1223932 A7 --- B7 五、發明說明（i) 發明背景： I發明領域： 本發明係有關於一種光纖通訊上使用之光接收器，更 明確而言’係有關於一種用於光接收器之電流放大器的監 控電路。 2·先前技術說明： 在光纖通訊系統中，會使用光電流監控電路以監控光 接收器所接收到的光強度是否異常。由光強度的狀況，可 以據以判斷遠端的雷射是否發生故障，或是近端光接收器 是否故障，而可以提早檢修或是更換，以維持光纖通訊系 統整體的使用穩定度以及可靠度。 在光接收器中，一般都是將光電二極體所接收到的光 電流，經過前置放大器放大並轉換成電壓訊號，再做訊號 處理。在習用技術中，係在光電二極體的一端接上監控電 路，以監控光電二極體之光電流，藉以判斷所接收到的光 強度。 經濟部智慧財產局員工消費合作社印製 請參見圖一，其係顯示習用之電壓輸出式光電流監控 電路概圖。如圖中所示，係使用一對射極連接至電壓源 Vex的雙載子電晶體(Q1，Q2)形成電流鏡，連接於光電2 極體PD之負端。方塊10係表示電流轉電壓輸出電路。 另，參考號碼15係表示前置放大器。 圖二係顯示習用之電流輸出式光電流監控電路概圖。 與圖一最大的不同之處在於該電路係不具有電流轉電壓輸 出電路。 & 1223932 A7 B7 五、發明說明（2) 美國專利第6,333,804號係揭示一種使用場效電晶體 (FET)之光電流監控電路。請參見圖三，係顯示該種光電 流監控電路之概圖。由圖中可知，於該專利案中，係利用 兩對MOS電流鏡(2c、2d以2e、2f及來達到監控光電流 之目的。 除了 一般的光電二極體，在光接收器中，亦有使用操 作於高電壓(例如70V)的崩潰式光電二極體(APD)。針對使 用崩潰式光電二極體的光接收器，亦有類似於前述之光電 流監控電路結構提出。例如美國專利第6，188,059號，係 藉由利用兩對電流鏡(2FQ1、2FQ2以及2RQ1、2RQ2)來 監控光電流，如圖四所示。因為崩潰式光電二極體係操作 於40V至80V的高電壓下，而場效電晶體的崩潰電壓大 約只有30V至60V，因此，一般係使用雙載子電晶體之電 流鏡。 .錦丨 經濟部智慧財產局員工消費合作社印製 上述習用之光電流監控電路基本上是以電流鏡加以監 控，對於光電二極體的微小電流必須將之放大甚至轉換成 電壓訊號才可進行處理。如果能有一種光電流監控電路在 不增加甚至減少元件數量的情形下，可以直接放大電流， 對於光學收發系統的小型化將是很有助益的。 發明概述： 本發明之目的係在於提供一種光電流監控電路，其除 了監控光電二極體之光電流之外，亦可直接將光電二極體 之光電流放大，以供後續訊號處理用。 -4- 本紙張尺度適用中國國家標準(CNS)A4規格（210 X 297公釐）一-—----- 1223932 A7 B7 五、發明說明（3 ) 本發明之另一目的係在於提供一種光電流監控電路， 其可將光電二極體之光電流直接轉換成電壓訊號以便後續 處理。 本發明之又一目的係在於提供一種光電流監控電路， 其可在不增加元件甚至節省元件的情況下，達到監控光電 流的目的，有助於光收發器的小型化。 本發明之再一目的係在於提供一種光電流監控電路， 其可藉由間單的電路結構而使得該光電流監控電路可應用 於高電壓操作的崩潰式光電二極體。 根據本發明之一方面，一種光電流監控電路係包括一 光電二極體，用於感測光強度，轉換成光電流；以及一電 晶體’其射極連接於電源電壓，其基極連結於該光電二極 體之一端，其集極接地並係輸出放大的感測電流。 根據本發明之另一方面，該光電流監控電路係具有一 齊納二極體連接於輸出端。 圖式簡單說明： 經濟部智慧財產局員工消費合作社印製 圖一係顯示習用之電壓輸出式光電流監控電路概圖； 圖二係顯示習用之電流輸出式光電流監控電路概圖； 圖三係顯示一種使用場效電晶體(FET)之習用光電流 監控電路概圖； 圖四係顯示用於崩潰式光電二極體之習用光電流監控 電路概圖； 圖五係顯示根據本發明之一實施例之光電流監控電路 本紙張尺度適用甲國國家標準(CNS)A4規格（21〇 χ 297公釐y 1223932 A7 B7 經濟部智慧財產局員工消費合作社印製 五、發明說明（4) 的概圖； 圖六係顯示基於圖五之另一實施例之光電流監控電 路； 圖七係顯示基於圖六之另一實施例之光電流監控電 路； 圖八係顯示基於圖五之另一實施例之光電流監控電 路； 圖九係顯示根據本發明之電壓輸出式電流鏡光電流監 控電路的概圖； 圖十係顯示根據本發明之電流輸出式電流鏡光電流監 控電路的概圖； 圖十一係顯示根據本發明之用於崩潰式光電二極體之 光電流監控電路的概圖； 圖十二係顯示根據本發明之另一種用於崩潰式光電二 極體之光電流監控電路的概圖； 圖十三係顯示根據本發明之又一種用於崩潰式光電二 極體之光電流監控電路的概圖； 圖十四係顯示根據本發明之用於崩潰式光電二極體之 場效電晶體型光電流監控電路的概圖；以及 圖十五係顯示根據本發明之用於崩潰式光電二極體之 另一種場效電晶體型光電流監控電路的概圖。 發明詳細說明： 現在將參照圖式詳細說明本發明之電路結構。圖五係 -6- 本紙張尺度適用中國國家標準(CNS)A4規格（210x297公釐)1223932 A7 --- B7 V. Description of the invention (i) Background of the invention: I Field of invention: The present invention relates to an optical receiver used in optical fiber communication, and more specifically, to an optical receiver used in optical receivers. Monitoring circuit for current amplifier. 2. Previous technical description: In the optical fiber communication system, a photocurrent monitoring circuit is used to monitor whether the light intensity received by the optical receiver is abnormal. Based on the condition of the light intensity, it can be used to determine whether the laser at the far end is faulty or whether the near-end optical receiver is faulty, and it can be repaired or replaced early to maintain the stability and reliability of the overall use of the optical fiber communication system. . In the optical receiver, the photocurrent received by the photodiode is generally amplified by a preamplifier and converted into a voltage signal, and then processed. In conventional technology, a monitoring circuit is connected to one end of the photodiode to monitor the photocurrent of the photodiode, so as to judge the received light intensity. