CN101593786A - Temperature Compensation Circuit for Avalanche Photodiodes - Google Patents

Abstract

The invention discloses a temperature compensation circuit for an avalanche photodiode, comprising: a high-precision temperature sensing module, which is used to convert the temperature of the tube core of the APD into an analog voltage signal, whose input end is connected with the APD light detection module, and whose output The terminal is connected to the APD bias control unit; the APD bias control unit is used to convert the voltage signal output by the high-precision temperature sensing module into a bias signal for controlling the APD; and the APD light detection module is used to feed back the die temperature, and The gain of the APD is controlled by the bias signal to make it constant, its input end is connected to the APD bias voltage control unit, and its output end is connected to a high-precision temperature sensing module. The present invention uses high-voltage control devices to form an APD bias control unit and related auxiliary circuit modules to design a practical high-precision APD bias control temperature compensation circuit, so that the APD's constant gain operating temperature range: -0 ° C ~ +50 ° C, Gain control accuracy is better than 0.5%.

Description

Temperature Compensation Circuit for Avalanche Photodiodes

technical field

The invention relates to a basic circuit in the technical field of optical communication, in particular to a bias control temperature compensation circuit for a high-precision avalanche photodiode (APD).

Background technique

At present, APD is widely used in optical fiber sensing and optical fiber communication network as a kind of photodetection device with high sensitivity, which can accurately receive data and measure optical power. It produces an avalanche multiplication effect by means of an internal strong electric field, and has a very high internal gain (up to 10-100 orders of magnitude). However, the variation of APD with temperature drift seriously affects the stability of its gain, and even causes the deterioration of measurement accuracy. Theoretically, it can be proved that the gain of the APD is a function of its bias voltage V and temperature T, both of which determine the gain of the APD when it is working, and there is a certain relationship between the bias voltage and the temperature under the condition that the APD gain is relatively constant. . Therefore, the bias voltage of the APD can be controlled to change according to a certain rule with the temperature. In this way, the APD gain can be kept basically constant to ensure its normal operation. This is the principle of bias compensation for APD temperature drift.

It can be seen that the bias voltage applied to the APD must be accurately controlled to ensure the performance of the optical fiber system. This design uses high-voltage control devices and related auxiliary circuit design for this requirement. A core circuit with high precision APD bias voltage control/light detection function is presented.

Contents of the invention

The technical problem to be solved by the present invention is to provide a temperature compensation circuit for avalanche photodiodes, which can make the constant gain operating temperature range of APD avalanche photodiodes: -0°C ~ +50°C, and the gain control accuracy is higher than 0.5%. .

In order to solve the above technical problems, the present invention provides a temperature compensation circuit for avalanche photodiodes, including:

A high-precision temperature sensing module is used to convert the die temperature of the APD into an analog voltage signal, its input end is connected to the APD light detection module, and its output end is connected to the APD bias control unit;

The APD bias control unit is used to convert the voltage signal output by the high-precision temperature sensing module into a bias signal for controlling the APD;

and the APD photodetection module, which is used to feed back the die temperature, and is controlled by the bias signal to make the gain of the APD constant, its input end is connected to the APD bias control unit, and its output end is connected to the The high-precision temperature sensing module described above.

The present invention uses high-voltage control devices to form an APD bias control unit and related auxiliary circuit modules to design a practical high-precision APD bias control temperature compensation circuit, so that the constant gain operating temperature range of the APD avalanche photodiode: -0 ° C ~ + 50℃, the gain control accuracy is higher than 0.5%.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is an overall circuit structure diagram of the present invention;

Fig. 2 is a circuit structure diagram of the APD bias voltage control unit of the present invention.

Detailed ways

Please refer to FIG. 1 , the present invention discloses a temperature compensation circuit for an avalanche photodiode, including: a high-precision temperature sensing module, an APD bias voltage control unit, and an APD light detection module.

The high-precision temperature sensing module uses a high-precision temperature sensor (accuracy ±0.1°C) to convert the core temperature of the APD light detection module into an analog voltage signal V _T ; VT is connected to the high-voltage control input terminal of the APD bias control unit, The high-voltage output terminals V _G of the APD bias voltage control unit are respectively connected to the bias voltage input pins of the APD photodetector, thus forming a closed-loop temperature compensation control for the APD photodetector.

A preferred embodiment of the APD bias control unit for the temperature compensation circuit of the avalanche photodiode of the present invention, wherein the output of the high-precision temperature sensing module is sequentially connected to the input terminal of the temperature feedback control circuit of the APD bias control unit, RC filter circuit (not shown in the figure, adding this block circuit can play the role of current limiting protection and reduce output voltage ripple, another implementation mode can set the RC filter circuit after the high-voltage conditioning circuit, and its output terminal is connected to Described APD optical detection module), high-voltage conditioning circuit, temperature feedback control circuit output end is connected with the input end of RC filter circuit, and its output end is connected with the input end of high-voltage conditioning circuit, and temperature feedback control circuit is composed of high-precision temperature sensor Formed with the corresponding compensation circuit. Among them, the temperature feedback control circuit is used to convert the temperature acquisition analog voltage of the APD into a temperature control voltage; the high voltage conditioning circuit is used to convert the temperature control voltage output by the temperature feedback control circuit into a high voltage signal that can control the bias voltage of the APD . The high-voltage power supply module is used to provide high-voltage power supply for the high-voltage conditioning circuit.

