A multi-dimensional signal eye diagram compensation circuit

Abstract

The present invention provides a multi-dimensional signal eye diagram compensation circuit, wherein the rising edge adjustment path and the falling edge adjustment path are respectively provided with detection circuits for extracting a rising edge / falling edge pulse signal of a certain width from the input signal; the rising edge / falling edge pulse signal of a certain width is passed through a MUX selector to generate a rising edge / falling edge pre-emphasis compensation signal or a rising edge / falling edge de-emphasis compensation signal; the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is weighted with the input signal on the high-speed main signal path to adjust the amplitude of the rising edge and falling edge of the input signal at the corresponding rising edge / falling edge pulse signal. The above-mentioned multi-dimensional signal eye diagram compensation circuit can adjust the phase, amplitude and pre-emphasis direction of the rising edge and falling edge of the eye diagram respectively, presenting four-dimensional eye diagram compensation, and improving the opening degree and symmetry of the eye diagram.

Description

Technical Field

[0001] The present invention relates to integrated circuits, and in particular to the adjustment of phase and amplitude of digital signals. Background Art

[0002] Improving signal quality has always been an important topic in the field of communication engineering and high-speed signal circuit design. Signal quality is generally judged by measuring the quality of the eye diagram, including the time of the rising and falling edges of the eye diagram, jitter, margin, DCD and other indicators, which can be summarized as the two major indicators of the eye diagram's opening and symmetry.

[0003] After the signal passes through the transmission medium, the quality of the signal and the eye diagram will be reduced, affecting the signal judgment and increasing the bit error rate. The explanation in the frequency domain is: the signal transmission medium exhibits low-pass filtering characteristics, and the high-frequency components of the signal are greatly attenuated during the transmission process. The high-frequency components of the signal are mainly reflected in the slew rate of the rising and falling edges of the signal. The rising and falling edges become slower, and the eye diagram opening is poor; and because the attenuation degree of the rising and falling edges is different, the symmetry of the eye diagram is poor. When the transmission signal rate is faster, the degree of eye diagram degradation is more obvious.

[0004] The degradation of eye diagram quality is mainly caused by the following physical reasons in practical applications: discontinuity of gain and parasitics of integrated circuit devices when large signals occur, package parasitics, routing attenuation of PCB and flexible boards, dispersion of optical fiber transmission, reflection caused by impedance mismatch, and especially discontinuity caused by parasitic effects of lasers, which will lead to degradation of signal quality at the receiving end input, and due to different degrees of degradation, signal eye diagram asymmetry will be caused. Therefore, high-speed signal transmission generally requires corresponding compensation technology.

[0005] Pre-emphasis technology is a common compensation circuit for high-speed signal transmission. The idea is to pre-enhance the high-frequency components of the signal at the transmitting end of the transmission line to compensate for the attenuation of the high-frequency components during transmission and enhance the slew rate at the rising and falling edges of the signal, thereby increasing the opening of the signal eye diagram.

[0006] Chinese patent CN102624374A adopts a typical pre-emphasis circuit, which delays, inverts, multiplies the original signal by a specific coefficient, and then adds it to the original signal, thereby increasing the amplitude of the signal conversion level. However, the technology proposed cannot adjust the phase, amplitude, and direction of pre-emphasis of the rising and falling edges of the eye diagram respectively. The adjustment strength of the four dimensions is consistent, and the adjustment means are monotonous.

[0007] US Patent US2018 / 0062343A1 has made corresponding improvements based on the typical pre-emphasis circuit. Two different delay signals are used to represent the delay of the rising edge and the falling edge. The signals obtained by the two signals are inverted, multiplied by a specific coefficient, and then superimposed on the original signal, thereby realizing the typical pre-emphasis function. At the same time, the phase of the rising edge and the falling edge of the eye diagram can be adjusted separately, improving the symmetry of the eye diagram and further improving the signal quality. Although the above technology can adjust the phase of the rising edge and the falling edge of the eye diagram separately, it cannot adjust the amplitude of the rising edge and the falling edge of the eye diagram and the direction of pre-emphasis separately; and the superposition of the delay signal of this technology is more complicated in circuit implementation.