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Please refer to Figure 1, which shows a schematic diagram of a conventional voltage output photocurrent monitoring circuit. As shown in the figure, a pair of bipolar transistors (Q1, Q2) whose emitter is connected to the voltage source Vex is used to form a current mirror, which is connected to the negative terminal of the photodiode PD. Box 10 indicates a current-to-voltage output circuit. The reference number 15 indicates a preamplifier. Figure 2 shows a schematic diagram of a conventional current output photocurrent monitoring circuit. The biggest difference from Figure 1 is that this circuit does not have a current-to-voltage output circuit. & 1223932 A7 B7 V. Description of the Invention (2) US Patent No. 6,333,804 discloses a photocurrent monitoring circuit using a field effect transistor (FET). Please refer to Figure 3, which shows the outline of this kind of photoelectric current monitoring circuit. It can be seen from the figure that in this patent case, two pairs of MOS current mirrors (2c, 2d and 2e, 2f and 2) are used to achieve the purpose of monitoring the photocurrent. In addition to the ordinary photodiode, in the optical receiver, also There are collapsed photodiodes (APDs) that operate at high voltages (such as 70V). For light receivers that use collapsed photodiodes, there is also a photocurrent monitoring circuit structure similar to the aforementioned. For example, the US patent No. 6,188,059 monitors the photocurrent by using two pairs of current mirrors (2FQ1, 2FQ2 and 2RQ1, 2RQ2), as shown in Figure 4. Because the collapsed photodiode system operates at a high voltage of 40V to 80V The breakdown voltage of the field effect transistor is only about 30V to 60V. Therefore, a current mirror using a bipolar transistor is generally used. Jin Jin 丨 The consumer property cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs printed the above-mentioned basic photocurrent monitoring circuit. The current is monitored by a current mirror. The tiny current of the photodiode must be amplified or even converted into a voltage signal before it can be processed. If there is a photocurrent monitoring circuit, it will not increase or even decrease. In the case of a small number of components, the current can be directly amplified, which is very helpful for the miniaturization of the optical transceiver system. SUMMARY OF THE INVENTION The object of the present invention is to provide a photocurrent monitoring circuit, which in addition to monitoring a photodiode In addition to the photocurrent of the photodiode, the photocurrent of the photodiode can be directly amplified for subsequent signal processing. -4- This paper size applies to the Chinese National Standard (CNS) A4 specification (210 X 297 mm)- ------- 1223932 A7 B7 V. Description of the invention (3) Another object of the present invention is to provide a photocurrent monitoring circuit, which can directly convert the photocurrent of a photodiode into a voltage signal for subsequent processing. Another object of the present invention is to provide a photocurrent monitoring circuit, which can achieve the purpose of monitoring photocurrent without