Adjustable electrical signal impedance matching circuit

Abstract

The invention provides an adjustable electrical signal impedance matching circuit, and belongs to the technical field of electronics. The circuit can preset the impedance of parallel terminating according to the matching impedance requirement of a transmission signal, monitor the change of signal voltage in the real-time transmission process of the signal, and adjust the current of the impedance conversion module according to the change of the voltage to realize the linear correspondence of the voltage and the current, thereby realizing the matching of the terminating impedance, and improving the transmission reliability of the signal. The impedance matching circuit can flexibly change the size of terminating impedance according to different signal transmission requirements, is particularly suitable for some occasions where various electrical characteristic signals need to be transmitted according to different application requirements, and improves the universality of equipment.

Description

Technical Field

[0001] The invention relates to the field of electronic technology, and in particular to an adjustable electrical signal impedance matching circuit. Background Art

[0002] During signal transmission, if the impedances between the signal source, transmission line, and load do not match, the signal will be reflected, and the reflected signal will affect the normal transmission and reception of the signal. In particular, with the development of electronic technology, people have higher and higher requirements for data reading and writing speeds and signal communication rates. At the same time, the signal voltage is getting lower and lower, and the adverse effects caused by the reflected signal are becoming more and more prominent. Therefore, it is increasingly important to ensure impedance matching between the signal source, transmission line, and load. At present, the commonly used method for signal impedance matching is to connect a resistor in series at the source end and a resistor in parallel at the load end. These two methods are simple in structure and low in cost. If the transmission signal is single and the matching impedance requirements of the transmission line remain unchanged, there is no problem. However, for these two methods, after the circuit design is completed, the matching impedance of the circuit cannot be changed. In some occasions where multiple electrical signals need to be transmitted according to different application requirements, it will be very inconvenient, such as in general signal controllers and signal test systems. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an adjustable electrical signal impedance matching circuit to solve the problem that the impedance is inconvenient to adjust the impedance of the current impedance matching circuit.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] An adjustable electrical signal impedance matching circuit comprises a signal voltage sampling unit, an impedance setting unit, an impedance matching unit, a signal sending unit, and a signal receiving unit. The signal sending unit is electrically connected to the impedance matching unit, the signal sending unit is electrically connected to the signal voltage sampling unit, the impedance matching unit is electrically connected to the impedance setting unit, the impedance matching unit is electrically connected to the signal receiving unit, and the signal voltage sampling unit is electrically connected to the impedance matching unit. The signal voltage sampling unit is a circuit for collecting a voltage signal of the signal sending unit and transmitting the signal to the impedance matching unit. The impedance setting unit is a circuit for setting a matching impedance value. The impedance matching unit is a circuit for completing matching impedance transformation. The signal sending unit is a circuit that can send signals of different electrical standards. The signal receiving unit is a circuit for receiving signals.

[0006] Furthermore, the impedance matching unit includes a signal processing module and an impedance transformation module. The signal processing module is electrically connected to the impedance transformation module. The signal processing module is a circuit that completes the digital-to-analog conversion and signal adjustment of the impedance setting signal. The impedance transformation module is a circuit that completes the conversion of different matching impedances.

[0007] Furthermore, the signal processing module includes a digital-to-analog conversion circuit, a signal conditioning circuit, and a voltage follower circuit. The digital-to-analog conversion circuit is electrically connected to the signal conditioning circuit, and the digital-to-analog conversion circuit is electrically connected to the voltage follower circuit. The digital-to-analog conversion circuit is a circuit that converts the digital signal of the impedance setting unit into an analog signal. The signal conditioning circuit is a circuit for conditioning the amplitude and polarity of the signal. The voltage follower circuit is a circuit that completes input voltage buffering and transmits the input voltage to the digital-to-analog conversion circuit.

[0008] Furthermore, the impedance transformation module includes a bandwidth adjustment circuit and a constant current source circuit. The bandwidth adjustment circuit is electrically connected to the constant current source circuit. The bandwidth adjustment circuit is a circuit for adjusting the impedance transformation rate, and the constant current source circuit is a circuit for completing impedance transformation.

