阅读说明：本技术 基于低通负群时延电路的高速互连传输信号延时均衡方法 (High-speed interconnection transmission signal delay equalization method based on low-pass negative group delay circuit ) 是由 万发雨 顾韬琛 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种基于低通负群时延电路的高速互连传输信号延时均衡方法,采用传输系统实现高速互连传输信号延时均衡,传输系统为低通负群时延电路,低通负群时延电路包括逻辑门电路、高速电路等效电路网络、低通负群时延单元和输出端口；首先基于电路理论、微波网络理论实现有源低通负群时延电路群时延解析公式和电路综合公式。然后基于时域电路仿真和频域S参数仿真优化有源低通负群时延电路参数,设计、加工并在时域和频域进行性能测试,得到负群时延大、带宽理想、无损耗的PCB板级低通负群时延电路。最后通过低通负群时延电路对数字基带信号的时延进行均衡,达到改善高速PCB信号完整性的目的。(The invention discloses a high-speed interconnected transmission signal delay equalization method based on a low-pass negative group delay circuit, which adopts a transmission system to realize the delay equalization of a high-speed interconnected transmission signal, wherein the transmission system is the low-pass negative group delay circuit, and the low-pass negative group delay circuit comprises a logic gate circuit, a high-speed circuit equivalent circuit network, a low-pass negative group delay unit and an output port; firstly, an active low-pass negative group delay circuit group delay analytical formula and a circuit comprehensive formula are realized based on a circuit theory and a microwave network theory. And then optimizing the parameters of the active low-pass negative group delay circuit based on time domain circuit simulation and frequency domain S parameter simulation, designing, processing and performing performance tests in the time domain and the frequency domain to obtain the PCB board-level low-pass negative group delay circuit with large negative group delay, ideal bandwidth and no loss. And finally, the time delay of the digital baseband signal is equalized through a low-pass negative group time delay circuit, so that the aim of improving the integrity of the high-speed PCB signal is fulfilled.)

1. A high-speed interconnection transmission signal delay equalization method based on a low-pass negative group delay circuit is characterized in that a transmission system is adopted to realize high-speed interconnection transmission signal delay equalization, the transmission system is a low-pass negative group delay circuit, and the low-pass negative group delay circuit comprises a logic gate circuit, a high-speed circuit equivalent circuit network, a low-pass negative group delay unit and an output port; the low-pass negative group delay unit comprises a first resistor, a first inductor and a field effect transistor, and the high-speed circuit equivalent circuit network comprises an equivalent resistor, an equivalent inductor and an equivalent capacitor; wherein the content of the first and second substances,

the output end of the logic gate circuit is connected with one end of the equivalent resistor, the other end of the equivalent resistor is connected with one end of the equivalent inductor, the other end of the equivalent inductor is respectively connected with one end of the equivalent capacitor, one end of the first resistor and the grid electrode of the field-effect tube, the other end of the equivalent capacitor is grounded, the other end of the first resistor is connected with one end of the first inductor, the other end of the first inductor is respectively connected with the output port and the drain electrode of the field-effect tube, and the source electrode of the field-effect tube is grounded.

2. The method for high-speed interconnect transmission signal delay equalization based on low-pass negative group delay circuit as claimed in claim 1,

wherein R is_dsIs the drain-source resistance, g, of the field effect transistor_mIs the transconductance, resistance and R of a field effect transistor_t＝R_s+R_ld，R_sIs the output resistance in the logic gate circuit, C_bIs an equivalent capacitance C_ld，L_tIs an equivalent inductance L_ld，L_bIs a first inductance, R_bIs the first resistance.

3. The method for high-speed interconnected transmission signal delay equalization based on the low-pass negative group delay circuit as claimed in claim 2, wherein the transmission function of the transmission system is expressed as follows:

wherein the content of the first and second substances,

g(s) is Laplace transform of low-pass negative group delay circuit transfer function, a₀、a₁、a₂And a₃All represent intermediate variables, s is the Laplace transform of frequency ω, R_bIs a first resistance, L_bIs a first inductance, R_ld is equivalent resistance, L_ld is equivalent inductance, C_ld is the equivalent capacitance.

Technical Field

The invention relates to the technical field of microwave engineering, in particular to a high-speed interconnection transmission signal delay equalization method based on a low-pass negative group delay circuit.

