジスタ６０２及びピークホールドの機能を発揮するためのコンデンサ６０３より構成される。トランジスタ６０１のＯＮ・ＯＦＦの動作はトランジスタ２０２の増幅信号（トランスインピーダンス）が行う。一方、トランジスタ６０２のＯＮ・ＯＦＦの動作はリセット回路６０５の出力信号によって行う。トランジスタ６０１のスイッチがＯＮの状態ではコンデンサ６０３に対して電荷が蓄積される。一方、トランジスタ６０２がＯＮの状態ではコンデンサ６０３に蓄積された電荷が除去される。 The peak hold circuit 608 includes a transistor 601 having a switch function, a transistor 602, and a capacitor 603 for exhibiting a peak hold function. The ON / OFF operation of the transistor 601 is performed by the amplified signal (transimpedance) of the transistor 202. On the other hand, the ON / OFF operation of the transistor 602 is performed by the output signal of the reset circuit 605. When the switch of the transistor 601 is ON, electric charge is accumulated in the capacitor 603. On the other hand, when the transistor 602 is ON, the electric charge accumulated in the capacitor 603 is removed.
　コンデンサ６０３に蓄積された電荷によって、比較器６０４に入力される出力電圧Ｖｘが決定される。この出力電圧Ｖｘは出力端子２０８の出力電圧の最大値を保持することとなる。 The output voltage Vx input to the comparator 604 is determined by the electric charge accumulated in the capacitor 603. This output voltage Vx holds the maximum value of the output voltage at the output terminal 208.
　入力端子６１３にトランスインピーダンスアンプの出力が入力されると、トランジスタ６０１のゲート端子に入力され、トランジスタ６０１がスイッチとして動作する。これにより、トランスインピーダンスアンプの出力に比例した電荷がコンデンサ６０３に蓄積される。コンデンサ６０３に蓄積された電荷により、比較器６０４の入力の一端にトランスインピーダンスアンプの出力に比例した出力電圧Ｖｘが誘起される。 When the output of the transimpedance amplifier is input to the input terminal 613, it is input to the gate terminal of the transistor 601, and the transistor 601 operates as a switch. As a result, a charge proportional to the output of the transimpedance amplifier is accumulated in the capacitor 603. The charge accumulated in the capacitor 603 induces an output voltage Vx proportional to the output of the transimpedance amplifier at one end of the input of the comparator 604.
　比較器６０４はピークホールド回路６０８の出力電圧Ｖｘとリファレンス電圧６１０を比較する。リファレンス電圧６１０よりピークホールド回路６０８の出力電圧Ｖｘが大きい場合に、比較器６０４は制御信号を出力する。比較器６０４の出力信号に調整係数ＣＲ、調整期計数ＣＢを乗算した後、制御信号ＳＲ、制御信号ＳＢとして可変抵抗２０３、可変電流源２０１に対して制御回路２０５は出力する。また、比較器６０４の出力信号はリセット回路６０５にも出力される。 The comparator 604 compares the output voltage Vx of the peak hold circuit 608 with the reference voltage 610. When the output voltage Vx of the peak hold circuit 608 is larger than the reference voltage 610, the comparator 604 outputs a control signal. After the output signal of the comparator 604 is multiplied by the adjustment coefficient C R and the adjustment period count C B , the control circuit 205 outputs the control signal S R and the control signal S B to the variable resistor 203 and the variable current source 201. Further, the output signal of the comparator 604 is also output to the reset circuit 605.
　比較器６０４の出力信号を受けて、リセット回路６０５はトランジスタ６０２のゲート端子に信号を出力する。これにより、コンデンサ６０３に蓄積された電荷が除去される。 In response to the output signal of the comparator 604, the reset circuit 605 outputs a signal to the gate terminal of the transistor 602. Thereby, the electric charge accumulated in the capacitor 603 is removed.
　リファレンス電圧６１０はトランスインピーダンスの出力電圧Ｖｘと比較するための電圧である。本発明においては、出力信号に含まれるノイズを検出するための閾値を設定することになるが、この閾値を決定するのがリファレンス電圧６１０である。 The reference voltage 610 is a voltage for comparison with the transimpedance output voltage Vx. In the present invention, a threshold value for detecting noise contained in the output signal is set. The reference voltage 610 determines this threshold value.
