Wide-range optical power detection circuit and optical module

Abstract

The utility model relates to the technical field of optical module receiving optical detection, in particular to a wide-range optical power detection circuit and an optical module, which comprise a photodiode PD, a differential current detection circuit, a TIA amplification circuit and a current compensation diode D1. The TIA amplification circuit is connected with the cathode of the PD, the differential current detection circuit is connected in series between the PD and the TIA amplification circuit, the D1 is connected in parallel with the TIA amplification circuit, the MCU comprises a first ADC and a second ADC, the output end of the TIA amplification circuit is connected with the first ADC, and the output end of the differential current detection circuit is connected with the second ADC. According to the utility model, the TIA amplification circuit and the differential current detection circuit which are connected in series are utilized, so that the detection range of the receiving end optical power is enlarged, the receiving optical detection problem of the ultra-long-distance optical module is solved, and the conditions that the receiving optical power detection value is saturated in a large optical section, jumps in a small optical section and the receiving end is abnormal in monitoring are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of optical module receiving light detection, in particular to a wide range optical power detection circuit and an optical module. Background Art

[0002] With the rapid development of cloud computing, big data, artificial intelligence, and 5G industry applications, network data traffic is growing rapidly, posing greater challenges to data center interconnection. Data center interconnection (DCI) refers to the interconnection between campuses, with interconnection distances typically exceeding tens of kilometers or even hundreds of kilometers. In an 80km application, the fiber link loss is typically 25.6dB to 28dB, with insertion loss and dispersion penalty of approximately 3.5dB, resulting in an overall link budget of approximately 29.1dB to 31.5dB.

[0003] The increase in optical module transmission distance has also put forward new requirements for functional characteristics such as optical module health monitoring and early fault warning. Real-time monitoring of the receiving optical power is a very important indicator. In optical modules with conventional distance transmission, the receiving optical power detection circuit is mainly composed of a photodiode and a sampling resistor. When the module receives light, the photodiode generates a photocurrent proportional to the optical power. The photocurrent forms a voltage through the sampling resistor, and then the ADC collects the voltage to complete the receiving optical power detection. For optical modules with ultra-long distance transmission of 80km, because it requires a higher link budget and a wider operating range of optical power, the conventional receiving optical power detection scheme will saturate the received optical power detection value in long optical segments. In small optical segments, the small amplitude of the ADC sampling voltage will cause jumps and abnormal receiving monitoring.

[0004] Based on this, how to solve the voltage saturation of high-power optical signals, the jump in low-power optical signal acquisition results, and the abnormal monitoring of the receiving end is a technical problem that needs to be solved urgently. Utility Model Content

[0005] The purpose of the utility model is to provide a wide-range optical power detection circuit and optical module, which utilizes a TIA amplifier circuit and a differential current detection circuit in series to improve the detection range of the optical power at the receiving end, solve the problem of received light detection in ultra-long-distance optical modules, and avoid saturation of the received optical power detection value in large optical segments, jumps in small optical segments, and abnormal monitoring at the receiving end.

[0006] The utility model is realized by the following technical solutions: a wide range optical power detection circuit, including an MCU, a photodiode, a differential current detection circuit, a TIA amplification circuit and a current compensation diode;

[0007] The TIA amplifier circuit is connected to the cathode of the photodiode, the differential current detection circuit is connected in series between the photodiode and the TIA amplifier circuit, the current compensation diode is connected in parallel with the TIA amplifier circuit, the MCU includes a first ADC and a second ADC, the output end of the TIA amplifier circuit is connected to the first ADC, and the output end of the differential current detection circuit is connected to the second ADC.

[0008] According to a preferred embodiment, the TIA amplifying circuit includes a first operational amplifier and a feedback resistor;

[0009] The inverting input terminal of the first operational amplifier is connected to the cathode of the photodiode, the non-inverting input terminal of the first operational amplifier is grounded, the output terminal of the first operational amplifier is connected to the first ADC, the first end of the feedback resistor is connected to the output terminal of the first operational amplifier, and the second end of the feedback resistor is connected to the inverting input terminal of the first operational amplifier.

