Pulse type driving circuit for enhancing SOA on-off extinction ratio

Abstract

The utility model discloses a pulse type driving circuit for enhancing the on-off extinction ratio of an SOA (semiconductor optical amplifier), which belongs to the field of semiconductor optical amplifiers and enables the SOA to be reversely biased and absorb input light when a pulse modulation signal is low in SOA intensity modulation, so that the on-off extinction ratio is greatly increased, and more stable and long-distance signal transmission is obtained. The circuit mainly comprises an input circuit I and an input circuit II, the input circuit I and the input circuit II are connected with an operational amplifier U6 through an H-bridge driver, the input circuit I comprises a comparator U1, the positive input end of the comparator U1 is connected with a radio frequency signal RF, the output end of the comparator U1 is connected with the positive input end of an operational amplifier U2, the input circuit II comprises a comparator U4, and the positive input end of the operational amplifier U2 is connected with the positive input end of the operational amplifier U6. The negative input end of the comparator U4 is connected with a radio frequency signal RF, and the output end of the comparator U4 is connected with the positive input end of the operational amplifier U5. The pulse driving circuit is mainly used for enhancing the on-off extinction ratio of the SOA.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor optical amplifiers, and more specifically, to a pulsed drive circuit that enhances the on / off extinction ratio of an SOA. Background Technology

[0002] Semiconductor optical amplifiers (SOAs) are optical amplifiers based on semiconductor gain media and are key building blocks of optical networks. Used as optical pulse modulation modules, they can perform high-speed intensity modulation of the input signal light, featuring fast rise time and high pulse extinction ratio. Due to the high extinction ratio of SOAs, current pulse modulation drive circuits, such as the multi-mode driver circuit and disk drive system (announcement number CN100530360C) and the method for driving the motor in this system, cannot completely turn off the SOA. Utility Model Content

[0003] The purpose of this invention is to provide a pulsed drive circuit that enhances the on / off extinction ratio of SOA. In SOA intensity modulation, when the pulse modulation signal is low, the SOA is reverse-biased and absorbs the input light, which greatly increases the on / off extinction ratio and obtains more stable and longer-distance signal transmission.

[0004] This utility model is achieved through the following technical solution:

[0005] A pulsed drive circuit for enhancing the on / off extinction ratio of an operational amplifier (SOA) includes an input circuit I and an input circuit II. Input circuit I and input circuit II are connected to an operational amplifier U6 via an H-bridge driver. Input circuit I includes a comparator U1, with its positive input connected to an RF signal (RF) and its negative input connected to a 2.5V voltage. The output of comparator U1 is connected to the positive input of operational amplifier U2. Input circuit II includes a comparator U4, with its negative input connected to the RF signal (RF) and its positive input connected to a 2.5V voltage. The output of comparator U4 is connected to the positive input of operational amplifier U5. The outputs of operational amplifiers U2 and U5 are both connected to an H-bridge driver. The negative inputs of operational amplifiers U2 and U5 are both connected to the output of operational amplifier U6. The positive input of operational amplifier U6 is connected to both the H-bridge driver and a sampling resistor R9. The negative input of operational amplifier U6 is connected to its output.

[0006] Furthermore, the positive input terminal of comparator U1 is connected to the radio frequency signal RF through resistor R2, and resistor R1 is also connected between the positive input terminal and the output terminal of comparator U1 to form a hysteresis comparator circuit, thereby enhancing the circuit's anti-interference capability.

[0007] Furthermore, the output of operational amplifier U2 is connected to an H-bridge driver via an RC circuit.

[0008] Furthermore, the negative input terminal of comparator U4 is connected to the radio frequency signal RF through resistor R5, and a resistor R8 is also connected between the negative input terminal and the output terminal of comparator U4 to form a hysteresis comparator circuit, thereby enhancing the circuit's anti-interference capability.

[0009] Furthermore, the output of operational amplifier U5 is also connected to an H-bridge driver via an RC circuit.

[0010] Furthermore, the RC circuit is a parallel circuit of a single resistor and a single capacitor, which can accelerate the switching speed of the transistor switch in the H-bridge driver.

[0011] Furthermore, the H-bridge driver includes transistors Q1, Q2, Q3, and Q4. Terminal 1 of transistor Q2 is connected to the output of operational amplifier U2 via an RC circuit, and terminal 1 of transistor Q4 is connected to the output of operational amplifier U5 via an RC circuit. Terminals 2 of both transistors Q3 and Q4 are connected to the positive input of operational amplifier U6. Sampling resistor R9 is also connected to terminals 2 of both transistors Q3 and Q4. Terminals 1 of both transistors Q1 and Q3 are connected to RC circuits.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] In SOA intensity modulation, when the pulse modulation signal is low, the circuit of this invention reverses the SOA and absorbs the input light, greatly increasing the on / off extinction ratio and obtaining more stable, long-distance signal transmission. Attached Figure Description

[0014] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings.

[0016] Example 1

[0017] like Figure 1As shown, a pulse-type drive circuit for enhancing the on / off extinction ratio of an operational amplifier (SOA) includes an input circuit I and an input circuit II. Input circuit I and input circuit II are connected to an operational amplifier U6 via an H-bridge driver. Input circuit I includes a comparator U1, with its positive input terminal connected to a radio frequency (RF) signal and its negative input terminal connected to a reference voltage VREF 2.5V. The output terminal of comparator U1 is connected to the positive input terminal of operational amplifier U2. Input circuit II includes a comparator U4, with its negative input terminal connected to the RF signal and its positive input terminal connected to the reference voltage VREF 2.5V. The output terminal of comparator U4 is connected to the positive input terminal of operational amplifier U5. The output terminals of operational amplifiers U2 and U5 are both connected to an H-bridge driver. The negative input terminals of operational amplifiers U2 and U5 are both connected to the output terminal of operational amplifier U6. The positive input terminal of operational amplifier U6 is connected to both the H-bridge driver and a sampling resistor R9. The negative input terminal of operational amplifier U6 is connected to its output terminal. By modifying the value of the sampling resistor R9, the SOA current is controlled, thereby controlling the SOA's output optical power. The H-bridge driver enables the SOA to drive forward when the external pulse signal is high, amplifying the input optical signal; and to supply power in reverse when the external pulse signal is low, absorbing the input optical signal, greatly enhancing the on / off extinction ratio.

