WO2015016467A1 - Light receiving device - Google Patents

Light receiving device Download PDF

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Publication number
WO2015016467A1
WO2015016467A1 PCT/KR2014/004168 KR2014004168W WO2015016467A1 WO 2015016467 A1 WO2015016467 A1 WO 2015016467A1 KR 2014004168 W KR2014004168 W KR 2014004168W WO 2015016467 A1 WO2015016467 A1 WO 2015016467A1
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Prior art keywords
voltage
amplifier
chip
receiving device
output
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PCT/KR2014/004168
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French (fr)
Korean (ko)
Inventor
오원석
박강엽
정명근
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전자부품연구원
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Priority claimed from KR20130103999A external-priority patent/KR101470578B1/en
Application filed by 전자부품연구원 filed Critical 전자부품연구원
Publication of WO2015016467A1 publication Critical patent/WO2015016467A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H04B10/69—Electrical arrangements in the receiver

Definitions

  • the present invention relates to an optical receiving apparatus for improving noise characteristics.
  • the optical receiver is a key block of the optical interconnect system, which determines the optical transmission distance, optical link system budget, and the like.
  • the optical receiver is a key block of the optical interconnect system, which determines the optical transmission distance, optical link system budget, and the like.
  • Pseudo Differential Amplification is mainly used to improve various common-mode noise characteristics.
  • a differential amplifier efforts have been made to remove common mode noise caused by power-supply noise and ground bouncing.
  • Differential amplifiers are effective at removing common-mode noise by amplifying differences in high-speed signals that are basically 180 degrees out of phase.
  • the optical receiver is basically a single mode in which only one input is input, and the conversion to the differential mode is required, and a DC offset error occurs in the process. Thus, additional blocks are needed to compensate for this.
  • the optical receiving system using the differential amplifier always loses 6dB in the transition gain than the single mode amplifier. Additional blocks are needed to compensate for these losses, resulting in very high power consumption.
  • the differential mode amplifier has problems such as large power consumption and offset error, and the single mode amplifier has a large common mode noise and offset error.
  • the problem to be solved by the present invention is a common mode by adding a noise canceling block (NCB) and a feedforward automatic threshold control (ATC) to a single mode optical receiver equipped with an on-chip regulator It is to provide an optical receiving device that minimizes noise and offset errors.
  • NNB noise canceling block
  • ATC feedforward automatic threshold control
  • an optical receiving apparatus includes an automatic boundary point controller for outputting a reference voltage, an on-chip regulator for generating an on-chip voltage lower than the external voltage from an external voltage, operating in a single mode, and a current signal from the photo detector.
  • a preamplifier for receiving the on-chip voltage from the on-chip regulator, converting and amplifying the current signal into a voltage signal, and outputting the voltage signal with minimized power voltage noise, and a reference output by the automatic boundary point controller.
  • a noise canceling block which receives a voltage and a common mode voltage output from the preamplifier, adds the voltage to the on-chip voltage, and outputs the sum to the preamplifier.
  • a post amplification unit which operates in a differential mode and is disposed at a rear end of the pre amplification unit
  • the automatic boundary point controller controls the automatic boundary point controller
  • It may include a feed forward structure to normalize the reference voltage to output the reference voltage of the post amplifier.
  • the post-amplifier and the pre-amplifier and the post-amplifier may further include a single-differential converter including the auto boundary point controller.
  • the apparatus may further include a low pass filter for removing an offset error of the post amplifier.
  • the post amplification unit The post amplification unit
  • Three stage high speed amplifier or four stage high speed amplifier may be included.
  • the apparatus may further include a driver configured to drive a transmission line or an input capacitance of the output terminal.
  • the low pass filter may further include an equalizer including a high pass filter that is inverse to the transfer function of the low pass filter.
  • the device may further include a peripheral part including a band cap reference and a physicality circuit and providing a bias current and a reference voltage.
  • a single-mode amplifier and an on-chip regulator with low power consumption and high integration are employed, and a power forward consumption control block is devised for a noise cancellation block for improving noise characteristics and a feedforward automatic boundary control block for improving offset errors. It is possible to improve the noise characteristics of the optical receiving apparatus without increasing, and to significantly reduce the offset error.
  • FIG 1 shows an optical receiving apparatus according to an embodiment of the present invention.
  • FIG. 2 is a view for comparing the configuration of the conventional preamplifier and the preamplifier according to an embodiment of the present invention.
  • FIG. 3 shows a conventional ATC configuration for comparison with an embodiment of the invention.
  • FIG. 4 shows a configuration of an ATC according to an embodiment of the present invention.
  • FIG 1 shows an optical receiving apparatus according to an embodiment of the present invention.
  • the optical receiver includes a preamplifier (PrA) 200 for converting and amplifying a minute current signal input from a photo detector (PD) 100 into a voltage signal. .
  • PrA preamplifier
  • Preamplifier (PrA) 200 is located at the very front of the optical receiving device, which is a cascade system, is a very important block for determining the overall noise performance.
  • the output voltage output from the regulator 300 is input to the preamplifier 200 in conjunction with the output voltage output from the noise canceling block (NCB) 400.
  • the regulator 300 is an on-chip regulator designed to generate an on-chip voltage VDDreg lower than the external voltage VDD from the external voltage VDD. At this time, not only a low voltage but also an on-chip voltage with improved regulated quality is generated.
  • the noise cancellation block 400 includes an amplifier 401 and an addition operator 403.
  • the amplifier 401 receives a reference voltage from a feed-forward automatic threshold controller (ATC) 501, and receives a common mode voltage output from the preamplifier 200. As such, the amplifier 401 feeds back the common mode voltage output from the preamplifier 200.