　比較器６０４はリファレンス電圧６１０とピークホールド回路６０８の出力電圧Ｖｘを対比する。ピークホールド回路６０８の出力電圧Ｖｘが一定値以上になると、広ダイナミックレンジに対応する。 The comparator 604 compares the reference voltage 610 with the output voltage Vx of the peak hold circuit 608. When the output voltage Vx of the peak hold circuit 608 exceeds a certain value, it corresponds to a wide dynamic range.
　メモリ２０６は、個々の制御回路２０５のばらつきを調整するための調整係数ＣＲ、調整期計数ＣＢを制御回路２０５に対して出力する回路である。この設定を変更することで、各光受信器の制御回路２０５の微調整を行う。 Memory 206 is a circuit for output adjustment factor for adjusting the variation in the individual control circuit 205 C R, the adjustment period count C B to the control circuit 205. By changing this setting, fine adjustment of the control circuit 205 of each optical receiver is performed.
　次に、この回路の特性及び用途について説明する。 Next, the characteristics and applications of this circuit will be described.
　図４は、可変電流源２０１の電流値を大きくし、可変抵抗２０３の抵抗値を小さくすることによる、広ダイナミックレンジ対応時の、このトランスインピーダンスアンプの入出力特性を表すグラフである。また、図５は図４の条件での、このトランスインピーダンスアンプの入力換算ノイズの周波数特性を表すグラフである。図４を見ても分かるとおり、入出力特性においては、全入力範囲（０ｍＡ～０．９ｍＡ）に対して、出力電圧が線形に変化しており、広ダイナミックレンジを実現していることが分かる。一方、入力換算ノイズは最低でも２．０Ｅ－１１Ａ／√Ｈｚであり、比較的高い。 FIG. 4 is a graph showing the input / output characteristics of this transimpedance amplifier when the wide dynamic range is supported by increasing the current value of the variable current source 201 and decreasing the resistance value of the variable resistor 203. FIG. 5 is a graph showing the frequency characteristics of the input conversion noise of this transimpedance amplifier under the conditions of FIG. As can be seen from FIG. 4, in the input / output characteristics, the output voltage changes linearly with respect to the entire input range (0 mA to 0.9 mA), and a wide dynamic range is realized. . On the other hand, the input conversion noise is 2.0E-11 A / √Hz at least, which is relatively high.
　一方、図６は可変電流源２０１の電流値を小さくし、可変抵抗２０３の抵抗値を大きくすることにより、入力換算ノイズを低減した場合のこのトランスインピーダンスアンプの入出力特性を表すグラフである。図７は図６の条件でのこのトランスインピーダンスアンプの入力換算ノイズの周波数特性を表す。このトランスインピーダンスアンプの広ダイナミックレンジ対応時に比べ、歪み無く電流信号から電圧信号に変換できる有効なレンジの幅は広くない（０ｍＡ～０．３ｍＡ）。一方で、入力換算ノイズは全周波数範囲において低減している。 On the other hand, FIG. 6 is a graph showing the input / output characteristics of this transimpedance amplifier when the input equivalent noise is reduced by decreasing the current value of the variable current source 201 and increasing the resistance value of the variable resistor 203. FIG. 7 shows the frequency characteristics of the input conversion noise of this transimpedance amplifier under the conditions of FIG. Compared to the case where this transimpedance amplifier is compatible with a wide dynamic range, the effective range that can be converted from a current signal to a voltage signal without distortion is not wide (0 mA to 0.3 mA). On the other hand, input conversion noise is reduced in the entire frequency range.
　本トランスインピーダンスアンプの使用に際しては、入力電流が大きいときに広ダイナミックレンジに対応することを想定している。したがって、入力換算ノイズが比較的大きくなっても、ノイズによるトランスインピーダンスアンプのエラーの発生等の悪影響は及ばない。 When using this transimpedance amplifier, it is assumed that a wide dynamic range is supported when the input current is large. Therefore, even if the input conversion noise becomes relatively large, there is no adverse effect such as the occurrence of an error in the transimpedance amplifier due to the noise.
　一方、入力換算ノイズを低減した場合には、入出力特性において非線形区間（図６の（ｂ）区間）が発生するが、非線形区間での使用は想定していないため、これも問題とはならない。 On the other hand, when the input conversion noise is reduced, a nonlinear interval (interval (b) in FIG. 6) occurs in the input / output characteristics. However, this is not a problem because it is not assumed to be used in the nonlinear interval. .
　次に、この回路の具体的な動作について説明する。 Next, the specific operation of this circuit will be described.
