Ultra-wideband waveform generation circuit and method, radar signal simulator

Abstract

This invention provides an ultra-wideband waveform generation circuit and method, and a radar signal simulator. The ultra-wideband waveform generation circuit includes: a baseband module that generates and outputs a baseband signal; a phase-locked module that receives the baseband signal, performs phase-locked frequency multiplication on the baseband signal, and outputs a first frequency multiplier signal; and a spread spectrum module that receives the first frequency multiplier signal, performs spread spectrum processing on the first frequency multiplier signal, and outputs a second frequency multiplier signal. By performing phase-locked frequency multiplication on the baseband signal output by the baseband module, its frequency can be quickly and effectively spread to the ultra-wideband frequency range to obtain the ultra-wideband first frequency multiplier signal. Then, by performing spread spectrum processing on the first frequency multiplier signal, a second frequency multiplier signal with a wider bandwidth is obtained. This achieves rapid and efficient generation of ultra-wideband waveforms, enabling the generation of commonly used radar waveforms such as continuous waves, conventional pulses, frequency repetition jitter, frequency repetition aberration, and dual-frequency pulses across the entire frequency band. Furthermore, the corresponding design structure is simple and low-cost.

Description

Technical Field

[0001] This invention relates to the field of radar signal simulator technology, and in particular to an ultra-wideband waveform generation circuit and method, and a radar signal simulator. Background Technology

[0002] In today's society, radar plays an indispensable role. It is not only an essential electronic equipment for the military, but also widely used in socio-economic development (such as weather forecasting, resource exploration, environmental monitoring, traffic control, etc.) and scientific research (such as astronomical research, atmospheric physics, ionospheric structure research, etc.).

[0003] In the development of various radars, radar signal simulators play a crucial role in the debugging and testing of radar performance. Currently, conventional radar simulator waveform generation schemes use DA (digital-to-analog converter) or DDS (direct digital synthesizer) to generate a narrow-bandwidth baseband signal, then shift the frequency to the radar's operating frequency band through multiple mixing operations. This method offers good flexibility, but due to the narrow baseband signal bandwidth, wideband radar simulation often requires multi-segment frequency splicing to extend the bandwidth, making the process extremely complex. Modern radars operate at increasingly higher frequencies and with increasingly wider bandwidths, covering hundreds of MHz to tens of GHz. Traditional simulator solutions are difficult to generalize, and their cost, power consumption, and size all increase with the increase in bandwidth.

[0004] Therefore, there is an urgent need for a radar simulator waveform generation solution that has a wide bandwidth, small size, and low cost. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an ultra-wideband waveform generation technology solution to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned objectives and other related objectives, the technical solution provided by the present invention is as follows.

[0007] An ultra-wideband waveform generation circuit includes:

[0008] The baseband module generates the output baseband signal;

[0009] The phase-locked module receives the baseband signal, performs phase-locked frequency multiplication on the baseband signal, and outputs the first multiplied frequency signal;

[0010] The spread spectrum module receives the first harmonic signal, spreads the first harmonic signal, and outputs the second harmonic signal.

[0011] Optionally, the baseband module includes a direct digital frequency synthesizer or a digital-to-analog converter.

[0012] Optionally, the phase-locked loop module includes a phase detector, a voltage-controlled oscillator (VCO), a first frequency divider, a power divider, and a second frequency divider. The input terminal of the phase detector is connected to the output terminal of the baseband module, the output terminal of the phase detector is connected to the input terminal of the VCO, the output terminal of the VCO is connected to the input terminal of the first frequency divider, the output terminal of the first frequency divider is connected to the input terminal of the power divider, the first output terminal of the power divider outputs the first multiplied frequency signal, the second output terminal of the power divider is connected to the input terminal of the second frequency divider, and the output terminal of the second frequency divider is connected to the feedback terminal of the phase detector.

[0013] Optionally, the first frequency divider includes a variable frequency divider.