  • ATC feed-forward automatic threshold controller
  • the addition operator 403 adds an output voltage output from the regulator 300 and a voltage output from the amplifier 401 and inputs the preamplification unit PrA 200.
  • the addition operator 403 removes the noise of the common mode voltage from the output voltage output from the regulator 300. Therefore, the output voltage output from the regulator 300 from which the noise of the common mode voltage is removed is input to the preamplifier 200.
  • the noise cancellation block 400 receives the reference voltage from the feed-forward ATC 501 and feeds back the preamplifier 200 in conjunction with the common mode voltage output from the preamplifier 200 to remove the common mode noise.
  • the noise characteristic is improved by controlling the output voltage of the regulator 300 in the direction of the direction.
  • the single-differential converter 500 includes a feed-forward ATC 501, and includes a preamplifier 200 operating in a single mode and a post amplifier (PoA) 600 operating in a differential mode. ).
  • the offset error generated in this process also greatly affects the overall noise performance.
  • the offset error can be minimized by using the feedforward ATC rather than the conventional feedback ATC.
  • the conventional feedback method feeds the signal of the differential node (ie, the node operating in the differential mode) through a low-pass filter to feed back to the cross. To remove it.
  • the feedforward method according to the embodiment of the present invention is a method of eliminating the offset error by detecting a swing at the post-amplifier 600 operating in the differential node, that is, the differential mode and selecting the intermediate value in real time.
  • the feed-forward ATC 501 may cause distortion and jitter and signal loss of the signal in the process of applying the signal output from the preamplifier 200 to the post amplifier 600, the reference level for preventing this Automatically generated. That is, it detects the maximum value and the minimum value of the input signal and outputs the DC value which is the intermediate value.
  • the amplifier 503 amplifies the difference between the value (DC value) outputted by the feed-forward ATC 501 and the input signal and transfers the difference to the post amplifier 600.
  • the post amplifier (PoA) 600 amplifies the output value of the amplifier 503. At this time, always have a constant output amplitude regardless of the input value.
  • the post amplifier 600 should exhibit a large voltage gain characteristic for sufficient output voltage.
  • the post amplifier 600 may be configured as a high speed amplifier of three to four stages.
  • the post amplifier 600 is connected to a low pass filter (LPF) 700.
  • the low pass filter 700 minimizes offset errors that may occur due to high voltage gain, that is, the post amplifier 600. That is, the DC value of each differential node, that is, the post amplifier 600, may be sensed through the low pass filter 700, and the offset error is eliminated by feeding back the cross value.
  • the driver 800 includes an equalizer 801 and a driver 803.
  • Equalizer 801 is a component that can be added or removed depending on the speed of operation of the optical receiving device.
  • the equalizer 801 has a form of a high pass filter that is inverse to a transfer function of a low pass filter form of the optical receiver.
  • the driver 803 consumes a large current so as to drive the input capacitance of the transmission line of the output terminal or the clock-data recoverer (not shown) which is the next block.
  • a clock-data reconstructor (not shown) is used after the optical receiver, but description thereof is omitted regardless of the embodiment of the present invention.
  • the peripheral device 900 includes a bandgap reference (BGR) 901 and a proportional to absolute temperature (PTAT) circuit 903.
  • BGR bandgap reference
  • PTAT proportional to absolute temperature
  • FIG. 2 is a view for comparing the configuration of the conventional preamplifier and the preamplifier according to an embodiment of the present invention.
  • the conventional preamplification unit uses the output voltage of the regulator as a power supply voltage.
  • the noise removing block 400 is the output of the regulator 300, the output of the preamplifier 200, ATC The output of step 501 is used as an input and the feedback output which removes the common mode noise is used as the power supply voltage.
  • FIG. 3 shows a conventional ATC configuration for comparison with an embodiment of the present invention
  • FIG. 4 shows a configuration of an ATC according to an embodiment of the present invention.
  • the conventional ATC is a feedback structure. That is, the conventional ATC receives a signal from an amplifier output stage, converts the signals into differential-to-single and passes a low pass filter to automatically find a threshold value.
  • ATC is a feed-forward structure. That is, the ATC 501 is configured to minimize the offset error by obtaining the DC value of the input signal, normalizing it, and using it as a reference voltage of the differential amplifier 600 coming next.
  • the ATC of the feedback structure requires a low pass filter (LPF) with a very low cutoff frequency to minimize the offset error. That is, R3 and CFB (cipher feedback) should have a very large value.
  • LPF low pass filter
  • the offset error can be minimized by configuring a separate offset canceller that can be controlled automatically or manually from the outside.
  • the values of the passive elements can be matched to values that can be implemented in the integrated circuit.
  • the optical receiver according to the embodiment of the present invention is a noise canceling block (NCB) and a feedforward automatic threshold control block (Auto Threshold) in a single mode optical receiver circuit equipped with an on-chip regulator Control and ATC) can be added to minimize common-mode noise and offset errors, thereby improving noise characteristics.
  • NNB noise canceling block
  • Auto Threshold feedforward automatic threshold control block

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)

Abstract

A light receiving device includes: an automatic boundary point controller outputting a reference voltage; an on-chip regulator generating, from an external voltage, an on-chip voltage lower than the external voltage; a pre-amplifier operating in a single mode, receiving a current signal from a photo detector, receiving the on-chip voltage from the on-chip regulator to convert and amplify the current signal into a voltage signal, and outputting the voltage signal having minimized power supply voltage noise; and a noise cancellation block receiving a reference voltage output by the automatic boundary point controller and a common mode voltage output by the pre-amplifier and adding said received voltages to the on-chip voltage for outputting to the pre-amplifier.

