CN112653459A - Radio frequency signal source capable of being calibrated in real time - Google Patents

The invention discloses a radio frequency signal source capable of being calibrated in real time, which consists of a reference source circuit, a phase-locked loop circuit, a filter circuit and a control circuit; the reference source circuit is used for providing a reference signal for the phase-locked loop circuit; the phase-locked loop circuit adopts a broadband frequency synthesizer integrated with a VCO to form a closed loop circuit and generate a frequency signal; the filter circuit realizes the segmented filtering of the frequency signal through shunting and outputs 20M-6G signals; and the control circuit performs gain control and real-time calibration on the 20M-6G signals output by the filter circuit and outputs a required radio frequency signal source. The signal source of the invention adopts the broadband frequency synthesizer integrated with the VCO to replace the traditional VCO, thereby reducing the cost and optimizing the stray.

Radio frequency signal source capable of being calibrated in real time

Technical Field

The invention belongs to the technical field of radio frequency signal sources, and particularly relates to a radio frequency signal source capable of being calibrated in real time.

Background

Due to the gradual development of the technical level of the communication industry in recent years, people have gradually entered the era of the communication industry, and the radio frequency information technology gradually covers more and more fields. The communication technology makes important contributions to national defense industry construction, aerospace industry development and communication development of other civil enterprises. Under this condition, the development of radio frequency signal sources for communication technology is an indispensable instrument. The demand of the radio frequency signal source is gradually increased, and the quality requirement of the radio frequency signal source is also improved. There is a need for efficient, convenient, and practical instruments. Most of the existing radio frequency signal sources are too large in size and heavy in mass, so that the radio frequency signal sources are not flexible and convenient enough in the using process, large in occupied space and inconvenient to move and carry, the using efficiency of the radio frequency signal sources is low, and the functions of instruments cannot be fully played. At present, most radio frequency signal sources have large power consumption, and the service life of the radio frequency signal sources is generally long, so that the power consumption of enterprises is caused. And the price of the instrument is high, so that the production cost of an enterprise is increased. Some radio frequency signal sources have small use frequency range (only 3G) and cannot meet the production use.

Disclosure of Invention

The invention provides a radio frequency signal source capable of being calibrated in real time, aiming at solving the technical problems of large volume, large power consumption or small using frequency range of the existing radio frequency signal source. The frequency range of the signal source in this embodiment is 20M-6000M, and the power range is-100 dBm-15 dBm.

The invention is realized by the following technical scheme:

the invention relates to a radio frequency signal source capable of being calibrated in real time, which consists of a reference source circuit, a phase-locked loop circuit, a filter circuit and a control circuit;

the reference source circuit is used for providing a reference signal for the phase-locked loop circuit;

the phase-locked loop circuit adopts a broadband frequency synthesizer integrated with a VCO to form a closed loop circuit and generate a frequency signal;

the filter circuit realizes the segmented filtering of the frequency signal through shunting and outputs 20M-6G signals;

and the control circuit performs gain control and real-time calibration on the 20M-6G signals output by the filter circuit and outputs a required radio frequency signal source.

Preferably, the reference source circuit of the invention comprises a crystal oscillator for generating a reference signal, wherein a signal generated by the crystal oscillator is amplified by a first amplifier and then sent to a first radio frequency switch after passing through a first resistance attenuator;

an external reference signal passes through a second resistance attenuator and then is sent to a second amplifier through a first-stage filter to be amplified and then is input to a first power divider, one path of output signal of the first power divider is sent to the first radio-frequency switch through a second-stage filter, the other path of output signal of the first power divider is input to the detection circuit, and the detection circuit output signal controls the first radio-frequency switch to select a signal output by the first attenuator or a signal output by the second-stage filter;

a signal passing through the first radio frequency switch passes through a third resistance attenuator and then is input into a third amplifier for amplification and then is input into a second power divider, and one path of output signal of the second power divider is output to the outside through a fourth-stage filter and used as reference output; and the other path of output signal of the second power divider passes through a third-stage filter and then is supplied to the phase-locked loop as a reference signal.

Preferably, the phase-locked loop circuit of the invention comprises a phase detector, a loop filter, a wideband frequency synthesizer of an integrated VCO, a fourth resistive attenuator and a fourth amplifier;

the phase detector receives the reference signal output by the reference source circuit, the output voltage controls the VCO part of the wideband frequency synthesizer of the integrated VCO after passing through the loop filter, the output of the wideband frequency synthesizer of the integrated VCO sequentially passes through the fourth resistance attenuator and the fourth amplifier and then is input to the feedback end of the phase detector, so that a closed loop is formed, and the output of the wideband frequency synthesizer of the integrated VCO is simultaneously sent to the filter circuit.