[0008] In summary, the existing technologies are not sufficient and flexible enough in compensating the signal eye diagram, and each has defects such as complex circuit design or excessive power consumption. In actual applications, additional compensation technology may be required, and the compatibility with lasers or loads is insufficient, which also puts pressure on the overall power consumption index. Summary of the invention

[0009] The present invention provides a multi-dimensional signal eye diagram compensation circuit, aiming to solve the problem of insufficient opening and symmetry of the eye diagram caused by signal attenuation in the prior art.

[0010] In order to solve the above technical problems, the present invention provides a multi-dimensional signal eye diagram compensation circuit, which is characterized by comprising: a rising edge adjustment path, a falling edge adjustment path, and a high-speed main signal path;

[0011] The rising edge adjustment path and the falling edge adjustment path are respectively provided with a detection circuit for extracting a rising edge / falling edge pulse signal of a certain width from the input signal; the rising edge / falling edge pulse signal of a certain width is directly output or inverted and then output to generate a rising edge / falling edge pre-emphasis compensation signal or a rising edge / falling edge de-emphasis compensation signal;

[0012] The rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is weighted with the input signal on the high-speed main signal path to adjust the amplitude of the rising edge and falling edge of the input signal at the corresponding rising edge / falling edge pulse signal.

[0013] In a preferred embodiment: the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is first added to obtain an edge pulse addition signal; and the edge pulse addition signal is then weighted with the input signal.

[0014] In a preferred embodiment: the weighting includes: multiplying the edge pulse addition signal by a certain compensation amplitude ΔA, and multiplying the input signal by a certain amplitude A, and then adding the two.

[0015] In a preferred embodiment: the rising edge adjustment path and the falling edge adjustment path are respectively provided with an enabling switch.

[0016] In a preferred embodiment: the rising edge adjustment path includes a rising edge detection circuit and a MUX selector; the falling edge adjustment path includes a falling edge detection circuit and a MUX selector.

[0017] In a preferred embodiment: the rising edge detection circuit and the falling edge detection circuit respectively include a delay module, a NOT gate and an AND gate;

[0018] The input signal is connected to the input end of the delay module through the enable switch; the output end of the delay module of the rising edge detection circuit is connected to the first input end of the first AND gate through the first NOT gate, the second input end of the first AND gate is connected to the input signal, the output end of the first AND gate is connected to the first input end of the first MUX selector through the second NOT gate, and the output end of the first AND gate is also directly connected to the second input end of the first MUX selector;

[0019] The output end of the delay module of the falling edge detection circuit is connected to the first input end of the second AND gate, the input signal is connected to the second input end of the second AND gate through the third NOT gate, the output end of the second AND gate is connected to the first input end of the second MUX selector through the fourth NOT gate, and the output end of the second AND gate is also directly connected to the second input end of the second MUX selector.

[0020] In a preferred embodiment: it also includes a first high-speed signal amplifier, and the input signal is input into the rising edge adjustment path and the falling edge adjustment path after passing through the first high-speed amplifier.

[0021] In a preferred embodiment: the high-speed main signal path also includes a second high-speed signal amplifier and a third high-speed signal amplifier. After the input signal passes through the second high-speed signal amplifier and the third high-speed signal amplifier in sequence, it is weighted with the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] 1. The present invention provides a multi-dimensional signal eye diagram compensation circuit, which realizes a four-dimensional (position of the rising edge and falling edge of the signal eye diagram, along the phase, along the amplitude and pre-emphasis direction) signal eye diagram compensation means. The compensation means is flexible and sufficient. While maximizing the eye diagram opening, it maximizes the symmetry of the eye diagram and fully improves the quality of the signal eye diagram.

