Mirror image control based voltage-controlled resistance adjustable termination resistance circuit and system

Abstract

This application provides a voltage-controlled resistor (VCR) adjustable termination resistor circuit and system based on mirror control, relating to the field of high-speed serial transmitter design technology. It includes: a working path, a mirror path, and a control loop; the mirror path and the working path operate in the same environment; the control loop applies control voltages to the VCR in the working path and the mirror VCR in the mirror path respectively to control their resistance values; the control loop compares the critical node voltage at the output of the mirror VCR with the reference voltage of a reference voltage source, and outputs a control voltage based on the real-time voltage deviation. The voltage-controlled resistor (VCR) adjustable termination resistor circuit and system provided in this application uses a mirror backup termination resistor to detect the impedance of the termination resistor in real time, and adjusts the termination resistor value in real time when the chip voltage and temperature change, to meet the termination resistor requirements of the high-speed serial interface.

Description

Technical Field

[0001] This application relates to the field of high-speed serial transmitter design technology, and in particular to a voltage-controlled resistor adjustable termination resistor circuit and system based on mirror control. Background Technology

[0002] With the rapid development of data centers, 5G communications, and artificial intelligence, the data transmission rate of high-speed serial interfaces (SerDes) continues to increase. Currently, the data transmission rate of high-speed serial interfaces has exceeded 112Gbps and is evolving towards 224Gbps. This poses unprecedented challenges to signal integrity, among which impedance matching is particularly prominent.

[0003] In high-speed serial links, the accuracy of the transmitter termination resistor directly affects signal quality. If the termination resistor does not match the characteristic impedance of the transmission line, it can lead to signal reflection, ringing, and a decrease in the horizontal eye opening. In severe cases, it can even cause the system's bit error rate (BER) to fail to meet requirements. For SerDes systems above 56Gbps, the BER must be below 1E-15, which places extremely high demands on the accuracy and stability of the termination resistor.

[0004] Therefore, there is an urgent need for an adjustable termination resistor technology with small parasitic capacitance, precise adjustment step size, real-time tracking of temperature and voltage changes, and easy integration into advanced processes. Summary of the Invention

[0005] The purpose of this application is to provide a voltage-controlled adjustable termination resistor circuit and system based on mirror control. The impedance of the termination resistor is detected in real time by mirror backup termination resistor, and the resistance value of the termination resistor is adjusted in real time when the chip voltage and temperature change, so as to meet the requirements of high-speed serial interface for termination resistor.

[0006] In a first aspect, this application provides a voltage-controlled resistor adjustable termination resistor circuit based on mirror control, comprising: The system comprises a working path, a mirror path, and a control loop; the mirror path operates in the same environment as the working path; the control loop applies control voltages to the voltage-controlled resistors in the working path and the mirror voltage-controlled resistors in the mirror path to control their resistance values; the control loop compares the critical node voltage at the output of the mirror voltage-controlled resistor with the reference voltage of a reference voltage source and outputs a control voltage based on the real-time voltage deviation; wherein, the control voltage output by the control loop simultaneously adjusts the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor to form a negative feedback that makes the critical node voltage approach the reference voltage; the same operating environment includes that the difference in operating environment parameters is within a preset error range.

[0007] Optionally, the circuit further includes: by pre-setting the reference voltage of the reference voltage source, such that when the negative feedback is stable, the critical node voltage of the mirror path is equal to the reference voltage.

[0008] Optionally, the working path includes a transmitter driver and a voltage-controlled resistor; the mirror path includes a mirror transmitter driver and a mirror voltage-controlled resistor; the input terminal of the voltage-controlled resistor is connected to the output terminal of the transmitter driver; the input terminal of the mirror voltage-controlled resistor is connected to the output terminal of the mirror transmitter driver to simulate the working environment of the voltage-controlled resistor.

[0009] Optionally, the output terminal of the mirror voltage-controlled resistor is connected to the mirror receiver termination resistor, and together with the mirror transmitter driver and the mirror receiver termination resistor, forms a mirror path for analog working path signal transmission.