Description

광 수신 장치Optical receiver
본 발명은 잡음 특성을 개선하기 위한 광 수신 장치에 관한 것이다.The present invention relates to an optical receiving apparatus for improving noise characteristics.
광 수신 장치는 광 인터커넥트 시스템의 핵심 블록으로 광 전송거리, 광링크 시스템 예산 등을 결정한다. 또한, 최근에는 상대적으로 낮은 성능을 갖는 실리콘 기반의 광검출소자(Photodiode)들이 출시되면서 광 수신 장치의 성능 향상에 대한 요구가 활발하다.The optical receiver is a key block of the optical interconnect system, which determines the optical transmission distance, optical link system budget, and the like. In addition, recently, with the introduction of silicon-based photodetectors having relatively low performance, there is an active demand for improving the performance of an optical receiver.
종래의 광 수신 장치 구조들은 잡음 특성을 개선하기 위해 다른 성능의 저하를 감수해 왔다. 기존에는 화합물 반도체 기반의 고성능 광검출소자의 채용으로 이러한 광 수신회로의 사용에 무리가 없었다. 그러나 최근 광 전송시스템의 가격 경쟁력이 이슈화되면서 값싼 광검출소자의 사용이 활발해지고 있는 상황에서는 광 수신회로의 성능 향상이 필수적이다.Conventional optical receiver structures have suffered from other performance degradation to improve noise characteristics. Conventionally, the adoption of such a high performance photodetector based on a compound semiconductor has been sufficient for the use of such an optical receiver circuit. However, as the price competitiveness of the optical transmission system has recently been raised, the use of cheap photodetectors has become active, and it is essential to improve the performance of the optical receiver circuit.
종래의 광 수신 장치에서는 각종 공통모드(Common-mode) 잡음 특성을 개선하기 위해 주로 수도 차동 증폭(Pseudo Differential Amplification) 방식을 사용한다. 즉, 차동 증폭기를 사용함으로써 전원 전압 잡음(Power-supply Noise) 및 그라운드 바운싱(Ground Bouncing) 현상 등에 의해 발생하는 공통모드 잡음들을 제거하려는 노력을 해왔다. 차동 증폭기는 기본적으로 180도의 위상 차이가 있는 고속 신호의 차이를 증폭하는 방식으로 공통모드 잡음을 제거하는데 효과적이다.In the conventional optical receiver, Pseudo Differential Amplification is mainly used to improve various common-mode noise characteristics. In other words, by using a differential amplifier, efforts have been made to remove common mode noise caused by power-supply noise and ground bouncing. Differential amplifiers are effective at removing common-mode noise by amplifying differences in high-speed signals that are basically 180 degrees out of phase.
그러나 광 수신 장치는 근본적으로 하나의 입력만 입력되는 싱글모드이며, 차동모드로의 변환이 필요하고 그 과정에서 DC 오프셋 에러(Offset Error)가 발생하게 된다. 따라서, 이를 보상하기 위한 추가의 블록이 필요하다. However, the optical receiver is basically a single mode in which only one input is input, and the conversion to the differential mode is required, and a DC offset error occurs in the process. Thus, additional blocks are needed to compensate for this.
또한, 같은 원인으로 인해 차동 증폭기를 이용한 광 수신 시스템은 싱글모드 증폭기를 이용한 경우보다 변환 이득(Transimpedance Gain)에서 항상 6dB의 손실이 있다. 이러한 손실들을 보상하기 위해 추가 블록들이 필요하며, 이에 따른 전력 소모도 매우 높다.In addition, due to the same cause, the optical receiving system using the differential amplifier always loses 6dB in the transition gain than the single mode amplifier. Additional blocks are needed to compensate for these losses, resulting in very high power consumption.
이와 같은 문제를 해결하기 위해 싱글모드 증폭기를 이용한 광 수신 방법들이 제안되고 있다. 싱글모드 증폭기는 공통모드 잡음에 취약하지만 전력소모가 작고 추가의 블록이 필요하지 않은 장점이 있다. 그러나 싱글모드 증폭기를 사용하는 경우에도 신호의 크기가 커지는 후치증폭기(Post Amplifier, PoA)에서는 차동모드로 동작해야 하므로, 역시 싱글모드에서 차동모드로 변환하는 추가 블록이 필요하게 되며 이 과정에서 역시 DC 오프셋에러가 발생한다.In order to solve this problem, optical reception methods using a single mode amplifier have been proposed. Single-mode amplifiers are vulnerable to common-mode noise, but have the advantage of low power consumption and no additional blocks. However, even in the case of using a single mode amplifier, a post amplifier (PoA) having a large signal must operate in differential mode, and thus, an additional block for converting from single mode to differential mode is needed. An offset error occurs.
또한, 공통모드 잡음 문제를 해결하기 위해 온칩 레귤레이터(On-chip Regulator) 회로를 추가로 삽입하는 것이 일반적이다. 온칩 레귤레이터는 공통모드 잡음 중 가장 큰 비중을 차지하는 전원 전압 잡음을 최소화하려는 시도이다. 하지만, 온칩 레귤레이터를 사용함에도 불구하고 공통 모드 잡음특성은 차동모드보다 현저히 낮은 성능을 갖는다. In addition, it is common to add an additional on-chip regulator circuit to solve the common-mode noise problem. On-chip regulators attempt to minimize supply voltage noise, which accounts for the largest portion of common-mode noise. However, despite using on-chip regulators, common-mode noise characteristics are significantly lower than differential mode.
