Non-uniform phase-shifted optical quantization analog-to-digital converter
Patent Information
- Application Number
- CN202210873729.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-21
- Publication Date
- 2026-10-09
- Estimated Expiration
- 2042-07-21
AI Technical Summary
该方案是一种电域的非均匀量化器不能直接用于光非均匀量化
[0028] 1. The quantization method of this invention adopts non-uniform quantization, which greatly reduces quantization noise and improves the quantization effect on non-uniformly distributed signals compared with uniform quantization. In particular, the improvement in quantization effect is more obvious for signals in which small signals occupy most of the market and large signals occupy a small part.
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Figure CN115225090B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave photonics technology, specifically relating to a non-uniform phase-shifting optical quantization analog-to-digital converter. Background Technology
[0002] Analog-to-digital converters (ADCs), serving as a bridge between the real analog world and the virtual digital world, play an indispensable role in practical life. With the continuous development of information technology, network traffic is surging, information transmission capacity is constantly increasing, and the demand for high-speed communication systems is also growing. The conversion rate requirements between analog and digital signals for transceivers in various communication links are also increasing. However, the development of traditional electronic ADCs has been greatly constrained by issues such as sample-and-hold circuit bandwidth and clock jitter. With the development of photonics technology, optical ADCs, a new generation of high-speed, high-precision ADCs that utilizes photonics technology to overcome the existing bottlenecks of electronic ADCs, have become a research hotspot in the field of optoelectronics. In real-world engineering applications, performance and cost are usually considered, and the cost of both electronic and optical ADCs increases with increasing accuracy. Therefore, improving the actual quantization performance of ADCs while maintaining theoretical quantization accuracy is essential.
[0003] Furthermore, ADCs can be categorized into uniform quantization ADCs and non-uniform quantization ADCs based on their quantization methods. Uniform quantization ADCs are widely used due to their simplicity and ease of implementation. However, the quantization performance of uniform quantization ADCs is highly susceptible to signal distribution, especially in analog-to-digital conversion (ADC) where small signals constitute the majority of the signal and large signals comprise only a small portion. Non-uniform quantization can improve quantization performance by reducing quantization noise based on the signal distribution. For example, the 2020 paper "A study on performance improvement of IMDD-UFMC with modified K-means non-uniform quantization" published in Optics Communications proposed a K-means-based non-uniform quantization method that improves system transmission performance while maintaining theoretical quantization accuracy. However, this scheme uses an electrical domain non-uniform quantizer and cannot be directly applied to optical non-uniform quantization. Therefore, researching optical ADCs based on non-uniform quantization to improve system transmission performance is essential. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a non-uniform phase-shifting optical quantization analog-to-digital converter to improve the quantization performance of existing uniform quantization ADCs.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A non-uniform phase-shifting optical quantization analog-to-digital converter includes an electro-optic modulator, a non-uniform phase shifter, and a non-uniform threshold decision module;
[0007] The electro-optic modulator modulates the analog electrical signal to be quantized and the optical pulse signal to obtain the modulated optical signal, and inputs the modulated optical signal into the non-uniform phase shifter.
[0008] The non-uniform phase shifter is used to perform phase shifting operation on the input optical signal, and the phase-shifted signal is input to the non-uniform threshold decision module.
[0009] The non-uniform threshold decision module is used to perform threshold decision on the input optical signal to output digital code.
[0010] As a preferred option, the analog electrical signal is x, and the normalized output light intensity is:
[0011]
[0012] Among them, V π This is the half-wave voltage of the modulator.
[0013] As a preferred embodiment, the non-uniform phase shifter module includes a beam splitter and n phase shifters. The input optical signal is split into n paths by the beam splitter and input into the n phase shifters respectively. After passing through the phase shifters, the light intensity y of the i-th optical channel is... i Normalized to:
[0014]
[0015] Among them, phase shift parameters The proportion R of the non-uniform quantization interval j It is determined that j = 1, 2, ..., n and ΣR j =1, phase shift parameter The specific value is:
[0016]
[0017] As a preferred embodiment, the non-uniform threshold decision module includes n threshold decision units. n optical signals undergoing non-uniform phase shifting enter the non-uniform threshold decision module. Each optical signal enters a threshold decision unit for threshold decision and outputs a digital code. During the decision process, if the signal strength is greater than the threshold, the output code is "1"; if the signal strength is less than the threshold, the output code is "0". The decision threshold T of the i-th threshold decision unit... i for:
[0018] The present invention also provides the following specific conversion process for a non-uniform phase-shifting optical quantization analog-to-digital converter capable of achieving arbitrary quantization ranges, as described above:
[0019] Step 1: Electro-optic modulation. The analog electrical signal to be quantized and the optical pulse signal are input into the electro-optic modulator module for modulation. The resulting modulated optical signal is then input into the non-uniform phase shifting module.
