Ultrafast pre- and post-pulse transmitter architecture

Abstract

The application discloses a kind of ultrafast front and rear narrow pulse transmitter structures, belong to the field of pulse shaping, comprising: vector pulse modulator, for generating phase synchronization phase difference adjustable I route signal and Q route signal, Q route signal is switched between +Q signal and-Q signal with phase difference;Drive amplifier, for pre-amplifying I route signal and Q route signal respectively;Vector power amplifier, for pre-amplified two-way signal is respectively amplified by power amplifier after power amplification by power combiner synthesis;When Q route signal is switched to-Q signal, -Q signal and I route signal are synthesized to cancel out, by first outlet output;When Q route signal is switched to+Q signal, +Q signal and I route signal are synthesized to enhance, by second outlet output, form ultrafast front and rear narrow pulse.The application can realize ultrafast front and rear narrow pulse, and give consideration to efficiency and reliability, suitable for communication, radar, medical treatment and other need high power narrow pulse signal application scene.

Description

Technical Field

[0001] This invention belongs to the field of pulse shaping technology, specifically relating to an ultrafast narrow pulse transmitter structure with leading and trailing edges. Background Technology

[0002] High-power narrow-pulse signals are widely used in communications, radar, medical fields, and other areas. The pulse leading-edge width of the narrow pulse is a key performance indicator that directly determines the upper limit of the system's performance. The main technical approaches to generating narrow pulses include vacuum electronic devices and semiconductor solid-state devices.

[0003] Currently, synthesizing high-power microwaves using solid-state devices has become a major development direction. Compared with traditional vacuum electronic devices, solid-state broadband high-power amplification devices, represented by GaN, exhibit significant advantages. They can achieve wide bandwidth coverage in frequency, pulse width in the order of nanoseconds to milliseconds, repetition rate in the order of hundreds of kHz to MHz, and digital phase control and beam scanning capabilities. Furthermore, by utilizing the flexibility of the pre-stage excitation source signal, pulses or frequencies can be combined or scanned more flexibly according to target characteristics, thereby effectively improving the system's application effect and range.

[0004] With the rapid increase in system output power and the demand for miniaturization, the heat density of high-power solid-state amplifiers (HPAs) has increased dramatically, making temperature rise a more prominent issue. Once the temperature exceeds the device's tolerance limit, it will lead to device damage. To address this problem, HPAs generally employ intermittent pulse operation to limit the channel temperature within the material's tolerance range. To achieve nanosecond-level pulse leading-edge widths and effectively control HPA temperature, current mainstream high-power narrow-pulse architectures utilize power-modulated pulse transmitters.

[0005] In the power-modulated pulse transmitter architecture, the duty cycle of the power amplifier is reduced by simultaneously modulating the microwave excitation signal and the power amplifier voltage, thereby limiting the average power and ultimately ensuring that its temperature remains within a safe and controllable range. To compress the pulse leading edge width, the power amplifier modulation voltage pulse needs to be wider than the microwave pulse input to the power amplifier, allowing the power amplifier transistors to pre-turn on during the rise time of the power amplifier drain voltage pulse to establish the operating voltage and current. Simultaneously, the operating current must remain consistent with the pre-established operating current within the microwave pulse to avoid voltage overshoot caused by current fluctuations, which would affect pulse stability and device reliability. The power amplifier needs to operate in a constant current mode similar to Class A. In this architecture, a pulse power supply circuit is required to provide the pulse modulation voltage to the power amplifier drain. As a crucial component of the power-modulated pulse transmitter architecture, the performance of the voltage modulation circuit affects key technical indicators such as the leading and trailing edges of the power amplifier drain pulse modulation voltage, voltage overshoot, and efficiency.

[0006] However, the above-mentioned power-modulated pulse transmitter architecture has the following inherent drawbacks: 1) It's difficult to balance pulse leading-edge width and system efficiency. To compress the output pulse leading-edge width, the power amplifier pulse modulation voltage needs to be wider than the microwave pulse input to the power amplifier. The power amplifier does not output microwaves at the leading and trailing edges of the pulse modulation voltage; all the power supplied to the power amplifier by the voltage modulation circuit becomes power loss. Due to the parasitic effects of the pulse voltage modulation circuit, the actual leading and trailing edges of the voltage modulation pulse are on the order of tens or hundreds of nanoseconds, making further compression difficult. When the microwave pulse width is narrow, the leading and trailing edges of the pulse modulation voltage significantly affect the power amplifier's efficiency. Simultaneously, within the microwave pulse, the power amplifier can only operate in a constant current mode similar to Class A, which also greatly reduces the power amplifier's efficiency.