[0009] Furthermore, the signal voltage sampling unit is implemented by discrete resistor and capacitor devices, instrument amplifiers or operational amplifiers. In a possible embodiment, the positive input terminal of the first-level operational amplifier is connected to the output terminal of the signal sending unit through a resistor, the negative input terminal of the first-level operational amplifier is connected to the reference plane of the signal sending unit through a resistor, the output terminal of the first-level operational amplifier is connected to the negative input terminal of the first-level operational amplifier through a resistor, the output terminal of the first-level operational amplifier is connected to the negative input terminal of the second-level operational amplifier through a resistor, the positive input terminal of the second-level operational amplifier is grounded through a resistor, the output terminal of the second-level operational amplifier is connected to the negative input terminal of the second-level operational amplifier through a resistor, and the output terminal of the second-level operational amplifier is connected to the digital-to-analog conversion circuit.

[0010] Furthermore, the signal conditioning circuit is implemented using an operational amplifier and discrete resistor-capacitor devices. In a possible embodiment, the positive input terminal of the operational amplifier is connected to the output terminal of the digital-to-analog conversion circuit through a resistor, the negative input terminal of the operational amplifier is grounded through a resistor, the output terminal of the operational amplifier is connected to the negative input terminal through another resistor, and the output terminal of the operational amplifier is output after impedance transformation or directly output.

[0011] Furthermore, the voltage follower circuit is implemented using a transistor or an operational amplifier in conjunction with discrete resistors and capacitors. In a possible embodiment, the positive input terminal of the operational amplifier is connected to the output of the signal voltage sampling unit, the negative input terminal of the operational amplifier is connected to the output of the operational amplifier, and the output of the operational amplifier is connected to the voltage reference of the digital-to-analog conversion circuit.

[0012] Furthermore, the bandwidth adjustment circuit is implemented using an operational amplifier, a switch, and discrete resistor and capacitor devices. In a possible embodiment, the resistor and the switch are connected in series to form a branch, and multiple groups of branches with different resistance values ​​are connected in parallel to form an impedance network. One end of the impedance network is connected to the output of the signal conditioning circuit, and the other end is connected to the negative input end of the operational amplifier. The positive input end is grounded through a resistor. One end of the feedback capacitor is connected to the negative input end of the operational amplifier, and the other end is connected to the output of the operational amplifier. The output of the operational amplifier is connected to the input of the constant current source circuit.

[0013] Furthermore, the constant current source circuit is implemented by an operational amplifier, a discrete resistor and capacitor device, a MOS tube or a triode. In a possible embodiment, the drain of the MOS tube is connected to the input end of the signal receiving unit, one end of the input resistor is connected to the output end of the bandwidth adjustment circuit, and the other end is connected to the positive input of the forward gain amplifier. The output of the forward operational amplifier is connected to the gate of the MOS tube through a resistor, the source of the MOS tube is connected to the input end of the feedback amplifier and the sampling resistor, the other end of the sampling resistor is grounded, the feedback amplifier is connected to the ground through a resistor, and is connected to the output of the feedback amplifier through another resistor, and the output end of the feedback amplifier is connected to the negative input of the forward gain amplifier.

[0014] The beneficial effect of the present invention is that by adding the impedance matching circuit of the present invention to the signal receiving end, flexible switching of multiple matching resistors can be achieved, thereby meeting the stable transmission of signals with different electrical characteristics, without causing signal reflection problems, and improving the adaptability and flexibility of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of electrical signal adjustable impedance matching circuit;

[0016] Figure 2 Schematic diagram of impedance matching unit circuit;

[0017] Figure 3 Circuit diagram of signal processing module;

[0018] Figure 4 Schematic diagram of impedance transformation module circuit;

[0019] Figure 5 Schematic diagram of the signal voltage sampling unit circuit;

[0020] Figure 6 Schematic diagram of digital-to-analog conversion circuit;

[0021] Figure 7 Schematic diagram of signal conditioning circuit;

[0022] Figure 8 Schematic diagram of voltage follower circuit;

[0023] Fig. 9 Schematic diagram of bandwidth adjustment circuit;

[0024] Fig.10 Schematic diagram of constant current source circuit.