Background

As the speed of digital systems increases and the rise and fall times of signals decrease, the density and complexity of interconnect structures increase dramatically, and the signal integrity problems arising in high-speed digital systems become more and more pronounced. The delay of the system is seriously affected by signal reflection, overshoot, undershoot, ringing, crosstalk and the like caused by the high-speed problem. Therefore, the delay problem is the most critical problem in high-speed interconnection design and is also an important problem to be solved. The low-pass negative group delay circuit can reduce the time delay generated by the signal in the transmission system. In order to compensate the variation of the time delay of the high-speed interconnection structure, the patent proposes a time delay equalizer based on a low-pass negative group time delay circuit to solve the problem of high-speed signal distortion.

The group delay refers to the time delay generated by signal envelope when a narrow-band signal passes through a linear time-invariant transmission system. The negative group delay refers to an abnormal electromagnetic wave transmission phenomenon that the group delay is a negative value. The peak signal envelope at the output of the negative group delay circuit may appear earlier than the peak signal envelope at the input (S.M muller, T. Rechel, R. Rimo-Donadio, Y. H. Kwak, H. Br us and C. Schuster, "Energy-Aware Signal Integrated analysis for High-Speed PCB Links," IEEE Transactions on Electromagnetic Compatibility, vol.57, No.5, pp.1226-1234, 2015). The low-pass negative group delay circuit refers to a circuit in which the group delay is negative in a frequency band from a direct current to a cutoff frequency, and the band-pass negative group delay circuit refers to a circuit in which the group delay is negative in a certain frequency band (F Wan, L Wang, Q Ji, B Ravelo, "acoustical transfer Function of band-pass NGD circuit," IET Circuits, Devices & Systems, vol.13, No.2, pp.13-21, 2019). The high-speed interconnect structure may transmit digital baseband signals as well as modulation signals. The low-pass negative group delay circuit can be used for compensating the delay of the digital baseband signal so as to solve the distortion problem. At present, the theory of an equalization technology for compensating the time delay of a high-speed digital signal by using a low-pass negative group time delay circuit is not mature, and particularly, the influence mechanism of a signal waveform on the equalization effect is not reported in documents. At present, high-speed interconnection transmission of high-frequency modulation signals reaches a millimeter wave frequency band, particularly, rapid development of 5G communication is achieved, delay problems of ultra-high-speed transmission are increasingly serious, and research on negative group delay circuits is urgent.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a high-speed interconnection transmission signal delay equalization method based on a low-pass negative group delay circuit.

The invention adopts the following technical scheme for solving the technical problems:

according to the high-speed interconnected transmission signal delay equalization method based on the low-pass negative group delay circuit, the transmission system is adopted to realize the high-speed interconnected transmission signal delay equalization, the transmission system is the low-pass negative group delay circuit, and the low-pass negative group delay circuit comprises a logic gate circuit, a high-speed circuit equivalent circuit network, a low-pass negative group delay unit and an output port; the low-pass negative group delay unit comprises a first resistor, a first inductor and a field effect transistor, and the high-speed circuit equivalent circuit network comprises an equivalent resistor, an equivalent inductor and an equivalent capacitor; wherein the content of the first and second substances,

the output end of the logic gate circuit is connected with one end of the equivalent resistor, the other end of the equivalent resistor is connected with one end of the equivalent inductor, the other end of the equivalent inductor is respectively connected with one end of the equivalent capacitor, one end of the first resistor and the grid electrode of the field-effect tube, the other end of the equivalent capacitor is grounded, the other end of the first resistor is connected with one end of the first inductor, the other end of the first inductor is respectively connected with the output port and the drain electrode of the field-effect tube, and the source electrode of the field-effect tube is grounded.

As a further optimization scheme of the high-speed interconnection transmission signal delay equalization method based on the low-pass negative group delay circuit,

wherein R is_dsIs the drain-source resistance, g, of the field effect transistor_mIs the transconductance, resistance and R of a field effect transistor_t＝R_s+R_ld，R_sIs the output resistance in the logic gate circuit, C_bIs an equivalent capacitance C_ld，L_tIs an equivalent inductance L_ld，L_bIs the firstAn inductor, R_bIs the first resistance.

As a further optimization scheme of the high-speed interconnected transmission signal delay equalization method based on the low-pass negative group delay circuit, the transmission function of a transmission system is expressed as follows:

g(s) is Laplace transform of low-pass negative group delay circuit transfer function, a₀、a₁、a₂And a₃All represent intermediate variables, s is the Laplace transform of frequency ω, R_bIs a first resistance, L_bIs a first inductance, R_ld is equivalent resistance, L_ld is equivalent inductance, C_ld is the equivalent capacitance.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

firstly, an active low-pass negative group delay circuit group delay analytical formula and a circuit comprehensive formula are realized based on a circuit theory and a microwave network theory. And then optimizing the parameters of the active low-pass negative group delay circuit based on time domain circuit simulation and frequency domain S parameter simulation, designing, processing and performing performance tests in the time domain and the frequency domain to obtain the PCB board-level low-pass negative group delay circuit with large negative group delay, ideal bandwidth and no loss. And finally, the time delay of the digital baseband signal is equalized through a low-pass negative group time delay circuit, so that the aim of improving the integrity of the high-speed PCB signal is fulfilled. And (4) carrying out equalizer equalization effect test in the time domain and the frequency domain, and analyzing and optimizing the equalization effects of attenuation, distortion and delay of the digital baseband signals from the angles of the time domain and the frequency domain until a good equalization effect is obtained.

