A voltage-controlled radio frequency source and acousto-optic modulation system

Abstract

The utility model relates to the technical field of voltage control radio frequency source, especially a kind of voltage control radio frequency source and acousto-optic modulation system. The utility model by introducing voltage frequency converter and phase-locked loop structure, the second frequency signal of voltage control radio frequency source final output is only decided by three highly stable factors of external voltage, voltage frequency conversion coefficient of voltage frequency converter and frequency division ratio of phase-locked loop;Wherein, the negative feedback mechanism inside the phase-locked loop can automatically compensate the frequency drift caused by temperature, voltage fluctuation of its internal voltage-controlled oscillator, so that the output frequency is no longer sensitive to temperature and other environmental changes;Make the output frequency of voltage control radio frequency source only related to external voltage and frequency division ratio of phase-locked loop, no longer affected by temperature change;The negative feedback mechanism of phase-locked loop effectively suppresses phase noise, improves the stability of high-frequency communication system output signal;Output frequency and external voltage are in strict linear relationship, facilitate system calibration and application extension.

Description

Technical Field

[0001] This utility model relates to the field of voltage-controlled radio frequency source technology, and in particular to a voltage-controlled radio frequency source and an acousto-optic modulation system. Background Technology

[0002] Traditional voltage-controlled RF sources typically use an external voltage to directly drive a voltage-controlled oscillator (VCO), and then amplify the RF signal using a power amplifier (PA) to achieve frequency modulation. While this structure is simple, it has the following significant drawbacks: 1. Poor temperature stability: When the external driving voltage remains constant, changes in ambient temperature can cause the VCO output frequency to drift, affecting the frequency stability of the system.

[0003] 2. High phase noise: The VCO output signal has high phase noise, which can lead to signal distortion and increased bit error rate, especially in applications such as communication systems where high frequency purity is required.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Utility Model Content

[0005] The technical problem to be solved by this invention is that the frequency output of traditional voltage-controlled radio frequency sources is greatly affected by temperature and has high phase noise, which affects the performance of high-frequency communication systems.

[0006] The present invention adopts the following technical solution: In one aspect, a voltage-controlled radio frequency source is provided, comprising: a voltage-frequency converter, a phase-locked loop, and a power amplifier connected in sequence; The voltage-frequency converter is used to convert external voltage into a first frequency signal; The phase-locked loop is used to lock the first frequency signal and generate a second frequency signal; The power amplifier is used to amplify the power of the second frequency signal before outputting it.

[0007] Preferably, the phase-locked loop includes a phase detector, a loop filter, a voltage-controlled oscillator, and a frequency divider; The phase detector, the loop filter, and the voltage-controlled oscillator are connected in sequence; The output terminal of the voltage-controlled oscillator is connected to the input terminal of the power amplifier and the input terminal of the frequency divider, respectively. The first input terminal of the phase detector is connected to the output terminal of the voltage-frequency converter; the output terminal of the frequency divider is connected to the second input terminal of the phase detector.

[0008] Preferably, the phase detector model includes: HMC439QS16G or HMC3716LP4E.

[0009] Preferably, the voltage-controlled oscillator includes models such as POS-100+, POS-150+, or POS-200+.

[0010] Preferably, the frequency divider model includes: HMC365S8G, HMC361S8G or HMC494LP3.

[0011] Preferably, the first frequency signal f1 = k × V; where k is the voltage-frequency conversion coefficient and V is the external voltage.

[0012] Preferably, the second frequency signal f2 = N × f1; where N is the frequency division ratio of the phase-locked loop and f1 is the first frequency signal.

[0013] Preferably, the voltage-frequency converter includes models such as AD654, AD652, or VFC110.

[0014] Preferably, the power amplifier model includes: ADL5545ARKZ, ADL5611ARKZ or HMC625BLP5ETR.