[0014] Optionally, the spread spectrum module includes a modulation switch, a frequency multiplier, a direct path, a first switch, and a second switch. The input terminal of the modulation switch is connected to the first output terminal of the power divider, the output terminal of the modulation switch is connected to the input terminal of the first switch, the first output terminal of the first switch is connected to the input terminal of the frequency multiplier, the output terminal of the frequency multiplier is connected to the first input terminal of the second switch, the second output terminal of the first switch is connected to the second input terminal of the second switch via the direct path, and the output terminal of the second switch outputs the second multiplied frequency signal.

[0015] A method for generating ultra-wideband waveforms includes:

[0016] Provides baseband signal;

[0017] The baseband signal is frequency multiplied by a phase-locked loop circuit to obtain a first frequency-multiplied signal.

[0018] The first frequency harmonic signal is spread by a spread spectrum circuit to obtain the second frequency harmonic signal.

[0019] Optionally, the baseband signal is subjected to at least one frequency multiplication process through the phase-locked loop circuit to obtain the first frequency multiplied signal.

[0020] Optionally, after providing the baseband signal and before performing frequency multiplication processing on the baseband signal through the phase-locked loop circuit, the ultra-wideband waveform generation method further includes:

[0021] The baseband signal is frequency and phase modulated, and frequency predistortion and phase predistortion processing are performed on the baseband signal according to the number of frequency doubling processes.

[0022] Optionally, after the baseband signal is frequency-multiplied by the phase-locked loop circuit and before the first frequency-multiplied signal is spread by the spread spectrum circuit, the ultra-wideband waveform generation method further includes:

[0023] The first frequency multiplier signal is modulated by a modulation switch so that the first frequency multiplier signal input to the spread spectrum circuit is always kept in a signal input state.

[0024] A radar signal simulator, comprising the ultra-wideband waveform generation circuit described in any of the preceding claims.

[0025] As described above, the ultra-wideband waveform generation circuit and method, and radar signal simulator provided by the present invention have at least the following beneficial effects:

[0026] The baseband signal generated by the baseband module is processed by the phase-locked loop (PLL) module to expand its frequency to an ultra-wideband frequency quickly and effectively. Its frequency and phase are simultaneously transmitted to the first frequency-multiplied signal, thus realizing the generation of an ultra-wideband waveform. The first frequency-multiplied signal is then processed by the spread spectrum module to obtain a second frequency-multiplied signal with a wider bandwidth, which enhances the bandwidth range of the final output waveform. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a radar signal simulator in the prior art.

[0028] Figure 2 This is a schematic diagram of the ultra-wideband waveform generation circuit in this invention.

[0029] Figure 3 This is a schematic diagram illustrating the steps of the ultra-wideband waveform generation method in this invention.

[0030] Explanation of icon numbers

[0031] V1—Baseband signal, V2—First harmonic signal, V3—Second harmonic signal. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] Please see Figures 1 to 3It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show components relevant to the present invention and are not drawn according to the actual number, shape, and size of the components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. The structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0034] In studying existing such Figure 1 When developing the radar signal simulator, the inventors discovered that using a DA (digital-to-analog converter) or DDS (direct digital frequency synthesizer) to generate a narrow-band baseband signal and then shifting the frequency to the radar operating band through multiple mixing steps offers good flexibility. However, the narrow bandwidth of the baseband signal necessitates the use of multiple frequency band splicing to extend the bandwidth in broadband radar simulation, making the link extremely complex. Furthermore, the use of multi-stage mixing for frequency band splicing easily causes intermodulation signals to fall into the in-band, creating clutter and reducing spectral purity, significantly increasing design difficulty. Additionally, the need for numerous filters to suppress intermodulation signals after mixing further increases design cost and size. Therefore, for modern radars with increasingly demanding bandwidth requirements, traditional simulator waveform generation techniques are becoming increasingly unsuitable in terms of bandwidth, cost, power consumption, and size.

[0035] Based on this, the present invention provides a radar simulator waveform generation technology solution: the baseband signal is subjected to at least one frequency multiplication process through a phase-locked loop circuit to expand its bandwidth; and then spread spectrum processing is performed through a spread spectrum circuit to further expand the bandwidth range.