adding components or even saving components, and contributes to the miniaturization of optical transceivers. The purpose is to provide a photocurrent monitoring circuit, which can be applied to a collapsed photovoltaic system operating at high voltage through a single circuit structure. According to one aspect of the present invention, a photocurrent monitoring circuit includes a photodiode for sensing light intensity and converting it into a photocurrent; and a transistor whose emitter is connected to a power source voltage and whose base is The photodiode is connected to one end of the photodiode, and its collector is grounded and outputs an amplified sense current. According to another aspect of the present invention, the photocurrent monitoring circuit has a Zener diode connected to the output. Brief description: Printed by the Intellectual Property Bureau Employee Consumer Cooperatives of the Ministry of Economics, the first is a schematic diagram showing a conventional voltage output photocurrent monitoring circuit; the second is a schematic diagram showing a conventional current output photocurrent monitoring circuit; the third is a display A schematic diagram of a conventional photocurrent monitoring circuit using a field effect transistor (FET); FIG. 4 is a schematic diagram of a conventional photocurrent monitoring circuit for a collapsed photodiode; FIG. 5 is a schematic diagram of a conventional photocurrent monitoring circuit for a collapsed photodiode; Photocurrent monitoring circuit This paper is applicable to National Standard A (CNS) A4 (21 × 297 mm y 1223932 A7 B7 Consumer Cooperative of Intellectual Property Bureau, Ministry of Economic Affairs Figure 5 is a schematic diagram of the invention description (4); Figure 6 shows a photocurrent monitoring circuit based on another embodiment of Figure 5; Figure 7 shows a photocurrent monitoring circuit based on another embodiment of Figure 6; Figure 8 Fig. 9 shows a photocurrent monitoring circuit based on another embodiment of Fig. 5; Fig. 9 shows a schematic diagram of a photocurrent monitoring circuit of a voltage output current mirror according to the present invention; Fig. 10 shows a current output current mirror according to the present invention A schematic diagram of a photocurrent monitoring circuit; FIG. 11 is a schematic diagram showing a photocurrent monitoring circuit for a collapsed photovoltaic diode according to the present invention; A schematic diagram of a photocurrent monitoring circuit of a diode; FIG. 13 is a schematic diagram showing a photocurrent monitoring circuit for a collapsed photodiode according to the present invention; FIG. 14 is a diagram illustrating a photocurrent monitoring circuit according to the present invention; An overview of a field-effect transistor-type photocurrent monitoring circuit for a collapse-type photodiode; and FIG. 15 shows another field-effect transistor for a collapse-type photodiode according to the present invention. Overview of the optical current monitoring circuit. Detailed description of the invention: The circuit structure of the present invention will now be described in detail with reference to the drawings. Figure 5 Series -6- This paper size applies to China National Standard (CNS) A4 (210x297 mm)