Preferably, the filter circuit of the present invention includes a fifth amplifier, a shunt filter unit, a fifth resistive attenuator, and a sixth amplifier;

and the fifth amplifier amplifies the output signal of the wideband frequency synthesizer of the integrated VCO, then sends the amplified output signal to the shunt filter unit for shunt filtering, and then sequentially processes the amplified output signal through the fifth resistance attenuator and the sixth amplifier and outputs the amplified output signal to the control circuit.

Preferably, the shunt filter unit of the present invention includes a single-pole multi-throw switch a, a single-pole multi-throw switch B, a single-pole multi-throw switch C, and a single-pole multi-throw switch D;

a plurality of filters are arranged in parallel between the single-pole multi-throw switch A and the single-pole multi-throw switch C; a plurality of filters are arranged in parallel between the single-pole multi-throw switch B and the single-pole multi-throw switch D; the single-pole multi-throw switch A and the single-pole multi-throw switch B are connected in parallel, and the single-pole multi-throw switch C and the single-pole multi-throw switch D are connected in parallel;

and the signals amplified by the fifth amplifier are switched and selected by the single-pole multi-throw switch A, the single-pole multi-throw switch B, the single-pole multi-throw switch C and the single-pole multi-throw switch D to enter a filter for filtering.

Preferably, 7 LFCN filters are arranged in parallel between the single-pole multi-throw switch a and the single-pole multi-throw switch C; 7 LC low-pass filters and 1 LFCN filter are arranged in parallel between the single-pole multi-throw switch B and the single-pole multi-throw switch D.

Preferably, the control circuit of the present invention includes a gain control module and a calibration module;

the gain control module is used for performing gain control on the signal output by the filter circuit and outputting a required radio frequency signal source;

and the calibration module is used for calibrating the signal source output by the gain control module in real time.

Preferably, the gain control module of the present invention comprises a first attenuator, a second radio frequency switch, a seventh amplifier, an eighth amplifier, and a third radio frequency switch;

the seventh amplifier and the eighth amplifier are arranged between the second radio frequency switch and the fourth radio frequency switch in parallel;

the signals output by the filter circuit are processed by the first attenuator and the second attenuator in sequence, and then 20M-3G signals and 3G-6G signals are respectively controlled by the seventh amplifier and the eighth amplifier through the second radio frequency switch branch circuit, so that the required signal power is obtained and is output through the third radio frequency switch.

Preferably, the eighth amplifier and the ninth amplifier of the present invention both employ controllable gain amplifiers.

Preferably, the calibration module of the present invention uses a logarithmic detector to detect the signal power output by the gain control module in real time and sends the signal power to the controller;

the controller processes the received signal power and outputs a corresponding control signal to control the parameter of the gain control module, so as to realize the real-time calibration of the output signal power.

The invention has the following advantages and beneficial effects:

1. compared with the traditional radio frequency signal source, which uses high-cost devices and a wide-band VCO (voltage controlled oscillator), the signal source of the invention adopts a wideband frequency synthesizer integrated with the VCO to replace the traditional VCO, thereby reducing the cost and optimizing the spurious simultaneously.

2. The signal source of the invention can realize real-time calibration and improve the reliability of the signal source.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a schematic block diagram of a frequency synthesizer of the present invention.

Fig. 2 is a control schematic block diagram of the present invention.

Fig. 3 is a front view of a signal source device of the present invention.

Fig. 4 is a top view of a signal source device according to the present invention.

Fig. 5 is a rear view of the signal source device of the present invention.

Reference numbers and corresponding part names in the drawings:

x1-radio frequency output interface, X2-power switch, X3-power socket, X4-network interface, X5-USB interface, X6-reference input interface and X7-reference output interface.

Detailed Description

Hereinafter, the term "comprising" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the present invention, the terms "comprises," "comprising," "includes," "including," "has," "having" and their derivatives are intended to mean that the specified features, numbers, steps, operations, elements, components, or combinations of the foregoing, are only meant to indicate that a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as first excluding the existence of, or adding to the possibility of, one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.

In various embodiments of the invention, the expression "or" at least one of a or/and B "includes any or all combinations of the words listed simultaneously. For example, the expression "a or B" or "at least one of a or/and B" may include a, may include B, or may include both a and B.

Expressions (such as "first", "second", and the like) used in various embodiments of the present invention may modify various constituent elements in various embodiments, but may not limit the respective constituent elements. For example, the above description does not limit the order and/or importance of the elements described. The foregoing description is for the purpose of distinguishing one element from another. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of various embodiments of the present invention.