[0036] In detail, such as Figure 2 As shown, the present invention provides an ultra-wideband waveform generation circuit, which includes:

[0037] The baseband module generates the output baseband signal V1;

[0038] The phase-locked module receives the baseband signal V1, performs phase-locked frequency multiplication on the baseband signal V1, and outputs the first frequency multiplier signal V2.

[0039] The spread spectrum module receives the first frequency harmonic signal V2, performs spread spectrum processing on the first frequency harmonic signal V2, and outputs the second frequency harmonic signal V3.

[0040] In detail, such as Figure 2 As shown, the baseband module includes a direct digital frequency synthesizer (DDS) or a digital-to-analog converter (DA). That is, the baseband signal V1 is still output through the direct digital frequency synthesizer (DDS) or the digital-to-analog converter (DA). For detailed structural principles, please refer to the prior art, which will not be repeated here.

[0041] In detail, such as Figure 2 As shown, the phase-locked loop module includes a phase detector, a voltage-controlled oscillator (VCO), a first frequency divider, a power divider, and a second frequency divider. The input of the phase detector is connected to the output of the baseband module. The output of the phase detector is connected to the input of the VCO. The output of the VCO is connected to the input of the first frequency divider. The output of the first frequency divider is connected to the input of the power divider. The first output of the power divider outputs a first multiplier signal V2. The second output of the power divider is connected to the input of the second frequency divider. The output of the second frequency divider is connected to the feedback of the phase detector.

[0042] The first frequency divider includes a variable frequency divider, such as a programmable frequency divider, which can perform various frequency division operations such as 1, 2, 4, 8, 16, etc. through digital control signals.

[0043] More in detail, such as Figure 2 As shown, the phase detector, voltage-controlled oscillator, first frequency divider, power divider, and second frequency divider connected in sequence constitute a phase-locked module (or phase-locked loop). This phase-locked module performs frequency multiplication on the baseband signal V1 by phase locking, expanding the frequency of the baseband signal V1 to an ultra-wideband frequency, to obtain the first frequency-multiplied signal V2. Its working principle is as follows:

[0044] The phase detector receives the baseband signal V1 and outputs a control voltage. Under the action of the control voltage, the voltage-controlled oscillator outputs an oscillation signal. The output bandwidth of the oscillation signal is determined by the structural design of the voltage-controlled oscillator itself. The oscillation signal is processed by the first frequency divider, which can effectively extend the lower limit of the oscillation signal and expand the bandwidth range of the oscillation signal. After the frequency division, a part of the oscillation signal is fed back to the phase detector through the power divider and the second frequency divider, and performs frequency and phase discrimination with the baseband signal V1. The other part of the oscillation signal after the frequency division is output through the power divider to obtain the first frequency-doubled signal V2. Based on the frequency and phase discrimination of the phase detector, the phase and frequency of the oscillation signal after the frequency division are locked to the baseband signal V1, so that the frequency information and phase information of the baseband signal V1 are transmitted to the first frequency-doubled signal V2, realizing the generation of ultra-wideband waveform.

[0045] In an optional embodiment of the present invention, the frequency of the baseband signal V1 is extended to an ultra-wideband frequency of 625MHz to 20GHz by a phase-locked loop module. The voltage-controlled oscillator is selected to span octaves from 10 to 20GHz, and the frequency is extended to 625MHz to 20GHz by a first frequency divider divided by 1 to 16. This frequency is fed back to the phase detector for frequency and phase discrimination with the baseband signal V1, so that the phase and frequency of the output first frequency-doubled signal V2 are locked to the baseband signal V1. Thus, the frequency and phase information of the baseband signal V1 are transmitted to the first frequency-doubled signal V2, realizing the generation of an ultra-wideband waveform. Since the subsequent circuit uses a phase-locked loop scheme to achieve frequency doubling, the baseband signal V1 can be selected as a narrowband signal of tens of MHz, and the carrier frequency of the baseband signal V1 can be reduced to below 500MHz, which greatly reduces the design pressure of the baseband signal V1.