[0024] 2. The present invention provides a multi-dimensional signal eye diagram compensation circuit, which has low power consumption itself, and because the compensation is sufficient, there is basically no need to use other eye diagram compensation technologies, which can reduce the overall power consumption of the chip or module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A circuit diagram of a multi-dimensional signal eye diagram compensation circuit in a preferred embodiment of the present invention;

[0026] Figure 2 It is a timing diagram of performing pre-emphasis compensation on the rising edge and falling edge of a signal in a preferred embodiment of the present invention;

[0027] Figure 3 This is a timing diagram of performing de-emphasis compensation on the rising edge of a signal and performing pre-emphasis compensation on the falling edge in a preferred embodiment of the present invention;

[0028] Figure 4 This is a timing diagram of performing pre-emphasis compensation only on the rising edge of the signal in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0030] refer to Figure 1 , the present invention provides a multi-dimensional signal eye diagram compensation circuit, including: a rising edge adjustment path, a falling edge adjustment path, and a high-speed main signal path;

[0031] The rising edge adjustment path and the falling edge adjustment path are respectively provided with detection circuits for extracting a rising edge / falling edge pulse signal of a certain width from the input signal; in this embodiment, the pulse width of the extracted rising edge pulse signal is ΔT1, and the pulse width of the falling edge pulse signal is ΔT2; wherein ΔT1 and ΔT2 are both less than 1UI (1 symbol period). Since the rising edge adjustment path and the falling edge adjustment path are respectively provided with detection circuits, the pulse widths of the extracted rising edge pulse signal and falling edge pulse signal can be adjusted respectively.

[0032] The rising edge / falling edge pulse signal of a certain width is selected for the direction of pre-emphasis through the control signals EMPHASIS_DIR_RISE and EMPHASIS_DIR_FALL of the MUX selector. If it is directly output without being inverted, a rising edge / falling edge pre-emphasis compensation signal is generated; if it is output after being inverted, a rising edge / falling edge de-emphasis compensation signal is generated; since the rising edge adjustment path and the falling edge adjustment path each have a MUX selector, the pre-emphasis compensation signal can be generated separately for the rising edge and the de-emphasis compensation signal can be generated for the falling edge, or vice versa, the pre-emphasis compensation signal can be generated for both the rising edge and the falling edge, or the de-emphasis compensation signal can be generated for both the rising edge and the falling edge.

[0033] The rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is weighted with the input signal on the high-speed main signal path to adjust the amplitude of the rising edge and falling edge of the input signal at the corresponding rising edge / falling edge pulse signal.

[0034] In this embodiment, the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is first added to obtain an edge pulse addition signal; and the edge pulse addition signal is then weighted with the input signal.

[0035] The weighting includes: multiplying the edge pulse addition signal by a certain compensation amplitude ΔA, multiplying the input signal by a certain amplitude A, and then adding the two.

[0036] In order to achieve the above circuit effect, in this embodiment, a multi-dimensional signal eye diagram compensation circuit specifically adopts the following circuit structure:

[0037] The rising edge adjustment path and the falling edge adjustment path are respectively provided with an enabling switch. By enabling the switch, it is possible to adjust the rising edge and the falling edge at the same time or only adjust one of the rising edge and the falling edge.

[0038] The rising edge adjustment path includes a rising edge detection circuit and the MUX selector; the falling edge adjustment path includes a falling edge detection circuit and the MUX selector.

[0039] The input signal is connected to the input end of the delay module through the enable switch; the output end of the delay module of the rising edge detection circuit is connected to the first input end of the first AND gate through the first NOT gate, the second input end of the first AND gate is connected to the input signal, the output end of the first AND gate is connected to the first input end of the first MUX selector through the second NOT gate, and the output end of the first AND gate is also directly connected to the second input end of the first MUX selector;

[0040] The output end of the delay module of the falling edge detection circuit is connected to the first input end of the second AND gate, the input signal is connected to the second input end of the second AND gate through the third NOT gate, the output end of the second AND gate is connected to the first input end of the second MUX selector through the fourth NOT gate, and the output end of the second AND gate is also directly connected to the second input end of the second MUX selector.