[0025] Description of labels:

[0026] 1. Signal voltage sampling unit; 2. Impedance setting unit; 3. Impedance matching unit; 4. Signal sending unit; 5. Signal receiving unit; 31. Signal processing module; 32. Impedance transformation module; 311. Digital-to-analog conversion circuit; 312. Signal conditioning circuit; 313. Voltage follower circuit; 321. Bandwidth adjustment circuit; 322. Constant current source circuit. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0029] In order to keep the following description of the embodiments of the present invention clear and concise, the present invention omits detailed descriptions of some known functions and known components.

[0030] Please refer to the figure, the embodiment of the present invention is:

[0031] An electrical signal adjustable impedance matching circuit comprises a signal voltage sampling unit 1, an impedance setting unit 2, an impedance matching unit 3, a signal sending unit 4, and a signal receiving unit 5. The signal sending unit 4 is electrically connected to the impedance matching unit 3 and the signal voltage sampling unit 1, and the impedance matching unit 3 is electrically connected to the signal voltage sampling unit 1, the impedance setting unit 2, and the signal receiving unit 5.

[0032] The impedance matching unit 3 includes a signal processing module 31 and an impedance transformation module 32 . The signal processing module 31 is electrically connected to the impedance transformation module 32 .

[0033] The signal processing module 31 includes a digital-to-analog conversion circuit 311 , a signal conditioning circuit 312 , and a voltage follower circuit 313 . The digital-to-analog conversion circuit 311 is electrically connected to the signal conditioning circuit 312 and the voltage follower circuit 313 , respectively.

[0034] The impedance transformation module 32 includes a bandwidth adjustment circuit 321 and a constant current source circuit 322 . The bandwidth adjustment circuit 321 is electrically connected to the constant current source circuit 322 .

[0035] The impedance setting unit 2 is implemented by a touch screen and an MCU, and the signal sending unit 4 and the signal receiving unit 5 are implemented by a programmable logic device with a serial transceiver module.

[0036] like Figure 5 As shown, the signal voltage sampling unit 1 adopts a high-speed operational amplifier and high-precision resistors, with a common mode rejection ratio of 80dB, a slew rate of 1000V / us, a gain bandwidth product of 400MHz, and a resistor accuracy of 1%, ensuring that the signal voltage sampling unit 1 still has good tracking capability at a signal frequency of 100MHz and has a strong suppression capability for common mode noise.

[0037] like Figure 6 As shown, the digital-to-analog conversion circuit 311 is implemented using a precision digital-to-analog converter with a linearity of 1LSB, a reference temperature drift of 10ppm / °C, and a resolution of 16 bits, ensuring that the digital-to-analog conversion circuit 311 still has high accuracy when the ambient temperature fluctuates.

[0038] like Figure 7 As shown, the signal conditioning circuit 312 is implemented using a precision operational amplifier, high-precision resistors and capacitors, and a switching diode. The precision operational amplifier has a noise of 77nVp-p, a maximum input bias current of 12nA, a maximum offset voltage of 75uV, a resistor accuracy of 1%, and capacitors using polypropylene film capacitors with an accuracy of 5%. The reverse current of the switching diode is less than 1uA, ensuring the signal conditioning circuit 312's ability to amplify high-frequency small signals.

[0039] like Figure 8As shown, the voltage follower circuit 313 adopts a high-speed operational amplifier and high-precision resistors, with a maximum offset voltage of 175uV, an input bias current of 100nA, a common-mode rejection ratio of 110dB, a bandwidth of 180MHz, and a resistance accuracy of 1%, thereby improving the voltage follower circuit 313's ability to suppress common-mode interference and its signal tracking ability.