[0010] Optionally, the voltage-controlled resistor and the mirror voltage-controlled resistor are MOS transistors, with the source and drain serving as the input and output terminals of the resistor, respectively, and the gate serving as the control terminal, adjusting the on-resistance by changing the gate voltage.

[0011] Optionally, the control loop includes: an operational amplifier; the two input terminals of the operational amplifier are respectively connected to the output terminal of the mirror voltage-controlled resistor and the output terminal of the reference voltage source; the output terminal of the operational amplifier is respectively connected to the control terminal of the mirror voltage-controlled resistor and the control terminal of the voltage-controlled resistor.

[0012] Optionally, the reference voltage source is a reference voltage provided by a bandgap reference source, or the voltage obtained by dividing the reference voltage with resistors.

[0013] Optionally, the mirror voltage-controlled resistor and the voltage-controlled resistor are devices of the same size, or the mirror voltage-controlled resistor and the voltage-controlled resistor are devices with sizes in a first preset ratio; the mirror transmitter driver and the transmitter driver are devices of the same size, or the mirror transmitter driver and the transmitter driver are devices with sizes in a second preset ratio.

[0014] Optionally, the transmitter driver and the mirror transmitter driver are: a voltage-mode transmitter driver composed of complementary P / N transistors, or a current-mode transmitter driver composed of a tail current source and a differential pair.

[0015] Secondly, this application also provides a high-speed serial port transmitter system based on mirror control, which is provided with a voltage-controlled resistor adjustable termination resistor circuit based on mirror control as described in the first aspect above.

[0016] This application provides a voltage-controlled resistor (VCR) adjustable termination resistor circuit and system based on mirror control, comprising: a working path, a mirror path, and a control loop; the mirror path and the working path operate in the same environment; the control loop applies control voltages to the VCR in the working path and the mirror VCR in the mirror path to control the resistance values ​​of the VCR and the mirror VCR; the control loop compares the critical node voltage at the output of the mirror VCR with the reference voltage of a reference voltage source, and outputs a control voltage based on the real-time voltage deviation; wherein, the control voltage output by the control loop is used to simultaneously adjust the resistance values ​​of the VCR and the mirror VCR to form a negative feedback that makes the critical node voltage approach the reference voltage; the same working environment includes: the difference in working environment parameters being within a preset error range. Thus, by using a mirror backup termination resistor to detect the impedance of the termination resistor in real time, and adjusting the termination resistor value in real time when the chip voltage and temperature change, the requirements of the high-speed serial interface for the termination resistor are met. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the architecture of the voltage-controlled resistor adjustable termination resistor circuit based on mirror control provided in this application. Figure 2 This is a schematic diagram of the architecture of the voltage-controlled resistor provided in this application; Figure 3 This is a schematic diagram of the control loop architecture provided in this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. All actions involving the acquisition of signal information or data in this application are performed in accordance with the relevant data protection laws and policies of the country where the application is located and with authorization from the owner of the relevant device.

[0021] The high-speed serial interface transmitter termination resistor technology in related technologies mainly faces three technical bottlenecks: First, at the physical implementation level, the impedance deviation caused by parasitic packaging parameters may exceed 15% in the high-frequency band (>50GHz), severely restricting the signal quality at the Nyquist frequency. Second, the resistance value dispersion caused by process fluctuations increases significantly at process nodes below 28nm, and the conventional ±10% tolerance range can no longer meet the BER<1E-15 requirement for SerDes above 56Gbps. Furthermore, the temperature coefficient (TCR) problem is further aggravated in 3D packaging systems. When the junction temperature rises from 25℃ to 125℃, the resistance value of a typical thin-film resistor can drift by 3-5%, directly causing the horizontal opening of the eye diagram to decrease by more than 30%.