Drawings

FIG. 1 is a schematic diagram of a low-pass negative group delay circuit.

FIG. 2 is a simulation result of a low-pass negative group delay circuit; wherein, (a) is group delay, (b) is reflection coefficient, and (c) is gain.

FIG. 3 is a schematic diagram of a low-pass negative group delay circuit for equalizing transmission delay of a high-speed PCB; wherein, (a) is a schematic diagram of an input signal outputting a distortion signal after being interfered, and (b) is a schematic diagram of an input signal outputting a compensation signal after being interfered and compensated by a low-pass negative group delay circuit.

Fig. 4 is a schematic diagram of the cascade connection of the low-pass negative group delay circuit and the transmission line.

Fig. 5 is a digital signal distortion diagram of a high-speed circuit configuration.

FIG. 6 illustrates a principle of a method for equalizing a transmission signal by a low-pass negative group delay circuit; wherein, (a) is amplitude compensation, and (b) is group delay compensation.

Fig. 7 is a circuit configuration diagram of a low-pass negative group delay circuit for equalizing a transmission signal.

FIG. 8 is a time domain simulation of the equalization of a transmission signal by a low pass negative group delay circuit; wherein, (a) is a time domain simulation result of equalizing the transmission signal by the low-pass negative group delay circuit with abscissa 0-4ns, and (b) is a partial enlarged view of (a) in fig. 8 with abscissa 0-1 ns.

FIG. 9 is a frequency domain simulation of the equalization of a transmission signal by a low-pass negative group delay circuit; wherein, (a) is amplitude compensation, and (b) is group delay compensation.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

The delay problem is the most critical in high-speed interconnection design and is also an important problem to be solved, and the trend of a modern high-speed circuit system to higher frequency is restricted. The low-pass negative group delay circuit can reduce the time delay generated by the signal in the transmission system. In order to compensate the time delay change of the high-speed interconnection structure, the invention provides a time delay equalizer based on a low-pass negative group time delay circuit to solve the problem of high-speed signal distortion, and theoretical analysis and electromagnetic simulation are carried out in a time domain and a frequency domain. The low-pass negative group delay circuit can compensate the delay of the digital baseband signal, thereby solving the distortion problem and improving the signal integrity of a circuit system. A new solution is provided for the delay problem in high-speed circuits and the delay problem in 5G communication channel transmission.

Fig. 1 is a schematic diagram of a low-pass negative group delay circuit, which can be implemented using an RL or RC circuit structure, and whose loss can be compensated by adding a triode or a radio frequency amplifier, fig. 1 is a two-unit RC low-pass negative group delay circuit plus a radio frequency amplifier, which can be analyzed using an S-parameter network model or a transfer function, and the S-parameter formula of the circuit is shown as follows:

wherein r is the reflection coefficient of the amplifier, t is the gain of the amplifier, and the isolation of the amplifier is simplified to 0; r₀R, C is the resistance and capacitance of the low-pass negative group delay circuit, omega is the frequency, j is the imaginary unit, S₂₁(j ω) is the forward transmission coefficient, i.e., gain, of the circuit.

At the DC frequency point (ω ≈ 0), the S parameter model is as follows:

wherein [ S (0) ] is a value of S11, S12, S21, S22 when the frequency ω is 0;

s11 is the first row and column element in the S parameter matrix of the low-pass negative group delay circuit;

s12 is a first row and a second column element in an S parameter matrix of the low-pass negative group delay circuit;

s21 is the second row and the first column of elements in the S parameter matrix of the low-pass negative group delay circuit;

s22 is the second row and the second column of elements in the S parameter matrix of the low-pass negative group delay circuit;

s11 is the reflection coefficient of the input port (port 1) of the low-pass negative group delay circuit when the output port (port 2) of the low-pass negative group delay circuit is matched;

s22 is the reflection coefficient of port 2 when the input ports of the circuit are matched;

s12 is the reverse transmission coefficient from port 2 to port 1 when port 1 is matched;

s21 is the forward transmission coefficient from port 1 to port 2 when port 2 is matched;

the group delay τ (ω) is the derivative of the transmission phase with respect to frequency, according to the definition of the group delay:

is the phase of the circuit transfer function;

wherein the transmission phase is:

obtaining an analytic formula of the group delay at the DC frequency point:

τ (0) is the value of the group delay at a frequency of 0 Hz;

the formula (5) can obtain that the group delay is unconditionally negative at a direct current frequency point, the larger C is, the smaller R is, the larger the negative group delay is,

τ(ω_c)＝0 (6)

τ(ω_c) Is a frequency of omega_cValue of group delay, omega_cIs the cut-off frequency;

the cutoff frequency ω can be obtained by solving the root of equation (6)_c：

The group delay and gain formula can analyze the influence of circuit parameters on the performance of the low-pass negative group delay circuit and deduce circuit parameters under ideal negative group delay performance. Let the gain required by the low-pass negative group delay circuit be g and the group delay be tau₀，τ₀Refers to the value of the group delay, τ, at a frequency of 0₀τ (0), equation (8) is obtained from analytical equations (2) and (5):

S₂₁(0) is the value of S21 at frequency 0;

the values of the resistance R and the capacitance C can be obtained by equation (9):

fig. 2 shows the simulation result of the low-pass negative group delay circuit, where (a) in fig. 2 shows the group delay, (b) in fig. 2 shows the reflection coefficient, and (c) in fig. 2 shows the gain. Based on theoretical analysis, simulation is carried out in ADS circuit simulation software, and the result is shown in figure 2, the group delay is negative in a DC-200MHz bandwidth and is called a low-pass negative group delay circuit, the bandwidth reaches 200MHz, the group delay is-280 ps, the reflection coefficient is less than-10 dB, and the gain is greater than 0 dB.

Fig. 3-5 are diagrams illustrating a method for equalizing transmission delay of a high-speed PCB by a low-pass negative group delay circuit. After the basic structure of the low-pass negative group delay circuit is designed, the low-pass negative group delay circuit can be used for balancing the high-speed signal. Fig. 3 shows a schematic diagram of a mechanism of equalizing the transmission delay of the high-speed PCB by the low-pass negative group delay circuit, (a) in fig. 3 is a schematic diagram of outputting a damaged signal after an input signal is interfered, (b) in fig. 3 is a schematic diagram of outputting a compensation signal after the input signal is interfered and compensated by the low-pass negative group delay circuit, and an ideal digital signal is subjected to interferenceThe transmission system suffers from delay and attenuation, and the output signal is severely distorted. After the low-pass negative group delay circuit is loaded, the waveform of an output signal is improved. Fig. 4 shows a schematic structural diagram of a cascade of a low-pass negative group delay circuit and a transmission line. Fig. 5 illustrates a digital signal distortion schematic diagram of the circuit configuration of fig. 4. And an input signal V_i(t) phase comparison, output signal V_l(t) the influence experienced can be evaluated from the attenuation of the signal amplitude, the rise and fall times of the signal, and the propagation delay, which is usually represented by the parameter Tp 50%, defined as the output signal V_l(t) the time required for the amplitude to reach 50% of the amplitude Vm.

In the frequency domain, the output signal V_l(t) is influenced by the transfer function G_l(t) represents. Its gain amplitude and group delay generally conform to the following inequality:

G_l(j ω) is the transfer function of the high speed circuit, τ_l(omega) is the group delay function of high speed circuits

The output is laplace transformed and the output signal can be written as:

v_l(s)＝G_l(s)·v_i(s) (12)

v_l(s) is the Laplace transform of the output signal function of the high speed circuit, G_l(s) Laplace transform of high speed circuit transfer function, v_i(s) is the laplace transform of the high speed circuit input signal, s is the laplace transform of frequency ω;

as shown in fig. 4 and 5, the mechanism for reducing the propagation delay is studied to find a mechanism for providing a signal as close to the input signal V as possible_l(t) (solid black curve) compensated output V_N(t) (black dotted line). I.e. V_i(t)≈V_N(t) of (d). Theoretically, the transmission system G allows for a good matching of the circuits_x(s) must satisfy the following equation:

v_N(s)＝G_l(s)·G_x(s)·v_i(s) (13)

v_N(s) is the output function after low-pass negative group delay circuit compensation;

transmission system G_x(s) refers to the transfer function of the low-pass negative group delay circuit,

therefore, in the frequency domain, the gain and the group delay of the low-pass negative group delay circuit must be equal to the expression (14), i.e., the loaded low-pass negative group delay circuit can provide both the gain and the low-pass negative group delay. The low-pass negative group delay circuit is also an equalization mechanism of the low-pass negative group delay circuit to the transmission delay of the high-speed PCB.