그러나 차동모드 증폭기의 경우 큰 전력소모 및 오프셋에러 발생과 같은 문제가 있으며, 싱글모드 증폭기의 경우 큰 공통모드 잡음과 오프셋에러가 발생하는 문제가 있다. However, the differential mode amplifier has problems such as large power consumption and offset error, and the single mode amplifier has a large common mode noise and offset error.
본 발명이 해결하고자 하는 과제는 온칩 레귤레이터를 탑재한 싱글모드 광 수신 장치에 잡음 취소 블록(Noise Cancelling Block, NCB) 및 피드 포워드(Feedforward) 자동 경계점 제어기(Auto Threshold Control, ATC)를 추가하여 공통모드 잡음과 오프셋 에러를 최소화하는 광 수신 장치를 제공하는 것이다.The problem to be solved by the present invention is a common mode by adding a noise canceling block (NCB) and a feedforward automatic threshold control (ATC) to a single mode optical receiver equipped with an on-chip regulator It is to provide an optical receiving device that minimizes noise and offset errors.
본 발명의 하나의 특징에 따르면, 광 수신 장치는 기준 전압을 출력하는 자동 경계점 제어기, 외부 전압으로부터 상기 외부 전압보다 더 낮은 온칩 전압을 생성하는 온칩 레귤레이터, 싱글모드로 동작하고, 광 검출기로부터 전류 신호를 입력받고, 상기 온칩 레귤레이터로부터 상기 온칩 전압을 입력받아 상기 전류 신호를 전압 신호로 변환 및 증폭하여 전원 전압 잡음이 최소화된 상기 전압 신호를 출력하는 전치 증폭부, 그리고 상기 자동 경계점 제어기가 출력하는 기준 전압 및 상기 전치 증폭기가 출력하는 공통 모드 전압을 입력받아 상기 온칩 전압과 합산하여 상기 전치 증폭부로 출력하는 잡음 취소 블록을 포함한다.According to one aspect of the present invention, an optical receiving apparatus includes an automatic boundary point controller for outputting a reference voltage, an on-chip regulator for generating an on-chip voltage lower than the external voltage from an external voltage, operating in a single mode, and a current signal from the photo detector. A preamplifier for receiving the on-chip voltage from the on-chip regulator, converting and amplifying the current signal into a voltage signal, and outputting the voltage signal with minimized power voltage noise, and a reference output by the automatic boundary point controller. And a noise canceling block which receives a voltage and a common mode voltage output from the preamplifier, adds the voltage to the on-chip voltage, and outputs the sum to the preamplifier.
차동 모드로 동작하고, 상기 전치 증폭부의 후단에 배치되는 후치 증폭부를 더 포함하고,A post amplification unit which operates in a differential mode and is disposed at a rear end of the pre amplification unit;
상기 자동 경계점 제어기는, The automatic boundary point controller,
상기 기준 전압을 정규화하여 상기 후치 증폭기의 레퍼런스 전압으로 출력하는 피드 포워드 구조를 포함할 수 있다.It may include a feed forward structure to normalize the reference voltage to output the reference voltage of the post amplifier.
상기 후치 증폭부, 그리고 상기 전치 증폭부와 상기 후치 증폭부를 연결하고, 상기 자동경계점 제어기가 포함되는 싱글-차동 변환부를 더 포함할 수 있다.The post-amplifier and the pre-amplifier and the post-amplifier may further include a single-differential converter including the auto boundary point controller.
상기 후치 증폭부의 오프셋 에러를 제거하는 저역 통과 필터를 더 포함할 수 있다.The apparatus may further include a low pass filter for removing an offset error of the post amplifier.
상기 후치 증폭부는,The post amplification unit,
3단의 고속 증폭기 또는 4단의 고속 증폭기를 포함할 수 있다.Three stage high speed amplifier or four stage high speed amplifier may be included.
출력단의 전송선 또는 입력 커패시턴스를 구동하는 구동부를 더 포함할 수 있다.The apparatus may further include a driver configured to drive a transmission line or an input capacitance of the output terminal.
상기 저역 통과 필터의 전달 함수에 역이 되는 고역 통과 필터를 포함하는 등화기를 더 포함할 수 있다.The low pass filter may further include an equalizer including a high pass filter that is inverse to the transfer function of the low pass filter.
밴드캡 레퍼런스 및 피티에이티 회로를 포함하고, 바이어스 전류 및 기준 전압을 제공하는 주변 기기부를 더 포함할 수 있다.The device may further include a peripheral part including a band cap reference and a physicality circuit and providing a bias current and a reference voltage.
본 발명의 실시예에 따르면, 전력 소모가 작고 집적도가 높은 싱글모드 증폭기와 온칩 레귤레이터를 채용하고, 잡음 특성 개선을 위한 잡음 취소 블록 및 오프셋 에러 개선을 위한 피드포워드 자동 경계점 제어 블록을 고안하여 전력소모의 증가없이 광 수신 장치의 잡음특성을 개선할 수 있으며, 오프셋 에러도 크게 감소시킬 수 있다. 또한, 이러한 구성을 통해 저가형 실리콘 기반 광검출소자를 사용하더라도 성능 저하 없이 광 전송 시스템을 구현하는 것이 가능하며, 최근 이슈가 되고 있는 초저전력형 광 송수신 시스템의 구현이 가능하다.According to an embodiment of the present invention, a single-mode amplifier and an on-chip regulator with low power consumption and high integration are employed, and a power forward consumption control block is devised for a noise cancellation block for improving noise characteristics and a feedforward automatic boundary control block for improving offset errors. It is possible to improve the noise characteristics of the optical receiving apparatus without increasing, and to significantly reduce the offset error. In addition, it is possible to implement an optical transmission system without degrading performance even when using a low-cost silicon-based photodetector through this configuration, and it is possible to implement an ultra-low-power optical transceiver system which has recently become an issue.
