Non-uniform phase-shifted optical quantization analog-to-digital converter resistant to pulse amplitude jitter
By introducing electro-optic modulation, non-uniform phase shifting, complementary light generation, and optical power control into a non-uniform phase-shifted optical quantization analog-to-digital converter, the impact of sampling pulse amplitude jitter on quantization performance is solved, achieving stable quantization performance and efficient conversion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HANGZHOU DIANZI UNIV
- Filing Date
- 2022-08-01
- Publication Date
- 2026-06-19
AI Technical Summary
Existing non-uniform phase-shifted optical quantization analog-to-digital converters suffer from quantization performance issues when faced with sampling pulse amplitude jitter, especially in non-uniform phase-shifted optical quantization systems where there is a lack of effective solutions.
By employing a combination of an electro-optic modulator, a non-uniform phase shifter, a complementary light generation module, an optical power control module, and a balance threshold decision module, the transmission characteristic curve is adjusted to achieve a zero decision threshold through complementary light generation, optical power attenuation, and balance detection, thereby reducing the impact of sampling pulse amplitude jitter on quantization performance.
This achieves stability of quantization performance under sampling pulse amplitude jitter conditions, reduces the impact of the decision threshold on jitter, and improves the performance of the quantization system.
Smart Images
Figure CN115242246B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave photonics technology, specifically relating to a non-uniform phase-shifted optical quantization analog-to-digital converter that resists pulse amplitude jitter. Background Technology
[0002] Analog-to-digital converters (ADCs), as a crucial bridge connecting the real world and the virtual digital world, play an indispensable role in daily life. With the continuous development of information technology, the transmission capacity of information is constantly increasing, and the demand for high-speed, high-capacity communication systems is also growing. This means that the requirements for the analog-to-digital conversion rate of transceivers in communication systems are also increasing. However, due to problems such as sample-and-hold circuit bandwidth, clock jitter, and comparator slack, traditional electronic ADCs can no longer meet the needs of high-speed, high-precision analog-to-digital conversion applications. With the development of photonics technology, optical ADCs, because they can utilize photonics to overcome the existing bottlenecks of electronic ADCs, have become a research hotspot in the field of optoelectronics. In practical engineering, both performance and cost are often considered, and the cost of both electronic and optical ADCs increases with the improvement of theoretical quantization accuracy. To improve the quantization performance of ADCs, a non-uniform quantization method that improves quantization performance by minimizing quantization noise has emerged. Therefore, researchers have combined photonics technology and non-uniform quantization to study non-uniform optical ADCs. For example, in 2021, a paper titled "A Nonuniform Quantization Scheme based on Optical Phase-shifted Devices" presented at the Asia Communications and Photonics Conference proposed a nonuniform quantization scheme based on phase-shifted optical quantization. This scheme utilizes improved phase-shifted optical quantization to enhance quantization performance while maintaining theoretical quantization accuracy. In phase-shifted optical quantization, whether uniform or nonuniform, the decision threshold is a value related to the maximum output light intensity. However, in reality, optical pulses are often affected by factors such as laser stability, system noise, and environmental interference, resulting in amplitude jitter in the sampled optical pulse. Consequently, the actual maximum output light power becomes unstable, affecting the threshold decision part of the phase-shifted optical quantization system, increasing the error in the threshold decision result, and thus degrading the performance of the analog-to-digital conversion system. To address the problem of sampling pulse amplitude jitter affecting quantization performance, some researchers have proposed using balanced detection instead of single-end detection. However, this scheme is applied to phase-shifting optical quantization systems under uniform quantization, and is not entirely applicable to phase-shifting optical quantization systems under non-uniform quantization. Currently, there is no corresponding scheme to solve the sampling pulse amplitude jitter problem in non-uniform phase-shifting optical quantization systems.
[0003] Therefore, it is essential to study and solve the problem of sampling pulse amplitude jitter in non-uniform phase-shifted optical quantization in order to improve quantization performance. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a non-uniform phase-shifted optical quantization analog-to-digital converter (ADC) that resists pulse amplitude jitter, thereby solving the problem of sampling pulse amplitude jitter affecting the quantization performance of the ADC.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A non-uniform phase-shifted optical quantization analog-to-digital converter with anti-sampling pulse amplitude jitter includes:
[0007] An electro-optic modulator is used to perform electro-optic conversion on the input analog electrical signal and complete optical sampling.
