CN103475423A

CN103475423A - Optical module transmission circuit transmitting HDTV signals

Info

Publication number: CN103475423A
Application number: CN2013104014244A
Authority: CN
Inventors: 汪润泉; 黄兰
Original assignee: CHENGDU NETON OPTOELECTRONIC TECHNOLOGIES Co Ltd
Current assignee: CHENGDU NETON OPTOELECTRONIC TECHNOLOGIES Co Ltd
Priority date: 2013-09-06
Filing date: 2013-09-06
Publication date: 2013-12-25

Abstract

The invention discloses the design of an optical module transmission circuit transmitting HDTV signals. The optical module transmission circuit meets and supports an SMPTE297-2006 standard and can transmit the signals of SMPTE259M, SMPTE344M, SMPTE292M, SMPTE424MSDI and other pathological code types.

Description

A kind of optical module radiating circuit that transmits the HDTV signal

Technical field

The invention belongs to the active photoelectric device class of optical fiber communication product, it relates to the design that a kind of pair of fibre or single fiber bi-directional high definition optical module radiating circuit are provided, relate in particular to the compatible SMPTE 297-2006 standard of energy, support speed and the SMPTE 259M of 50M-3Gbps, SMPTE 344M, the optical-electric module radiating circuit implementation of the HDTV signal of the ill patterns such as SMPTE 292M and SMPTE 424MSDI.

Background technology

Along with the continuous lifting that transmission of video and safety-security area require video quality, the user is to seeing that image has very high requirement clearly.Reach such requirement and need a kind of novel optical transceiver module, the compatible SMPTE 297-2006 standard of this module energy, support the speed of 50M～3Gbps and can realize SMPTE 259M, SMPTE 344M, the transmission of the ill pattern signals such as SMPTE 292M and SMPTE 424MSDI.The ill pattern of SMPTE test as depicted in figs. 1 and 2.

The structural representation of conventional optical module is as figure 3shown in, wherein comprise light emission component (101), laser detection backlight (102), comparator (103) and bias current are controlled assemblies such as (104).

Complete this normal optical module information transfer capability schematic diagram as shown in Figure 4, by sampling resistor (R), the back facet current of laser is converted into to voltage signal, then pass through comparator (compartor) and regulate the size of controlling laser bias current, reach the purpose of controlling luminous power.

Because the operating voltage of optical module is lower, saturated in order to prevent, the resistance that can use just can not be too large, simultaneously, due to the volume restrictions of module, adds the effect of leakage of electric capacity, and the electric capacity of maintenance voltage also can not be very large, so its time constant is less than 1 millisecond.Like this 19 " 1 ", one " 0 ", perhaps 19 " 0 ", when " a 1 " continuous several times repeats to transmit, because the time constant of sampling hold circuit is very little, when transmitting above-mentioned ill pattern, transmit signal power there will be very significantly fluctuation, the opening width of eye pattern diminishes, and shake increases, and the extinction ratio shake also acutely increases, cause the receiving terminal erroneous judgement, cause the signal pattern distortion.As shown in Figure 5, at stage " I ", 19 " 1 ", in one " 0 " continuous 720 times or 1920 repeating signals, because " 1 " is many, testing circuit is when detecting, effective value is larger, be mistaken for luminous power larger, control circuit gradually reduces bias current, and the peak light power of laser is reduced gradually; At stage " II ", 19 " 0 ", one " 1 ", the continuous transmission repeated for 720 times or 1920 times, because " 0 " is many, testing circuit is when detecting, and effective value is big or small, be mistaken for luminous power less, control circuit progressively increases bias current, and the peak light power of laser is increased gradually; If continuous duplication stages " I " afterwards, the signal in stage " II ", the peak power of laser is constantly fluctuation just, causes receiving terminal to reply difficulty, produces error code.Can not meet the ill pattern transmission of high-definition signal.

Optical module radiating circuit provided by the invention can effectively overcome above-mentioned deficiency, realizes the transmission of special ill-condition signal.

Summary of the invention

The invention provides a kind of SMPTE 297-2006 standard of supporting that meets, can transmit SMPTE 259M, SMPTE 344M, the optical module radiating circuit design of the ill patterns such as SMPTE 292M and SMPTE 424M SDI, its structure as shown in Figure 6, in figure, 101 is light emission component, and 102 is laser detection backlight, and 103 is comparator, 104 is bias current control, 105 is buffer stage I, and 106 is the storage holding unit, and 107 is buffer stage II.