　図８は入力換算ノイズ低減時に、制御回路２０５が動作した場合の、このトランスインピーダンスアンプの入出力特性を示す。一方、図９は広ダイナミックレンジ対応時に、制御回路２０５が動作した場合の、このトランスインピーダンスアンプの入出力特性を示す。 FIG. 8 shows the input / output characteristics of this transimpedance amplifier when the control circuit 205 operates when the input conversion noise is reduced. On the other hand, FIG. 9 shows the input / output characteristics of the transimpedance amplifier when the control circuit 205 is operated when the wide dynamic range is supported.
　図８と図９を対比すれば分かるように図８は入力電流に比例して出力電圧が上昇する期間が短い（３．０Ｅ－０４Ａまで）。一方、図９ではこの区間が約６．０Ｅ－０４Ａまで伸びる。本発明に関わる制御回路２０５の、この切り替えの手段を以下で説明する。 As can be seen by comparing FIG. 8 and FIG. 9, FIG. 8 has a short period in which the output voltage rises in proportion to the input current (up to 3.0E-04A). On the other hand, in FIG. 9, this section extends to about 6.0E-04A. This switching means of the control circuit 205 according to the present invention will be described below.
　ここでは初期状態は図８の入力換算ノイズを低減時のものとして想定する。 Here, the initial state is assumed to be when the input conversion noise in FIG. 8 is reduced.
　入力端子２０７から入力される入力電流範囲（出力端子２０８の電圧に反映される）が図９の０ｍＡないし０．５ｍＡの場合、ピークホールド回路６０８の出力電圧Ｖｘ（＝出力端子２０８の出力電圧の最大値）がリファレンス電圧６１０以下となるようにリファレンス電圧６１０を設定する。 When the input current range input from the input terminal 207 (reflected in the voltage of the output terminal 208) is 0 mA to 0.5 mA in FIG. 9, the output voltage Vx of the peak hold circuit 608 (= the output voltage of the output terminal 208). The reference voltage 610 is set so that the maximum value becomes equal to or lower than the reference voltage 610.
　一方、０．５ｍＡを越えるとピークホールド回路６０８の出力電圧Ｖｘ（＝出力端子２０８の出力電圧の最大値）がリファレンス電圧６１０以上になる。このときに、制御回路２０５の比較器６０４が制御信号を発し、リセット回路６０５はコンデンサ６０３に蓄積された電荷が除去されるようトランジスタ６０２のゲート端子に信号を出力する。このコンデンサ６０３の電荷の除去によりピークホールド回路６０８の出力電圧Ｖｘはリファレンス電圧６１０以下にもどる。 On the other hand, if it exceeds 0.5 mA, the output voltage Vx of the peak hold circuit 608 (= the maximum value of the output voltage of the output terminal 208) becomes the reference voltage 610 or more. At this time, the comparator 604 of the control circuit 205 issues a control signal, and the reset circuit 605 outputs a signal to the gate terminal of the transistor 602 so that the charge accumulated in the capacitor 603 is removed. By removing the charge of the capacitor 603, the output voltage Vx of the peak hold circuit 608 returns to the reference voltage 610 or lower.
　また６１１、６１２経由で可変抵抗２０３及び可変電流源２０１に対し、比較器６０４の制御信号から生成された制御信号ＳＲと制御信号ＳＢが出力される。これにより、可変抵抗２０３及び可変電流源２０１は図９の広ダイナミックレンジ対応時の特性に移行することができる。 Also with respect to the variable resistor 203 and the variable current source 201 through 611 and 612, the control signal S B and the control signal S R which is generated from the control signal of the comparator 604 is output. As a result, the variable resistor 203 and the variable current source 201 can shift to the characteristics corresponding to the wide dynamic range shown in FIG.
　なお、図９の広ダイナミックレンジ対応時から図８の入力換算ノイズ低減時に戻る際には、図示しない回路によって出力端子２０８の出力振幅が所望の振幅より小さい場合に可変電流源２０１及び可変抵抗２０３の特性を切り替える。 When returning from the time corresponding to the wide dynamic range of FIG. 9 to the reduction of the input equivalent noise of FIG. 8, if the output amplitude of the output terminal 208 is smaller than the desired amplitude by a circuit (not shown), the variable current source 201 and the variable resistor 203. Switching the characteristics.
　以上の動作により、入力範囲において波形にひずみ無く電流信号を電圧信号に変換するトランスインピーダンスアンプを実現することが可能となる。 By the above operation, it becomes possible to realize a transimpedance amplifier that converts a current signal into a voltage signal without distortion in the waveform in the input range.