[0008] A non-uniform phase shifter is used to perform phase shifting operations on the optical signal input to an electro-optic modulator.
[0009] The complementary light generation module is used to split the optical signal input from the non-uniform phase shifter into two optical signals with complementary amplitudes.
[0010] The optical power control module is used to control the power ratio between the two complementary lights input to the complementary light generation module;
[0011] The balanced threshold decision module is used to perform differential detection on the complementary light output by the optical power control module and to perform threshold decision output quantization encoding.
[0012] As a preferred embodiment, the non-uniform phase shifter module includes a beam splitter and n phase shifters.
[0013] As a preferred embodiment, the complementary light generation module includes n complementary light generators.
[0014] As a preferred embodiment, the optical power control module includes n optical attenuators.
[0015] As a preferred embodiment, the balanced threshold decision module includes n differential detectors and a threshold decision unit.
[0016] The conversion process of the aforementioned non-uniform phase-shifted optical quantization analog-to-digital converter, which is resistant to sampling pulse amplitude jitter, is as follows:
[0017] Step 1: Electro-optic modulation: The analog electrical signal and the sampled optical pulse are input into the electro-optic modulator module for electro-optic modulation to obtain the modulated optical signal, and then input into the non-uniform phase shifting module;
[0018] Step 2: Phase shifting: Use n phase shifters to perform phase shifting operations on the n optical signals generated by the beam splitter, and input the phase-shifted signals into the complementary light generation module;
[0019] Step 3: Complementary light generation: The input n phase-shifted optical signals enter n complementary light generators. Each complementary light generator generates two optical signals with complementary amplitudes, generating a total of 2n optical signals, which then enter the power control module.
[0020] Step 4: Optical power control: Odd-numbered optical signals from the 2n input optical signals enter the optical attenuator for power attenuation, while even-numbered optical signals do not undergo power attenuation. The optical signals after power control enter the balance threshold decision module.
[0021] Step 5: Differential detection and threshold decision: Use n differential detectors to perform differential detection on the 2n input optical signals, generating n differential signals. The differential signals enter n threshold decision units for threshold decision and output quantization code.
[0022] As a preferred embodiment, in the electro-optic modulator: the input electrical signal is x, and the output light intensity is normalized as:
[0023]
[0024] Among them, V π This is the half-wave voltage of the modulator.
[0025] As a preferred embodiment, in a non-uniform phase shifter: the input optical signal is split into n paths by a beam splitter and input into n phase shifters. The light intensity y of the i-th optical channel after passing through the phase shifters... i Normalized to:
[0026]
[0027] Among them, phase shift parameters The proportion R of the non-uniform quantization interval j (j=1,2,…,n and ∑R j =1) determines the non-uniform quantization interval R i The phase shift parameter can be arbitrarily set according to specific needs, or the optimal value for a specific signal can be determined through a non-uniform quantization algorithm. The specific value is:
[0028]
[0029] As a preferred embodiment, the complementary light generation module consists of n optical signals that have undergone non-uniform phase shifting. Each optical signal enters a complementary light generator and generates two complementary optical signals. The intensity of the two complementary lights generated by the i-th optical channel is normalized to:
[0030]
[0031] As a preferred embodiment, in the optical power control module: 2n complementary optical signals enter the power control module, and an odd number of optical signals enter n optical attenuators to generate power-controlled optical signals. The light intensity of the two complementary lights generated by the i-th optical channel after power control is:
[0032]
[0033] Where, α i Let R be the parameter of the i-th optical attenuator, whose value is determined by the proportion of the non-uniform quantization interval. j The decision is as follows:
[0034]
[0035] As a preferred embodiment, in the balanced threshold decision module: the decision thresholds of all n decision thresholders are zero. When the input signal is greater than zero, the threshold decision device outputs "1", and when the input signal is less than zero, the threshold decision device outputs "0".
[0036] This invention also discloses a non-uniform phase-shifted optical quantization analog-to-digital converter (ADC) resistant to sampling pulse amplitude jitter, comprising a dual-ended output Mach-Zehnder modulator, an attenuator, and a balance threshold decision module connected in sequence; wherein,
[0037] A dual-output Mach-Zehnder modulator is used for electro-optic sampling of electrical signals, non-uniform phase shifting of optical signals, and generation of complementary light; specifically, V bi (i = 1, 2, ..., n) represents the bias voltage of the Mach-Zehnder modulator, used to control the phase shift, V s (t) is the analog electrical signal to be quantized, and the comparator threshold is zero; by adjusting V bi To adjust the phase shift as This causes a non-uniform phase shift in the modulation characteristic curves between the dual-output Mach-Zehnder modulators, respectively input to V s (t) and optical sampling pulses are fed to n double-ended Mach-Zehnder modulators for electro-optic modulation, phase shifting, and complementary light generation.