[0015] In a second aspect, an acousto-optic modulation system is provided, comprising a voltage-controlled radio frequency source as described in the first aspect and an acousto-optic device, wherein the input terminal of the acousto-optic device is used to connect to the output terminal of the power amplifier.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention introduces a voltage-to-frequency converter and a phase-locked loop (PLL) structure. The second frequency signal output by the voltage-controlled RF source is determined only by three highly stable factors: the external voltage, the voltage-to-frequency conversion coefficient of the voltage-to-frequency converter, and the division ratio of the PLL. The negative feedback mechanism within the PLL automatically compensates for frequency drift caused by temperature and voltage fluctuations in its internal voltage-controlled oscillator, thus making the output frequency insensitive to environmental changes such as temperature. This ensures that the output frequency of the voltage-controlled RF source is only related to the external voltage and the division ratio of the PLL, and is no longer affected by temperature changes. Simultaneously, the negative feedback mechanism of the PLL effectively suppresses phase noise, improving the stability of the output signal of the high-frequency communication system. The output frequency exhibits a strict linear relationship with the external voltage, facilitating system calibration and application expansion. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an existing voltage-controlled radio frequency source provided in an embodiment of this utility model; Figure 2 This is a schematic diagram of the structure of a voltage-controlled radio frequency source provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a phase-locked loop provided in an embodiment of this utility model; Figure 4 This is a schematic diagram of the specific structure of a voltage-controlled radio frequency source provided in this embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0020] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0021] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0022] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling" or "wireless connection." The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0023] Furthermore, the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0024] Example 1: In traditional circuits, such as Figure 1 As shown, the output frequency of a VCO can drift with factors such as ambient temperature and component aging, resulting in unstable output frequency even when the control voltage remains constant. On the other hand, traditional VCOs inherently have high phase noise, leading to an impure spectrum in the output signal, which is a fatal weakness in applications requiring high signal-to-noise ratio and low bit error rate (such as communication and precision measurement).

[0025] To address the aforementioned problems, this embodiment proposes a voltage-controlled radio frequency source. In one embodiment, such as... Figure 2 As shown, it includes: a voltage-to-frequency converter (VFC), a phase-locked loop (PLL), and a power amplifier (PA) connected in sequence; the voltage-to-frequency converter is used to convert an external voltage into a first frequency signal; the PLL is used to lock the first frequency signal and generate a second frequency signal; the power amplifier is used to amplify the power of the second frequency signal and output it.

[0026] This embodiment employs an innovative three-stage cascaded architecture of VFC+PLL+PA. Specifically, the first stage uses a voltage-to-frequency converter to linearly and stably convert the external voltage, an analog quantity, into a low-frequency first-frequency signal. This transitions from the easily disturbed voltage domain to a more stable and accurate frequency domain. In one embodiment, the voltage-to-frequency converter may be an AD654, AD652, or VFC110.

[0027] The second stage is the core of the entire embodiment. It uses a phase-locked loop (PLL) to take the first frequency signal output by the voltage-to-frequency converter as its reference frequency. A negative feedback closed-loop system, including a phase-frequency detector, loop filter, and frequency divider, forces the second frequency signal generated by the internal voltage-controlled oscillator to maintain strict synchronization with the reference frequency (i.e., the first frequency signal). The PLL includes a VCO, and its specific structure is described in the following embodiment.

[0028] Finally, a third-stage power amplifier amplifies the optimized and stabilized RF signal (i.e., the second frequency signal) to ensure it has sufficient power to drive subsequent loads. In one embodiment, the power amplifier may be an ADL5545ARKZ, ADL5611ARKZ, or HMC625BLP5ETR.

[0029] In one embodiment, the first frequency signal f1 = k × V; where k is the voltage-to-frequency conversion coefficient and V is the external voltage. The second frequency signal f2 = N × f1; where N is the frequency division ratio of the phase-locked loop and f1 is the first frequency signal.

[0030] In one embodiment, combining the above formula, the second frequency signal ultimately output by the voltage-controlled RF source is determined only by three highly stable factors: the external voltage V, the voltage-to-frequency conversion coefficient k of the voltage-to-frequency converter, and the frequency division ratio N of the phase-locked loop. The negative feedback mechanism within the phase-locked loop automatically compensates for frequency drift caused by temperature and voltage fluctuations in its internal voltage-controlled oscillator, thus making the output frequency less sensitive to environmental changes such as temperature.