[0041] The circuit of this embodiment further includes a first high-speed signal amplifier, and the input signal is input into the rising edge adjustment path and the falling edge adjustment path after passing through the first high-speed amplifier.

[0042] The high-speed main signal path also includes a second high-speed signal amplifier and a third high-speed signal amplifier. After the input signal passes through the second high-speed signal amplifier and the third high-speed signal amplifier in sequence, it is added to the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal.

[0043] Further references Figure 2-Figure 4 , the eye diagram compensation effect of the present invention is described in three cases below.

[0044] 1)Reference Figure 2 , which is a timing diagram for performing pre-emphasis compensation on both the rising edge and the falling edge of the signal;

[0045] In this mode, the enable switches of the rising edge adjustment path and the falling edge adjustment path are closed respectively, the first MUX selector of the rising edge is in direct output mode, and the second MUX selector of the falling edge is in inverted output mode;

[0046] It can be seen that the rising edge pre-emphasis compensation signal and the falling edge pre-emphasis compensation signal are respectively Figure 2 The RISING EDGE PULES and FALLING EDGE PULSE in the equation are added together to get Figure 2 The edge pulse addition signal EDGEPLUS PULSE in the input signal INPUT is weighted, and the compensation amplitude ΔA is added to the amplitude of the rising edge and falling edge of the edge pulse addition signal EDGE PLUS PULSE corresponding to the rising edge and falling edge of the input signal INPUT to obtain the output signal OUTPUT.

[0047] 2)Reference Figure 3 , which is a timing diagram for performing de-emphasis compensation on the rising edge of the signal and pre-emphasis compensation on the falling edge;

[0048] In this mode, the enable switches of the rising edge adjustment path and the falling edge adjustment path are closed respectively, and the first MUX selector of the rising edge is in the inverted output mode, and the second MUX selector of the falling edge is in the inverted output mode.

[0049] It can be seen that the rising edge de-emphasis compensation signal and the falling edge pre-emphasis compensation signal are respectively Figure 3 The RISING EDGE PULES and FALLING EDGE PULSE in the equation are added together to get Figure 3 The edge pulse addition signal EDGEPLUS PULSE in the output signal is weighted with the input signal INPUT, and the amplitude of the rising edge position of the edge pulse addition signal EDGE PLUS PULSE corresponding to the rising edge of the input signal INPUT is reduced by the compensation amplitude ΔA, and the amplitude of the falling edge position of the edge pulse addition signal EDGE PLUS PULSE corresponding to the falling edge of the input signal INPUT is increased by the compensation amplitude ΔA to obtain the output signal OUTPUT.

[0050] 3)Reference Figure 4 , which is a timing diagram that only performs pre-emphasis compensation on the rising edge of the signal.

[0051] In this mode, the enable switch of the rising edge adjustment path is closed, and the enable switch of the falling edge adjustment path is opened; and the MUX selector of the rising edge is in direct output mode.

[0052] It can be seen that the rising edge pre-emphasis compensation signal is Figure 4 After RISING EDGE PULES is weighted with the input signal INPUT, the compensation amplitude ΔA is increased at the amplitude of the position of the rising edge of the pulse addition signal EDGEPLUS PULSE corresponding to the rising edge of the input signal INPUT to obtain the output signal OUTPUT.

[0053] The circuit intrinsic delays of the main signal path and the compensation path of the present invention are equal, that is, the circuit intrinsic delay from INPUT to INPUT' is equal to the circuit intrinsic delay from INPUT to EDGE_PLUS_PULSE, so that the extracted rising edge and falling edge pulses are phase-aligned with the rising edge and falling edge of the signal, respectively, to achieve the effect of correct compensation. If the delay deviation exceeds a certain range, the compensation effect will be poor.

[0054] Figure 2 , 3 4 are just examples of three application scenarios involved in the present invention, but the circuit application scenarios protected by the present invention include but are not limited to these three application scenarios. In addition, the above example uses voltage signals, and current signals can also be used for calculation. If the current signal, the rising edge and falling edge it refers to are opposite to the voltage signal in the figure.

