TW201507302A - Circuit and method for driving laser with temperature compensation - Google Patents

Abstract

A laser driving circuit with temperature compensation, used to drive a laser component, comprising: a temperature compensation circuit, generating a second current according to a first current and a temperature-independent current; and a modulation current generation circuit, generating a modulation current according to the second current and modulating optical output power of the laser component according to the modulation current, wherein the first current is proportional to absolute temperature, and a rate of change of the second current with respect to absolute temperature is larger than that of the first current with respect to absolute temperature.

Description

Temperature-compensated laser driving circuit and laser driving method

The present invention relates to laser drive circuits and methods, and more particularly to temperature-compensated laser drive circuits and methods.

With the development of optical transmission technology, optical fiber transmission has considerable advantages in transmission rate, transmission distance and anti-interference ability, so optical transmission devices have been more and more widely used. In an optical transmission device, a light Amplification by Simulated Emi component is usually used to convert an electronic signal into an optical signal to transmit an optical signal through a transmission medium such as an optical fiber. Among them, Vertical Cavity Surface Emitting Laser (VCSEL) components are commonly used as laser light sources in optical transmission devices. The VCSEL element has high reliability, can be driven at a high speed, can be arrayed on a large scale, and can reduce production cost because it can be mass-produced. In addition, VCSEL components also have very low laser critical currents, single longitudinal modes, and low dispersion laser beams. Therefore, VCSEL components have become very important laser sources in various fiber-optic communication and optical storage systems, especially high-speed long-distance fiber-optic communication systems.

The optical output power of a VCSEL component is positively related to its drive current magnitude, but it also varies with its operating temperature. In general, when the operating temperature is high, the drive current of the VCSEL component must be increased to reach The same light output power as when the operating temperature is low. Therefore, a temperature compensation mechanism is needed to adjust the drive current correspondingly as the operating temperature changes. The conventional temperature compensation mechanism may adjust the driving current by detecting the operating temperature. However, this method makes the driving current unable to be adjusted instantaneously and continuously with the operating temperature. In addition, in the conventional temperature compensation mechanism, the amount of current to temperature change may not be large enough, so that the compensation effect and efficiency are limited.

In view of the above, the present invention utilizes a current proportional to absolute temperature and a temperature uncorrelated current to generate a modulated current for driving the laser element to adjust the laser element in real time and continuously with different operating temperatures. The current is driven to thereby achieve temperature compensation, and the slope of the current versus temperature of the laser element is adjusted by the synchronous offset current proportional to the absolute temperature and the temperature uncorrelated current.

An embodiment of the present invention provides a temperature-compensated laser driving circuit for driving a laser device, comprising: a temperature compensation circuit for generating a second current according to a first current and a temperature uncorrelated current; a modulation current generating circuit, generating a modulation current according to the second current, and adjusting an optical output power of the laser element according to the modulation current; wherein the first current is proportional to an absolute temperature; wherein the second The rate of change of the current relative to the absolute temperature is greater than the rate of change of the first current relative to the absolute temperature.

Another embodiment of the present invention provides a temperature-compensated laser driving method for driving a laser device, comprising: generating a second current according to a first current and a temperature uncorrelated current, wherein the first current The current is proportional to the absolute temperature; a modulated current is generated according to the second current, and according to the modulated power The flow adjusts the optical output power of the laser element; wherein the rate of change of the second current relative to the absolute temperature is greater than the rate of change of the first current relative to the absolute temperature.

10, 40‧‧ ‧ laser device

100‧‧‧ Laser components

110, 410‧‧ ‧ laser drive circuit

1110, 3110‧‧‧ Temperature compensation circuit

1120‧‧‧ modulated current generating circuit

1130‧‧‧Butable current generating circuit

11200, 41200‧‧‧ current mirror circuit

FF1, FF2, FF3‧‧‧ fast process boundary

INA, INB‧‧‧ control signals

I ₁ , I ₂ , I ₃ , I ₄ , I _indep , I _C ‧‧‧ current

I _mod , I _mod' ‧‧‧ modulated current

I _th ‧‧‧Bist current

M1, M2‧‧‧ transistor

M3, M4‧‧‧ switching transistor

S ₁ , S ₂ , S ₃ , S ₄ , S _indep , S _C ‧‧‧ current source

S _th ‧‧‧ bias current source

SS1, SS2, SS3‧‧‧ slow process boundaries

TT1, TT2, TT3‧‧‧ typical process boundary

1 is a circuit diagram of a laser device according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing a relationship between a supply current of a current source and an operating temperature under different conditions; and FIG. 3 is a diagram showing a relationship according to the present invention. A circuit diagram of a current generating circuit of another embodiment; and FIG. 4 is a circuit diagram of a laser device including a laser element and a temperature-compensated laser driving circuit according to another embodiment of the present invention.