As shown in Figure 2, a preferred embodiment of the temperature feedback control circuit: the voltage output terminal of the high-precision temperature sensor is connected to the non-inverting input terminal of an ultra-low noise operational amplifier A1, and the feedback resistor _R2 sub-circuit of the amplifier A1 There is also a potentiometer W1 in series, and the output of the amplifier A1 is connected to the input terminal of the high-voltage conditioning circuit after being connected in series through a resistor R; the voltage output terminal V _REF of the high-precision reference voltage source is connected to the non-inverting input terminal of an ultra-low noise operational amplifier A2 There is also a potentiometer W2 in series on the feedback resistor R4 sub-circuit of the amplifier A2, the output of the amplifier A2 is limited by the resistor _R5 and the output of the amplifier A1 is connected in parallel to the output voltage V _T0 after the current is limited by the resistor _R6 . V _T0 is filtered by an RC filter circuit and connected to the input end of the high voltage conditioning circuit. The RC type filter circuit is used to protect the current limit and reduce the output voltage ripple at the same time. The output end of the high-voltage conditioning circuit is filtered by an RC filter circuit and then connected to the bias voltage input pin of the APD photodetector.

Preferably, the APD element of the present invention uses mounting holes to fix its metal housing base on the heat dissipation plate, and the gaps are filled with thermal conductive grease, which can achieve better heat dissipation.

The description and application of the invention herein is illustrative and is not intended to limit the scope of the invention to the above-described embodiments. Variations and changes to the embodiments disclosed herein are possible, and substitutions and equivalents for various components of the embodiments are known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be realized in other forms, structures, arrangements, proportions, and with other elements, materials and components without departing from the spirit or essential characteristics of the present invention. Other modifications and changes may be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims (7)

1. A temperature compensation circuit for an avalanche photodiode; characterized in that it comprises: A high-precision temperature sensing module is used to convert the die temperature of the APD into an analog voltage signal, its input end is connected to the APD light detection module, and its output end is connected to the APD bias control unit; The APD bias control unit is used to convert the voltage signal output by the high-precision temperature sensing module into a bias signal for controlling the APD; and the APD photodetection module, which is used to feed back the die temperature, and is controlled by the bias signal to make the gain of the APD constant, its input end is connected to the APD bias control unit, and its output end is connected to the The high-precision temperature sensing module described above. 2. The temperature compensation circuit for avalanche photodiodes according to claim 1, wherein the APD bias control unit comprises: The temperature feedback control circuit is used to convert the temperature acquisition analog voltage of the APD into a temperature control voltage, its input end is connected to the output end of the high-precision temperature sensing module, and its output end is connected to the high-voltage conditioning circuit; The high-voltage conditioning circuit is used to convert the temperature control voltage output by the temperature feedback control circuit into a high-voltage signal that can control the bias voltage of the APD, its input end is connected to the output end of the temperature feedback control circuit, and its output end Connect the APD light detection module; The high-voltage power supply module is used to provide high-voltage power for the high-voltage conditioning circuit, and its output terminal is connected to the high-voltage conditioning circuit. 3. The temperature compensation circuit for an avalanche photodiode according to claim 2, wherein said APD bias control unit further comprises at least one RC filter circuit. 4. The temperature compensation circuit for an avalanche photodiode according to claim 3, wherein said RC filter circuit is arranged between said temperature feedback control circuit and said high voltage conditioning circuit. 5. The temperature compensation circuit for avalanche photodiodes according to claim 3, characterized in that, the RC filter circuit is arranged after the high voltage conditioning circuit, and the output terminal of the RC filter circuit is connected to the The APD light detection module. 6. The temperature compensation circuit for avalanche photodiodes as claimed in claim 2, wherein said temperature feedback circuit comprises: The first operational amplifier A1, its noninverting input terminal is connected to the output terminal of the high-precision temperature sensing module, a first potentiometer W1 is connected in series on its feedback resistor _R2 sub-road, and its output terminal is connected to the high-voltage conditioning circuit through a resistor R6 connect; The second operational amplifier A2 is connected to a reference voltage source at its non-inverting input terminal, and a second potentiometer W2 is connected in series on its feedback resistor _R4 sub-circuit, and its output terminal is connected to the high voltage conditioning circuit through a resistor R5. 7. The temperature compensation circuit for avalanche photodiodes according to claim 1 or 2, wherein the APD uses mounting holes to fix its metal shell base on the heat sink, and the gaps are filled with thermal grease.

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