[0018] Example 2

[0019] A pulse-type drive circuit for enhancing the on / off extinction ratio of an operational amplifier (SOA) includes a comparator U1 whose positive input is connected to the radio frequency (RF) signal via resistor R2. A resistor R1 is also connected between the positive input and output of comparator U1 to form a hysteresis comparator circuit, enhancing the circuit's anti-interference capability. The output of operational amplifier U2 is connected to an H-bridge driver via an RC circuit. Similarly, a comparator U4 whose negative input is connected to the RF signal via resistor R5, and a resistor R8 is connected between the negative input and output of comparator U4 to form a hysteresis comparator circuit, further enhancing the circuit's anti-interference capability. The output of operational amplifier U5 is also connected to an H-bridge driver via an RC circuit, which consists of a parallel connection of a single resistor and a single capacitor. The circuit (such as RC circuit: capacitor C1, resistor R3; RC circuit: capacitor C3, resistor R6, etc.) can accelerate the switching speed of the transistor switches in the H-bridge driver. The H-bridge driver includes transistors Q1, Q2, Q3, and Q4. Terminal 1 of transistor Q2 is connected to the output terminal of operational amplifier U2 through an RC circuit. Terminal 1 of transistor Q4 is connected to the output terminal of operational amplifier U5 through an RC circuit. Terminals 2 of transistors Q3 and Q4 are both connected to the positive input terminal of operational amplifier U6. Terminals 2 of transistors Q3 and Q4 are also connected to sampling resistor R9. Terminals 1 of transistors Q1 and Q3 are both connected to RC circuits. Other aspects are the same as in Example 1.

[0020] An external radio frequency (RF) signal is injected and enters the positive input terminal of comparator U1. The output signal of comparator U1 enters the positive input terminal of operational amplifier U2. The negative input terminal of operational amplifier U2 is connected to the output terminal of operational amplifier U6. The positive input terminal of operational amplifier U6 is connected to sampling resistor R9, forming a constant current circuit. Through closed-loop feedback, the voltage change of sampling resistor R9 is fed back to the negative input terminal of operational amplifier U2, controlling the output change of operational amplifier U2. Subsequently, transistors Q2 and Q3 are turned on, enabling SOA to be forward driven, and SOA outputs light.

[0021] When the RF signal is low, comparator U4 outputs a high level. The output signal of comparator U4 enters the positive input of operational amplifier U5. The negative input of operational amplifier U5 is connected to the output of operational amplifier U6. The positive input of operational amplifier U6 is connected to sampling resistor R9, forming a constant current circuit. Through closed-loop feedback, the voltage change of sampling resistor R9 is fed back to the negative input of operational amplifier U5, controlling the output change of operational amplifier U5. Subsequently, transistors Q1 and Q4 are turned on, causing SOA to reverse drive. SOA absorbs the input light and does not output light.

Claims

1. A pulsed drive circuit for enhancing the on / off extinction ratio of an SOA, comprising input circuit I and input circuit II, wherein input circuit I and input circuit II are connected to operational amplifier U6 via an H-bridge driver, characterized in that: The input circuit I includes comparator U1, the positive input terminal of which is connected to the radio frequency signal RF, and the output terminal of comparator U1 is connected to the positive input terminal of operational amplifier U2. The input circuit II includes comparator U4, the negative input terminal of which is connected to the radio frequency signal RF, and the output terminal of comparator U4 is connected to the positive input terminal of operational amplifier U5. The output terminals of operational amplifier U2 and operational amplifier U5 are both connected to H-bridge drivers. The negative input terminals of operational amplifier U2 and operational amplifier U5 are both connected to the output terminal of operational amplifier U6. The positive input terminal of operational amplifier U6 is connected to an H-bridge driver and a sampling resistor R9.

2. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 1, characterized in that: The positive input terminal of comparator U1 is connected to the radio frequency signal RF through resistor R2, and resistor R1 is also connected between the positive input terminal and the output terminal of comparator U1.

3. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 1, characterized in that: The output of operational amplifier U2 is also connected to an H-bridge driver via an RC circuit.

4. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 1, characterized in that: The negative input terminal of comparator U4 is connected to the radio frequency signal RF through resistor R5, and resistor R8 is also connected between the negative input terminal and the output terminal of comparator U4.

5. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 1, characterized in that: The output of operational amplifier U5 is also connected to an H-bridge driver via an RC circuit.

6. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 3 or 5, characterized in that: The RC circuit is a parallel circuit consisting of a single resistor and a single capacitor.

7. The pulse-type drive circuit for enhancing the SOA on / off extinction ratio according to claim 6, characterized in that: The H-bridge driver includes transistors Q1, Q2, Q3, and Q4. Terminal 1 of transistor Q2 is connected to the output of operational amplifier U2 via an RC circuit. Terminal 1 of transistor Q4 is connected to the output of operational amplifier U5 via an RC circuit. Terminals 2 of both transistors Q3 and Q4 are connected to the positive input of operational amplifier U6. Sampling resistor R9 is also connected to terminals 2 of both transistors Q3 and Q4. Terminals 1 of both transistors Q1 and Q3 are connected to RC circuits.

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