[0010] According to a preferred embodiment, the differential current detection circuit includes a second operational amplifier and a sampling resistor;

[0011] The sampling resistor is connected in series between the photodiode and the inverting input terminal of the first operational amplifier, the inverting input terminal of the second operational amplifier is connected between the photodiode and the sampling resistor, the non-inverting input terminal of the second operational amplifier is connected between the sampling resistor and the second end access point of the feedback resistor, and the output terminal of the second operational amplifier is connected to the second ADC.

[0012] According to a preferred embodiment, the first end of the current compensation diode is connected between the non-inverting input terminal access point of the second operational amplifier and the second end access point of the feedback resistor, and the second end of the current compensation diode is grounded.

[0013] According to a preferred embodiment, the maximum acquisition voltage of the first ADC is lower than the maximum output voltage of the first operational amplifier.

[0014] According to a preferred embodiment, the maximum acquisition voltage of the first ADC is 2.5V, and the maximum output voltage of the first operational amplifier is 3.3V.

[0015] The utility model also provides an optical module, comprising the wide-range optical power detection circuit as described above.

[0016] The technical solution of a wide-range optical power detection circuit and an optical module provided by the present invention has at least the following advantages and beneficial effects: (1) By utilizing a series-connected TIA amplifier circuit and a differential current detection circuit, the detection range of the optical power at the receiving end is improved, and the problem of receiving light detection of an ultra-long-distance optical module is solved, thereby avoiding saturation of the received optical power detection value in a large optical segment, jumps in a small optical segment, and abnormal monitoring at the receiving end; (2) The optical power detection range of the receiving end reaches 42dB, and the accuracy deviation can be controlled within 0.5dB in the entire receiving range, thereby avoiding misjudgment of the insertion or release of the switching process of the RX_LOS signal indicating whether the receiving end has received a valid optical signal, and having high functional reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a design block diagram of the wide-range optical power detection circuit provided in Example 1 of the present utility model. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0019] Example 1

[0020] Figure 1 This is a design block diagram of a wide range optical power detection circuit provided by the utility model. Figure 1 As shown, the wide-range optical power detection circuit includes an MCU, a photodiode PD, a differential current detection circuit, a TIA amplification circuit, and a current compensation diode D1.

[0021] The TIA amplifier circuit is connected to the cathode of the PD, the differential current detection circuit is connected in series between the PD and the TIA amplifier circuit, and the D1 is connected in parallel with the TIA amplifier circuit; the MCU includes a first ADC and a second ADC, Figure 1 The first ADC is represented by ADC1, the second ADC is represented by ADC2, the output end of the TIA amplifier circuit is connected to ADC1, and the output end of the differential current detection circuit is connected to ADC2.

[0022] In this embodiment, the TIA amplification circuit includes a first operational amplifier U1 and a feedback resistor R2. The inverting input of U1 is connected to the cathode of the PD, the non-inverting input of U1 is grounded, the output of U1, Vout1, is connected to ADC1, the first end of R2 is connected to the output of U1, and the second end of R2 is connected to the inverting input of U1. Furthermore, the maximum acquisition voltage of ADC1 is lower than the maximum output voltage of U1. Preferably, the maximum acquisition voltage of ADC1 is 2.5V, and the maximum output voltage and supply voltage of U1 are both 3.3V.

[0023] The differential current detection circuit includes U2 and R1; R1 is connected in series between PD and the inverting input terminal of U1, the inverting input terminal of U2 is connected between PD and R1, the non-inverting input terminal of U2 is connected between R1 and the second end access point of R2, and the output terminal Vout2 of U2 is connected to ADC2.

[0024] The first end of D1 is connected between the non-inverting input terminal access point of U2 and the second end access point of R2, and the second end of D1 is grounded.

[0025] It should be noted that the solution provided in this embodiment utilizes a series-connected TIA amplifier circuit and a differential current detection circuit to improve the detection range of the optical power at the receiving end, solve the problem of received light detection in ultra-long-distance optical modules, and avoid saturation of the received light power detection value in large light segments, jumps in small light segments, and abnormal monitoring at the receiving end; the optical power detection range at the receiving end reaches 42dB, and the accuracy deviation can be controlled within 0.5dB throughout the entire receiving range, thereby avoiding misjudgment of the insertion or release of the RX_LOS signal indicating whether the receiving end has received a valid optical signal during the switching process, and has high functional reliability.