[0038] An attenuator is used to control optical power; specifically, of the 2n optical signals output from the double-ended Mach-Zehnder modulator, the odd-numbered optical signals are attenuated by a parameter α. i Attenuator;
[0039] The balanced threshold decision module consists of a balanced photodetector and a comparator, which are responsible for differential detection and threshold comparison output quantization encoding, respectively. Specifically, 2n optical signals after optical power control enter the balanced photodetector for photoelectric conversion and differential detection to output n electrical signals. The electrical signals are input to the comparator with a threshold voltage of zero for threshold decision and output quantization encoding.
[0040] The core of this invention is to adjust the bias of the transmission characteristic curve by generating complementary light, attenuating optical power, and using balanced detection, so that the decision threshold of the non-uniform phase-shifted optical quantization analog-to-digital converter is zero. Compared with the prior art non-uniform phase-shifted optical quantization analog-to-digital converter using single-end detection, it has the following advantages:
[0041] 1. The decision threshold is zero, which makes implementation simpler and easier, while avoiding the influence of the threshold level on the decision;
[0042] 2. The impact of sampling pulse amplitude jitter on quantization performance is related to both the degree of jitter and the decision threshold. When the decision threshold is zero, the quantization performance of the non-uniform phase-shifted optical quantization analog-to-digital converter can be almost unaffected by sampling pulse amplitude jitter. This invention reduces the decision threshold to zero, thus solving the problem of sampling pulse amplitude jitter affecting quantization performance in non-uniform phase-shifted optical quantization analog-to-digital converters. Attached Figure Description
[0043] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:
[0044] Figure 1 This is a schematic diagram of the principle of the non-uniform phase-shifted optical quantization analog-to-digital converter with anti-sampling pulse amplitude jitter in Example 1.
[0045] Figure 2 This is a schematic diagram of the principle of a non-uniform phase shifting module.
[0046] Figure 3 This is a schematic diagram of the complementary light generation module.
[0047] Figure 4 This is a schematic diagram of the optical power control module.
[0048] Figure 5 A schematic diagram of the principle of the balanced threshold decision module.
[0049] Figure 6 This is a schematic diagram of non-uniform phase-shifting optical quantization encoding when n=8.
[0050] Figure 7 Example 2 is a non-uniform phase-shifting optical quantization analog-to-digital converter based on a dual-output Mach-Zehnder modulator (DOMZM).
[0051] Figure 8This is a graph showing the effective bit of number (ENOB) for different signals after non-uniform phase-shifted optical analog-to-digital conversion under different sampling pulse amplitude jitter. Detailed Implementation
[0052] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0053] Example 1
[0054] This embodiment provides a non-uniform phase-shifted optical quantization analog-to-digital converter that resists sampling pulse amplitude jitter, in order to solve the problem that sampling pulse amplitude jitter affects quantization performance in non-uniform phase-shifted optical quantization analog-to-digital converters.
[0055] like Figure 1-5 As shown, this embodiment of a non-uniform phase-shifted optical quantization analog-to-digital converter with anti-sampling pulse amplitude jitter includes an electro-optic modulator module, a non-uniform phase shifter module, a complementary light generation module, an optical power control module, and a balance threshold decision module connected in sequence.
[0056] An electro-optic modulator is used to sample an input analog electrical signal and convert it into an optical signal, thus completing the optical sampling.
[0057] A non-uniform phase shifter is used to perform phase shifting operations on an input optical signal; specifically, a non-uniform phase shifter includes a beam splitter and n phase shifters.
[0058] The complementary light generation module is used to split the input optical signal into two optical signals with complementary amplitudes; specifically, the complementary light generation module includes n complementary light generators.
[0059] The optical power control module is used to control the power ratio between two input complementary lights; specifically, the optical power control module includes n optical attenuators.
[0060] The balanced threshold decision module is used to perform differential detection on the output complementary light and perform threshold decision output quantization encoding; specifically, it includes n differential detectors and a threshold decision unit.