[0031] In the locked state, the phase noise of the output signal in the region far from the center frequency depends primarily on the performance of its internal voltage-controlled oscillator (VCO), while in the critical region closer to the center frequency, its phase noise is mainly determined by the phase noise of the reference source (i.e., the first frequency signal). Since voltage-to-frequency converters can typically operate at lower frequencies and can be designed to be very stable, their phase noise is much lower than that of VCOs operating directly at radio frequency. Therefore, the near-end phase noise of the entire system is significantly optimized. Finally, the final stage power amplifier ensures that the system achieves excellent frequency stability and spectral purity without sacrificing its driving capability, enabling direct application in various practical scenarios. The specific amplification level of the power amplifier needs to be set according to the actual application scenario, and will not be discussed further in this embodiment.

[0032] In one embodiment, such as Figure 3 and Figure 4 As shown, the phase-locked loop includes a phase detector (PFD), a loop filter, a voltage-controlled oscillator (VCO), and an N divider; the phase detector, the loop filter, and the VCO are connected in sequence; refer to Figure 4 The output terminal of the voltage-controlled oscillator (i.e., the RF OUT terminal) is connected to the input terminal of the power amplifier and the input terminal of the frequency divider (i.e., the IN terminal), respectively; the first input terminal of the phase detector (i.e., the REF terminal) is connected to the output terminal of the voltage-frequency converter; and the output terminal of the frequency divider (i.e., the OUT terminal) is connected to the second input terminal of the phase detector (i.e., the VCO terminal).

[0033] The system uses a voltage-to-frequency converter as its front end to linearly convert the external voltage into a stable, low-frequency first frequency signal.

[0034] In one embodiment, the phase detector receives a reference frequency (first frequency signal) from a voltage-to-frequency converter at its first input terminal and a feedback frequency f2 / N from a frequency divider at its second input terminal. The phase and frequency of the two signals are continuously compared, and an error signal proportional to the difference between them is output. The phase detector may be of model HMC439QS16G or HMC3716LP4E.

[0035] The loop filter filters the error signal output by the phase detector, removes high-frequency noise, and converts it into a smooth and stable DC control voltage. In one embodiment, the loop filter can use a conventional operational amplifier, and the specific selection of the loop filter is not specifically limited in this embodiment.

[0036] The voltage-controlled oscillator generates a final second frequency signal based on the control voltage provided by the loop filter. In one embodiment, the voltage-controlled oscillator includes models such as POS-100+, POS-150+, or POS-200+.

[0037] The frequency divider divides the high output frequency (second frequency) signal of the voltage-controlled oscillator (VCO) to obtain f2 / N, and sends this ratio back to the phase detector for comparison with f1, thus closing the loop. The division ratio N determines the ratio between the final output frequency and the reference frequency. In one embodiment, the frequency divider includes models such as HMC365S8G, HMC361S8G, or HMC494LP3.

[0038] Finally, the power amplifier amplifies the RF signal (i.e., the second frequency signal) after it has been optimized and stabilized by the phase-locked loop to drive the subsequent load.

[0039] In one embodiment, refer to Figure 4 The +VS terminal of the voltage-frequency converter is used to receive external voltage. The FOUT terminal of the voltage-frequency converter is connected to the REF terminal of the phase detector. The NU and ND terminals of the phase detector are connected to the negative and positive input terminals of the loop filter, respectively. The output terminal of the loop filter is connected to the V-TUNE terminal of the voltage-controlled oscillator. The RF OUT terminal of the voltage-controlled oscillator is connected to the input terminal of the power amplifier. The RF OUT terminal of the voltage-controlled oscillator is also connected to the IN terminal of the frequency divider. The OUT terminal of the frequency divider is connected to the VCO terminal of the phase detector.

[0040] It is worth noting that the specific circuit structure of the voltage-controlled radio frequency source is described in reference to... Figure 4 Different models of devices have different connection methods, which will not be explained in detail in this embodiment.