[0022] Current industry solutions mainly fall into two technical routes: one is to use segmented adjustable resistor arrays. While this method achieves ±1% adjustment accuracy, it introduces additional switching on-resistance (typically 200mΩ) and parasitic capacitance (approximately 15fF); the other is active impedance regulation technology based on FinFET process (such as Intel's US10784898B2 announced in 2020), which uses transistor gate voltage to modulate channel resistance, but suffers from increased power consumption and poor linearity. It is particularly noteworthy that in 112Gbps PAM4 systems, neither of these solutions can simultaneously meet the dual requirements of return loss (RL) <-15dB (0-53GHz) and insertion loss (IL) <1.5dB / mm.

[0023] Evolving market demands have driven technological innovation: the QSFP-DD800 standard for data center optical modules requires single-channel power consumption of less than 5pJ / bit, while the AEC-Q100 Grade 1 certification for automotive SerDes requires impedance stability within an operating temperature range of -40℃ to 150℃. These stringent requirements pose a risk of obsolescence for traditional termination solutions in new application scenarios. This application proposes an innovative adjustable termination resistor circuit based on a mirror-controlled voltage-controlled resistor to address the current challenges faced by high-speed SerDes termination resistors.

[0024] The adjustable termination resistor circuit based on mirror control provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0025] like Figure 1 As shown in the figure, an adjustable termination resistor circuit based on mirror control provided in this application includes: The system includes a working path, a mirror path, and a control loop; the mirror path operates in the same environment as the working path; the control loop applies control voltages to the voltage-controlled resistor in the working path and the mirror voltage-controlled resistor in the mirror path, respectively, to control the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor.

[0026] For example, the control loop is used to compare the critical node voltage at the output terminal of the mirror voltage-controlled resistor with the reference voltage of the reference voltage source, and output a control voltage based on the real-time voltage deviation.

[0027] The control voltage output by the control loop is used to simultaneously adjust the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor to form negative feedback that makes the critical node voltage approach the reference voltage. The identical operating environment includes the difference in operating environment parameters being within a preset error range. By pre-setting the reference voltage of the reference voltage source, when the negative feedback is stable, the critical node voltage of the mirror path is equal to the reference voltage.

[0028] Understandably, after the system powers on, the mirror voltage-controlled resistor and the mirror transmitter driver are controlled to simulate the operating environment of the actual transmitter. By connecting the mirror receiver termination resistor, the mirror path completely simulates the actual transmitter-to-receiver operating path. The control loop simultaneously controls the mirror voltage-controlled resistor and the voltage-controlled resistor, measuring the voltage at key nodes and comparing it to a reference voltage source to ensure the key node voltage in the mirror path matches the reference voltage. Since the key node voltage is directly affected by the transmitter termination resistor value, maintaining a certain key node voltage value controls the transmitter termination resistor value. By pre-designing the reference voltage source voltage, the transmitter termination resistor value can be controlled to the desired value.

[0029] For example, such as Figure 1 As shown, the working path and the mirror path are arranged adjacent to each other in the layout and use the same process, device type and layout structure, so that the difference between the working environment parameters (including temperature, voltage, process angle, etc.) of the two are within the preset error range (for example, the temperature difference is less than 1℃ and the power supply voltage difference is less than 5mV).

[0030] Specifically, the working path includes a transmitter driver and a voltage-controlled resistor; the mirror path includes a mirror transmitter driver and a mirror voltage-controlled resistor; the input terminal of the voltage-controlled resistor is connected to the output terminal of the transmitter driver; the input terminal of the mirror voltage-controlled resistor is connected to the output terminal of the mirror transmitter driver to simulate the working environment of the voltage-controlled resistor.

[0031] Understandably, during operation, the control loop continuously compares the critical node voltage with the reference voltage. When a real-time voltage deviation exists between the two, the control loop generates a control voltage based on this deviation. This control voltage is simultaneously applied to the control terminals of both the voltage-controlled resistor and its mirror resistor, thereby adjusting the resistance values ​​of both resistors concurrently. The adjustment direction brings the critical node voltage closer to the reference voltage, forming a negative feedback closed-loop control.