　（第２の実施の形態）
　図１０は本発明の第２の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。これを用いて第２の実施の形態について説明する。 (Second Embodiment)
FIG. 10 is a circuit configuration diagram of a transimpedance amplifier according to the second embodiment of the present invention. The second embodiment will be described using this.
　このトランスインピーダンスアンプはトランジスタ３０１、トランジスタ３０６より構成される可変電流源と、ゲート接地のトランジスタ３０２、トランジスタ３０７と、抵抗素子３０３、３０８と制御回路３０９及びメモリ３１０より構成される。また、入力端子３１１及び出力端子３１２を入出力端子として有する。 The transimpedance amplifier includes a variable current source including transistors 301 and 306, a gate-grounded transistor 302, a transistor 307, resistance elements 303 and 308, a control circuit 309, and a memory 310. In addition, an input terminal 311 and an output terminal 312 are provided as input / output terminals.
　トランジスタ３０１、トランジスタ３０６より構成される可変電流源は第１の実施の形態の可変電流源２０１に相当する。トランジスタ３０６は、可変電流源の電流量を調整する回路として用いられる。なお、この図ではトランジスタを２つ並列化したものを用いているが、３つ以上のトランジスタを並列化することでも同様の効果が得られる。 The variable current source including the transistor 301 and the transistor 306 corresponds to the variable current source 201 of the first embodiment. The transistor 306 is used as a circuit for adjusting the current amount of the variable current source. In this figure, two transistors are used in parallel, but the same effect can be obtained by paralleling three or more transistors.
　抵抗素子３０３は第１の実施の形態の可変抵抗２０３と異なり固定抵抗値を取る。この代わりに、トランジスタ３０７及び抵抗素子３０８がトランスインピーダンスを調整するための回路として配置されている。なお、トランスインピーダンスを切り替える回路として、トランジスタ３０６と抵抗素子３０８を複数並列化しても同様の効果が得られる。 Unlike the variable resistor 203 of the first embodiment, the resistance element 303 takes a fixed resistance value. Instead, the transistor 307 and the resistance element 308 are arranged as a circuit for adjusting the transimpedance. Note that the same effect can be obtained even when a plurality of transistors 306 and resistor elements 308 are arranged in parallel as a circuit for switching the transimpedance.
　制御回路３０９は、出力端子３１２の出力電圧に応じて、トランジスタ３０６及びトランジスタ３０７のゲート端子を制御（ＯＮ・ＯＦＦ）することで、可変電流源の電流量及びトランスインピーダンスを調整する回路である。 The control circuit 309 is a circuit that adjusts the current amount and transimpedance of the variable current source by controlling (ON / OFF) the gate terminals of the transistor 306 and the transistor 307 in accordance with the output voltage of the output terminal 312.
　本実施の形態ではトランジスタ３０６及びトランジスタ３０７のＯＮ・ＯＦＦを切り替えることで、広ダイナミックレンジ対応と入力換算ノイズ低減対応とを切り替えることができる。これにより、第１の実施の形態に比べ、トランスインピーダンスアンプを構成する素子数を減らすことが可能になる。また、可変抵抗素子に用いられるトランジスタの非線形動作の影響が抑えられるので、より波形歪みの無い出力信号を得ることが可能となる。 In this embodiment, by switching ON / OFF of the transistor 306 and the transistor 307, it is possible to switch between wide dynamic range support and input conversion noise reduction support. As a result, the number of elements constituting the transimpedance amplifier can be reduced as compared with the first embodiment. In addition, since the influence of the non-linear operation of the transistor used for the variable resistance element can be suppressed, an output signal without waveform distortion can be obtained.
　（第３の実施の形態）
　図１１は本発明の第３の実施の形態に関わるトランスインピーダンスアンプの回路構成図である。これを用いて第３の実施の形態について説明する。 (Third embodiment)
FIG. 11 is a circuit configuration diagram of a transimpedance amplifier according to the third embodiment of the present invention. The third embodiment will be described using this.
　このトランスインピーダンスアンプは可変電流源４０１、トランジスタ４０２、抵抗素子４０３、トランジスタ４０４、抵抗素子４０５、トランジスタ４０６、抵抗素子４０７、トランジスタ４０８、抵抗素子４０９、トランジスタ４１０、制御回路４１１、メモリ４１２より構成される。また、このトランスインピーダンスアンプは入出力端子として入力端子４１３及び出力端子４１４を有する。 The transimpedance amplifier includes a variable current source 401, a transistor 402, a resistor element 403, a transistor 404, a resistor element 405, a transistor 406, a resistor element 407, a transistor 408, a resistor element 409, a transistor 410, a control circuit 411, and a memory 412. The The transimpedance amplifier has an input terminal 413 and an output terminal 414 as input / output terminals.