[0040] like Fig. 9 As shown, the bandwidth adjustment circuit 321 is implemented by analog switches, high-precision resistors and capacitors, and operational amplifiers. The analog switch off capacitance is 1pF, rail-to-rail operation, the operational amplifier noise is 77nVp-p, the input bias current is maximum 12nA, the offset voltage is maximum 75uV, the resistor accuracy is 1%, and the capacitors are polypropylene film capacitors with an accuracy of 5%, which improves the integration capability of the bandwidth adjustment circuit 321 for small signals. Under the premise of ensuring the stability of the loop, it has a good response speed to signals of different frequencies.

[0041] like Fig.10 As shown, the constant current source circuit 322 is implemented by a high-speed operational amplifier, a high-precision resistor, and a MOS tube. The high-speed operational amplifier has a maximum offset voltage of 175uV, an input bias current of 100nA, a common-mode rejection ratio of 110dB, a bandwidth of 180MHz, a total gate charge of the high-speed MOS tube of less than 1nC, a drain-source on-resistance of less than 100mΩ, and a resistor accuracy of 1%, ensuring that the constant current source circuit can adjust the current change in time during the high-speed signal change process, thereby achieving precise impedance matching.

[0042] The principle of the present invention is: first, the operator sets the impedance value of the impedance setting unit according to the actual impedance requirement of the transmitted signal, the signal processing module adjusts the digital quantity of the digital-to-analog conversion circuit according to the preset impedance value, and then the signal voltage sampling unit samples the voltage signal of the signal sending unit in real time and transmits the signal to the impedance matching unit. The bandwidth adjustment circuit of the impedance matching unit matches the appropriate conversion bandwidth according to the transmission rate of the signal, and finally the constant current source circuit controls the current according to the required impedance value and the real-time voltage to achieve the set impedance value, thereby completing the impedance transformation.

[0043] In summary, the present invention provides an adjustable electrical signal impedance matching circuit, which monitors the magnitude of the signal voltage in real time during the signal transmission process, and adjusts the current magnitude of the impedance matching unit of the signal receiving end in real time, thereby realizing parallel termination of the signal receiving end and completing impedance matching. The circuit can realize impedance matching of different resistance values ​​according to the requirements of different signals. The impedance adjustment is flexible, easy to use, and has a wide range of signal adaptability.

[0044] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An adjustable electrical signal impedance matching circuit, characterized in that include: A signal voltage sampling unit, an impedance setting unit, an impedance matching unit, a signal sending unit, and a signal receiving unit. The signal sending unit is electrically connected to the impedance matching unit, the signal sending unit is electrically connected to the signal voltage sampling unit, the impedance matching unit is electrically connected to the impedance setting unit, the impedance matching unit is electrically connected to the signal receiving unit, the signal voltage sampling unit is electrically connected to the impedance matching unit, the signal voltage sampling unit is a circuit for collecting the voltage signal of the signal sending unit and transmitting the signal to the impedance matching unit, the impedance setting unit is a circuit for setting the matching impedance value, the impedance matching unit is a circuit for completing the matching impedance transformation, the signal sending unit is a circuit that can send signals of different electrical standards, and the signal receiving unit is a circuit for receiving signals.

2. The adjustable electrical signal impedance matching circuit according to claim 1, characterized in that: The impedance matching unit includes a signal processing module and an impedance transformation module. The signal processing module is electrically connected to the impedance transformation module. The signal processing module is a circuit that completes the digital-to-analog conversion and signal adjustment of the impedance setting signal. The impedance transformation module is a circuit that completes the conversion of different matching impedances.

3. The adjustable electrical signal impedance matching circuit according to claim 2, characterized in that: The signal processing module includes a digital-to-analog conversion circuit, a signal conditioning circuit, and a voltage follower circuit. The digital-to-analog conversion circuit is electrically connected to the signal conditioning circuit, and the digital-to-analog conversion circuit is electrically connected to the voltage follower circuit. The digital-to-analog conversion circuit is a circuit that converts the digital signal of the impedance setting unit into an analog signal. The signal conditioning circuit is a circuit for conditioning the amplitude and polarity of the signal. The voltage follower circuit is a circuit that completes input voltage buffering and transmits the input voltage to the digital-to-analog conversion circuit.