[0032] Furthermore, since the mirror path and the working path operate in the same environment, and the mirror voltage-controlled resistor is subjected to the same control voltage as the voltage-controlled resistor, the resistance value of the mirror voltage-controlled resistor remains consistent with that of the voltage-controlled resistor. Through negative feedback, when the system is stable, the voltage at the critical node in the mirror path is locked at the reference voltage, thereby indirectly controlling the resistance value of the voltage-controlled resistor in the working path to the desired value.

[0033] For example, the negative feedback in the embodiments of this application includes: 1. When the resistance increases: the critical node voltage will deviate from the reference value. The control loop detects the difference and adjusts the control voltage to reduce the resistance of the voltage-controlled resistor, thus restoring the critical node voltage.

[0034] 2. When the resistance decreases: the critical node voltage deviates in the reverse direction. The control loop detects the difference and adjusts the control voltage to increase the voltage-controlled resistor resistance value, causing the critical node voltage to return to normal.

[0035] Regarding the real-time performance of the technical solution in this application, it includes: 1. No clock wait: Analog circuits operate continuously without a sampling clock cycle. Even a small change in the voltage at a critical node (such as a change in the voltage-controlled resistor due to temperature drift) will immediately reflect the change in voltage by altering the charge on the gate capacitor at the operational amplifier's input.

[0036] 2. No Quantization Delay: Traditional digital measurements require a series of steps such as sampling, holding, and quantization encoding, which introduce delay. However, this method uses an operational amplifier for direct comparison, and the delay is merely the propagation delay of the electrical signal within the wires and transistors (in the picosecond range). For tracking changes in temperature and voltage, this is equivalent to instantaneous measurement.

[0037] For example, such as Figure 2 The diagram shown is a schematic of the architecture of a voltage-controlled resistor provided in an embodiment of this application. The voltage-controlled resistor includes an input terminal, an output terminal, and a control terminal. When different control voltages are applied to the control terminal, the voltage-controlled resistor can generate corresponding resistance values. That is, by changing the control voltage, the resistance value of the voltage-controlled resistor can be changed.

[0038] Specifically, the transmitter driver and the mirror transmitter driver are: a voltage-mode transmitter driver composed of complementary P / N transistors, or a current-mode transmitter driver composed of a tail current source and a differential pair.

[0039] Specifically, the output terminal of the mirror voltage-controlled resistor is connected to the mirror receiver termination resistor, and together with the mirror transmitter driver and the mirror receiver termination resistor, it forms a mirror path for analog working path signal transmission.

[0040] In one possible implementation, the mirror voltage-controlled resistor is a device of the same size as the voltage-controlled resistor; the mirror transmitter driver is a device of the same size as the transmitter driver.

[0041] In another possible implementation, the mirror voltage-controlled resistor and the voltage-controlled resistor are devices with dimensions in a first preset ratio; the mirror transmitter driver and the transmitter driver are devices with dimensions in a second preset ratio.

[0042] Specifically, the voltage-controlled resistor and the mirror voltage-controlled resistor are MOS transistors, with the source and drain serving as the input and output terminals of the resistor, respectively, and the gate serving as the control terminal, adjusting the on-resistance by changing the gate voltage.

[0043] like Figure 1 As shown, the operating path includes a transmitter driver and a voltage-controlled resistor (VCR). The input of the VCR is connected to the output of the transmitter driver, and the output of the VCR is grounded or connected to a power supply (depending on the driver type). In operation, the VCR acts as a termination resistor between the transmitter output and the transmission line. The mirror path includes a mirror transmitter driver and a mirror VCR. The mirror transmitter driver has the same circuit structure as the transmitter driver, and the mirror VCR has the same circuit structure and device dimensions as the VCR. The input of the mirror VCR is connected to the output of the mirror transmitter driver.