[0046] Furthermore, since the baseband signal V1 has undergone frequency multiplication processing by the phase-locked loop module, pre-distortion processing is required for the baseband signal V1. The sinusoidal signal function of the baseband signal V1 is:

[0047]

[0048] Where A is the amplitude of the baseband signal V1, and ω is the angular velocity of the baseband signal V1. This is the initial phase of the baseband signal V1;

[0049] Frequency multiplication is the product of signals, and its expression is:

[0050]

[0051] According to the sum-to-product formula, we can obtain:

[0052]

[0053] Therefore, when performing N-fold harmonics, if N is an even number, When N is an odd number

[0054] From the above calculations, the relationship between the first frequency-multiplied signal V2 and the baseband signal V1 after N frequency multiplications can be approximated as follows:

[0055] f out ≈N*f ref ;

[0056]

[0057] Among them, f out f is the frequency of the first harmonic signal V2. ref The frequency of the baseband signal V1, The phase of the first harmonic signal V2, Let N be the phase of the baseband signal V1, and let N be the frequency multiplication factor, where N is an integer greater than or equal to 1.

[0058] As can be seen, after the frequency multiplication process of the phase-locked loop module, the frequency and phase of the first frequency multiplied signal V2 are approximately multiples of the frequency and phase of the baseband signal V1. Therefore, when the baseband signal V1 is frequency and phase modulated, the baseband signal V1 needs to be pre-distorted according to the frequency multiplication number N to ensure that the first frequency multiplied signal V2 obtains the required modulation signal.

[0059] In detail, such as Figure 2 As shown, the spread spectrum module includes a modulation switch, a frequency multiplier, a direct path, a first switch, and a second switch. The input terminal of the modulation switch is connected to the first output terminal of the power divider, the output terminal of the modulation switch is connected to the input terminal of the first switch, the first output terminal of the first switch is connected to the input terminal of the frequency multiplier, the output terminal of the frequency multiplier is connected to the first input terminal of the second switch, the second output terminal of the first switch is connected to the second input terminal of the second switch via the direct path, and the output terminal of the second switch outputs the second multiplied frequency signal V3.

[0060] More in detail, such as Figure 2 As shown, the spread spectrum module includes two parallel paths through the first and second switches at both ends. One path has a frequency multiplier connected in series to multiply the input first frequency multiplier signal V2. The other path is a direct path that outputs the input first frequency multiplier signal V2 directly. By selecting and superimposing the two paths, the first frequency multiplier signal V2 is further spread to obtain a second frequency multiplier signal V3 with a larger bandwidth.

[0061] In an optional embodiment of the present invention, the first frequency multiplier signal V2 of 625MHz to 20GHz is multiplied by a path with a frequency multiplier in the spread spectrum module to achieve an output of 1.25 to 40GHz. Another direct path directly outputs the first frequency multiplier signal V2 of 625MHz to 20GHz, and finally synthesizes the second frequency multiplier signal V3 with a bandwidth of 625MHz to 40GHz.

[0062] More in detail, such as Figure 2As shown, the modulation signal waveforms used in radar systems are mostly pulse modulation. Within the pulse width of the modulation signal, there is a signal output; otherwise, there is no output signal. When a phase-locked module (or phase-locked loop circuit) is used as the frequency multiplier circuit, if the baseband signal V1 is pulse-modulated, the phase-locked module will lose lock when the baseband signal V1 is not present, resulting in unnecessary spurious signals. Therefore, in this invention, a modulation switch is added at the output of the phase-locked module (or the input of the spread spectrum module). The modulation switch modulates the first frequency multiplier signal V2, ensuring that the first frequency multiplier signal V1 input to the spread spectrum module always maintains a signal input state, thus preventing spurious signals generated by the phase-locked module losing lock from interfering with the first frequency multiplier signal V1.

[0063] Ultimately, as Figure 2 As shown, the ultra-wideband waveform generation circuit of this invention is designed based on a baseband module, a phase-locked loop (PLL) module, and a spread spectrum module. By performing phase-locked frequency multiplication on the baseband signal through the PLL module, its frequency can be quickly and effectively spread to the ultra-wideband frequency to obtain the first harmonic signal of the ultra-wideband. Then, by performing spread spectrum processing on the first harmonic signal through the spread spectrum module, a second harmonic signal with a wider bandwidth is obtained. This achieves ultra-wideband waveform generation quickly and efficiently, and the corresponding design structure is simple and low in cost.