[0020] Step 2: Phase shifting. The input optical signal is phase shifted using n phase shifters. The phase-shifted signal is then input into the non-uniform threshold decision module.
[0021] Step 3: Threshold decision. Input n phase-shifting optical signals into the corresponding n threshold decision units to perform threshold decision operations and obtain the output code.
[0022] This invention also discloses a non-uniform phase-shifting optical quantization analog-to-digital converter, comprising a Mach-Zehnder modulator, a non-uniform threshold decision unit, a photodetector, and a comparator; wherein:
[0023] Mach-Zehnder modulator: modulates electrical signals to electro-optical signals and phase-shifts non-uniform optical signals;
[0024] Non-uniform threshold decision unit: It includes a photodetector and a comparator. The optical signal input from the Mach-Zehnder modulator enters the photodetector for photoelectric conversion and the converted electrical signal is input into the comparator. By setting the threshold voltage of the comparator, the input electrical signal is compared and decided, and non-uniform quantization is completed and quantization code is output.
[0025] As a preferred option, adjust V bi To adjust the phase shift as This causes a non-uniform phase shift in the modulation characteristic curves between the Mach-Zehnder modulators, resulting in the transmission characteristic curves required for non-uniform phase-shifted optical quantization. These curves are then input into V... s (t) and optical sampling pulses are fed to n Mach-Zehnder modulators for electro-optic modulation and phase shifting; where, V bi (i = 1, 2, ..., n) represents the bias voltage of the Mach-Zehnder modulator, used to control the phase shift; Vs (t) represents the analog electrical signal to be quantized.
[0026] The present invention is a non-uniform phase-shift optical quantization ADC that fully considers the performance advantages of non-uniform quantization and the rate advantages of photonics technology, thereby ensuring the ADC rate while improving the ADC quantization performance.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] 1. The quantization method of this invention adopts non-uniform quantization, which greatly reduces quantization noise and improves the quantization effect on non-uniformly distributed signals compared with uniform quantization. In particular, the improvement in quantization effect is more obvious for signals in which small signals occupy most of the market and large signals occupy a small part.
[0029] 2. This invention is an ADC based on optical devices, which solves the problem of large clock jitter in traditional electronic ADCs.
[0030] 3. The non-uniform quantization interval of the present invention can be modified arbitrarily according to requirements, thereby improving the adaptability.
[0031] 4. In the non-uniform decision threshold module of this invention, the decision threshold of each channel is close to zero, and is less affected by sampling pulse amplitude jitter. Compared with uniform phase-shifting optical quantization ADC, it improves the resistance to pulse amplitude jitter. Attached Figure Description
[0032] 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:
[0033] Figure 1 This is a schematic diagram of the principle of the non-uniform phase-shifting optical quantization analog-to-digital converter in Example 1.
[0034] Figure 2 This is a schematic diagram of the principle of the non-uniform phase shifter in Example 1.
[0035] Figure 3 This is a schematic diagram of the non-uniform threshold decision module in Example 1.
[0036] Figure 4 The non-uniform phase shift curve and its code are shown for n=8.
[0037] Figure 5 Example 2 is a non-uniform phase-shifting optical quantization analog-to-digital converter based on a Mach-Zehnder modulator (MZM). Detailed Implementation
[0038] 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.
[0039] This invention provides a non-uniform phase-shift optical quantization analog-to-digital converter that can achieve arbitrary quantization ranges, thereby improving the quantization performance of existing uniform quantization ADCs.
[0040] Example 1
[0041] like Figure 1-3 As shown, the non-uniform phase-shifting optical quantization analog-to-digital converter in this embodiment includes an electro-optic modulator, a non-uniform phase shifter, and a non-uniform threshold decision module.
[0042] An electro-optic modulator is used to sample an input analog electrical signal and convert it into an optical signal.
[0043] A non-uniform phase shifter is used to perform phase shifting operations on the input optical signal; specifically, a non-uniform phase shifter includes a beam splitter and n phase shifters.
[0044] The non-uniform threshold decision module is used to perform threshold decision on the input optical signal to output digital code; specifically, the non-uniform threshold decision module includes n threshold decision units.
[0045] The conversion process of this embodiment, which enables a non-uniform phase-shifting optical quantization analog-to-digital converter with arbitrary quantization range, is as follows:
[0046] Step 1: Electro-optic modulation. The analog electrical signal to be quantized and the optical pulse signal are input into the electro-optic modulator for modulation. The resulting modulated optical signal is then input into the non-uniform phase shifter.
