Dual-tone reference signal generation circuit

Abstract

The invention provides a dual-tone reference signal generating circuit, which comprises a power divider for receiving a reference signal and dividing the reference signal into a first reference signal and a second reference signal; the digital frequency divider is connected with the power divider to receive the first reference signal and generate a first multi-tone signal; the filter is connected with the power divider and is used for acquiring a first target signal; the combiner is used for receiving the first target signal and the second reference signal and carrying out combining processing to generate a combined output signal; the output amplifier is connected with the combiner and used for adjusting the amplitude of the combined output signal to form a second multi-tone signal; and the dual-frequency filter is connected with the output amplifier and is used for carrying out dual-frequency filtering on the second multi-tone signal to obtain a first target frequency component and a second target frequency component so as to form a dual-tone reference signal. According to the circuit, the dual-tone reference signal with an extremely high phase noise index can be obtained, the problem of phase noise deterioration caused by Nth harmonic waves of fundamental waves does not exist, and the index requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of microwave technology, and in particular to a dual-tone reference signal generating circuit. Background Art

[0002] Reference signals are the reference signals in the field of microwave technology, especially in frequency synthesis technology. The clock, local oscillator, calibration signal, etc. in the microwave system are based on the reference signal. In the long term, single-tone reference signals are the main ones in microwave technology frequency synthesis. Single-tone reference signals have limitations in generating special frequency synthesis. To meet the needs of special frequency synthesis, dual-tone reference signals are gradually being used.

[0003] The generation of a dual-tone reference signal requires that each frequency component has extremely low phase noise. A simple dual-tone reference signal generation method utilizes the multi-harmonic characteristics of the frequency-divided pulse to generate multiple harmonic signals of the fundamental signal generated by the frequency division of the input signal, from which a dual-tone signal is obtained. This method has the disadvantage that the phase noise of each frequency component deteriorates as the number of harmonic multiples of the dual-tone frequency component relative to the fundamental signal increases. For example, a 100MHz signal is divided by a 4-frequency divider to generate a 25MHz frequency component and its harmonic signal. The phase noise of the 125MHz frequency component deteriorates by about 14dB relative to the 25MHz frequency component (attenuation algorithm: 20log(125MHz / 25MHz)), and the 25MHz phase noise is limited by the divider noise floor. When the divider noise floor is -150dBc / Hz@1kHz, the theoretical phase noise limit of the 125MHz signal generated by this method is about -136dBc / Hz@1kHz, which is difficult to meet higher index requirements. Summary of the invention

[0004] The present invention aims to at least solve the technical problem in the prior art that the phase noise of each frequency component in the existing dual-tone reference signal generating circuit deteriorates as the number of harmonic multiples of the dual-tone frequency component relative to the fundamental signal increases.

[0005] To this end, the present invention provides a dual-tone reference signal generating circuit.

[0006] The present invention provides a dual-tone reference signal generating circuit, comprising:

[0007] A power divider receives a reference signal, and the power divider at least divides the reference signal into a first reference signal and a second reference signal;

[0008] A digital frequency divider, connected to the power divider, receives the first reference signal, and performs N-frequency division on the first reference signal to generate a first multi-tone signal;

[0009] A filter, connected to the power divider, filters the first multi-tone signal to obtain a first target signal with a set frequency;

[0010] A combiner, connected to the power divider and the filter respectively, to receive the first target signal and the second reference signal, and the combiner combines the first target signal and the second reference signal to generate a combined output signal;

[0011] an output amplifier connected to the combiner, and adjusting the amplitude of the combined output signal to form a second multi-tone signal;

[0012] A dual-frequency filter is connected to the output amplifier, and performs dual-frequency filtering on the second multi-tone signal to obtain a first target frequency component and a second target frequency component to form a dual-tone reference signal.

[0013] The dual-tone reference signal generating circuit according to the above technical solution of the present invention may also have the following additional technical features:

[0014] The above technical solution also includes:

[0015] A first signal adjuster is arranged between the filter and the combiner, and the first target signal is input into the combiner after the signal amplitude is adjusted by the first signal adjuster;

[0016] Wherein, the first signal adjuster includes an amplifier or an attenuator.