五 經濟部智慧財產局員工消費合作社印製 發明說明（ 顯不根據本發明之-實施例之光電流監控電路的概圖。如 圖中所示，於該電路結構中，最主要係使用—個PNP型 之雙載子電晶體(BJT) 51，該雙載子電晶體51之射極係連 接於電源電壓Vee ’ -電阻器55係跨接於該雙載子電晶體 之基極與射極之間，_基極係經由—電阻^ 53連接於 光電二極體PD之-端，而該雙載子電晶體5ι之集極係經 由一電阻器57接地。其中電阻器53以及55係可省略不 用，換言之，電阻器53短路而電阻器55斷路。 根據電晶體的特性，集極電流Ic、基極電流ΐβ與射 極電流IE之間的關係如下： 1〇=β ................................. ⑴The Consumer Property Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs printed a description of the invention (showing a schematic diagram of a photocurrent monitoring circuit according to an embodiment of the present invention. As shown in the figure, in this circuit structure, the most important is to use a PNP type BJT 51, the emitter of the BJT 51 is connected to the power supply voltage Vee '-the resistor 55 is connected across the base and the emitter of the BJT In between, the _base is connected to the-terminal of the photodiode PD via -resistor ^ 53, and the collector of the bipolar transistor 5m is grounded via a resistor 57. The resistors 53 and 55 are It is omitted, in other words, the resistor 53 is short-circuited and the resistor 55 is open-circuited. According to the characteristics of the transistor, the relationship between the collector current Ic, the base current ΐβ, and the emitter current IE is as follows: 1〇 = β ..... ............... ⑴
Ie=Ib+Ic ...................... 如 電 此 器 輸 其”為電晶體的放大率，通常石的值相當大，約在ι〇〇 到400左右。由式⑺可知，圖五中pD的光電流係被放大 了万倍。-般而言，光電流的大小大約為⑻到ι〇〇" A，經過放大之後，即可到達_的等級，便於處理。 圖五中所示，放大之光電流係經由電阻器57被轉換成 壓輸出。亦可如圖六所示，放大之光電流係經由電流鏡 (於本實施例中，為-對NPN型電晶體61、62)輸出。 外，亦可在圖六中電阻器63的地方再並聯一個電阻 73 ’以便藉由分電流來輕輪出範圍，如圖谓示。總训 出電流W與流經電阻器63、73的分電流、、^之間的 關係如下：Ie = Ib + Ic ............ If the device loses its power, it is the magnification of the transistor, usually the value of stone is quite large, about ι〇00 to about 400. From the formula, it can be seen that the photocurrent of pD in Figure 5 is magnified 10,000 times.-In general, the magnitude of the photocurrent is about ⑻ to ι〇〇 " A. After zooming in, You can reach the level of _ for easy processing. As shown in Figure 5, the amplified photocurrent is converted into a voltage output through the resistor 57. As shown in Figure 6, the amplified photocurrent is passed through a current mirror (in the present In the embodiment, it is-for NPN type transistor 61, 62). In addition, a resistor 73 ′ can also be connected in parallel with the resistor 63 in FIG. 6 to lightly turn out the range by dividing the current, as shown in the figure. The relationship between the total training current W and the sub-currents flowing through the resistors 63 and 73 is as follows:
Itotle=l63+l73 ........................... ,. ....... 本紙張尺度適用中國國家標準(CNS)A4規格（210 X 297公爱"3------- 1223932 A7 B7 五、發明說明（6 ) 173/163^63^73 ...........................(4) 其中Iftle表示總電流值，I63、I73分別表示流經電阻器 63、73之電流值，而R63、R73分別表示電阻器63、73之 電阻值。 圖八係顯示基於圖五之另一實施例之光電流監控電 路，其中係加上一個NPN型電晶體81 _接於電晶體51 與電阻器57之間。該電晶體81的作用係在於提昇電路之 穩定性。 除了刖述利用單個電晶體以達到監控光電流之目的的 電路結構，本發明亦提出另一種新穎的電流鏡光電流監控 電路。如前所述，於先前技術之光電流監控電路中，電流 鏡之構成係將兩個相同的BJT電晶體基極相連接、且射極 均接至電源電壓vcc而具有相同的基極_射極電壓vbe，使 得二電晶體之集極電流Ic相同。本發明提出另一種不同的 電流鏡連接方式。 經濟部智慧財產局員工消費合作社印製 如圖九所示’本發明的電流鏡之連接方式為使用一個 PNP型電晶體91以及一個NPN型電晶體92,其中兩個電 晶體的基極相連接’ PNP型電晶體91之射極以及NPN型 電晶體92之集極連接至電源電壓vce，PNP型電晶體91 之集極係經由電阻器93接地，而NPN型電晶體92之射 極係與光電二極體PD之一端連接。其中監控電流係經由 電阻器93而轉換成電壓。或者，如圖十所示，電阻器93 亦可以電流鏡（電晶體101、102)取代，而輸出電流。