도 1은 본 발명의 실시예에 따른 광 수신 장치를 나타낸다.1 shows an optical receiving apparatus according to an embodiment of the present invention.
도 2는 종래의 전치 증폭부 및 본 발명의 실시예에 따른 전치 증폭부의 구성을 비교하기 위한 도면이다.2 is a view for comparing the configuration of the conventional preamplifier and the preamplifier according to an embodiment of the present invention.
도 3은 본 발명의 실시예와 비교하기 위한 종래의 ATC 구성을 나타낸다. 3 shows a conventional ATC configuration for comparison with an embodiment of the invention.
도 4는 본 발명의 실시예에 따른 ATC의 구성을 나타낸다.4 shows a configuration of an ATC according to an embodiment of the present invention.
아래에서는 첨부한 도면을 참고로 하여 본 발명의 실시예에 대하여 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 용이하게 실시할 수 있도록 상세히 설명한다. 그러나 본 발명은 여러 가지 상이한 형태로 구현될 수 있으며 여기에서 설명하는 실시예에 한정되지 않는다. 그리고 도면에서 본 발명을 명확하게 설명하기 위해서 설명과 관계없는 부분은 생략하였으며, 명세서 전체를 통하여 유사한 부분에 대해서는 유사한 도면 부호를 붙였다.DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.
명세서 전체에서, 어떤 부분이 어떤 구성요소를 "포함"한다고 할 때, 이는 특별히 반대되는 기재가 없는 한 다른 구성요소를 제외하는 것이 아니라 다른 구성요소를 더 포함할 수 있는 것을 의미한다.Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.
이하, 도면을 참조로 하여 본 발명의 실시예에 따른 광 수신 장치에 대하여 상세히 설명한다.Hereinafter, an optical receiver according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 본 발명의 실시예에 따른 광 수신 장치를 나타낸다.1 shows an optical receiving apparatus according to an embodiment of the present invention.
도 1을 참조하면, 광 수신 장치는 광 검출기(Photo Detector, PD)(100)로부터 입력되는 미세한 전류 신호를 전압 신호로 변환하고 증폭하는 전치 증폭부(Pre Amplifier, PrA)(200)를 포함한다.Referring to FIG. 1, the optical receiver includes a preamplifier (PrA) 200 for converting and amplifying a minute current signal input from a photo detector (PD) 100 into a voltage signal. .
전치 증폭부(PrA)(200)는 캐스캐이드(cascade) 시스템인 광 수신 장치의 맨 앞단에 위치하며, 전체 잡음 성능을 결정하는 매우 중요한 블록이다.Preamplifier (PrA) 200 is located at the very front of the optical receiving device, which is a cascade system, is a very important block for determining the overall noise performance.
레귤레이터(300)가 출력하는 출력 전압은 잡음 취소 블록(Noise Cancelling Block, NCB)(400)이 출력하는 출력 전압과 연동하여 전치 증폭부(200)로 입력된다.The output voltage output from the regulator 300 is input to the preamplifier 200 in conjunction with the output voltage output from the noise canceling block (NCB) 400.
이때, 레귤레이터(300)는 외부 전압(VDD)으로부터 외부 전압(VDD)보다 더 낮은 온칩 전압(VDDreg)을 발생하기 위하여 설계된 온칩 레귤레이터이다. 이때, 단순히 낮은 전압일 뿐만 아니라 레귤레이션(regulation)된 품질이 향상된 온칩 전압을 발생시킨다.At this time, the regulator 300 is an on-chip regulator designed to generate an on-chip voltage VDDreg lower than the external voltage VDD from the external voltage VDD. At this time, not only a low voltage but also an on-chip voltage with improved regulated quality is generated.
여기서, 잡음 취소 블록(400)은 증폭기(401) 및 덧셈 연산기(403)를 포함한다. 증폭기(401)는 피드-포워드 자동 경계점 제어기(Feed-forward Automatic Threshold Control, ATC)(501)로부터 기준 전압을 입력받고, 전치 증폭부(200)가 출력하는 공통모드 전압을 입력받는다. 이처럼, 증폭기(401)는 전치 증폭부(200)가 출력하는 공통모드 전압을 피드백한다.Here, the noise cancellation block 400 includes an amplifier 401 and an addition operator 403. The amplifier 401 receives a reference voltage from a feed-forward automatic threshold controller (ATC) 501, and receives a common mode voltage output from the preamplifier 200. As such, the amplifier 401 feeds back the common mode voltage output from the preamplifier 200.
덧셈 연산기(403)는 레귤레이터(300)가 출력하는 출력 전압 및 증폭기(401)가 출력하는 전압을 덧셈 연산하여 전치 증폭부(PrA)(200)로 입력한다. 덧셈 연산기(403)는 레귤레이터(300)가 출력하는 출력 전압에서 공통모드 전압의 잡음이 제거되도록 한다. 따라서, 공통모드 전압의 잡음이 제거된 레귤레이터(300)가 출력하는 출력 전압이 전치 증폭부(200)로 입력된다. The addition operator 403 adds an output voltage output from the regulator 300 and a voltage output from the amplifier 401 and inputs the preamplification unit PrA 200. The addition operator 403 removes the noise of the common mode voltage from the output voltage output from the regulator 300. Therefore, the output voltage output from the regulator 300 from which the noise of the common mode voltage is removed is input to the preamplifier 200.