[0064] Currently, major international instrument manufacturers such as Keysight Technologies' M9384B and Rohde & Schwarz's SMW200A can generate waveforms with output frequencies up to 40GHz, suitable for radar simulators. However, their prices are all over one million yuan, and their dimensions are standard chassis, approximately 500mm*450mm*200mm. In contrast, the waveform generator using the ultra-wideband waveform generation circuit of this invention, with an output frequency coverage of 625MHz to 40GHz, measures only 135mm*80mm*24mm. It can generate commonly used radar waveforms across the entire frequency band, including continuous waves, conventional pulses, frequency repetition jitter, frequency repetition aberration, dual-frequency pulses, frequency conversion signals, grouped signals, two-phase coding, and linear frequency modulation. Its production cost is only around one hundred thousand yuan, significantly reducing development costs.

[0065] Furthermore, based on the same inventive concept as the aforementioned ultra-wideband waveform generation circuit, this invention also provides an ultra-wideband waveform generation method, such as... Figure 3 As shown, it includes:

[0066] S1 provides baseband signals;

[0067] S2. The baseband signal is frequency multiplied by a phase-locked loop circuit to obtain the first frequency-multiplied signal;

[0068] S3. Spread the first frequency harmonic signal through a spread spectrum circuit to obtain the second frequency harmonic signal.

[0069] In detail, in step S1, a baseband signal is generated using direct digital frequency synthesis technology or digital-to-analog conversion technology.

[0070] Optionally, after providing the baseband signal and before performing frequency multiplication on the baseband signal via a phase-locked loop circuit, the ultra-wideband waveform generation method further includes:

[0071] Stp1 modulates the baseband signal in terms of frequency and phase. According to the number of frequency multiplication processes, the baseband signal is subjected to frequency predistortion and phase predistortion processing. Then, after subsequent frequency multiplication processing, the first frequency multiplication signal that meets the modulation requirements is obtained.

[0072] In detail, in step S2, the baseband signal is subjected to at least one frequency multiplication process through a phase-locked loop circuit to obtain a first frequency-multiplied signal. However, considering the bandwidth range of the obtained first frequency-multiplied signal, the baseband signal is not limited to one frequency multiplication process; it can undergo two or more frequency multiplication processes, which is not limited here.

[0073] Optionally, after the baseband signal is frequency-multiplied by a phase-locked loop circuit and before the first frequency-multiplied signal is spread by a spread spectrum circuit, the ultra-wideband waveform generation method further includes:

[0074] Stp2: The first frequency multiplier signal is modulated by the modulation switch so that the first frequency multiplier signal input to the spread spectrum circuit is always kept in a signal input state, so as to avoid the interference of stray signals generated by the phase-locked loop circuit losing lock on the first frequency multiplier signal.

[0075] In detail, in step S3, the spread spectrum circuit includes two or more parallel paths. Each path either performs a direct pass-through process on the first harmonic signal or performs N-fold spread spectrum processing on the first harmonic signal. The output signals of each path are then superimposed and synthesized to complete the spread spectrum processing of the first harmonic signal, resulting in a second harmonic signal with a larger bandwidth.

[0076] Furthermore, based on the aforementioned ultra-wideband waveform generation circuit, the present invention also provides a radar signal simulator, which includes the aforementioned ultra-wideband waveform generation circuit. Through the aforementioned ultra-wideband waveform generation circuit, it can generate various commonly used radar waveforms with a wide bandwidth, and the corresponding size is small and the cost is low.