[0026] The principle of the wide-range optical power detection circuit is explained below:

[0027] Since the supply voltage of U1 is 3.3V, the maximum output voltage is 3.3V, and the maximum acquisition voltage of ADC1 is 2.5V, there will be two saturation points when the PD receives light that changes from small to large:

[0028] Saturation point 1: U1 output reaches 2.5V but does not reach 3.3V. At this point, ADC1 sampling is saturated.

[0029] Saturation point 2: U1 output reaches 3.3V and U1 output is saturated.

[0030] Assume that the optical power corresponding to saturation point 1 is P1, and the optical power corresponding to saturation point 2 is P2.

[0031] When the PD light receiving range is 0 to P1, ADC1 and U1 are not saturated. At this time, U1 can provide all the photocurrent. When the photocurrent flows through R2 and R1, a voltage is formed on R2, which is collected by ADC1.

[0032] When the PD's light receiving range is from P1 to P2, ADC1 is saturated and cannot collect light normally, but U1 is not saturated and can still provide all the photocurrent. The photocurrent flows through R1, forming a voltage difference on R1, and the voltage is collected by the differential current detection circuit.

[0033] When the PD's light receiving range is greater than P2, U1 is saturated and can no longer provide additional photocurrent. At this time, D1 provides additional current to flow through R1, forming a voltage difference on R1, and the voltage is collected by the differential current detection circuit.

[0034] In addition, since the detection of optical power is completed in sections, this embodiment also sets a hysteresis interval in program control, which is composed of a first threshold TH1 and a second threshold TH2. 2.5V is greater than or equal to TH1 and greater than TH2.

[0035] It should be noted that when the PD receives light that increases from low to high, if the Vout1 voltage exceeds TH1, the actual collected value is provided by ADC2. When Vout1 falls below TH2, the actual collected value is provided by ADC1. TH1 and TH2 form a hysteresis range, which enhances the circuit's anti-interference ability and effectively prevents oscillation near the switching point between ADC1 and ADC2.

[0036] Example 2

[0037] This embodiment provides an optical module based on the technical solution provided in Example 1. The optical module includes the wide-range optical power detection circuit provided in Example 1.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A wide range optical power detection circuit, characterized in that: Including MCU, photodiode, differential current detection circuit, TIA amplifier circuit and current compensation diode; The TIA amplifier circuit is connected to the cathode of the photodiode, the differential current detection circuit is connected in series between the photodiode and the TIA amplifier circuit, the current compensation diode is connected in parallel with the TIA amplifier circuit, the MCU includes a first ADC and a second ADC, the output end of the TIA amplifier circuit is connected to the first ADC, and the output end of the differential current detection circuit is connected to the second ADC.

2. The wide range optical power detection circuit according to claim 1, wherein: The TIA amplifying circuit includes a first operational amplifier and a feedback resistor; The inverting input terminal of the first operational amplifier is connected to the cathode of the photodiode, the non-inverting input terminal of the first operational amplifier is grounded, the output terminal of the first operational amplifier is connected to the first ADC, the first end of the feedback resistor is connected to the output terminal of the first operational amplifier, and the second end of the feedback resistor is connected to the inverting input terminal of the first operational amplifier.

3. The wide range optical power detection circuit according to claim 2, wherein: The differential current detection circuit includes a second operational amplifier and a sampling resistor; The sampling resistor is connected in series between the photodiode and the inverting input terminal of the first operational amplifier, the inverting input terminal of the second operational amplifier is connected between the photodiode and the sampling resistor, the non-inverting input terminal of the second operational amplifier is connected between the sampling resistor and the second end access point of the feedback resistor, and the output terminal of the second operational amplifier is connected to the second ADC.

4. The wide range optical power detection circuit according to claim 3, wherein: The first end of the current compensation diode is connected between the non-inverting input terminal access point of the second operational amplifier and the second end access point of the feedback resistor, and the second end of the current compensation diode is grounded.

5. The wide-range optical power detection circuit according to any one of claims 1 to 4, characterized in that: The maximum acquisition voltage of the first ADC is lower than the maximum output voltage of the first operational amplifier.

6. The wide range optical power detection circuit according to claim 5, wherein: The maximum acquisition voltage of the first ADC is 2.5V, and the maximum output voltage of the first operational amplifier is 3.3V.

7. An optical module, characterized in that: The wide-range optical power detection circuit comprises the circuit according to any one of claims 1 to 6.

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