이처럼, 싱글 모드로 동작하는 전치 증폭부(200)는 전원 전압 잡음에 매우 취약하므로 레귤레이터(300)를 사용하여 전원 전압 잡음을 최소화한다. 그리고 잡음 취소 블록(400)은 피드-포워드 ATC(501)로부터 기준 전압을 입력받아 전치 증폭부(200)가 출력하는 공통모드 전압과 연동하여 전치 증폭부(200)에 피드백함으로써 공통모드 잡음이 제거되는 방향으로 레귤레이터(300)의 출력 전압을 제어함으로써 잡음 특성을 개선한다.As such, since the preamplifier 200 operating in the single mode is very vulnerable to power supply voltage noise, the regulator 300 minimizes the power supply voltage noise. The noise cancellation block 400 receives the reference voltage from the feed-forward ATC 501 and feeds back the preamplifier 200 in conjunction with the common mode voltage output from the preamplifier 200 to remove the common mode noise. The noise characteristic is improved by controlling the output voltage of the regulator 300 in the direction of the direction.
한편, 싱글-차동 변환부(500)는 피드-포워드 ATC(501)를 포함하며, 싱글 모드로 동작하는 전치 증폭부(200)와 차동 모드로 동작하는 후치 증폭부(Post Amplifier, PoA)(600)를 연결한다. 이 과정에서 발생하는 오프셋 에러 또한 전체 잡음 성능에 큰 영향을 미치는데, 기존의 피드백 방식의 ATC가 아닌 피드포워드 방식의 ATC를 사용하여 오프셋 에러를 최소화시킬 수 있다. 기존의 피드백 방식은 오프셋 에러를 최소화할 수 있도록 차동 노드(즉 차동 모드로 동작하는 노드)의 신호를 저역통과필터(Low-Pass Filter)를 통과시켜 크로스(Cross)로 피드백하는 방식을 통해 오프셋 에러를 제거하는 방식이다. 반면, 본 발명의 실시예에 따른 피드포워드 방식은 차동 노드 즉 차동 모드로 동작하는 후치 증폭부(600)에서의 스윙을 감지하여 그 중간값을 실시간으로 선택함으로써 오프셋 에러를 제거하는 방식이다.Meanwhile, the single-differential converter 500 includes a feed-forward ATC 501, and includes a preamplifier 200 operating in a single mode and a post amplifier (PoA) 600 operating in a differential mode. ). The offset error generated in this process also greatly affects the overall noise performance. The offset error can be minimized by using the feedforward ATC rather than the conventional feedback ATC. In order to minimize the offset error, the conventional feedback method feeds the signal of the differential node (ie, the node operating in the differential mode) through a low-pass filter to feed back to the cross. To remove it. On the other hand, the feedforward method according to the embodiment of the present invention is a method of eliminating the offset error by detecting a swing at the post-amplifier 600 operating in the differential node, that is, the differential mode and selecting the intermediate value in real time.
피드-포워드 ATC(501)는 전치 증폭기(200)가 출력하는 신호를 후치 증폭기(600)에 인가하는 과정에서 신호의 왜곡 및 지터(jiter) 및 신호 유실이 발생할 수 있으므로, 이를 방지하기 위한 기준 레벨을 자동으로 발생시킨다. 즉, 입력 신호의 최대값과 최소값을 감지하여 그 중간값인 DC값을 출력한다.Since the feed-forward ATC 501 may cause distortion and jitter and signal loss of the signal in the process of applying the signal output from the preamplifier 200 to the post amplifier 600, the reference level for preventing this Automatically generated. That is, it detects the maximum value and the minimum value of the input signal and outputs the DC value which is the intermediate value.
증폭기(503)는 피드-포워드 ATC(501)가 출력하는 값(DC값)과 입력 신호의 차이를 증폭하여 후치 증폭부(600)에게 전달한다.The amplifier 503 amplifies the difference between the value (DC value) outputted by the feed-forward ATC 501 and the input signal and transfers the difference to the post amplifier 600.
한편, 후치 증폭부(Post Amplifier, PoA)(600)는 증폭기(503)의 출력값을 증폭한다. 이 때, 입력값에 관계없이 항상 일정한 출력진폭을 갖도록 한다.On the other hand, the post amplifier (PoA) 600 amplifies the output value of the amplifier 503. At this time, always have a constant output amplitude regardless of the input value.
후치 증폭부(600)는 충분한 출력 전압을 위해 큰 전압 이득 특성을 보여야 한다. 후치 증폭부(600)는 3~4단의 고속 증폭기로 구성될 수 있다. 그리고 후치 증폭부(600)는 저역 통과 필터(Low-Pass Filter, LPF)(700)와 연결된다. 저역 통과 필터(700)는 높은 전압이득 즉 후치 증폭부(600)으로 인해 생길 수 있는 오프셋 에러를 최소화시킨다. 즉, 각 차동 노드 즉 후치 증폭부(600)의 DC값을 저역통과필터(700)를 통해 감지할 수 있고, 이를 크로스로 피드백함으로써 오프셋에러를 제거한다.The post amplifier 600 should exhibit a large voltage gain characteristic for sufficient output voltage. The post amplifier 600 may be configured as a high speed amplifier of three to four stages. The post amplifier 600 is connected to a low pass filter (LPF) 700. The low pass filter 700 minimizes offset errors that may occur due to high voltage gain, that is, the post amplifier 600. That is, the DC value of each differential node, that is, the post amplifier 600, may be sensed through the low pass filter 700, and the offset error is eliminated by feeding back the cross value.
구동부(800)는 등화기(801) 및 구동기(803)를 포함한다. The driver 800 includes an equalizer 801 and a driver 803.
등화기(801)는 광 수신 장치의 동작 속도에 따라 추가되거나 또는 제거될 수 있는 구성 요소이다. 등화기(801)는 광 수신 장치가 갖고 있는 저역통과필터 형태의 전달함수에 역이 되는 고역통과필터의 형태를 갖는다. Equalizer 801 is a component that can be added or removed depending on the speed of operation of the optical receiving device. The equalizer 801 has a form of a high pass filter that is inverse to a transfer function of a low pass filter form of the optical receiver.