[0047] Wherein, the input electrical signal is x, and the normalized output light intensity is:
[0048]
[0049] Among them, V π The half-wave voltage of the modulator;
[0050] Step 2: Phase shifting. The input optical signal is phase shifted using n phase shifters. The phase-shifted signal is then input into the non-uniform threshold decision module.
[0051] 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 is... i Normalized to:
[0052]
[0053] Among them, phase shift parameters The proportion R of the non-uniform quantization interval j (j = 1, 2, ..., 2N and ∑R) j =1) determines the non-uniform quantization interval R i The phase shift parameter can be set arbitrarily as needed, or its optimal value for a specific signal can be determined using a non-uniform quantization algorithm. The specific value is:
[0054]
[0055] Step 3: Threshold decision. Input n phase-shifting optical signals into the corresponding n threshold decision units to perform threshold decision operations and obtain the output code.
[0056] In this system, n optical signals undergo non-uniform phase shifting enter a non-uniform threshold decision module. Each optical signal enters a threshold decision unit for threshold decision and outputs a digital code. During the decision process, if the signal strength is greater than the threshold, the output code is "1"; if the signal strength is less than the threshold, the output code is "0". The decision threshold T of the i-th threshold decision unit is... i for:
[0057]
[0058] Specifically, such as Figure 4 As shown in the figure, the principle diagram of non-uniform phase-shifting optical quantization coding with n=8 and the corresponding coding of the quantization interval are given. The quantization interval ratio in the figure is 8:4:2:1:1:2:4:8 as an example.
[0059] Example 2
[0060] like Figure 5 As shown, this embodiment discloses a non-uniform phase-shifting optical quantization analog-to-digital converter based on an MZM array, including an MZM, a photonics detector (PD), and a comparator (COMP). The MZM is responsible for electro-optic modulation of the electrical signal and non-uniform phase shifting of the optical signal. The PD and COMP are combined to form a non-uniform threshold decision module, responsible for threshold comparison and output quantization encoding. Different comparators have different threshold voltages to achieve non-uniform quantization. Furthermore, 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. In a non-uniform phase-shifted optical quantization analog-to-digital converter based on an MZM array, V is first adjusted... bi To adjust the phase shift as This causes a non-uniform phase shift in the modulation characteristic curves between MZMs, resulting in the transmission characteristic curves required for non-uniform phase-shifted optical quantization. These curves are then input into V... s (t) and the optical sampling pulse are fed to n MZMs for electro-optic modulation and phase shifting. The optical signal from the MZM enters the PD for photoelectric conversion and the converted electrical signal is input into the COMP. Finally, the input electrical signal is judged and compared by setting the threshold voltage of the corresponding COMP to complete the non-uniform quantization and output the quantization code.
[0061] In summary, the non-uniform phase-shift optical quantization analog-to-digital converter of this invention better considers the impact of signal distribution on signal quantization, reduces quantization noise, and improves the quantization performance of the ADC at the same theoretical quantization accuracy. Simultaneously, optoelectronic technology can solve the problem of significant clock jitter in traditional electronic ADCs, greatly increasing the ADC speed. Furthermore, the decision thresholds in the threshold decision module of this invention are all less than half of the maximum output and close to zero, exhibiting better resistance to pulse amplitude jitter compared to uniform phase-shift optical quantization ADCs. Therefore, the analog-to-digital converter of this invention can be well applied to practical communication systems and meets the needs of signal acquisition systems.
[0062] 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-shifting optical quantization analog-to-digital converter, characterized in that, Includes an electro-optic modulator, a non-uniform phase shifter, and a non-uniform threshold decision module; The electro-optic modulator modulates the analog electrical signal to be quantized and the optical pulse signal to obtain the modulated optical signal, and inputs the modulated optical signal into the non-uniform phase shifter. The non-uniform phase shifter is used to perform phase shifting operation on the input optical signal, and the phase-shifted signal is input to the non-uniform threshold decision module. The non-uniform threshold decision module is used to perform threshold decision on the input optical signal to output digital code; The analog electrical signal is The output light intensity is normalized to: ； in, The half-wave voltage of the modulator; The non-uniform phase shifter includes a beam splitter and n phase shifters. The input optical signal is split into n paths by the beam splitter and input into the n phase shifters respectively. After passing through the phase shifters, 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 n=2N, phase shift parameters The specific value is: ； The non-uniform threshold decision includes n threshold decision units. n optical signals undergoing non-uniform phase shifting enter the non-uniform threshold decision module. Each optical signal enters a threshold decision unit for threshold decision and outputs a digital code. During the decision process, if the signal strength is greater than the threshold, the output code is "1"; if the signal strength is less than the threshold, the output code is "0". The decision threshold of the i-th threshold decision unit... for: 。