It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. In contrast, when one constituent element is "directly connected" to another constituent element, it is understood that there is no third constituent element between the first constituent element and the second constituent element.

The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Examples

Compared with the existing signal source, which has the problems of large volume, poor signal quality, high cost and the like, the embodiment provides the radio frequency signal source capable of being calibrated in real time. In this embodiment, a wideband frequency synthesizer integrated with a VCO (voltage-controlled oscillator) is used to replace a conventional VCO to implement a radio frequency signal source, so that the cost can be reduced, spurious signals can be optimized, and the quality of the signal source can be improved.

The radio frequency signal source of the embodiment mainly comprises a low-spurious, low-phase noise frequency synthesizer and a control circuit.

Specifically, as shown in fig. 1, the frequency synthesizer of the present embodiment includes a reference source circuit, a phase-locked loop circuit, and a filter circuit.

The control module of this embodiment adopts logarithm wave detector and AD conversion device to realize real-time calibration power, and the logarithm wave detector has excellent logarithm intercept, and through feeding back the radio frequency signal of test to the logarithm wave detector, the logarithm wave detector realizes real-time calibration power through connecting the AD converter, is exported AD sign indicating number value by the AD converter at last, improves the quality of signal source. As shown in fig. 2, the control circuit of the present embodiment includes a gain control module, a calibration module, and a controller (not shown in the figure).

In this embodiment, the reference source circuit is configured to provide a reference signal for the phase-locked loop circuit; the phase-locked loop circuit adopts a broadband frequency synthesizer integrated with a VCO to form a closed loop circuit and generate a frequency signal; the filter circuit realizes the segmented filtering of the frequency signal through shunting and outputs 20M-6G signals; the control circuit performs gain control and real-time calibration on the 20M-6G signals output by the filter circuit and outputs a required radio frequency signal source.

Specifically, as shown in fig. 1, the reference source circuit of this embodiment includes a crystal oscillator VCXO for generating a reference signal, a first amplifier, a first resistive attenuator ATT1, a first rf switch SPDT1, a second stage filter, a detector circuit, a first power divider, a second amplifier, a first stage filter, a second resistive attenuator ATT2, a third resistive attenuator ATT3, a third amplifier, a fourth stage filter, a second power divider, and a third stage filter.

A signal generated by the crystal oscillator is amplified by the first amplifier, passes through the first resistance attenuator and is sent to the first radio frequency switch; an external reference signal is transmitted to a second amplifier through a first-stage filter after passing through a second resistance attenuator and then is amplified and then is input to a first power divider, one path of output signal of the first power divider is transmitted to a first radio frequency switch through a second-stage filter, the other path of output signal of the first power divider is input to a detection circuit, and the detection circuit outputs a signal to control the first radio frequency switch to select a signal output by the first attenuator or a signal output by the second-stage filter; a signal passing through the first radio frequency switch passes through a third resistance attenuator and then is input into a third amplifier for amplification and then is input into a second power divider, and one path of output signal of the second power divider is output to the outside through a fourth-stage filter and used as reference output; and the other output signal of the second power divider is supplied to a phase-locked loop as a reference signal after passing through a third-stage filter.

The phase-locked loop circuit of this embodiment includes a phase detector, a loop filter, a wideband frequency synthesizer of the integrated VCO, a fourth resistive attenuator ATT4, and a fourth amplifier.

The phase detector receives a reference signal output by the reference source circuit, the output voltage controls a VCO part of the wideband frequency synthesizer of the integrated VCO after passing through the loop filter, the output of the wideband frequency synthesizer of the integrated VCO sequentially passes through the fourth resistance attenuator and the fourth amplifier and then is input to a feedback end of the phase detector, so that a closed loop is formed, and the output of the wideband frequency synthesizer of the integrated VCO is simultaneously sent to the filter circuit.

The filter circuit of the present embodiment includes a fifth amplifier, a shunt filter unit, a fifth resistive attenuator ATT5, and a sixth amplifier.

The fifth amplifier amplifies the output signal of the wideband frequency synthesizer integrated with the VCO, then the amplified output signal is sent to the shunt filtering unit for shunt filtering, and then the amplified output signal is processed by the fifth resistance attenuator and the sixth amplifier in sequence and output to the control circuit.

In this embodiment, more path selection is realized by connecting single-pole multi-throw switches in parallel, the branching filtering unit of this embodiment adopts a radio frequency switch to realize multi-path filter segmented filtering, and specifically, the branching filtering unit of this embodiment includes a single-pole multi-throw switch a, a single-pole multi-throw switch B, a single-pole multi-throw switch C, and a single-pole multi-throw switch D. In this embodiment, the signal amplified by the fifth amplifier is selectively switched by the single-pole multi-throw switch a, the single-pole multi-throw switch B, the single-pole multi-throw switch C, and the single-pole multi-throw switch D into a filter for filtering.