The following description is an embodiment of the present invention. The intent is to exemplify the general principles of the invention and should not be construed as limiting the scope of the invention, which is defined by the scope of the claims.

It is noted that the following disclosure may provide embodiments or examples for practicing various features of the present invention. The specific elements and arrangements of the elements described below are merely illustrative of the spirit of the invention and are not intended to limit the scope of the invention. In addition, the following description may reuse the same or similar component symbols or characters in various examples. However, the re-use is for the purpose of providing a simplified and clear description, and is not intended to limit the relationship between the various embodiments and/or configurations discussed below. In addition, the description of one of the features described in the following description is coupled to, coupled to, and/or formed on another feature, etc., and may include a plurality of different embodiments, including direct contact of such features, Or other additional features are included between the features, etc. such that the features are not in direct contact.

In the operation of laser excitation by a Vertical Cavity Surface Emitting Laser (VCSEL) element, the threshold current of the VCSEL element is different depending on the operating temperature, so if it is turned on each time. When the VCSEL component restarts the VCSEL component, the startup current will be different each time the VCSEL component is activated. To avoid this, usually a bias current flows through the VCSEL element, leaving the VCSEL element at the edge of the excitation region or at the edge of the power linearly varying region but emitting very weak light, equivalent to a logic "0. "." The current of the bias current is set according to the characteristics of the VCSEL element and may be equal to or slightly larger than the critical current of the VCSEL element. When the VCSEL device is driven, when the modulation current flows through the VCSEL device in addition to the bias current, the VCSEL device emits light having a more significant luminance than the bias current only, which is equivalent to logic "1". The magnitude of the modulated current changes the optical output power of the VCSEL element. The larger the modulation current, the greater the optical output power.

1 is a circuit diagram of a laser device 10 in accordance with an embodiment of the present invention. This laser device 10 includes a laser element 100 and a temperature compensated laser drive circuit 110. The laser driving circuit 110 includes a temperature compensation circuit 1110, a modulation current generating circuit 1120, and a bias current generating circuit 1130. The temperature compensation circuit 1110 can generate a second current I ₂ according to a first current I ₁ and a temperature uncorrelated current I _indep . The modulated current generating circuit 1120 can generate a modulated current I _mod according to the second current I ₂ and adjust the optical output power of the laser element 100 according to the modulated current I _mod . The current value of the first current I ₁ is proportional to the absolute temperature, and the rate of change of the second current I ₂ with respect to the absolute temperature is greater than the rate of change of the first current I ₁ with respect to the absolute temperature. Bias current generating circuit 1130 may _th S by a bias current source for generating a bias current I _th flows through the laser element 100, to provide a conduction state laser element 100 is in a logic "0". In this embodiment, the laser element 100 is a vertical cavity surface emissive laser (VCSEL) element for an active optical fiber (AOC).

The temperature compensation circuit 1110 includes current sources S ₁ , S ₂ and S _indep . The current source S _indep is a temperature independent current source, and generates a temperature uncorrelated current I _indep according to a bandgap voltage and an internal resistance. In general, the bandgap voltage does not theoretically change with temperature. Although the resistance of the internal resistor may be affected by temperature, the circuit of the current source proportional to the absolute temperature is also affected by the internal resistivity, which can be regarded as The offset effects are mutually offset, so the temperature uncorrelated current I _indep is considered to not affect the magnitude of the current as a function of temperature over the appropriate operating temperature range. The current source S ₁ is a current source proportional to a Proportional To Absolute Temperature (PTAT), which can generate a current proportional to the absolute temperature, that is, the current of the first current I ₁ as the absolute temperature rises. The value also increases. As shown in FIG. 1, the temperature-independent current source S _indep and the second current source S _{2 are} coupled to a ground through the first current source S ₁ . _1, S ₂ and S configuration _indep known manner by the current source S, a current source S ₂ of the second current source current I ₂ is equal to S ₁ I ₁ of the first current by subtracting the current of the current source S _indep I _indep, That is, I ₂ =I ₁ -I _indep .