[0017] In the above technical solution, the signal amplitude relationship between the two frequency components in the dual-tone reference signal is adjusted by the first signal adjuster.

[0018] The above technical solution also includes:

[0019] A second signal adjuster is arranged between the combiner and the power divider, and the second reference signal is input into the combiner after the signal amplitude is adjusted by the second signal adjuster;

[0020] Wherein, the second signal adjuster includes an amplifier or an attenuator.

[0021] In the above technical solution, the amplitude adjustment standard of the second reference signal by the second signal adjuster includes:

[0022] The part of the combined output signal having the same frequency as the reference signal can make the output amplifier operate in a near-saturation state.

[0023] In the above technical solution, the method for setting the set frequency in the filter includes:

[0024]

[0025] Among them, f s Indicates the set frequency, f 0 represents the frequency of the reference signal, and N represents the division coefficient set by the digital divider.

[0026] In the above technical solution, the selection principles of the output amplifier include: low noise floor and low linearity;

[0027] Wherein, the low noise floor is the phase noise addition of the output amplifier not exceeding -150dBc / Hz@1kHz;

[0028] Low linearity means that the second-order intermodulation intercept point of the output amplifier is set low enough to enable the circuit to obtain an intermodulation signal.

[0029] In the above technical solution, the first target frequency component is equal to the frequency of the reference signal, and the second target frequency component is equal to the sum of the reference signal frequency and the first target signal frequency.

[0030] In the above technical solution, the first target frequency component is equal to the frequency of the reference signal, and the second target frequency component is equal to the difference between the reference signal frequency and the first target signal frequency.

[0031] In the above technical solution, the frequency of the reference signal is 100 MHz.

[0032] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are:

[0033] By adopting the circuit design of the present invention, a dual-tone reference signal with extremely high phase noise index can be obtained, and there is no phase noise deterioration problem caused by the Nth harmonic of the fundamental wave, and the index requirements are met. Specifically, the two frequency components in the present invention have homologous coherence, which can be well adapted to various usage requirements, has universality, and the circuit structure is easy to build, and has good engineering applicability.

[0034] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0036] Figure 1 It is a schematic diagram of the principle of a dual-tone reference signal generating circuit according to an embodiment of the present invention;

[0037] Figure 2 The present invention is a schematic diagram of a dual-tone reference signal generating circuit containing 100MHz / 125MHz frequency components according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0040] Refer to the following Figure 1 and Figure 2 A dual-tone reference signal generating circuit according to some embodiments of the present invention is described.

[0041] Some embodiments of the present application provide a dual-tone reference signal generating circuit.

[0042] like Figure 1 As shown, the first embodiment of the present invention provides a dual-tone reference signal generating circuit, including: a power divider, a digital frequency divider, a filter, a combiner, an output amplifier and a dual-frequency filter.

[0043] Among them, the power divider receives a reference signal, and the power divider at least divides the reference signal into a first reference signal and a second reference signal; and related signal processing is performed on the signal links where the first reference signal and the second reference signal are located, respectively, so as to ensure that the two frequency components in the final dual-tone reference signal have homologous coherence.

[0044] The digital frequency divider is connected to the power divider, receives the first reference signal, and divides the first reference signal by N to generate a first polyphonic signal. Specifically, the first reference signal is input into the digital frequency divider for frequency division to generate the first polyphonic signal. It is understandable that the first polyphonic signal includes a first target signal with a set frequency and multiple frequency components such as harmonics of the first target signal.

[0045] The filter is connected to the power divider to filter the first polyphonic signal to obtain a first target signal with a set frequency. The filter is mainly used to extract a frequency component with a set frequency from the first polyphonic signal.

[0046] Specifically, the method for setting the set frequency in the filter includes:

[0047]

[0048] Among them, f s Indicates the set frequency, f 0represents the frequency of the reference signal, and N represents the division coefficient set by the digital divider.

[0049] The combiner is connected to the power divider and the filter respectively to receive the first target signal and the second reference signal. The combiner combines the first target signal and the second reference signal to generate a combined output signal.