[0041] In summary, this embodiment proposes an improved circuit to address the shortcomings of conventional circuits, thereby enhancing frequency stability and phase noise. The specific implementation method is as follows: an external voltage is converted into a first frequency signal f1 with a correlation to it using a voltage-to-frequency converter, specifically f1 = k × V; simultaneously, a phase-locked loop (PLL) negative feedback circuit architecture is introduced, ensuring a strong positive correlation between the second frequency signal f2 output by the VCO and the first frequency signal f1 of the VFC, specifically f2 = N × f1; ultimately, the VCO output frequency f2 = k × N × V. Using this method, the VCO output frequency is no longer affected by temperature changes and is only related to the external voltage. Furthermore, the presence of the PLL optimizes phase noise.

[0042] This embodiment introduces a voltage-to-frequency converter and a phase-locked loop (PLL) structure, so that the output frequency of the voltage-controlled RF source is only related to the external voltage and the division ratio of the PLL, and is no longer affected by temperature changes. At the same time, the negative feedback mechanism of the PLL effectively suppresses phase noise and improves the stability of the output signal of the high-frequency communication system. The output frequency has a strict linear relationship with the external voltage, which facilitates system calibration and application expansion.

[0043] Example 2: This embodiment proposes an acousto-optic modulation system, including the voltage-controlled radio frequency source and the acousto-optic device, wherein the input terminal of the acousto-optic device is used to connect to the output terminal of the power amplifier.

[0044] This embodiment introduces a voltage-to-frequency converter and a phase-locked loop (PLL) structure, so that the output frequency of the voltage-controlled RF source is only related to the external voltage and the division ratio of the PLL, and is no longer affected by temperature changes. At the same time, the negative feedback mechanism of the PLL effectively suppresses phase noise and improves the stability of the output signal of the high-frequency communication system. The output frequency has a strict linear relationship with the external voltage, which facilitates system calibration and application expansion.

[0045] For the specific structure of the voltage-controlled radio frequency source, please refer to Embodiment 1, which will not be repeated in this embodiment.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A voltage-controlled radio frequency source, characterized in that, include: A voltage-to-frequency converter, a phase-locked loop, and a power amplifier are connected in sequence. The voltage-frequency converter is used to convert external voltage into a first frequency signal; The phase-locked loop is used to lock the first frequency signal and generate a second frequency signal; The power amplifier is used to amplify the power of the second frequency signal before outputting it; The phase-locked loop includes a phase detector, a loop filter, a voltage-controlled oscillator, and a frequency divider; The phase detector, the loop filter, and the voltage-controlled oscillator are connected in sequence; The output terminal of the voltage-controlled oscillator is connected to the input terminal of the power amplifier and the input terminal of the frequency divider, respectively. The first input terminal of the phase detector is connected to the output terminal of the voltage-frequency converter; the output terminal of the frequency divider is connected to the second input terminal of the phase detector.

2. The voltage-controlled radio frequency source according to claim 1, characterized in that, The phase detector models include HMC439QS16G or HMC3716LP4E.

3. The voltage-controlled radio frequency source according to claim 1, characterized in that, The voltage-controlled oscillator models include: POS-100+, POS-150+, or POS-200+.

4. The voltage-controlled radio frequency source according to claim 1, characterized in that, The frequency divider models include: HMC365S8G, HMC361S8G, or HMC494LP3.

5. The voltage-controlled radio frequency source according to claim 1, characterized in that, The first frequency signal f1 = k × V; where k is the voltage-frequency conversion coefficient and V is the external voltage.

6. The voltage-controlled radio frequency source according to claim 1, characterized in that, The second frequency signal f2 = N × f1; where N is the frequency division ratio of the phase-locked loop and f1 is the first frequency signal.

7. The voltage-controlled radio frequency source according to claim 1, characterized in that, The voltage-frequency converter models include AD654, AD652, or VFC110.

8. The voltage-controlled radio frequency source according to claim 1, characterized in that, The power amplifier models include: ADL5545ARKZ, ADL5611ARKZ, or HMC625BLP5ETR.

9. An acousto-optic modulation system, characterized in that, Includes a voltage-controlled radio frequency source as described in any one of claims 1-8 and an acousto-optic device, wherein the input terminal of the acousto-optic device is used to connect to the output terminal of the power amplifier.

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