τ_x(omega) is the group delay function of the low-pass negative group delay circuit, G_x(j omega) is the transfer function of the low-pass negative group delay circuit_dBExpressed in dB for the value of the transfer function;

fig. 6 shows the principle of the equalization method of the low-pass negative group delay circuit on the transmission signal, where (a) in fig. 6 is amplitude compensation and (b) in fig. 6 is group delay compensation, and the low-pass negative group delay circuit provides both gain and low-pass negative group delay on the same frequency band as the transmission signal, so that the distorted signal is better recovered.

The transmission system is a low-pass negative group delay circuit and comprises a logic gate circuit, a high-speed circuit equivalent circuit network, a low-pass negative group delay unit and an output port; the low-pass negative group delay unit comprises a first resistor R_bFirst inductance L_bAnd a field effect transistor FET, the high-speed circuit equivalent circuit network including an equivalent resistor R_ld. Equivalent inductance L_ld and equivalent capacitance C_ld; the output end of the logic gate circuit is connected with one end of the equivalent resistor, the other end of the equivalent resistor is connected with one end of the equivalent inductor, the other end of the equivalent inductor is respectively connected with one end of the equivalent capacitor, one end of the first resistor and the grid of the field effect transistor, and the other end of the equivalent capacitor is groundedThe other end of the first resistor is connected with one end of a first inductor, the other end of the first inductor is respectively connected with the output port and the drain electrode of the field effect tube, and the source electrode of the field effect tube is grounded. FIG. 7 is a block diagram of a low pass negative group delay circuit for equalizing a transmission signal with a high speed circuit using an RLC equivalent circuit network and driven by a logic gate circuit, where R is_sAs an output resistor. The low-pass negative group delay circuit model consists of an RL and a field effect transistor. In fig. 7 Vi is the input signal and Vgs is the gate voltage of the FET.

According to the circuit in fig. 7, the transfer function of the whole system can be expressed as follows:

wherein R is_dsIs the drain-source resistance, g, of the field effect transistor_mIs the transconductance, resistance and R of a field effect transistor_t＝R_s+R_ld，R_sIs the output resistance in the logic gate circuit, C_bIs an equivalent capacitance C_ld，L_tIs an equivalent inductance L_ld，L_bIs a first inductance, R_bIs a first resistance; g(s) is Laplace transform of low-pass negative group delay circuit transfer function, a₀、a₁、a₂And a₃All represent intermediate variables, s is the Laplace transform of frequency ω, R_bIs a first resistance, L_bIs a first inductance, R_ld is equivalent resistance, L_ld is equivalent inductance, C_ld is the equivalent capacitance.

At very low frequencies (ω ≈ 0), the gain G (0) and propagation delay T of the whole system_pCan be expressed as:

according to the balance target of the low-pass negative group delay circuit in the formula (14), circuit parameters can be synthesized by utilizing a comprehensive theory:

fig. 8 is a time domain simulation result of the equalization of the transmission signal by the low-pass negative group delay circuit, wherein (a) in fig. 8 is an abscissa of 0-4ns, a time domain simulation result of the equalization of the transmission signal by the low-pass negative group delay circuit is a time domain simulation result, and (b) in fig. 8 is a partial enlarged view of (a) in fig. 8 on the abscissa of 0-1 ns. At the input signal V_iWith a period of 2ns, V_iIs about 92ps (blue black curve plus triangle). Output signal V of high-speed interconnection circuit_rlcIndicated by a black dotted line, whose propagation delay T_p304 ps. Output signal V added with low-pass negative group delay circuit_NRepresented by the black curve, its propagation delay T_p44ps, it can be seen that the low-pass negative group delay circuit equalizes approximately 85% of the transmission delay. In addition to this, with the input signal V_iCompared with the output signal V_NThere is neither attenuation nor overshoot, and the waveform is also greatly improved.

Fig. 9 is a frequency domain simulation result of the low-pass negative group delay circuit for equalizing the transmission signal, and (a) and (b) in fig. 9 respectively show the frequency domain simulation result of the amplitude and delay equalization performance after the low-pass negative group delay circuit is loaded. When the low-pass negative group delay circuit is not loaded, the signal attenuation is-20 dB, the group delay change is 0.4ns, and after the low-pass negative group delay circuit is loaded, the amplitude attenuation of a transmission function of the whole circuit is less than 2dB and the group delay change is less than 68ps in the range of 0-3 GHz.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.