[0007] 2) Limited system reliability. At the moment of switching at the pulse edge, a huge inrush current is generated in the circuit, causing voltage overshoot and ringing effect, which seriously affects the long-term reliability of devices and systems.

[0008] Therefore, how to achieve ultrafast narrow pulse transmission with leading and trailing edges without sacrificing efficiency, while ensuring system reliability, has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0009] In view of the above, the purpose of this invention is to provide an ultrafast leading and trailing edge narrow pulse transmitter structure. This transmitter adopts a structure combining vector pulse modulation and vector power amplification. By controlling the phase switching of the Q-channel signal between +Q and -Q, the synthesized signal is rapidly guided between the first and second outputs, thereby forming a narrow pulse output with ultrafast leading and trailing edges. Simultaneously, a Class C power amplifier is used, whose operating voltage is constantly applied, eliminating the need for power supply modulation circuitry to control pulse on / off. This avoids overshoot and ringing effects caused by voltage and current surges in traditional architectures, significantly improving system efficiency and reliability while achieving ultrafast pulse leading and trailing edges. This transmitter is suitable for applications requiring high-power narrow pulse signals, such as communication, radar, and medical applications.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution: An embodiment of the present invention provides an ultrafast narrow pulse transmitter structure with leading and trailing edges, comprising: A vector pulse modulator is used to generate phase-synchronized, phase-difference-adjustable I-channel and Q-channel signals, wherein the Q-channel signal switches between a +Q signal and a -Q signal with a phase difference. A driver amplifier, connected to the vector pulse modulator, is used to pre-amplify the I-channel signal and the Q-channel signal, respectively; A vector power amplifier, connected to the drive amplifier, is used to amplify the two pre-amplified signals separately and then combine them with a power combiner. When the Q signal is switched to -Q, the -Q signal cancels out the I signal and is output from the first output. When the Q signal is switched to +Q, the +Q signal enhances the I signal and is output from the second output, forming an ultrafast narrow pulse with leading and trailing edges.

[0011] Preferably, the phase of the I-channel signal remains constant, and the phase difference between the +Q and -Q signals of the Q-channel signal is 180°.

[0012] Preferably, in the vector pulse modulator, the two signals are modulated by digital control oscillation or analog local oscillation to provide a synchronization carrier for the I-channel signal and the Q-channel signal, and to independently control the amplitude and phase of the two signals.

[0013] Preferably, in the vector power amplifier, the power amplifier includes a single-stage or multi-stage power amplifier.

[0014] Preferably, in the vector power amplifier, the power amplifier is a Class C power amplifier.

[0015] Preferably, in the vector power amplifier, the power combiner includes a bridge or waveguide combiner.

[0016] Preferably, the first outlet is connected to an absorption load or an energy recovery circuit, and the second outlet is a radio frequency output port.

[0017] Preferably, it also includes a voltage modulation circuit for reducing the operating voltage of the power amplifier during transmitter RF pulse shutdown to reduce the transmitter noise figure.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least the following: This invention utilizes a vector pulse shaping architecture, leveraging the phase switching of the Q-channel signal between +Q and -Q to achieve rapid signal guidance for the synthesized signal, thereby directly generating ultrafast narrow pulses with leading and trailing edges. While employing a Class C power amplifier, the slow leading and trailing edge characteristics are completely eliminated by the phase synthesis mechanism of this invention. The ultrafast leading and trailing edges of the output are determined by phase switching rather than the switching characteristics of the power amplifier itself. Therefore, it retains the advantages of high efficiency and reliability of Class C power amplifiers while avoiding the voltage overshoot and ringing problems caused by power jumps in traditional Class A constant current modes. This achieves a synergy of ultrafast narrow pulses with leading and trailing edges, high efficiency, and high reliability, and has broad application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an overall architecture diagram of the ultrafast leading and trailing edge narrow pulse transmitter structure provided in the embodiments of the present invention; Figure 2 This is the I / Q channel signal vector diagram provided in the embodiments of the present invention; Figure 3 This is a schematic diagram illustrating the working principle of the ultrafast leading and trailing edge narrow pulse transmitter structure provided in this embodiment of the invention. Figure 4 This is a time-domain waveform diagram of the voltage-controlled synchronization signal of the ultrafast leading and trailing edge narrow pulse transmitter structure provided in the embodiments of the present invention; Figure 5 This is a schematic diagram of the test results of the verification platform provided in the embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 invention and do not limit the scope of protection of this invention.

[0022] like Figure 1 As shown, the embodiment provides an ultrafast narrow pulse transmitter structure with leading and trailing edges, including: a vector pulse modulator, a driver amplifier, and a vector power amplifier.