[0044] Specifically, the reference voltage source is a reference voltage provided by a bandgap reference source, or a voltage obtained by dividing the reference voltage with resistors.

[0045] For example, in this embodiment of the application, by adding a mirror receiver termination resistor, the mirror path fully simulates the load conditions of the actual signal transmission link: the output signal of the mirror transmitter driver is absorbed by the mirror receiver termination resistor after passing through the mirror voltage-controlled resistor. This makes the voltage at the critical node not only affected by the resistance value of the mirror voltage-controlled resistor, but also by the voltage division effect of the mirror receiver termination resistor, thus more accurately reflecting the voltage state at the transmitter output terminal in the actual working path. In the working path, the output terminal of the transmitter driver is connected to the external transmission line and the receiver termination resistor. Therefore, the voltage at the critical node in the mirror path corresponds to the voltage at the transmitter output terminal in the actual working path, improving control accuracy.

[0046] It should be noted that the reference voltage source in this embodiment can be a voltage less affected by PVT fluctuations provided by a bandgap reference source, or a voltage obtained by resistive voltage division. The reference voltage source can also be an off-chip reference voltage or a voltage obtained by resistive voltage division. Furthermore, the reference voltage source can be other on-chip voltages or voltages obtained by resistive voltage division.

[0047] For example, compared to traditional termination resistors, the termination resistors in this embodiment reduce area and parasitic capacitance, while enabling more precise and real-time control of the termination resistor value to meet the requirements of high-speed SerDes for termination resistors. The voltage-controlled resistor in this embodiment can use P-type or N-type transistors, adjusting the transistor's on-resistance by controlling the gate voltage. The voltage-controlled resistor in this embodiment can also use other devices whose on-resistance is voltage-controlled. The transmitter driver in this embodiment can be a voltage-mode transmitter composed of complementary P / N-type transistors. The transmitter driver in this embodiment can also be a current-mode transmitter composed of a tail current source and a differential pair. The transmitter driver in this embodiment can also be other related transmitter structures used for driving.

[0048] For example, the mirror voltage-controlled resistor in this embodiment can be a device of the same size as the voltage-controlled resistor in the working path, while its voltage, temperature, and layout environment should be as similar as possible to the voltage-controlled resistor. Alternatively, the mirror voltage-controlled resistor in this embodiment can be a device with a different size ratio than the voltage-controlled resistor in the working path, while its voltage, temperature, and layout environment should be as similar as possible to the voltage-controlled resistor. Similarly, the mirror transmitter driver in this embodiment can be a device of the same size as the transmitter driver in the working path, while its voltage, temperature, and layout environment should be as similar as possible to the transmitter driver. Alternatively, the mirror transmitter driver in this embodiment can be a device with a different size ratio than the mirror transmitter driver in the working path, while its voltage, temperature, and layout environment should be as similar as possible to the transmitter driver. The mirror receiver termination resistor in this embodiment can be a resistor with a fixed resistance value. Alternatively, the mirror receiver termination resistor in this embodiment can be a resistor with an adjustable resistance value. Alternatively, the mirror receiver termination resistor in this embodiment can also be other types of resistors.

[0049] For example, such as Figure 3 As shown, the control loop in this embodiment can be constructed using an operational amplifier. By comparing the difference between the critical node voltage in the mirror path and the reference voltage, a voltage value is output to control the voltage-controlled resistor and the mirror voltage-controlled resistor. By controlling the polarity, a negative feedback path is formed, which can control the resistance values ​​of the mirror voltage-controlled resistor and the voltage-controlled resistor, thereby making the critical node voltage in the mirror path the same as the reference voltage. Since the mirror path and the working path are related, the voltage-controlled resistor voltage in the working path is also controlled by the control loop. If the voltage-controlled resistor experiences resistance fluctuations due to temperature or voltage fluctuations, the mirror voltage-controlled resistor will also experience the same fluctuations because it completely mirrors the environment of the voltage-controlled resistor. In this case, the control loop can stabilize it back to the desired resistance value.