[0061] Specifically, the conversion process of the non-uniform phase-shifted optical quantization analog-to-digital converter with anti-sampling pulse amplitude jitter in this embodiment is as follows:
[0062] Step 1: Electro-optic modulation. The analog electrical signal and the sampled optical pulse are input into the electro-optic modulator module for electro-optic modulation to obtain the modulated optical signal, which is then input into the non-uniform phase shifting module.
[0063] Let the input electrical signal be x, and the normalized output light intensity be:
[0064]
[0065] Among them, V π The half-wave voltage of the modulator;
[0066] Step 2: Phase shifting. Use n phase shifters to perform phase shifting operations on the n optical signals generated by the beam splitter. The phase-shifted signals are then input into the complementary light generation module.
[0067] Among them, the light intensity y of the i-th optical channel after passing through the phase shifter i Normalized to:
[0068]
[0069] Among them, phase shift parameters The proportion R of the non-uniform quantization interval j (j=1,2,…,n and ∑R j =1) determines the non-uniform quantization interval R i The phase shift parameter can be arbitrarily set according to specific needs, or the optimal value for a specific signal can be determined through a non-uniform quantization algorithm. The specific value is:
[0070]
[0071] Step 3: Complementary light generation. The input n phase-shifted optical signals enter n complementary light generators. Each complementary light generator generates two optical signals with complementary amplitudes, generating a total of 2n optical signals, which then enter the power control module.
[0072] The intensity of the two complementary lights generated by the i-th optical channel is normalized as follows:
[0073]
[0074] Step 4: Optical power control. The odd-numbered optical signals from the 2n input optical signals enter the optical attenuator for a certain power attenuation, while the even-numbered optical signals do not undergo power attenuation. The optical signals after power control enter the balance threshold decision module.
[0075] The light intensities of the two complementary lights generated by the i-th optical channel after power control are:
[0076]
[0077] Where, α i Let R be the parameter of the i-th optical attenuator, whose value is determined by the proportion of the non-uniform quantization interval. j The decision is as follows:
[0078]
[0079] Step 5: Differential detection and threshold decision. Use n differential detectors to perform differential detection on the 2n input optical signals, generating n differential signals. The differential signals enter n threshold decision devices with a decision threshold of zero for threshold decision and output quantization code. The output quantization code rule is: when the input signal is greater than zero, the threshold decision device outputs "1"; when the input signal is less than zero, the threshold decision device outputs "0".
[0080] like Figure 6 As shown in the figure, the non-uniform phase-shifting optical quantization coding principle of this embodiment with n=8 is illustrated, along with the corresponding coding for the quantization interval.
[0081] Example 2
[0082] This embodiment also discloses a non-uniform phase-shift optical quantization analog-to-digital converter based on DOMZM and resistant to sampling pulse amplitude jitter, such as Figure 7 As shown, the system includes a DOMZM, an attenuator, a Balanced Photonics Detector (BPD), and a Comparator (COMP) connected in sequence. The DOMZM is responsible for electro-optic sampling of the electrical signal, non-uniform phase shifting of the optical signal, and generation of complementary light. The attenuator is responsible for optical power control. The BPD and COMP are combined to form a balanced threshold decision module, responsible for differential detection and threshold comparison output quantization encoding, respectively. Wherein, V... bi (i = 1, 2, ..., n) represents the bias voltage of the MZM, used to control the phase shift, V s (t) represents the analog electrical signal to be quantized, and the comparator threshold is zero. In this embodiment, the non-uniform phase-shifting optical quantization analog-to-digital converter based on DOMZM is first adjusted by V... bi To adjust the phase shift as This causes a non-uniform phase shift in the modulation characteristic curves between DOMZMs, and then V is input respectively. s (t) and the optical sampling pulse are fed to n DOMZMs for electro-optic modulation, phase shifting, and complementary light generation. 2n optical signals emerge from the DOMZMs, of which the odd number of optical signals are attenuated by a parameter α. iThe attenuator, after optical power control, sends 2n optical signals into the BPD for photoelectric conversion and differential detection to output n electrical signals. The electrical signals are then input into the COMP with a threshold voltage of zero for threshold decision and output quantization encoding.