The modulated current generating circuit 1120 includes a current mirror circuit 11200 and switching transistors M3 and M4. The switching transistors M3 and M4 can be controlled by control signals INB and INA which are mutually inverted. When the switching transistor M3 is turned on and the switching transistor M4 is turned off, the modulated current I _mod does not flow through the laser element 100, and only the bias current I _th flows through the laser element 100, which is equivalent to the laser element 100 being in logic. The status of "0". When the switching transistor M3 is turned off and the switching transistor M4 is turned on, the modulation current I _mod plus the bias current I _th flows through the laser device 100, which is equivalent to the state in which the laser device 100 is in a logic "1", and is excited. The laser element 100 emits light. At this time, the modulation current generating circuit 1120 can adjust the light output power of the laser element 100 according to the magnitude of the current of the modulation current I _mod .

The current mirror circuit 11200 includes a third current source S ₃ , a first transistor M1 , and at least a second transistor M2 . The third current source S ₃ may mirror or copy the second current I ₂ to generate a third current I ₃ . The first transistor M1 and the second transistor M2 can generate a modulated current I _mod according to a current gain, thereby adjusting the optical output power of the laser element 100.

In one embodiment, the first transistor M1 and the second transistor M2 are N-type metal oxide semiconductor field effect transistors (NMOS), and the channel width to length ratio of the first transistor M1 and the second transistor M2. Same (channel width length (W/L) ratio). The drain of the first transistor M1 is coupled to the gate of the first transistor M1 (ie, the diode connection) to turn on the third current I ₃ to the ground. The gate of the first transistor M1 is coupled to the gate of the second transistor M2 for coupling the third current I ₃ to each of the second transistors M2. It is worth noting that the current gain described above is related to the number of second transistors M2. For example, when there is only a single second transistor M2, the modulation current I _mod is equal to the third current I ₃ . When there are n second transistors M2, the modulation current I _mod is equal to n times the third current I ₃ . That is to say, the number of second transistors M2 can be used to control the relationship between the modulation current I _mod and the third current I ₃ . Therefore, a plurality of switches (not shown) are used to selectively turn on the plurality of second transistors M2 to set the current gain described above.

The current gain of the current mirror circuit 11200 is preset according to the characteristics of the laser element 100 and the process corner, such as a Typical-Typical (TT) process boundary, a Fast-Fast (FF) process boundary, and a slow speed. (Slow-Slow, SS) process boundary. The current gain of the current mirror circuit is independent of temperature and can be no longer changed after the current gain is set to the desired state.

Modulation current generating circuit 1120 may be a second current mirror current I _{2 3} (Mirror) or copy (copy) to a current source S I _3. Since I ₂ =I ₁ -I _indep , the temperature uncorrelated current I _{indep is} not affected by temperature and the current I ₁ becomes larger as the temperature rises, so the second current I ₂ is a positive temperature coefficient current. Similarly, the third current I ₃ and the modulated current I _mod are also positive temperature coefficient currents such that the laser element 100 can be uncorrelated by the first current I ₁ and the temperature according to the absolute temperature, depending on the operating temperature. The modulation current I _mod generated by the current I _indep is compensated. Since the first current I _{1 changes} instantaneously and continuously with the operating temperature, the modulated current I _mod also changes instantaneously and continuously with the operating temperature, that is, the temperature of the laser element 100 The compensation is immediate and continuous. Further, the rate of change of the second current I ₂ with respect to the absolute temperature is greater than the rate of change of the first current I ₁ with respect to the absolute temperature. The rate of change of the first current I ₁ and the second current I ₂ with respect to the absolute temperature will be described in detail below.

Figure 2 is a graph showing the relationship between the supply current of the current source and the operating temperature under different conditions, which is plotted according to Table 1, Table 2, and Table 3 below. Table 1, Table 2 and Table 3 below are the current values of the second current I ₂ with respect to temperature under different conditions. The setting conditions corresponding to Table 1 are: (1) the temperature uncorrelated current I _{indep is} set to 0 μA; and (2) at the typical process boundary TT, the operating temperature is 70 ° C, which will correspond to the first of the typical process boundaries TT Current I _{1 was} set to 100 microamperes (μA). Then, the current value of the second current I ₂ is obtained under the conditions of the typical process boundary TT, the slow process boundary SS, and the fast process boundary FF at different operating temperatures. Since the temperature uncorrelated current I _indep is 0 μA, and the temperature uncorrelated current I _indep does not change with the operating temperature, the temperature uncorrelated current I _indep is 0 μA at each operating temperature, which is equivalent to directly The current source S ₁ acts as a second current source S ₂ . That is, although Table 1 corresponds to the second current I ₂ , the I _indep under the typical process boundary TT is 0 μA, so the second current I ₂ under the typical process boundary TT = the first current I ₁ =100μA. When the operating temperature drops to 20 ° C, the second current I ₂ at the typical process boundary TT = the first current I ₁ = 84.1 μA. That is, from 70 ° C to 20 ° C, the current value of the second current I ₂ is only reduced by about 15.9%. In contrast, the current value of the first current I ₁ is also decreased from 70 ° C to 20 ° C. The ratio is also 15.9%.