[0050] The combiner can perform addition or subtraction processing on the first target signal and the second reference signal, and should be set according to the use requirements of the dual-tone reference signal.

[0051] The output amplifier is connected to the combiner to adjust the amplitude of the combined output signal to form a second polyphonic signal. It is understandable that the second polyphonic signal includes multiple frequency components such as the reference signal frequency, the sum of the reference signal frequency and the set frequency, and the difference between the reference signal frequency and the set frequency.

[0052] The dual-frequency filter is connected to the output amplifier, performs dual-frequency filtering on the second multi-tone signal, obtains a first target frequency component and a second target frequency component, and forms a dual-frequency reference signal.

[0053] In a specific embodiment, the first target frequency component is equal to the frequency of the reference signal, and the second target frequency component is equal to the sum of the reference signal frequency and the first target signal frequency.

[0054] In another specific embodiment, the first target frequency component is equal to the frequency of the reference signal, and the second target frequency component is equal to the difference between the reference signal frequency and the first target signal frequency.

[0055] In some embodiments, the dual-tone reference signal generating circuit further includes a first signal adjuster.

[0056] The first signal adjuster is arranged between the filter and the combiner, and the first target signal is input into the combiner after the signal amplitude is adjusted by the first signal adjuster; wherein, the first signal adjuster can be an amplifier or an attenuator. By adjusting the signal amplitude of the first target signal input into the combiner through the first signal adjuster, the signal amplitude relationship of the two frequency components in the dual-tone reference signal can be adjusted.

[0057] In some embodiments, the dual-tone reference signal generating circuit further includes a second signal adjuster.

[0058] The second signal adjuster is arranged between the combiner and the power divider. The second reference signal is input into the combiner after the signal amplitude is adjusted by the second signal adjuster. The second signal adjuster may be an amplifier or an attenuator.

[0059] Specifically, the amplitude adjustment standard of the second reference signal by the second signal adjuster includes: making the frequency component of the combined output signal with the same frequency as the reference signal enable the output amplifier to operate in a near-saturation state.

[0060] It should be noted that in an actual application circuit, only one of the first signal adjuster and the second signal adjuster can be provided, or both can be provided at the same time, and can be flexibly selected according to the signal level.

[0061] In some embodiments, the selection principles of the output amplifier include: low noise floor, that is, low phase noise addition; and poor linearity, especially amplifiers with low OIP2 (output second-order intermodulation intercept point) indicators are preferred.

[0062] In a specific embodiment, the phase noise addition of the output amplifier does not exceed -150dBc / Hz@1kHz; the low linearity of the output amplifier specifically refers to: the value of the second-order intermodulation intercept point of the output amplifier is low, and its value is related to the signal link design, with the purpose of ensuring that the intermodulation signal is obtained.

[0063] In a specific embodiment, it is preferred to use a reference signal with a frequency of 100 MHz as the main signal to make the output amplifier work in a near saturation state.

[0064] Based on the 100MHz reference signal, a dual-tone reference signal containing two frequency components of 100MHz and 125MHz is generated. The phase noise of a single frequency component is better than -153dBc / Hz@1kHz. Figure 2 shown.

[0065] Among them, the 100MHz reference signal has an output power of 7dBm and a phase noise index better than -157dBc / Hz@1kHz. The first reference signal and the second reference signal generated after the power divider are input into the digital divider and the 1dB attenuator respectively.

[0066] A digital frequency divider with a low noise floor of -150dBc / Hz@1kHz and a frequency division coefficient of N=4 is used. According to the first reference signal, the digital frequency divider outputs a first multi-tone signal including multiple frequency components such as 25MHz and harmonics of 25MHz.

[0067] A 25MHz filter is used to extract the 25MHz frequency component of the first multi-tone signal to form a first target signal. The first target signal is input to the combiner after passing through a 3dB attenuator, and the amplitude of the 25MHz frequency signal in the combiner output signal is kept at about -10dBm.

[0068] The second reference signal is input to the combiner after passing through a 1 dB attenuator.