本發 明之此種電流鏡除可應用於光電二極體之光電流監控電 本紙張尺度適用中國國家標準(CNS)A4規格（210 X 297公釐） 1223932 A7Itotle = l63 + l73 ................., ........ This paper size applies to Chinese National Standards (CNS ) A4 specification (210 X 297 public love " 3 ------ 1223932 A7 B7 V. Description of the invention (6) 173/163 ^ 63 ^ 73 .............. ............. (4) where Iftle represents the total current value, I63 and I73 represent the current values flowing through resistors 63 and 73, and R63 and R73 represent the resistors 63 and 73 respectively Fig. 8 shows a photocurrent monitoring circuit based on another embodiment of Fig. 5, in which an NPN transistor 81 _ is connected between the transistor 51 and the resistor 57. The transistor 81 The function is to improve the stability of the circuit. In addition to describing the circuit structure using a single transistor to achieve the purpose of monitoring photocurrent, the present invention also proposes another novel current mirror photocurrent monitoring circuit. As mentioned above, in the prior art In the photocurrent monitoring circuit, the structure of the current mirror is to connect two identical BJT transistor bases, and the emitters are connected to the power supply voltage vcc to have the same base_emitter voltage vbe, so that the two transistors are The collector current Ic is the same. A different current mirror connection method is proposed. The consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs has printed a graph as shown in Figure 9. 'The connection method of the current mirror of the present invention is to use a PNP type transistor 91 and an NPN type transistor 92, The bases of two transistors are connected. The emitter of the PNP transistor 91 and the collector of the NPN transistor 92 are connected to the power supply voltage vce. The collector of the PNP transistor 91 is grounded via a resistor 93, and The emitter of the NPN transistor 92 is connected to one end of the photodiode PD. The monitoring current is converted into a voltage by a resistor 93. Alternatively, as shown in Fig. 10, the resistor 93 can also be a current mirror (transistor) 101, 102) instead, and output current. The current mirror of the present invention can be applied to photocurrent monitoring of photodiodes. The paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm) 1223932. A7
1223932 經濟部智慧財產局員工消費合作社印製 A7 B7 五、發明說明（8 ) 圖號說明： Q1 雙載子電晶體 Q2 雙載子電晶體 PD 光電二極體 10 電流轉電壓輸出電路 15 前置放大器 APD 崩潰式光電二極體 51 PNP型雙載子電晶體 53 電阻器 55 電阻器 57 電阻器 61 NPN型電晶體 62 NPN型電晶體 63 電阻器 73 電阻器 81 NPN型電晶體 91 PNP型電晶體 92 NPN型電晶體 93 電阻器 101 電晶體 102 電晶體 110 齊納二極體 -10- 本紙張尺度適用中國國家標準(CNS)A4規格（210x297公釐）1223932 Printed by A7 B7, Consumer Cooperatives, Intellectual Property Bureau, Ministry of Economic Affairs V. Description of the invention (8) Illustration of drawing number: Q1 Bipolar transistor Q2 Bipolar transistor PD Photodiode 10 Current-to-voltage output circuit 15 Front Amplifier APD breakdown type photodiode 51 PNP type bipolar transistor 53 resistor 55 resistor 57 resistor 61 NPN transistor 62 NPN transistor 63 resistor 73 resistor 81 NPN transistor 91 PNP transistor Crystal 92 NPN Transistor 93 Resistor 101 Transistor 102 Transistor 110 Zener Diode-10- This paper size applies to China National Standard (CNS) A4 (210x297 mm)