The setting conditions corresponding to the following Table 2 are: (1) the temperature uncorrelated current I _{indep is} set to 150 μA; and (2) the first current I ₁ corresponding to the typical process boundary TT is set to 250 μA under the typical process boundary TT . Then, the current value of the second current I ₂ is obtained under the conditions of the typical process boundary TT, the slow process boundary SS, and the fast process boundary FF at different operating temperatures. When the operating temperature is 70 ° C, the first current I ₁ at a typical process boundary TT proportional to the absolute temperature is set to 250 μA and the temperature uncorrelated current I _{indep is} set to 150 μA, so the second current I under a typical process boundary TT ₂ is equal to the first current I ₁ minus the current I _{indep is} approximately equal to 100 μA (99.7 μA in Table 2). Further, according to Table 1, it can be seen that the current value of the first current I ₁ at the typical process boundary TT after the operating temperature was lowered from 70 ° C to 20 ° C was 84.1% at 70 ° C. Therefore, the magnitude of the current at the operating temperature of 20 ° C corresponding to the first current I ₁ in the table 2 corresponding to the typical process boundary TT is approximately 250 μA × 84.1%. The temperature uncorrelated current I _{indep is} still independent of temperature, so when the operating temperature becomes 20 ° C, the current is still 150 μA. Since I ₂ =I ₁ -I _indep , in Table 2, when the operating temperature drops to 20 ° C, the second current I ₂ corresponding to the typical process boundary TT is approximately equal to 250 μA × 84.1% - 150 μA = 60.25 μA (Table) 2 is 61.7 μA). That is, when the operating temperature is lowered from 70 ° C to 20 ° C, the current of the second current I ₂ is reduced by 39.45 μA (that is, 99.7-60.25), which is about 40% lower. Therefore, the rate of change of the second current I ₂ with respect to the absolute temperature (40%) is greater than the rate of change of the first current I ₁ with respect to the absolute temperature (15.9%).

The setting conditions corresponding to the following Table 3 are: (1) the temperature uncorrelated current I _{indep is} set to 275 μA; and (2) the first current I ₁ corresponding to the typical process boundary TT is set to 375 μA under the typical process boundary TT . Then, the current value of the second current I ₂ is obtained under the conditions of the typical process boundary TT, the slow process boundary SS, and the fast process boundary FF at different operating temperatures. When the operating temperature is 70 ° C, the first current I ₁ at a typical process boundary TT proportional to the absolute temperature is set to 375 μA and the temperature uncorrelated current I _{nd ep is} set to 275 μA, so the second current I under a typical process boundary TT ₂ is equal to the first current I ₁ minus the current I _{indep is} approximately equal to 100 μA (99.5 μA in Table 3). Further, as can be seen from Table 1, after the operating temperature was lowered from 70 ° C to 20 ° C, the current value of the first current I ₁ at the typical process boundary TT became 84.1% at 70 °C. Therefore, the magnitude of the current when the first current I ₁ at the typical process boundary TT corresponding to the table 3 becomes 20 ° C at the operating temperature is about 375 μA × 84.1%. The temperature uncorrelated current I _{indep is} still independent of temperature, so the current is still 275 μA when the operating temperature becomes 20 °C. Since I ₂ =I ₁ -I _indep , in Table 3, when the operating temperature drops to 20 ° C, the second current I ₂ corresponding to the typical process boundary TT is approximately equal to 375 μA × 84.1% - 275 μA = 40.375 μA ( In Table 2, it is 43 μA). That is to say, when the operating temperature is lowered from 70 ° C to 20 ° C, the current value of the second current I ₂ is reduced by 59.125 μA (that is, 99.5-40.375), which is about 60% lower than that of 15.9% in Table 1 and 40% in Table 2 is large. The rate of change of the second current I ₂ with respect to the absolute temperature (60%) is greater than the rate of change of the first current I ₁ with respect to the absolute temperature (15.9%). Compared to Table 2 in the second current I ₂ relative to the rate of change of the absolute temperature, a second current I ₂ of Table 3 with respect to the absolute rate of change of temperature is also large. It should be noted that the current values of the first current I ₁ and the temperature non-correlated current I _indep listed above are merely exemplary and are not intended to limit the present invention, and those skilled in the art may according to the laser. The characteristics of the element 110, the operating environment, and the like adjust the current value of the first current I ₁ and the temperature-independent current I _indep .