[0083] Figure 8 The quantization performance of sinusoidal and UFMC signals after passing through the non-uniform phase-shifted optical quantization analog-to-digital converter of this embodiment is presented under different sampling pulse amplitude jitter conditions. The horizontal axis represents the ratio of the noise standard deviation of the sampling pulse to the mean optical power, and the horizontal axis represents the effective quantization bits. It can be observed that the quantization performance index does not change with increasing sampling pulse amplitude jitter, which means that the analog-to-digital converter of this embodiment is almost unaffected by sampling pulse amplitude jitter.
[0084] In summary, this invention solves the problem of sampling pulse amplitude jitter affecting the quantization system performance in non-uniform phase-shifted optical quantization analog-to-digital converters. Therefore, compared with general non-uniform phase-shifted optical quantization analog-to-digital converters without sampling pulse amplitude immunity, the analog-to-digital converter of this invention can be better applied to communication systems and meet the system's noise immunity and quantization performance requirements.
[0085] Specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.
Claims
1. A non-uniform phase-shifted optical quantization analog-to-digital converter with anti-pulse amplitude jitter, characterized in that, Includes an electro-optic modulator, a non-uniform phase shifter, a complementary light generation module, an optical power control module, and a balance threshold decision module; The electro-optic modulator is used to perform electro-optic conversion on the input analog electrical signal and complete optical sampling; The non-uniform phase shifter is used to perform phase shifting operation on the optical signal input to the electro-optic modulator; The complementary light generation module is used to split the optical signal input from the non-uniform phase shifter into two optical signals with complementary amplitudes. In the aforementioned complementary light generation module, n optical signals undergoing non-uniform phase shifting enter the complementary light generation module. Each optical signal enters a complementary light generator and generates two optical signals with complementary amplitudes. The light intensities of the two complementary lights generated by the optical channel are normalized to: wherein, is a half-wave voltage of the modulator; is a phase shift parameter; The optical power control module is used to control the power ratio between the two complementary lights input to the complementary light generation module; The optical power control module is used for the 2n complementary optical signals, the odd optical signals enter n optical attenuators to generate optical signals after power control, and the optical signals after power control enter the balanced threshold decision module. The optical intensities of the two complementary optical signals generated by the optical channel after power control are: wherein, is a parameter of the i-th optical attenuator, and the value of is determined by the proportion of non-uniform quantization interval is determined, specifically: The balance threshold decision module is used to perform differential detection on the complementary light output by the optical power control module and to perform threshold decision output quantization encoding. The aforementioned balanced threshold decision module includes n differential detectors and threshold decision units. The n differential detectors perform differential detection on the 2n input optical signals to generate n differential signals. The differential signals enter the n threshold decision units for threshold decision and output quantized codes. The decision threshold of the n decision threshold units is zero. When the input signal is greater than zero, the threshold decision unit outputs "1" and when the input signal is less than zero, the threshold decision unit outputs "0".
2. The non-uniform phase-shift quantized analog-to-digital converter of claim 1, wherein, In the electro-optical modulator, the input electrical signal is , and the output light intensity is normalized as: 。 3. The non-uniform phase-shifting optical quantization analog-to-digital converter according to claim 2, characterized in that, The non-uniform phase shifter includes a beam splitter and n phase shifters. The n phase shifters perform phase shifting operations on the n optical signals generated by the beam splitter, and the phase-shifted signals are input to the complementary light generation module.
4. The non-uniform phase-shift quantization analog-to-digital converter of claim 3, wherein, In the aforementioned non-uniform phase shifter, the input optical signal is split into n paths by a beam splitter and input into n phase shifters; After the phase shifter, the first Light intensity of each optical channel Normalized to: Among them, phase shift parameters The proportion of non-uniform quantization intervals It is determined that j=1,2,…,n and Non-uniform quantization interval Phase shift parameters can be arbitrarily set according to specific needs or determined using non-uniform quantization algorithms to achieve the optimal value for a specific signal; The specific value is: 。 5. The non-uniform phase-shift quantization analog-to-digital converter according to claim 3 or 4, characterized in that, The complementary light generation module includes n complementary light generators. The input n phase-shifted light signals enter the n complementary light generators. Each complementary light generator generates two complementary light signals, generating a total of 2n light signals, which then enter the power control module.
6. The non-uniform phase-shift quantized analog-to-digital converter of claim 5, wherein, The optical power control module includes n optical attenuators. The odd-numbered optical signals from the 2n input optical signals enter the optical attenuators for a certain power attenuation, while the even-numbered optical signals do not undergo power attenuation. The optical signals after power control enter the balance threshold decision module.