　可変電流源４０１は第１の実施の形態の可変電流源２０１同様の機能を有する。 The variable current source 401 has the same function as the variable current source 201 of the first embodiment.
　トランジスタ４０２、抵抗素子４０３、トランジスタ４０４、抵抗素子４０５はレギュレイテッド型トランスインピーダンスアンプを構成する。 Transistor 402, resistance element 403, transistor 404, and resistance element 405 constitute a regulated transimpedance amplifier.
　トランジスタ４０６、抵抗素子４０７、トランジスタ４０８、抵抗素子４０９、トランジスタ４１０はトランスインピーダンス調整回路４２０を構成する。トランスインピーダンス調整回路４２０は制御回路４１１によりトランジスタ４１０のＯＮ・ＯＦＦを制御することで、このトランスインピーダンスアンプの特性を切り替える。 The transistor 406, the resistance element 407, the transistor 408, the resistance element 409, and the transistor 410 constitute a transimpedance adjustment circuit 420. The transimpedance adjustment circuit 420 switches the characteristics of the transimpedance amplifier by controlling ON / OFF of the transistor 410 by the control circuit 411.
　本実施の形態ではレギュレイテッド型トランスインピーダンスアンプを使用することで、第１の実施の形態に関わるトランスインピーダンスアンプに比べ周波数帯域を広帯域化することができる。これにより、第1の実施の形態に比べ本実施の形態のトランスインピーダンスアンプは大容量データ転送の用途に向く。 In this embodiment, by using the regulated transimpedance amplifier, the frequency band can be widened as compared with the transimpedance amplifier according to the first embodiment. As a result, the transimpedance amplifier according to the present embodiment is more suitable for large-capacity data transfer than the first embodiment.
　（第４の実施の形態）
　図１２は本発明の上記トランスインピーダンスアンプを搭載したＬＳＩを適用した装置形態を示す。本発明のトランスインピーダンスアンプの制御回路の出力信号を、リアルタイムに観測可能な制御信号モニタ９０１を装置上に設けることで、装置の経年変化や温度変動を確認することができ、装置の信頼性を向上することが可能となる。 (Fourth embodiment)
FIG. 12 shows an apparatus configuration to which an LSI equipped with the transimpedance amplifier of the present invention is applied. By providing a control signal monitor 901 capable of observing the output signal of the control circuit of the transimpedance amplifier of the present invention in real time on the apparatus, it is possible to confirm the secular change and temperature fluctuation of the apparatus, and to improve the reliability of the apparatus. It becomes possible to improve.
　以上、本発明者によってなされた発明を実施の形態に基づき具体的に説明したが、本発明は前記の実施の形態に限定されるものではなく、その要旨を逸脱しない範囲で種々変更が可能であることは言うまでもない。 As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.
　本発明に関わるトランスインピーダンスアンプは、光受信器に用いられることを想定しているが、必ずしもこれには限られない。トランスインピーダンスアンプに線形性を要求する分野においては適用の余地がある。 The transimpedance amplifier according to the present invention is assumed to be used in an optical receiver, but is not necessarily limited thereto. There is room for application in fields where transimpedance amplifiers require linearity.