In the prior art, the rate of change of temperature with respect to the current directly proportional to the absolute temperature (such as the first current I ₁ in the present invention) is generally used as a reference value for temperature compensation. However, when the current proportional to the absolute temperature (such as the first current I ₁ in the present invention) is not sufficiently large for the rate of change of temperature, it may not be sufficient to compensate the optical output power of the laser element 100 to an ideal condition.

As described above, the magnitude of the current of the second current I ₂ affects the magnitude of the current of the third current I ₃ and the modulated current I _mod . Therefore, the rate of change of the current of the current I ₂ to the temperature affects the current I _mod . The magnitude of the compensation. Compared with the prior art, the present invention can adjust the temperature non-correlated current I _indep and the value of the first current I ₁ , thereby adjusting the rate of change of the second current I ₂ relative to the absolute temperature, and can perform a larger range. Temperature compensation.

It should be noted that the bias current I _{th in} FIG. 1 can be mirrored or copied to the second current I ₂ and then generated by a specific multiple reduction. Therefore, the bias current I _th can also have a temperature compensated characteristic.

Figure 3 is a circuit diagram of a temperature compensation circuit 3110 in accordance with another embodiment of the present invention. Other details of the temperature compensation circuit 3110, the drive circuit coupled to the temperature compensation circuit (such as the modulation current generation circuit 1120 and the bias current generation circuit 1130 in FIG. 1), and the laser elements to which the drive circuit is coupled are The embodiment of Fig. 1 is the same and therefore will not be described again. The difference between the temperature compensation circuit 3110 and the temperature compensation circuit 1110 is that the current I ₂ of the temperature compensation circuit 1110 is a positive temperature coefficient current, so that the positive temperature coefficient compensation of the laser element 100 can be performed. The temperature compensation circuit 3110 of FIG. 3, a first current source and a second current source S ₁ S ₂ through a current source of the temperature of the non-related S _indep coupled to a ground terminal. A second current source S ₂ of the second current I ₂ is equal to the non-temperature dependent current source current I _indep S _indep subtracting a first current source is proportional to first current I ₁ S _1, i.e. I ₂ = I _indep -I ₁ . Therefore, the second current I ₂ of the temperature compensation circuit 3110 is a negative temperature coefficient current, so that the negative temperature coefficient compensation of the laser element 100 can be performed.

4 is a circuit diagram of a laser device 40 including a laser element 100 and a temperature compensated laser drive circuit 410, in accordance with another embodiment of the present invention. In this embodiment, the laser element 100 is a VCSEL element for an active fiber optic cable, and the active fiber optic cable can be used to communicate two USB electronic devices (eg, a USB host and a USB device).

The laser driving circuit 410 differs from the laser driving circuit 110 of FIG. 1 in the current sources S ₄ and S _C , and the operations of the remaining transistors M1 and M2 , the switching transistors M3 and M4 , and the bias current source S _th are The laser driving circuit 110 of Fig. 1 is the same and therefore will not be described again. In the laser driving circuit 410, the fourth current source S ₄ is a current source that provides a fourth current I ₄ and is temperature uncorrelated, and the current source is a current source whose S _{C is} proportional to the absolute temperature, which generates a temperature non- The associated current I _C , current I _C can be a positive temperature coefficient current or a negative temperature coefficient current. As shown in FIG. 4, the reference current I _ref is equal to the fourth current I ₄ minus the current I _C . Since the current I _C can be a positive temperature coefficient current or a negative temperature coefficient current, the reference current I _ref can be a negative temperature coefficient current. Or positive temperature coefficient current. The current mirror circuit 41200 can generate the modulation current I _{mod '} according to the reference current I _ref and a current gain, and adjust the optical output power of the laser element 100 according to the modulation current I _{mod '} . The current gain is preset based on the characteristics of the laser element 100 and the process boundaries, such as typical process boundaries, fast process boundaries, and slow process boundaries. The current gain is temperature independent and can no longer be changed after the current gain is set to the desired state. Since the reference current I _ref can be a negative temperature coefficient current or a positive temperature coefficient current, the modulation current I _{mod ′} can also be a negative temperature coefficient current or a positive temperature coefficient current, so that the laser element 100 can be varied with the operating temperature. Negative temperature coefficient compensation or positive temperature coefficient compensation is performed by the modulation current I _{mod '} . Since the current I _{C changes} instantaneously and continuously with the operating temperature, the modulation current I _{mod '} also changes instantaneously and continuously with the operating temperature, that is, the temperature compensation of the laser element 100 It is instant and continuous.