7 LFCN filters are arranged in parallel between the single-pole multi-throw switch A and the single-pole multi-throw switch C; 7 LC low-pass filters (LPF) and 1 LFCN filter are arranged in parallel between the single-pole multi-throw switch B and the single-pole multi-throw switch D; and the single-pole multi-throw switch A and the single-pole multi-throw switch B are connected in parallel, and the single-pole multi-throw switch C and the single-pole multi-throw switch D are connected in parallel. That is, in this embodiment, 8 LFCN low-pass filters are commonly used, wherein 7 of the LFCN low-pass filters are switched by the single-pole multi-throw switch a and enter the LFCN low-pass filter, and then are sent to the single-pole multi-throw switch C, the 8 th LFCN filter and the 7 th low-pass filter are switched and controlled by the single-pole multi-throw switch B to realize segmented filtering, and then are combined by the single-pole multi-throw switch D, and then fed into the single-pole multi-throw switch C, and output to the fifth resistance attenuator and the sixth amplifier for processing, and finally, output signals (20M to 6G) to the control module.

The control circuit of this embodiment adopts attenuator and controllable gain amplifier to realize the gain control of output signal in order to obtain required signal power, and the control circuit of this embodiment adopts the logarithm detector real-time detection output signal power to carry out real-time calibration, thereby obtain more accurate signal power.

Specifically, as shown in fig. 2, the control circuit of the present embodiment includes a gain control module and a calibration module.

The seventh amplifier and the eighth amplifier are arranged between the second radio frequency switch and the fourth radio frequency switch in parallel;

signals (20M-6G) output by the filter circuit are processed by the first attenuator and the second attenuator in sequence, then divided into 20M-3G signals (low frequency) and 3G-6G signals (high frequency) by the second radio frequency switch, and respectively controlled by the seventh amplifier and the eighth amplifier to obtain required signal power which is output by the third radio frequency switch.

The eighth amplifier and the ninth amplifier of the present embodiment both employ controllable gain amplifiers.

The calibration module of the present embodiment includes a sixth resistive attenuator ATT6, a fourth radio frequency switch SPTD4, a ninth amplifier, a seventh resistive attenuator ATT7, a fifth radio frequency switch SPDT5, and a logarithmic detector;

in this embodiment, after the signal power output by the gain control module is fed back to the sixth resistive attenuator for processing, the signal power is switched by the fourth radio frequency switch and enters the ninth amplifier and the seventh resistive attenuator for processing, and then the signal power is output to the logarithmic detector by the fifth radio frequency switch.

The logarithmic detector sends the detected signal to the AD converter, the AD converter converts the received signal into an AD code value and sends the AD code value to the controller (the controller can adopt but is not limited to an FPGA), and the controller controls parameters in the gain control module in real time according to the change of the AD code value, so that the power of the signal finally output by the gain control module can reach the theoretically required power to the maximum extent. The power range can reach-130 dBm to 15 dBm.

The principle of obtaining the AD code value in this embodiment is as follows: the measured rf signal is applied to a logarithmic detector. The device is configured in a so-called "measurement mode". In this mode, the output voltage is in a linear dB relationship with the input signal level (nominally-24 mV/dB), with a typical output voltage range of 0.5V to 2.1V. The AD converter can be configured into a single-channel or double-channel working mode through the controller control register; the output of the logarithmic detector is directly connected to the AD converter; the ADC uses an internal reference voltage source of the ADC, and the input range of the ADC is 0V-2.5V; when the logarithmic detector provides a slope of nominal-24 mV/dB, the digital resolution is 39.3 LSB/dB; with such a high resolution, the 0.5V to 2.1V signal from the logarithmic detector is adjusted.

In another preferred embodiment, the controller is provided with a temperature monitor, and the power output of the control signal can be suitable for the change of the ambient temperature at any time according to the external temperature change, so that the power error is reduced.

As shown in fig. 3 to 5, in the radio frequency signal source device obtained in this embodiment, circuit modules of a radio frequency signal source are all integrated in a box, and a radio frequency output interface X1, a power switch X2, a power socket X3, a network port X4, a USB interface X5, a reference input interface X6, and a reference output interface X7 are arranged on a wall of the box.

The radio frequency output interface X1 and the power switch X2 are arranged on the same surface of the box body, the power socket X3, the network port X4, the USB interface X5, the reference input interface X6 and the reference output interface X7 are arranged on the other surface of the box body, and the two surfaces are opposite.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.