　２０１　可変電流源
　２０２　トランジスタ
　２０３　可変抵抗
　２０４　定電圧源
　２０５　制御回路
　２０６　メモリ
　２０７　入力端子
　２０８　出力端子
　３０１　トランジスタ
　３０２　トランジスタ
　３０３　抵抗素子
　３０６　トランジスタ
　３０７　トランジスタ
　３０８　抵抗素子
　３０９　制御回路
　３１０　メモリ
　４０１　可変電流源
　４０２　トランジスタ
　４０３　抵抗素子
　４０４　トランジスタ
　４０５　抵抗素子
　４０６　トランジスタ
　４０７　抵抗素子
　４０８　トランジスタ
　４０９　抵抗素子
　４１０　トランジスタ
　４１１　制御回路
　４１２　メモリ
　４２０　トランスインピーダンス調整回路
　６０１　トランジスタ
　６０２　トランジスタ
　６０３　コンデンサ
　６０４　比較器
　６０５　リセット回路
　６０６　乗算器
　６０７　乗算器
　６０８　ピークホールド回路 DESCRIPTION OF SYMBOLS 201 Variable current source 202 Transistor 203 Variable resistance 204 Constant voltage source 205 Control circuit 206 Memory 207 Input terminal 208 Output terminal 301 Transistor 302 Transistor 303 Resistance element 306 Transistor 307 Transistor 308 Resistance element 309 Control circuit 310 Memory 401 Variable current source 402 Transistor 403 Resistive element 404 Transistor 405 Resistive element 406 Transistor 407 Resistive element 408 Transistor 409 Resistive element 410 Transistor 411 Control circuit 412 Memory 420 Transimpedance adjustment circuit 601 Transistor 602 Transistor 603 Capacitor 604 Comparator 605 Reset circuit 606 Multiplier 607 Multiplier 608 Multiplier 608 circuit

Claims (8)

  1. 　第１のトランジスタを有し、前記第１のトランジスタのソース端子に可変電流源及び入力端子が接続され、前記第１のトランジスタのドレイン端子に出力端子及び前記ドレイン端子の電位を決定する抵抗素子が接続されるトランスインピーダンスアンプであって、
    　前記抵抗素子が可変抵抗であることを特徴とするトランスインピーダンスアンプ。     A resistance element having a first transistor, a variable current source and an input terminal connected to the source terminal of the first transistor, and a potential of the output terminal and the drain terminal determined to the drain terminal of the first transistor; A transimpedance amplifier connected,
    The transimpedance amplifier, wherein the resistance element is a variable resistance.
  2. 　請求項１に記載のトランスインピーダンスアンプにおいて、更に制御回路を有し、前記制御回路が前記可変電流源及び前記可変抵抗を制御することを特徴とするトランスインピーダンスアンプ。 2. The transimpedance amplifier according to claim 1, further comprising a control circuit, wherein the control circuit controls the variable current source and the variable resistance.
  3. 　請求項２に記載のトランスインピーダンスアンプにおいて、前記出力端子の出力信号を検出して前記制御回路が前記可変電流源及び前記可変抵抗を制御することを特徴とするトランスインピーダンスアンプ。 3. The transimpedance amplifier according to claim 2, wherein the control circuit controls the variable current source and the variable resistor by detecting an output signal of the output terminal.
  4. 　請求項１に記載のトランスインピーダンスアンプにおいて、前記可変電流源が２以上のトランジスタより構成されることを特徴とするトランスインピーダンスアンプ。 2. The transimpedance amplifier according to claim 1, wherein the variable current source includes two or more transistors.
  5. 　請求項１記載のトランスインピーダンスアンプにおいて、更に制御回路と第２のトランジスタを有し、
    　前記第２のトランジスタのソース端子には、前記第１のトランジスタのソース端子と同じ可変電流源及び入力端子が接続され、
    　前記第２のトランジスタのゲート端子は前記制御回路によって制御されることを特徴とするトランスインピーダンスアンプ。     The transimpedance amplifier according to claim 1, further comprising a control circuit and a second transistor,
    The same variable current source and input terminal as the source terminal of the first transistor are connected to the source terminal of the second transistor,
    The transimpedance amplifier, wherein the gate terminal of the second transistor is controlled by the control circuit.
  6. 　可変電流源と、トランジスタと、抵抗素子とで構成されるレギュレイテッド型トランスインピーダンスアンプにおいて、入力端子にトランスインピーダンス調整回路が接続され、出力信号に応じて制御回路により前記可変電流源の電流値および前記トランスインピーダンス調整回路を調整することを特徴とするレギュレイテッド型トランスインピーダンスアンプ。 In a regulated transimpedance amplifier composed of a variable current source, a transistor, and a resistance element, a transimpedance adjustment circuit is connected to an input terminal, and a current value of the variable current source and a control circuit according to an output signal A regulated transimpedance amplifier characterized by adjusting the transimpedance adjustment circuit.
  7. 　請求項１に記載のトランスインピーダンスアンプを含むことを特徴とする光受信器。 An optical receiver comprising the transimpedance amplifier according to claim 1.
  8. 　請求項６に記載のレギュレイテッド型トランスインピーダンスアンプを含むことを特徴とする光受信器。
          An optical receiver comprising the regulated transimpedance amplifier according to claim 6.
PCT/JP2009/059806 2008-05-29 2009-05-28 Transimpedance amplifier, regulated type transimpedance amplifier, and optical receiver WO2009145273A1 (en)

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