Another embodiment of the present invention provides a temperature compensated laser driving method for driving a laser element, such as laser element 100 of FIG. In this embodiment, the laser element is a vertical cavity surface illuminating laser element for an active fiber optic cable. In the temperature-compensated laser driving method, a second current is generated according to a first current and a temperature uncorrelated current according to a first current proportional to an absolute temperature (for example, the current I _{1 of} FIG. ₁ or I _C ) in Fig. 4 and a temperature-independent current (for example, current I _{indep in} Fig. 1 or I 4 in Fig. ₄ ) generate a modulated current (for example, current I _{mod of} Fig. 1 or Fig. 4) The current I _mod' ) controls the light output power of the laser element according to the modulation current. In the temperature-compensated laser driving method, a switching circuit is further used to determine whether to couple the modulation current to the laser component according to a control signal, so that the laser component is in a conducting state or a low energy consumption. status. For example, as shown in FIG. 1, the switching transistors M3 and M4 are controlled in accordance with the control signal INA and its inverted control signal INB to cause the modulation current I _{mod to} flow through or not through the laser element 100. In the generation of the modulation current, the current is generated by the current mirror circuit based on the second current and a current gain to drive the laser element. The current gain of the current mirror circuit is preset according to the characteristics of the laser element and the process boundary, and is independent of temperature, and can be no longer changed after setting to the ideal state.

In summary, the present invention generates a modulated current of a laser element according to a current proportional to an absolute temperature and a temperature uncorrelated current, and adjusts the optical output power of the laser element according to the modulated current, as it is proportional to the absolute temperature. The current source instantaneously and continuously changes the magnitude of the current supplied by the current proportional to the absolute temperature as the operating temperature is different, so that the modulated current changes instantaneously and continuously with the operating temperature, thereby being The laser element provides instant and continuous temperature compensation. In addition, by the different configurations of the current source proportional to the absolute temperature and the temperature-independent current source, for example, the configuration of the current sources S ₁ and S _indep in the temperature compensation circuit 1110 of FIG. ₁ and the temperature of FIG. 3 The configuration of the current sources S ₁ and S _indep in the compensation circuit 3110 can generate a modulated current of a positive temperature coefficient or a negative temperature coefficient, so that the positive temperature coefficient compensation or the negative temperature coefficient compensation of the laser element can be performed. Furthermore, as shown in FIG. 2, by comparing the current proportional to the absolute temperature and the current value of a temperature uncorrelated, the rate of change of the modulation current with respect to temperature can be adjusted, thereby adjusting the compensation range, and the compensation effect can be improved. effectiveness.

The above is an overview feature of the embodiment. Those having ordinary skill in the art should be able to use the present invention as a basis for design or adaptation to achieve the same objectives and/or achieve the same advantages of the embodiments described herein. It should be understood by those of ordinary skill in the art that the same configuration should not depart from the spirit and scope of the present invention, and various changes, substitutions and substitutions can be made without departing from the spirit and scope of the present invention. The illustrative methods are merely illustrative of the steps, but are not necessarily performed in the order presented. Additional The steps of adding, replacing, changing the order and/or eliminating the steps are adjusted as appropriate and are consistent with the spirit and scope of the disclosed embodiments.