[0069] The combiner combines the attenuated first target signal and the second reference signal to generate a combined output signal, and inputs the combined output signal to the output amplifier; wherein the gain of the output amplifier is 22dB, the output P-1 is 20dBm, and has a noise floor better than -153dBc / Hz@1kHz. The amplitude of the 100MHz frequency component input to the output amplifier is approximately 0dBm, so that the amplifier works in a near saturation state.

[0070] The output signal of the output amplifier includes signals of frequencies such as 100MHz, 100MHz+25MHz, 100MHz-25MHz, etc. A dual-tone reference signal including 100MHz and 125MHz components is output through a 100MHz / 125MHz dual-frequency filter.

[0071] In this embodiment, thanks to the fact that both the 100MHz signal and the 25MHz signal have a phase noise index better than -150dBc / Hz@1kHz, and the output amplifier has a noise floor better than -150dBc / Hz@1kHz; the output amplifier, as an amplitude gain device, will not cause the problem of raising the noise floor of amplitude insertion loss devices (such as mixers), and the 100MHz and 125MHz frequency component signals in the final output signal have a phase noise index better than -150dBc / Hz@1kHz.

[0072] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0073] Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-tone reference signal generating circuit, characterized in that: include: A power divider receives a reference signal, and the power divider at least divides the reference signal into a first reference signal and a second reference signal; A digital frequency divider, connected to the power divider, receives the first reference signal, and performs N-frequency division on the first reference signal to generate a first multi-tone signal; A filter, connected to the power divider, filters the first multi-tone signal to obtain a first target signal with a set frequency; A combiner, connected to the power divider and the filter respectively, to receive the first target signal and the second reference signal, and the combiner combines the first target signal and the second reference signal to generate a combined output signal; An output amplifier connected to the combiner, adjusting the amplitude of the combined output signal and forming a second multi-tone signal through intermodulation; A dual-frequency filter is connected to the output amplifier, and performs dual-frequency filtering on the second multi-tone signal to obtain a first target frequency component and a second target frequency component to form a dual-tone reference signal.

2. The dual-tone reference signal generating circuit according to claim 1, wherein: Also includes: A first signal adjuster is arranged between the filter and the combiner, and the first target signal is input into the combiner after the signal amplitude is adjusted by the first signal adjuster; Wherein, the first signal adjuster includes an amplifier or an attenuator.

3. The dual-tone reference signal generating circuit according to claim 2, wherein: The signal amplitude relationship between two frequency components in the dual-tone reference signal is adjusted by the first signal adjuster.

4. The dual-tone reference signal generating circuit according to claim 1, wherein: Also includes: A second signal adjuster is arranged between the combiner and the power divider, and the second reference signal is input into the combiner after the signal amplitude is adjusted by the second signal adjuster; Wherein, the second signal adjuster includes an amplifier or an attenuator.

5. The dual-tone reference signal generating circuit according to claim 4, wherein: The amplitude adjustment standard of the second reference signal by the second signal adjuster includes: The part of the combined output signal having the same frequency as the reference signal can make the output amplifier operate in a near-saturation state.

6. The dual-tone reference signal generating circuit according to claim 1, characterized in that: The method for setting the set frequency in the filter includes: Among them, f s represents the set frequency, f0 represents the frequency of the reference signal, and N represents the division coefficient set by the digital divider.

7. The dual-tone reference signal generating circuit according to claim 1, characterized in that: The selection principles of the output amplifier include: low noise floor and low linearity; Wherein, the low noise floor is the phase noise addition of the output amplifier not exceeding -150dBc / Hz@1kHz; Low linearity means that the second-order intermodulation intercept point of the output amplifier is set low enough to enable the circuit to obtain an intermodulation signal.

8. The dual-tone reference signal generating circuit according to claim 1, characterized in that: The first target frequency component is equal to a frequency of a reference signal, and the second target frequency component is equal to a sum of a frequency of the reference signal and a frequency of the first target signal.

9. The dual-tone reference signal generating circuit according to claim 1, characterized in that: The first target frequency component is equal to the frequency of the reference signal, and the second target frequency component is equal to the difference between the reference signal frequency and the first target signal frequency.

10. The dual-tone reference signal generating circuit according to claim 1, characterized in that: The frequency of the reference signal is 100 MHz.

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