The optical module radiating circuit schematic diagram of transmission HDTV signal provided by the invention as shown in Figure 7.

Its operation principle is: 1. by sampling resistor, the back facet current of laser is converted into to voltage signal, then stores through C1; 2. give peak value memory C2 storage again after the input buffer stage isolation of high input impedance, 3. after the output stage buffering, deliver to comparative degree and compare, 4. comparative degree compares the size of rear control laser bias current, reaches the purpose of controlling luminous power.Owing to adopting the two-stage buffering, driving force is stronger, can realize quick sampling, and the bias current of laser is adjusted in response fast.Because the impedance of second level buffer stage input is very high, reach 10 ¹²ohm, hold period is mainly determined by bleeder resistance R like this, is easy to realize the sampling period more than 1 second.Like this 19 " 1 ", one " 0 ", or 19 " 0 ", when " a 1 " continuous several times repeats to transmit, because the time constant of sampling hold circuit is very large, the peak light power of laser is along with the variation fluctuation of signal is very little.As shown in Figure 8, at stage " I ", 19 " 1 ", in one " 0 " continuous 720 or 1920 repeating signals, " 1 " is many; At stage " II ", 19 " 0 ", one " 1 ", the continuous transmission repeated for 720 times or 1920 times, " 0 " is many, because the retention time of sampling hold circuit is very long, within the whole design cycle, luminous power remains unchanged substantially, has so just guaranteed to transmit needed ill pattern.

accompanying drawing and accompanying drawing explanation

Fig. 1: the ill pattern figure of SDTV-SDI 270Mbps test

Fig. 2: the ill pattern figure of HDTV-SDI 1.485Gpbs test

The structural representation that Fig. 3 is general module

Fig. 3 explanation: in figure, 101 is light emission component, and 102 is laser detection backlight, and 103 is comparator, and 104 bias currents are controlled

Fig. 4: the schematic diagram of the information transfer capability of normal optical module

Fig. 4 explanation: wherein LD is light emission component; PD is detection means backlight; The R sampling resistor; C is for keeping electric capacity; Comparator is comparator, and NPN is for driving triode

The peak value of Fig. 5 laser large schematic diagram that fluctuates

Fig. 6 transmits the optical module radiating circuit structure chart of HDTV signal

Fig. 6 explanation: in figure, 101 is light emission component, and 102 is laser detection backlight, and 103 is comparator, and 104 control for bias current, and 105 is buffer stage I, and 106 is the storage holding unit, and 107 is buffer stage II.

Fig. 7 transmits the schematic diagram of the optical module radiating circuit of HDTV signal

The peak value of Fig. 8 laser keeps constant schematic diagram substantially

Embodiment

Below in conjunction with Fig. 4 and accompanying drawing 7 embodiment, the present invention is described in further detail, embodiments of the present invention include but not limited to following embodiment.

In Fig. 4, the luminous power of laser LD is converted into photoelectric current through detection diode PD backlight, and through sampling resistor, R is converted into voltage signal, and keeps through capacitor C, and delivers to comparator C omparator and compare, then drives triode NPN to carry out the bias current adjusting.Less for its time constant, the light luminous power has larger fluctuation.

In Fig. 7, the luminous power of laser LD is converted into photoelectric current through detection diode PD backlight, through sampling resistor, R is converted into voltage signal, and keep through capacitor C, after buffer stage, by peak value sampling electric capacity, sampled again, deliver to comparator C omparator again after buffer stage II buffering and compare, then drive triode NPN to carry out the bias current adjusting.Very long for its time constant, the fluctuation of light luminous power is very little.In this example, that laser, detector backlight adopt is the TME-5B83-537 of the ring of light, and that operational amplifier adopts is LM358, and comparator sampling LM358 replaces.

Claims

1. an optical module radiating circuit that transmits the HDTV signal, is characterized in that having adopted the luminous power peak detection circuit.

2. a kind of optical module radiating circuit that transmits the HDTV signal according to claim 1, is characterized in that it has comprised the quick point sample circuit.

3. a kind of optical module radiating circuit that transmits the HDTV signal according to claim 2, is characterized in that it has comprised high resistant holding circuit when long.