10‧‧‧ Laser device

100‧‧‧ Laser components

110‧‧‧Laser drive circuit

1110‧‧‧ Temperature compensation circuit

1120‧‧‧ modulated current generating circuit

1130‧‧‧Butable current generating circuit

11200‧‧‧current mirror circuit

INA, INB‧‧‧ control signals

I ₁ , I ₂ , I ₃ , I _indep ‧‧‧ current

I _mod ‧‧‧ modulated current

I _th ‧‧‧Bist current

M1, M2‧‧‧ transistor

M3, M4‧‧‧ switching transistor

S ₁ , S ₂ , S ₃ , S _indep ‧‧‧ current source

S _th ‧‧‧ bias current source

Claims (19)

A temperature-compensated laser driving circuit for driving a laser component, comprising: a temperature compensation circuit for generating a second current according to a first current and a temperature uncorrelated current; and a modulation current generating circuit Generating a modulation current according to the second current, and adjusting an optical output power of the laser element according to the modulation current; wherein the first current is proportional to an absolute temperature; wherein the second current is relative to an absolute temperature The rate of change is greater than the rate of change of the first current relative to the absolute temperature. The temperature-compensated laser driving circuit according to claim 1, further comprising a bias current generating circuit for generating a bias current flowing through the laser element. The temperature-compensated laser drive circuit of claim 1, wherein the laser element is a vertical cavity surface illuminating laser element for an active fiber optic cable. The temperature-compensated laser driving circuit of claim 1, wherein the modulation current generating circuit further comprises: a switching circuit that determines whether to couple the modulation current to the laser according to a control signal. The component is placed in a conducting state or a low power state. The temperature-compensated laser driving circuit of claim 1, wherein the modulated current generating circuit further comprises: a current mirror circuit, wherein the adjusting is generated according to the second current and a current gain A variable current is applied to drive the laser element. The temperature-compensated laser driving circuit of claim 5, wherein the current mirror circuit further comprises: a first transistor, the first transistor having a drain coupled to the first transistor The first transistor is configured to conduct a third current to a ground, wherein the third current is equal to the second current; and at least one second transistor, the gate of each of the second transistors is coupled to the gate The gate of the first transistor to generate the modulated current. A temperature-compensated laser drive circuit as described in claim 5, wherein the current gain is independent of temperature. The temperature-compensated laser driving circuit of claim 1, wherein the second current is a positive temperature coefficient reference current or a negative temperature coefficient reference current. The temperature-compensated laser driving circuit of claim 8, wherein the temperature compensation circuit further comprises: a first current source for generating the first current; and a temperature uncorrelated current source, a second current source for generating the positive temperature coefficient reference current; wherein the temperature uncorrelated current source and the second current source are coupled to the first current source A ground terminal. The temperature-compensated laser driving circuit of claim 8, wherein the temperature compensation circuit further comprises: a first current source for generating the first current; a temperature uncorrelated current source for generating the temperature uncorrelated current; and a second current source for generating the negative temperature coefficient reference current; wherein the first current source and the second current source pass through the The temperature uncorrelated current source is coupled to a ground terminal. A temperature-compensated laser driving method for driving a laser component, comprising: generating a second current according to a first current and a temperature uncorrelated current, wherein the first current is proportional to an absolute temperature; The second current generates a modulated current, and the optical output power of the laser element is adjusted according to the modulated current; wherein a rate of change of the second current relative to the absolute temperature is greater than a change of the first current relative to an absolute temperature rate. The temperature-compensated laser driving method of claim 11, further comprising generating a bias current flowing through the laser element. The temperature-compensated laser driving method of claim 11, wherein the laser element is a vertical cavity surface illuminating laser element for an active fiber optic cable. The temperature-compensated laser driving method of claim 11, further comprising: using a switching circuit to determine whether to couple the modulation current to the laser element according to a control signal, so that the laser The component is in a conducting state or a low power state. Temperature-compensated laser driver as described in claim 11 The method further includes: generating, by the current mirror circuit, the modulated current according to the second current and a current gain to drive the laser element. A temperature-compensated laser driving method as described in claim 15 wherein the current gain is independent of temperature. The temperature-compensated laser driving method according to claim 11, wherein the second current is a positive temperature coefficient reference current or a negative temperature coefficient reference current. The temperature-compensated laser driving method of claim 17, further comprising: generating the first current by using a first current source; generating a temperature uncorrelated current by using a temperature uncorrelated current source; And subtracting the temperature uncorrelated current from the first current to generate the positive temperature coefficient reference current. The temperature-compensated laser driving method of claim 17, further comprising: generating the first current by using a first current source; generating a temperature uncorrelated current by using a temperature uncorrelated current source; And subtracting the first current from the temperature uncorrelated current to generate the negative temperature coefficient reference current.