구동기(803)는 출력단의 전송선 또는 다음 블록인 클록-데이터 복원기(미도시)의 입력 커패시턴스를 구동할 수 있도록 큰 전류를 소모한다. 여기서, 일반적으로 광수신기 뒤에는 클록-데이터 복원기(미도시)가 쓰이나, 본 발명의 실시예와 무관하여 설명은 생략한다. The driver 803 consumes a large current so as to drive the input capacitance of the transmission line of the output terminal or the clock-data recoverer (not shown) which is the next block. Here, in general, a clock-data reconstructor (not shown) is used after the optical receiver, but description thereof is omitted regardless of the embodiment of the present invention.
또한, 레귤레이터(300)에서 출력되는 품질좋은 레퍼런스 전압을 전원 전압으로 사용함으로써 각 블록(200~800)의 잡음 특성이 개선될 수 있다.In addition, by using a high quality reference voltage output from the regulator 300 as a power supply voltage, noise characteristics of each block 200 to 800 may be improved.
주변 기기부(900)는 밴드갭 레퍼런스(Bandgap Reference, BGR)(901) 및 피티에이티(Proportional To Absolute Temperature, PTAT) 회로(903)로 구성된다. 이러한 주변 기기부(900)는 레귤레이터(300) 및 광 수신 장치의 모든 블록들의 바이어스 전류 및 기준 전압을 제공한다.The peripheral device 900 includes a bandgap reference (BGR) 901 and a proportional to absolute temperature (PTAT) circuit 903. The peripheral unit 900 provides the bias current and the reference voltage of all the blocks of the regulator 300 and the optical receiving device.
도 2는 종래의 전치 증폭부 및 본 발명의 실시예에 따른 전치 증폭부의 구성을 비교하기 위한 도면이다.2 is a view for comparing the configuration of the conventional preamplifier and the preamplifier according to an embodiment of the present invention.
먼저, 도 2의 (a)를 참조하면, 종래의 전치 증폭부는 레귤레이터의 출력 전압을 그대로 전원 전압으로 사용하는 형태이다.First, referring to FIG. 2 (a), the conventional preamplification unit uses the output voltage of the regulator as a power supply voltage.
반면, 도 2의 (b)를 참조하면, 본 발명의 실시예에 따른 전치 증폭부(200)는 잡음 제거 블록(400)가 레귤레이터(300)의 출력, 전치 증폭부(200)의 출력, ATC(501)의 출력을 입력으로 받아 공통모드 잡음을 제거한 피드백된 출력을 전원 전압으로 사용한다. On the other hand, referring to Figure 2 (b), in the preamplifier 200 according to an embodiment of the present invention, the noise removing block 400 is the output of the regulator 300, the output of the preamplifier 200, ATC The output of step 501 is used as an input and the feedback output which removes the common mode noise is used as the power supply voltage.
도 3은 본 발명의 실시예와 비교하기 위한 종래의 ATC 구성을 나타내고, 도 4는 본 발명의 실시예에 따른 ATC의 구성을 나타낸다.3 shows a conventional ATC configuration for comparison with an embodiment of the present invention, and FIG. 4 shows a configuration of an ATC according to an embodiment of the present invention.
먼저, 도 3을 참조하면, 종래의 ATC는 피드백 구조이다. 즉, 종래의 ATC는 증폭기 출력단의 신호를 입력받아 그 신호들을 디퍼렌셜-투-싱글(Differential-to-Single)로 변환하고 저역통과필터를 통과시킴으로써 자동으로 쓰레스홀드(Threshold)값을 찾는다.First, referring to FIG. 3, the conventional ATC is a feedback structure. That is, the conventional ATC receives a signal from an amplifier output stage, converts the signals into differential-to-single and passes a low pass filter to automatically find a threshold value.
반면, 도 4를 참조하면, 본 발명의 실시예에 따른 ATC는 피드-포워드 구조이다. 즉, ATC(501)는 입력 신호의 DC값을 구하고, 이를 정규화하여 다음단에 오는 차동 증폭기(600)의 레퍼런스 전압으로 활용함으로써 오프셋 에러를 최소화하도록 구성되어 있다.On the other hand, referring to Figure 4, ATC according to an embodiment of the present invention is a feed-forward structure. That is, the ATC 501 is configured to minimize the offset error by obtaining the DC value of the input signal, normalizing it, and using it as a reference voltage of the differential amplifier 600 coming next.
이처럼, 피드백 구조의 ATC는 오프셋 에러를 최소화하기 위해 매우 낮은 컷오프주파수를 갖는 저역통과필터(LPF)를 필요로 한다. 즉, R3와 CFB(cipher feedback)가 매우 큰 값을 가져야 한다. 그러나 본 발명의 실시예에 따른 피드포워드 ATC에서는 저역통과필터의 컷오프주파수가 높더라도, 외부에서 자동 또는 수동으로 제어할 수 있는 별도의 오프셋 취소기(Offset Canceller)를 구성하여 오프셋 에러를 최소화할 수 있으며, 2단의 LPF를 구성하여 수동소자의 값들을 집적회로 내부에 구현가능한 수치들로 맞출 수 있다.As such, the ATC of the feedback structure requires a low pass filter (LPF) with a very low cutoff frequency to minimize the offset error. That is, R3 and CFB (cipher feedback) should have a very large value. However, in the feedforward ATC according to the embodiment of the present invention, even if the cutoff frequency of the low pass filter is high, the offset error can be minimized by configuring a separate offset canceller that can be controlled automatically or manually from the outside. In addition, by configuring a two-stage LPF, the values of the passive elements can be matched to values that can be implemented in the integrated circuit.