[0050] The voltage-controlled adjustable termination resistor circuit based on mirror control in this embodiment can be widely used in high-speed serial interface transmitters, and is particularly suitable for fields with high requirements for signal integrity and impedance matching accuracy, such as optical modules with speeds of 56Gbps and above, SerDes, data center interconnects, and vehicle communications. Through real-time negative feedback control, this invention significantly improves the accuracy and stability of the termination resistor, reduces parasitic capacitance, effectively improves signal quality, reduces bit error rate, and meets the stringent requirements of high-speed communication systems.

[0051] The voltage-controlled resistor adjustable termination resistor circuit based on mirror control provided in this application has the following advantages over termination resistor technology in related technologies: it has small parasitic capacitance, has little impact on transmitter bandwidth, can achieve finer step sizes, the parasitic capacitance of the transmitter node is less affected by changes in the termination resistor value, can track temperature and voltage changes in real time, and is easier to integrate using a transistor structure, making it more suitable for advanced processes such as FinFET. These advantages are described below.

[0052] Small parasitic capacitance and minimal impact on transmitter bandwidth: Compared to traditional adjustable termination resistors that adjust the number of parallel resistors by switching transistors, this invention does not use transistors coupled to the high-speed output node as switches. Therefore, its parasitic capacitance is smaller than that of traditional adjustable termination resistors, resulting in a higher transmitter bandwidth and less impact from termination resistors.

[0053] Finer step size: Traditional adjustable termination resistors adjust the number of parallel resistors by switching transistors. If the step size is too small, more transistors are needed, resulting in larger parasitic capacitance coupled to the high-speed output node. Simultaneously, a smaller step size leads to a larger area for the traditional adjustable termination resistor, making it less suitable for placement near the transmitter. The voltage-controlled resistor (VCR) based on mirror control in this invention controls the resistance value by adjusting the voltage across the VCR. Reducing the adjustment step size only requires generating a finer control voltage, without the limitations of traditional adjustable termination resistors. Therefore, this invention allows for a much finer adjustment step size.

[0054] The parasitic capacitance of the transmitter node is less affected by the termination resistor value: Traditional adjustable termination resistors, which adjust the number of parallel resistors by switching transistors, affect the parasitic capacitance coupled to the high-speed output node when the transistors are on and off. This impacts the output node's bandwidth and introduces more complex variations into the system. In contrast, the termination resistor value in this invention is adjusted by a control voltage, resulting in a much smaller change in parasitic capacitance compared to traditional adjustable termination resistors. Therefore, the parasitic capacitance of the transmitter node in this invention is less affected by changes in the termination resistor value.

[0055] Real-time tracking of temperature and voltage changes: Traditional adjustable termination resistors lack a control loop, so their suitability can only be inferred from the bit error rate on the RX side or the quality changes of the eye diagram in the oscilloscope. This invention, by employing a control loop and mirror path, can track changes in the termination resistor caused by environmental variations in real time, resulting in faster control.

[0056] The transistor structure facilitates integration and is better suited for advanced processes such as FinFET: In advanced processes like FinFET, traditional thin-film resistors or poly resistors are often difficult to miniaturize. This makes it even more difficult to integrate adjustable termination resistors, which traditionally adjust the number of parallel resistors by switching transistors, into transmitter drivers. This invention, however, uses transistors as voltage-controlled resistors, which are better suited to the FinFET design language and easier to integrate into FinFET layouts.

