Feedback analog-to-digital converter based on LC voltage-controlled oscillator and implementation method thereof
By using a feedback analog-to-digital converter based on an LC-type voltage-controlled oscillator in Sigma-Delta analog-to-digital converter, the signal-to-noise ratio in traditional analog-to-digital converters is solved by quantizing the phase information of the oscillating signal using the feedback loop and the phase identification module. Reduce the problem of high phase noise, achieving higher precision and low power consumption analog-to-digital conversion effect.
Patent Information
- Application Number
- CN202411252980.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2044-09-09
AI Technical Summary
In the development of semiconductor processes, traditional Sigma-Delta analog-to-digital converters face the problems of reduced signal-to-noise ratio and high phase noise. In particular, the small number of phase nodes of LC-type voltage-controlled oscillators lead to difficulty in high-precision phase quantization, and voltage-frequency Conversion nonlinearity affects analog-to-digital conversion performance.
Design a feedback analog-to-digital converter based on LC-type voltage-controlled oscillator, including an operational amplifier module, an LC-type voltage-controlled oscillator module, a reference clock module and a phase identification module based on the delay chain, through feedback loops and phase identification The module quantizes the phase information of the oscillating signal, uses the incoherence of the input signal frequency and the sampling clock frequency to achieve dynamic element matching, reducing phase noise and nonlinear influence.
It achieves lower phase noise and higher linearity, improves analog-to-digital conversion accuracy, reduces the nonlinear influence of the phase identification module, and has the characteristics of low power consumption and simple structure.
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Figure CN118783968B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of analog-to-digital conversion based on time domain, and in particular to a feedback type analog-to-digital converter based on an LC type voltage-controlled oscillator and an implementation method thereof. Background Art
[0002] Analog-to-digital conversion technology is a bridge connecting the real world and modern information technology. The development of the modern Internet of Things has significantly increased the demand for miniaturized and low-power analog-to-digital conversion technology. Traditional analog-to-digital conversion technology is based on the voltage domain. Through precise voltage measurement and comparison, high-precision digitization is achieved. After decades of development, this technical idea has formed a diversified technical architecture that covers the needs of different application fields. However, with the development of semiconductor process technology, the operating voltage of chips is getting lower and lower. Although the reduction in operating voltage is conducive to the realization of large-scale digital integrated circuits, it brings new challenges to analog-to-digital conversion technology based on the voltage domain. Specifically, the reduction in operating voltage reduces the dynamic range of analog circuits and increases the difficulty of circuit structure migration with the process. The technical route of completing digitization in the time domain through voltage-time conversion provides a new idea for breaking through the many limitations faced by voltage domain analog-to-digital conversion. Voltage-controlled oscillator is a common voltage-to-time conversion device. This technical route converts the voltage signal into frequency or phase in the time domain through a voltage-controlled oscillator, and then realizes the digitization of electrical signals through frequency or phase measurement. The measurement of time quantities such as frequency or phase can be completely realized by digital circuits, and the measurement of high-precision time quantities is more in line with the development of advanced semiconductor processes.
[0003] In terms of technical characteristics, the analog-to-digital conversion technology based on voltage-controlled oscillators corresponds to the Sigma-Delta analog-to-digital converter (Σ-Δ ADC) in the voltage domain. In the era of the Internet of Things, Sigma-Delta analog-to-digital converters have been widely recognized. However, circuit modules such as operational transconductance amplifiers (OTAs) and comparators in traditional Sigma-Delta analog-to-digital converters may encounter many limitations during the development of semiconductor processes. With the development of semiconductor processes, the inherent gain of transistors decreases, and the power supply voltage of the circuit also decreases, which limits the input range of the circuit and leads to a decrease in the signal-to-noise ratio. Therefore, it is very important to design a Sigma-Delta analog-to-digital converter that adapts to the development of semiconductor processes.