[0077] In summary, the ultra-wideband waveform generation circuit and method and radar signal simulator provided by this invention utilize phase-locked loop (PLL) module to perform phase-locked frequency multiplication on the baseband signal output by the baseband module. This allows for rapid and effective expansion of the baseband signal's frequency to the ultra-wideband frequency range, resulting in the first frequency multiplication signal. Furthermore, the first frequency multiplication signal is spread using a spread spectrum module to obtain a second frequency multiplication signal with an even wider bandwidth. This achieves rapid and efficient generation of ultra-wideband waveforms, enabling the generation of commonly used radar waveforms across the entire frequency band, including continuous waves, conventional pulses, frequency repetition jitter, frequency repetition aberration, dual-frequency pulses, frequency conversion signals, grouped signals, two-phase coding, and linear frequency modulation. Moreover, the design is simple, compact, and inexpensive.

[0078] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An ultra-wideband waveform generation circuit, comprising: include: The baseband module generates the output baseband signal; The phase-locked module receives the baseband signal, performs phase-locked frequency multiplication on the baseband signal, and outputs the first multiplied frequency signal; The spread spectrum module receives the first harmonic signal, spreads the first harmonic signal, and outputs the second harmonic signal. The phase-locked loop module includes a phase detector, a voltage-controlled oscillator (VCO), a first frequency divider, a power divider, and a second frequency divider. The input terminal of the phase detector is connected to the output terminal of the baseband module. The output terminal of the phase detector is connected to the input terminal of the VCO. The output terminal of the VCO is connected to the input terminal of the first frequency divider. The output terminal of the first frequency divider is connected to the input terminal of the power divider. The first output terminal of the power divider outputs the first multiplied frequency signal. The second output terminal of the power divider is connected to the input terminal of the second frequency divider. The output terminal of the second frequency divider is connected to the feedback terminal of the phase detector. Based on the phase detector, the phase and frequency of the oscillation signal after frequency division are locked to the baseband signal, thereby transmitting the frequency and phase information of the baseband signal to the first harmonic signal. The spread spectrum module includes a modulation switch, a frequency multiplier, a direct path, a first switch, and a second switch. The input terminal of the modulation switch is connected to the first output terminal of the power divider, the output terminal of the modulation switch is connected to the input terminal of the first switch, the first output terminal of the first switch is connected to the input terminal of the frequency multiplier, the output terminal of the frequency multiplier is connected to the first input terminal of the second switch, the second output terminal of the first switch is connected to the second input terminal of the second switch via the direct path, and the output terminal of the second switch outputs the second multiplied frequency signal. The modulation switch is configured to modulate the first frequency multiplier signal when the baseband signal is a pulse modulation signal and is in the pulse gap, so that the input terminal of the first switch always maintains a valid signal input, thereby preventing the stray signal generated by the phase-locked module due to loss of lock from being transmitted to the spread spectrum module through the first output terminal of the power divider.

2. The ultra-wide band waveform generating circuit of claim 1, wherein, The baseband module includes a direct digital frequency synthesizer or a digital-to-analog converter.

3. The ultra-wide band waveform generating circuit of claim 2, wherein, The first frequency divider includes a variable frequency divider.

4. An ultra-wideband waveform generation method, comprising: include: Provides baseband signal; The baseband signal is frequency multiplied by a phase-locked loop circuit to obtain a first frequency-multiplied signal. The first frequency harmonic signal is spread by a spread spectrum circuit to obtain the second frequency harmonic signal; After providing the baseband signal and before performing frequency multiplication on the baseband signal through the phase-locked loop circuit, the ultra-wideband waveform generation method further includes: The baseband signal is frequency and phase modulated, and frequency predistortion and phase predistortion processing are performed on the baseband signal according to the number of frequency doubling processes. After the baseband signal is frequency multiplied by the phase-locked loop circuit and before the first frequency-multiplied signal is spread by the spread spectrum circuit, the ultra-wideband waveform generation method further includes: The first frequency multiplier signal is modulated by a modulation switch so that the first frequency multiplier signal input to the spread spectrum circuit is always kept in a signal input state.

5. The ultra-wide band waveform generating method of claim 4, wherein, The baseband signal is multiplied at least once by the phase-locked loop circuit to obtain the first multiplied signal.

6. A radar signal simulator, characterized by An ultra-wideband waveform generation circuit comprising any of claims 1-3.

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