4. The adjustable electrical signal impedance matching circuit according to claim 2, characterized in that: The impedance transformation module includes a bandwidth adjustment circuit and a constant current source circuit. The bandwidth adjustment circuit is electrically connected to the constant current source circuit. The bandwidth adjustment circuit is a circuit for adjusting the impedance transformation rate, and the constant current source circuit is a circuit for completing impedance transformation.

5. The adjustable electrical signal impedance matching circuit according to claim 1, characterized in that: The signal voltage sampling unit is implemented by discrete resistor and capacitor devices, instrument amplifier or operational amplifier. In a possible embodiment, the positive input terminal of the first-level operational amplifier is connected to the output terminal of the signal sending unit through a resistor, the negative input terminal of the first-level operational amplifier is connected to the reference plane of the signal sending unit through a resistor, the output terminal of the first-level operational amplifier is connected to the negative input terminal of the first-level operational amplifier through a resistor, the output terminal of the first-level operational amplifier is connected to the negative input terminal of the second-level operational amplifier through a resistor, the positive input terminal of the second-level operational amplifier is grounded through a resistor, the output terminal of the second-level operational amplifier is connected to the negative input terminal of the second-level operational amplifier through a resistor, and the output terminal of the second-level operational amplifier is connected to the digital-to-analog conversion circuit.

6. The adjustable electrical signal impedance matching circuit according to claim 3, characterized in that: The signal conditioning circuit is implemented using an operational amplifier and discrete resistor and capacitor devices. In a possible embodiment, the positive input terminal of the operational amplifier is connected to the output terminal of the digital-to-analog conversion circuit through a resistor, the negative input terminal of the operational amplifier is grounded through a resistor, the output terminal of the operational amplifier is connected to the negative input terminal through another resistor, and the output terminal of the operational amplifier is output after passing through the next stage amplification circuit or is directly output.

7. The adjustable electrical signal impedance matching circuit according to claim 3, characterized in that: The voltage follower circuit is implemented using a transistor or an operational amplifier in conjunction with discrete resistors and capacitors. In a possible embodiment, the positive input terminal of the operational amplifier is connected to the output of the signal voltage sampling unit, the negative input terminal of the operational amplifier is connected to the output of the operational amplifier, and the output of the operational amplifier is connected to the voltage reference of the digital-to-analog conversion circuit.

8. The adjustable electrical signal impedance matching circuit according to claim 4, characterized in that: The bandwidth adjustment circuit is implemented by an operational amplifier, a switch, and discrete resistor and capacitor devices. In a possible embodiment, a resistor and a switch are connected in series to form a branch, and multiple groups of branches with different resistance values ​​are connected in parallel to form an impedance network. One end of the impedance network is connected to the output of the signal conditioning circuit, and the other end is connected to the negative input end of the operational amplifier. The positive input end is grounded through a resistor. One end of the feedback capacitor is connected to the negative input of the operational amplifier, and the other end is connected to the output of the operational amplifier. The output of the operational amplifier is connected to the input of the constant current source circuit.

9. The adjustable electrical signal impedance matching circuit according to claim 4, characterized in that: The constant current source circuit is implemented by an operational amplifier, a discrete resistor and capacitor device, a MOS tube or a triode. In a possible embodiment, the drain of the MOS tube is connected to the input end of the signal receiving unit, one end of the input resistor is connected to the output end of the bandwidth adjustment circuit, and the other end is connected to the positive input of the forward gain amplifier. The output of the forward operational amplifier is connected to the gate of the MOS tube, the source of the MOS tube is connected to the input end of the feedback amplifier and the sampling resistor, the other end of the sampling resistor is grounded, the feedback amplifier is connected to the ground through a resistor, and is connected to the output of the feedback amplifier through another resistor, and the output end of the feedback amplifier is connected to the negative input of the forward gain amplifier.

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