[0004] Ring Oscillation (RO) type voltage controlled oscillator is a method to realize voltage controlled oscillator. RO type voltage controlled oscillator is realized by connecting several delay circuits in series to form an oscillation loop. The inverter circuit in the digital circuit is a typical delay unit. With the development of semiconductor technology, the unit delay of the delay circuit can be made smaller, which makes the structure more adaptable to the development of semiconductor technology. In the RO type voltage controlled oscillator, the phase quantization of the oscillation signal can be cleverly realized by using the output of each delay circuit node, which to a certain extent promotes the development of analog-to-digital conversion technology based on RO type voltage controlled oscillator. However, the phase noise of the voltage controlled oscillator is a key factor limiting the analog-to-digital conversion performance based on the voltage controlled oscillator. Under the same conditions, the phase noise of the RO type voltage controlled oscillator is higher than that of the LC type voltage controlled oscillator. Using LC type voltage controlled oscillator to realize analog-to-digital conversion is a potential implementation technology. However, the number of phase nodes of the LC type voltage controlled oscillator is only one, which increases the difficulty of high-precision phase quantization. At the same time, similar to the analog-to-digital converter implemented by the RO type voltage-controlled oscillator, the analog-to-digital converter based on the LC type voltage-controlled oscillator also needs to solve the impact of the voltage-frequency conversion nonlinearity of the voltage-controlled oscillator on the analog-to-digital conversion performance.
[0005] In view of this, the present invention is proposed. Summary of the invention
[0006] The purpose of the present invention is to provide a feedback type analog-to-digital converter based on an LC type voltage-controlled oscillator and an implementation method thereof, which can suppress the influence of the voltage-frequency conversion nonlinearity of the LC type voltage-controlled oscillator on the analog-to-digital conversion accuracy and improve the linearity. The scheme has the characteristics of low power consumption, simple structure, noise shaping, and self-contained phase quantization dynamic element matching, and can accurately measure the signal. Compared with the analog-to-digital converter implemented by using an oscillating ring type voltage-controlled oscillator, the present invention has better phase noise.
[0007] The objective of the present invention is achieved through the following technical solutions:
[0008] A feedback type analog-to-digital converter based on an LC type voltage-controlled oscillator comprises: an operational amplifier module, an LC type voltage-controlled oscillator module, a reference clock module, a phase identification module based on a delay chain and a digital-to-analog conversion module; wherein:
[0009] The operational amplifier module is used to calculate the difference between the input signal and the feedback signal output by the digital-to-analog conversion module;
[0010] The LC type voltage-controlled oscillator module is used to sense the difference result output by the operational amplifier module and convert it into an oscillation signal; wherein LC refers to the inductor L and the voltage-controlled capacitor C;
[0011] The reference clock module is used to generate a reference clock signal and output it to a phase identification module based on a delay chain;
[0012] The delay chain-based phase identification module is used to sample the oscillation signal output by the LC-type voltage-controlled oscillator module and identify the phase difference between the oscillation signal and the reference clock signal;
[0013] The digital-to-analog conversion module is used to perform digital-to-analog conversion on the phase difference value output by the phase identification module based on the delay chain, and output the feedback signal obtained after the conversion to the operational amplifier module.
[0014] A method for implementing a feedback analog-to-digital converter based on an LC voltage-controlled oscillator is implemented based on the aforementioned feedback analog-to-digital converter, the method comprising:
[0015] The difference between the input signal and the feedback signal output by the digital-to-analog conversion module is calculated by the operational amplifier module, and the difference is sent to the LC voltage-controlled oscillator module; the LC voltage-controlled oscillator module converts the difference into an oscillation signal; with the assistance of the reference clock signal generated by the reference clock module, the phase identification module based on the delay chain quantizes the phase information of the oscillation signal and the reference clock signal, and calculates the phase difference between the two signals. After the phase difference is converted by the digital-to-analog conversion module, the feedback signal obtained is output to the operational amplifier module.
[0016] It can be seen from the technical solution provided by the present invention that by quantizing the phase information of the voltage-controlled oscillator oscillation signal through a phase identification module and in combination with a feedback loop, the problem that the phase information quantization accuracy is limited by the single-phase node output of the LC-type voltage-controlled oscillator in the process of realizing analog-to-digital conversion using an LC-type voltage-controlled oscillator can be solved. Compared with the analog-to-digital converter implemented based on the RO-type voltage-controlled oscillator, the present invention uses an LC-type voltage-controlled oscillator to realize the conversion of voltage signals to time domain signals, and has better phase noise. The present invention also uses the incoherence of the input signal frequency and the sampling clock frequency to automatically realize dynamic element matching of phase quantization when quantizing the phase information of the voltage-controlled oscillator oscillation signal, thereby reducing the nonlinear influence of the phase identification module. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.