[0055] In addition, the load driven by the output OUTPUT signal shown in the present invention is not necessarily a DML type laser (such as a DFB / FB / VCSEL laser), but can also be an EAM modulator, a resistor or other load.

[0056] The multi-dimensional signal eye diagram compensation circuit shown can be used not only at the signal transmitting end but also at the signal receiving end.

[0057] The above is only a preferred embodiment of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the content of the specification should still fall within the scope of the present invention.

Claims

1. A multi-dimensional signal eye diagram compensation circuit, characterized in that include: Rising edge adjustment path, falling edge adjustment path, high-speed main signal path; The rising edge adjustment path and the falling edge adjustment path are respectively provided with a detection circuit for extracting a rising edge / falling edge pulse signal of a certain width from the input signal; the rising edge / falling edge pulse signal of a certain width is directly output or inverted and then output to generate a rising edge / falling edge pre-emphasis compensation signal or a rising edge / falling edge de-emphasis compensation signal; The rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is weighted with the input signal on the high-speed main signal path to adjust the amplitude of the rising edge and the falling edge of the input signal at the corresponding rising edge / falling edge pulse signal; The rising edge adjustment path and the falling edge adjustment path are respectively provided with an enabling switch; they also include a first high-speed signal amplifier, and the input signal is input into the rising edge adjustment path and the falling edge adjustment path after passing through the first high-speed amplifier; the high-speed main signal path also includes a second high-speed signal amplifier and a third high-speed signal amplifier, and the input signal is weighted with the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal after passing through the second high-speed signal amplifier and the third high-speed signal amplifier in sequence.

2. The multi-dimensional signal eye diagram compensation circuit according to claim 1, characterized in that: The rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal is first added to obtain an edge pulse addition signal; the edge pulse addition signal is then weighted with the input signal.

3. The multi-dimensional signal eye diagram compensation circuit according to claim 2, characterized in that: The weighting includes: multiplying the edge pulse addition signal by a certain compensation amplitude ΔA, and multiplying the input signal by a certain amplitude A, and then adding the two.

4. The multi-dimensional signal eye diagram compensation circuit according to claim 3, characterized in that: The rising edge adjustment path includes a rising edge detection circuit and a MUX selector; the falling edge adjustment path includes a falling edge detection circuit and a MUX selector.

5. The multi-dimensional signal eye diagram compensation circuit according to claim 4, characterized in that: The rising edge detection circuit and the falling edge detection circuit respectively include a delay module, a NOT gate and an AND gate; The input signal is connected to the input end of the delay module through the enable switch; the output end of the delay module of the rising edge detection circuit is connected to the first input end of the first AND gate through the first NOT gate, the second input end of the first AND gate is connected to the input signal, the output end of the first AND gate is connected to the first input end of the first MUX selector through the second NOT gate, and the output end of the first AND gate is also directly connected to the second input end of the first MUX selector; The output end of the delay module of the falling edge detection circuit is connected to the first input end of the second AND gate, the input signal is connected to the second input end of the second AND gate through the third NOT gate, the output end of the second AND gate is connected to the first input end of the second MUX selector through the fourth NOT gate, and the output end of the second AND gate is also directly connected to the second input end of the second MUX selector.

6. The multi-dimensional signal eye diagram compensation circuit according to claim 5, characterized in that: It also includes a first high-speed signal amplifier, and the input signal is input into the rising edge adjustment path and the falling edge adjustment path after passing through the first high-speed amplifier.

7. The multi-dimensional signal eye diagram compensation circuit according to claim 6, characterized in that: The high-speed main signal path also includes a second high-speed signal amplifier and a third high-speed signal amplifier. After the input signal passes through the second high-speed signal amplifier and the third high-speed signal amplifier in sequence, it is weighted with the rising edge / falling edge pre-emphasis compensation signal or the rising edge / falling edge de-emphasis compensation signal.

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