[0057] The voltage-controlled resistor adjustable termination resistor circuit based on mirror control provided in this application embodiment includes: a working path, a mirror path, and a control loop; the mirror path and the working path are in the same working environment; the control loop applies control voltages to the voltage-controlled resistor in the working path and the mirror voltage-controlled resistor in the mirror path respectively to control the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor; the control loop is used to compare the critical node voltage at the output terminal of the mirror voltage-controlled resistor with the reference voltage of the reference voltage source, and outputs a control voltage according to the real-time voltage deviation; wherein, the control voltage output by the control loop is used to simultaneously adjust the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor to form a negative feedback that makes the critical node voltage approach the reference voltage; the same working environment includes: the difference in working environment parameters is within a preset error range. Thus, by using the mirror backup termination resistor to detect the impedance of the termination resistor in real time, and adjusting the resistance value of the termination resistor in real time when the chip voltage and temperature change, the requirements of the high-speed serial interface for the termination resistor are met.

[0058] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A voltage-controlled resistor adjustable termination resistor circuit based on mirror control, characterized in that, include: The system includes a working path, a mirror path, and a control loop; the mirror path operates in the same environment as the working path. The control loop applies control voltages to the voltage-controlled resistor in the working path and the mirror voltage-controlled resistor in the mirror path, respectively, to control the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor; The control loop is used to compare the critical node voltage at the output terminal of the mirror voltage-controlled resistor with the reference voltage of the reference voltage source, and output a control voltage based on the real-time voltage deviation. The control voltage output by the control loop is used to simultaneously adjust the resistance values ​​of the voltage-controlled resistor and the mirror voltage-controlled resistor to form a negative feedback that makes the voltage at the critical node approach the reference voltage; the same working environment includes: the difference in working environment parameters is within a preset error range.

2. The circuit according to claim 1, characterized in that, Also includes: By pre-setting the reference voltage of the reference voltage source, the critical node voltage of the mirror path is equal to the reference voltage when the negative feedback is stable.

3. The circuit according to claim 1, characterized in that, The working path includes a transmitter driver and a voltage-controlled resistor; the mirror path includes a mirror transmitter driver and a mirror voltage-controlled resistor; the input terminal of the voltage-controlled resistor is connected to the output terminal of the transmitter driver; the input terminal of the mirror voltage-controlled resistor is connected to the output terminal of the mirror transmitter driver, for simulating the working environment of the voltage-controlled resistor.

4. The circuit according to claim 3, characterized in that, The output terminal of the mirror voltage-controlled resistor is connected to the mirror receiver termination resistor, and together with the mirror transmitter driver and the mirror receiver termination resistor, it forms a mirror path for analog working path signal transmission.

5. The circuit according to claim 3 or 4, characterized in that, The voltage-controlled resistor and the mirror voltage-controlled resistor are MOS transistors, with the source and drain serving as the input and output terminals of the resistor, respectively, and the gate serving as the control terminal. The on-resistance is adjusted by changing the gate voltage.

6. The circuit according to claim 5, characterized in that, The control loop It includes: an operational amplifier; the two input terminals of the operational amplifier are respectively connected to the output terminal of the mirror voltage-controlled resistor and the output terminal of the reference voltage source; the output terminal of the operational amplifier is respectively connected to the control terminal of the mirror voltage-controlled resistor and the control terminal of the voltage-controlled resistor.

7. The circuit according to claim 1, characterized in that, The reference voltage source is a reference voltage provided by a bandgap reference source, or a voltage obtained by dividing the reference voltage with resistors.

8. The circuit according to claim 1, characterized in that, The mirror voltage-controlled resistor and the voltage-controlled resistor are devices of the same size, or the mirror voltage-controlled resistor and the voltage-controlled resistor are devices with sizes in a first preset ratio; The mirror transmitter driver and the transmitter driver are devices of the same size, or the mirror transmitter driver and the transmitter driver are devices of a second preset size ratio.

9. The circuit according to claim 1, characterized in that, The transmitter driver and the mirror transmitter driver are: a voltage-mode transmitter driver composed of complementary P / N transistors, or a current-mode transmitter driver composed of a tail current source and a differential pair.

10. A high-speed serial port transmitter system, characterized in that, It is provided with a voltage-controlled resistor adjustable termination resistor circuit based on mirror control as described in any one of claims 1 to 9.

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