전술한 바에 따르면, 본 발명의 실시예에 따른 광 수신 장치는 온칩 레귤레이터를 탑재한 싱글 모드 광 수신회로에 잡음취소블록(Noise Cancelling Block, NCB) 및 피드포워드(Feedforward) 자동경계점제어블록(Auto Threshold Control, ATC)을 추가하여 공통모드 잡음과 오프셋 에러를 최소화함으로써, 잡음 특성을 개선할 수 있다.As described above, the optical receiver according to the embodiment of the present invention is a noise canceling block (NCB) and a feedforward automatic threshold control block (Auto Threshold) in a single mode optical receiver circuit equipped with an on-chip regulator Control and ATC) can be added to minimize common-mode noise and offset errors, thereby improving noise characteristics.
이상에서 본 발명의 바람직한 실시예에 대하여 상세하게 설명하였지만 본 발명의 권리범위는 이에 한정되는 것은 아니고 다음의 청구범위에서 정의하고 있는 본 발명의 기본 개념을 이용한 당업자의 여러 변형 및 개량 형태 또한 본 발명의 권리범위에 속하는 것이다.Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (8)

  1. 기준 전압을 출력하는 자동 경계점 제어기,Automatic threshold controller outputting a reference voltage,
    외부 전압으로부터 상기 외부 전압보다 더 낮은 온칩 전압을 생성하는 온칩 레귤레이터, An on-chip regulator for generating an on-chip voltage lower than the external voltage from an external voltage,
    싱글모드로 동작하고, 광 검출기로부터 전류 신호를 입력받고, 상기 온칩 레귤레이터로부터 상기 온칩 전압을 입력받아 상기 전류 신호를 전압 신호로 변환 및 증폭하여 전원 전압 잡음이 최소화된 상기 전압 신호를 출력하는 전치 증폭부, 그리고Preamplification, which operates in a single mode, receives a current signal from a photo detector, receives the on-chip voltage from the on-chip regulator, converts and amplifies the current signal into a voltage signal, and outputs the voltage signal with minimal power voltage noise. Wealth, and
    상기 자동 경계점 제어기가 출력하는 기준 전압 및 상기 전치 증폭기가 출력하는 공통 모드 전압을 입력받아 상기 온칩 전압과 합산하여 상기 전치 증폭부로 출력하는 잡음 취소 블록A noise canceling block which receives a reference voltage output from the automatic boundary point controller and a common mode voltage output from the preamplifier, adds it to the on-chip voltage, and outputs the summed voltage to the preamplifier.
    을 포함하는 광 수신 장치.Optical receiving device comprising a.
  2. 제1항에 있어서,The method of claim 1,
    차동 모드로 동작하고, 상기 전치 증폭부의 후단에 배치되는 후치 증폭부를 더 포함하고,A post amplification unit which operates in a differential mode and is disposed at a rear end of the pre amplification unit;
    상기 자동 경계점 제어기는, The automatic boundary point controller,
    상기 기준 전압을 정규화하여 상기 후치 증폭기의 레퍼런스 전압으로 출력하는 피드 포워드 구조를 포함하는 광 수신 장치.And a feed forward structure for normalizing the reference voltage to output the reference voltage of the post amplifier.
  3. 제2항에 있어서,The method of claim 2,
    상기 후치 증폭부, 그리고The post amplifier, and
    상기 전치 증폭부와 상기 후치 증폭부를 연결하고, 상기 자동경계점 제어기가 포함되는 싱글-차동 변환부A single-differential converter connecting the preamplifier and the post amplification unit, wherein the auto boundary point controller is included.
    를 더 포함하는 광 수신 장치.Optical receiving device further comprising.
  4. 제3항에 있어서,The method of claim 3,
    상기 후치 증폭부의 오프셋 에러를 제거하는 저역 통과 필터를 더 포함하는 광 수신 장치.And a low pass filter for canceling the offset error of the post amplifier.
  5. 제4항에 있어서,The method of claim 4, wherein
    상기 후치 증폭부는,The post amplification unit,
    3단의 고속 증폭기 또는 4단의 고속 증폭기를 포함하는 광 수신 장치.Optical receiving device comprising a three stage high speed amplifier or four stage high speed amplifier.
  6. 제4항에 있어서,The method of claim 4, wherein
    출력단의 전송선 또는 입력 커패시턴스를 구동하는 구동부Driver for driving transmission line or input capacitance of output stage
    를 더 포함하는 광 수신 장치.Optical receiving device further comprising.
  7. 제6항에 있어서,The method of claim 6,
    상기 저역 통과 필터의 전달 함수에 역이 되는 고역 통과 필터를 포함하는 등화기An equalizer comprising a high pass filter inverse to the transfer function of the low pass filter
    를 더 포함하는 광 수신 장치.Optical receiving device further comprising.
  8. 제3항에 있어서,The method of claim 3,
    밴드캡 레퍼런스 및 피티에이티 회로를 포함하고, 바이어스 전류 및 기준 전압을 제공하는 주변 기기부Peripheral part including bandcap reference and fixture circuits, providing bias current and reference voltage
    를 더 포함하는 광 수신 장치.Optical receiving device further comprising.
PCT/KR2014/004168 2013-07-30 2014-05-09 Light receiving device WO2015016467A1 (en)

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Citations (4)

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KR20080079952A (en) * 2007-02-28 2008-09-02 고려대학교 산학협력단 Optical receiver with threshold convergence, audio apparatus and communication apparatus using this
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