[0018] Figure 1 A schematic diagram of a feedback analog-to-digital converter based on an LC voltage-controlled oscillator provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.
[0020] First, the terms that may be used in this article are explained as follows:
[0021] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.
[0022] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.
[0023] The following is a detailed description of a feedback analog-to-digital converter based on an LC voltage-controlled oscillator and its implementation method provided by the present invention. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professional and technical personnel in the field. If no specific conditions are specified in the embodiments of the present invention, the conventional conditions in the field or the conditions recommended by the manufacturer are followed. If the manufacturer of the instruments used in the embodiments of the present invention is not specified, they are all conventional products that can be purchased commercially.
[0024] Embodiment 1
[0025] The embodiment of the present invention provides a feedback type analog-to-digital converter based on an LC type voltage-controlled oscillator, such as Figure 1As shown, it mainly includes: an operational amplifier module, an LC-type voltage-controlled oscillator module, a reference clock module, a phase identification module based on a delay chain, and a digital-to-analog conversion module; wherein: the operational amplifier module is used to calculate the difference result between the input signal and the feedback signal output by the digital-to-analog conversion module; the LC-type voltage-controlled oscillator module is used to sense the difference result (voltage signal) output by the operational amplifier module and convert it into an oscillation signal (time domain information); wherein LC refers to the inductor L and the voltage-controlled capacitor C; the reference clock module is used to generate a reference clock signal and output it to the phase identification module based on the delay chain; the phase identification module based on the delay chain is used to sample the oscillation signal output by the LC-type voltage-controlled oscillator module and identify the phase difference between it and the reference clock signal; the digital-to-analog conversion module is used to perform digital-to-analog conversion on the phase difference output by the phase identification module based on the delay chain, and output the feedback signal obtained after the conversion to the operational amplifier module to form a feedback loop. The feedback loop realizes the same frequency between the oscillation signal generated by the LC-type voltage-controlled oscillator module and the clock signal generated by the reference clock module. Then, when the oscillation signal generated by the LC-type voltage-controlled oscillator module is transmitted in the delay chain, the phase sampling and quantization of the oscillation signal of the LC-type voltage-controlled oscillator module can be realized through the phase identification module based on the delay chain with the assistance of the reference clock module.
[0026] like Figure 1 As shown in the figure, the main structure of the feedback analog-to-digital converter based on the LC type voltage-controlled oscillator is demonstrated; the meanings of the various marks are as follows: 1—input signal; 2—difference result of the input signal and the feedback signal; 3—LC type voltage-controlled oscillator module; 4—oscillation signal of the LC type voltage-controlled oscillator module; 5—reference clock signal of the reference clock module; 6—phase identification module based on delay chain; 7—phase identification result (i.e., phase difference information) of the phase identification module based on delay chain; 8—feedback signal.
[0027] In an embodiment of the present invention, the operational amplifier module realizes a subtractor function with a single-ended output, and includes two input terminals and one output terminal, wherein the two input terminals respectively input an input signal or a feedback signal output by the digital-to-analog conversion module, and the output terminal outputs a difference result.
[0028] In the embodiment of the present invention, the LC type voltage controlled oscillator module includes: an oscillation network composed of an inductor L and a voltage controlled capacitor C, through which a voltage signal is sensed and converted into an oscillation signal; the voltage signal is a signal corresponding to the difference result. The LC type voltage controlled oscillator used in the embodiment of the present invention has very low phase noise and can better realize the conversion of voltage signals to time domain signals.
[0029] In the embodiment of the present invention, the reference clock module is implemented using a clock generating device, and the reference clock signal generated by the reference clock module is used as an input signal of the delay chain-based phase identification module to assist the operation of the delay chain-based phase identification module.
[0030] In the embodiment of the present invention, the phase identification module based on the delay chain includes two delay chains (i.e. Figure 1 The delay chain A and the delay chain B in the embodiment of the present invention) and the phase identification circuit, each delay chain inputs the oscillation signal or the reference clock signal separately, and the outputs of the two delay chains are passed through the phase identification circuit to obtain the phase difference information. The phase identification module based on the delay chain used in the embodiment of the present invention can use the delay chain to achieve a very high equivalent sampling rate, thereby improving the phase quantization accuracy of the oscillation signal of the LC type voltage-controlled oscillator module.
[0031] In the embodiment of the present invention, each delay chain is composed of a set number of delay units. For example, the number of delay units constituting each delay chain may be 50. Of course, the specific number may be set according to actual conditions, and the present invention does not limit it.
[0032] In an embodiment of the present invention, in a feedback loop, the oscillation frequency of the LC-type voltage-controlled oscillator module is adjusted by the difference result to achieve the same frequency of the signal center frequency of the LC-type voltage-controlled oscillator module and the reference clock signal; when the feedback loop tends to be stable, that is, the feedback loop follows the input signal change to achieve the same frequency of the output signal center frequency of the voltage-controlled oscillator module and the reference clock signal, the delay chain in the phase identification module based on the delay chain is used to divide the phase of the oscillation signal and the reference clock signal equally; when the oscillation signal generated by the LC-type voltage-controlled oscillator module and the reference clock signal generated by the reference clock module are transmitted in the delay chain, the sampling and quantization of the phase can be respectively achieved by sampling the delay unit state of the delay chain.
[0033] In the embodiment of the present invention, when the feedback loop tends to be stable, the oscillation frequency of the LC type voltage controlled oscillator module changes with the input signal, and the center frequency of the oscillation signal remains the same as the reference clock frequency. Due to the incoherence of the input signal frequency and the sampling clock frequency, when the oscillation signal phase is quantized through the delay chain, it will automatically have a dynamic element matching function, which can effectively suppress the nonlinear effect caused by the non-uniformity of the delay unit of the delay chain.
[0034] The feedback analog-to-digital converter provided in the embodiments of the present invention can solve the following technical problems: (1) The performance of the analog-to-digital converter implemented based on the RO voltage-controlled oscillator is limited by its phase noise; (2) In the analog-to-digital converter implemented based on the LC voltage-controlled oscillator, the phase information quantization accuracy is limited by the single-phase node output of the LC voltage-controlled oscillator; (3) In the analog-to-digital converter implemented based on the LC voltage-controlled oscillator, the "voltage-frequency" conversion nonlinearity of the LC voltage-controlled oscillator limits the analog-to-digital conversion performance.
[0035] In addition, the following beneficial effects can be achieved: based on the phase identification module of the delay chain, the phase information of the oscillation signal of the voltage-controlled oscillator is quantized in combination with the feedback loop, which can solve the problem that the quantization accuracy of the phase information is limited by the single-phase node output of the LC-type voltage-controlled oscillator in the process of realizing analog-to-digital conversion using the LC-type voltage-controlled oscillator. Compared with the analog-to-digital converter realized by the RO-type voltage-controlled oscillator, the present invention uses an LC-type voltage-controlled oscillator to realize the conversion of the voltage signal to the time domain signal, and has better phase noise. The present invention also uses the incoherence of the input signal frequency and the sampling clock frequency to automatically realize the dynamic element matching of the phase quantization when quantizing the phase information of the oscillation signal of the voltage-controlled oscillator, thereby reducing the nonlinear influence of the phase identification module based on the delay chain.
[0036] Embodiment 2
[0037] The present invention also provides a method for implementing a feedback analog-to-digital converter based on an LC voltage-controlled oscillator, which is mainly based on the feedback analog-to-digital converter provided by the above embodiment. The method mainly includes:
[0038] The difference between the input signal and the feedback signal output by the digital-to-analog conversion module is calculated by the operational amplifier module, and the difference is sent to the LC voltage-controlled oscillator module; the LC voltage-controlled oscillator module converts the difference into an oscillation signal; with the assistance of the reference clock signal generated by the reference clock module, the phase identification module based on the delay chain quantizes the phase information of the oscillation signal and the reference clock signal, and calculates the phase difference between the two signals. After the phase difference is converted by the digital-to-analog conversion module, the feedback signal obtained is output to the operational amplifier module.
[0039] Considering that the main technical principles involved in this method have been introduced in detail in the previous embodiments, they will not be repeated here.
[0040] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A feedback type analog-to-digital converter based on an LC type voltage-controlled oscillator, characterized in that: include: Operational amplifier module, LC voltage-controlled oscillator module, reference clock module, delay chain-based phase identification module and digital-to-analog conversion module; wherein: The operational amplifier module is used to calculate the difference between the input signal and the feedback signal output by the digital-to-analog conversion module; The LC type voltage-controlled oscillator module is used to sense the difference result output by the operational amplifier module and convert it into an oscillation signal; wherein LC refers to the inductor L and the voltage-controlled capacitor C; The reference clock module is used to generate a reference clock signal and output it to a phase identification module based on a delay chain; The delay chain-based phase identification module is used to sample the oscillation signal output by the LC-type voltage-controlled oscillator module and identify the phase difference between the oscillation signal and the reference clock signal; The digital-to-analog conversion module is used to perform digital-to-analog conversion on the phase difference value output by the phase discrimination module based on the delay chain, and output the feedback signal obtained after the conversion to the operational amplifier module to form a feedback loop; When the feedback loop tends to be stable, that is, the feedback loop follows the input signal change to achieve the same frequency of the center frequency of the output signal of the voltage-controlled oscillator module as the reference clock signal, the delay chain in the delay chain-based phase identification module is used to divide the phase of the oscillation signal and the reference clock signal equally; and, when the feedback loop tends to be stable, the oscillation signal frequency of the LC-type voltage-controlled oscillator module follows the input signal change, and the center frequency of the oscillation signal remains the same as the reference clock signal frequency. When the oscillation signal phase is quantized through the delay chain, dynamic element matching of the phase quantization is automatically achieved.
2. The feedback analog-to-digital converter based on an LC voltage-controlled oscillator according to claim 1, characterized in that: The operational amplifier module realizes the subtractor function of single-ended output, and comprises two input terminals and one output terminal. The two input terminals respectively input input signals or feedback signals output by the digital-to-analog conversion module, and the output terminal outputs a difference result.
3. The feedback analog-to-digital converter based on an LC voltage-controlled oscillator according to claim 1, characterized in that: The LC type voltage-controlled oscillator module includes: an oscillation network composed of an inductor L and a voltage-controlled capacitor C, through which a voltage signal is sensed and converted into an oscillation signal; the voltage signal is a signal corresponding to the difference result.
4. The feedback analog-to-digital converter based on an LC voltage-controlled oscillator according to claim 1, characterized in that: The reference clock module is implemented using a clock generating device. The reference clock signal generated by the reference clock module is used as an input signal of the phase identification module based on the delay chain to assist the operation of the phase identification module based on the delay chain.
5. The feedback analog-to-digital converter based on an LC voltage-controlled oscillator according to claim 1, characterized in that: The delay chain-based phase identification module comprises two delay chains and a phase identification circuit. Each delay chain is independently input with an oscillation signal or a reference clock signal. The outputs of the two delay chains are passed through the phase identification circuit to obtain a phase difference.
6. The feedback type analog-to-digital converter based on the LC type voltage-controlled oscillator according to claim 5, characterized in that: Also includes: Each delay chain is composed of a set number of delay units.
7. A feedback analog-to-digital converter based on an LC voltage-controlled oscillator according to any one of claims 1 to 6, characterized in that: Also includes: In the feedback loop, the oscillation frequency of the LC type voltage controlled oscillator module is adjusted by the difference result, so that the signal center frequency of the LC type voltage controlled oscillator module is synchronized with the reference clock signal; When the feedback loop tends to be stable, that is, the feedback loop follows the input signal change to achieve the same frequency of the output signal center frequency of the voltage-controlled oscillator module as the reference clock signal, the delay chain in the delay chain-based phase identification module is used to divide the phase of the oscillation signal and the reference clock signal equally; when the oscillation signal generated by the LC-type voltage-controlled oscillator module and the reference clock signal generated by the reference clock module are transmitted in the delay chain, the sampling and quantization of the phase are respectively realized by sampling the delay unit state of the delay chain.
8. A method for implementing a feedback analog-to-digital converter based on an LC voltage-controlled oscillator, characterized in that: Based on the feedback analog-to-digital converter according to any one of claims 1 to 7, the method comprises: The difference between the input signal and the feedback signal output by the digital-to-analog conversion module is calculated by the operational amplifier module, and the difference is sent to the LC voltage-controlled oscillator module; the LC voltage-controlled oscillator module converts the difference into an oscillation signal; with the assistance of the reference clock signal generated by the reference clock module, the phase identification module based on the delay chain quantizes the phase information of the oscillation signal and the reference clock signal, and calculates the phase difference between the two signals. After the phase difference is converted by the digital-to-analog conversion module, the feedback signal obtained is output to the operational amplifier module.