[0023] The vector pulse modulator is used to generate two RF modulation signals, I and Q, respectively. The I signal maintains a constant phase of 0°, while the Q signal can switch between two states with a 180° phase difference, referred to as +Q and -Q signals, respectively. The vector power amplifier contains two amplification branches, I and Q, each composed of a single-stage or multi-stage power amplifier. The two amplification branches are combined by a synthesizer. The initial phase difference between the Q and I signals is adjusted according to the synthesizer's characteristics. When a -Q signal is input to the Q channel, the combined power signals are output from the first output (load port) and absorbed by the load, while the second output (RF output port) of the vector power amplifier has no power output. When a +Q excitation signal is input to the Q channel, the combined power signals are output from the RF output port, while the load port has no power output. The vector diagrams for the two operating states are shown below. Figure 2 As shown.

[0024] Obviously, by utilizing Figure 2The vector synthesis relationship shown allows for RF power output to the absorption load or output port by simply switching the phase of the Q-channel signal between +Q and -Q, while maintaining the output power of the I / Q single-channel vector power amplifier at a constant level. Therefore, when the excitation signal corresponding to the narrow input pulses in both I and Q channels is obtained, the narrow pulse can be achieved at the output of the vector power amplifier through vector pulse shaping.

[0025] Similar to power modulation transmitters, this invention also requires pre-establishing the quiescent operating voltage and current for the power amplifier in the vector power amplifier before outputting the RF pulse. The difference is that this invention uses a Class C power amplifier, which has zero quiescent current, allows for sustained application of the operating voltage, and automatically establishes the operating current using a slowly varying RF waveform to excite the power amplifier. This eliminates the need for an additional power switching circuit and avoids abrupt changes in physical quantities such as voltage and current. This is the fundamental difference between this invention and power modulation transmitters.

[0026] The working principle of the ultrafast leading and trailing edge narrow pulse transmitter structure of the present invention is as follows: Figure 3 As shown. When the rising edge of the current synchronization signal arrives, the transmitter begins to establish the operating current for the RF pulse. The vector pulse modulator outputs a slowly varying I / Q signal. As the amplitude of the I / Q signal increases, the power amplifier's supply current begins to rise gradually from 0 to its maximum value I. max During this period, the current is completely controlled by the waveform of the I / -Q RF signal. By optimizing the waveform, sudden current changes and voltage overshoots can be effectively avoided. When the power amplifier's operating current rises to the target operating current I... max Afterward, the transmitter enters the ready-to-transmit state. At this time, the power amplifier link is already operating at full power, but due to the vector synthesis relationship, all power is absorbed by the absorption load, and there is no power output from the RF output port. Until the rising edge of the RF synchronization signal arrives, the vector pulse modulator switches the phase of the Q-channel excitation signal to +Q. At this time, all RF power is switched to the RF output port. During this switching process, the power level of each power device remains unchanged; only the phase of the Q-channel power amplifier changes, thus all physical quantities remain stable. Similarly, at the falling edge of the RF synchronization signal, the phase of the vector pulse modulator output signal switches back to I / +Q, while the amplitude remains unchanged until the falling edge of the current synchronization signal, at which point the excitation signal smoothly decreases to 0, awaiting the next pulse. It can be seen that throughout the entire operation, the transmitter's operating state is stable and controllable, with no abrupt changes in any physical quantity, significantly improving the transmitter's stability and reliability.

[0027] It is important to note that Figure 1In the basic architecture shown, the power amplifier voltage is continuously applied. The ultrafast narrow pulse transmitter structure of this invention does not rely on voltage modulation itself. However, for certain considerations, such as reducing the transmitter noise figure, voltage modulation can be added to the transmitter. In this case, the timing signal is as follows: Figure 4 As shown.

[0028] To verify the feasibility of the proposed ultrafast narrow pulse transmitter structure, a principle verification was conducted using a verification platform based on the aforementioned vector pulse shaping principle. In the verification platform, the vector pulse modulator consists of an FPGA board and a DAC board. The FPGA board is a TI TSW14J59EVM evaluation board, used to generate dual-channel baseband signals with controllable frequency, amplitude, and phase difference. The DAC board is a TI DAC39RF10EVM evaluation board, used to generate the I-channel and Q-channel signals of a dual-channel 9GHz carrier. A 90° quadrature bridge is used in the vector power amplifier, with a synthesized output power in the kilowatt range. The driver amplifier is selected in conjunction with the vector power amplifier to select appropriate gain and power levels.

[0029] Using a vector pulse modulator to output I and Q signals, the bridge synthesizes the 0° and 90° input ports to generate... Figure 3 The test results for the I-channel and Q-channel signals at the 9GHz carrier frequency are shown below. Figure 5 As shown, during the RF pulse transmission time, the RF power is output to the bridge output port; outside the RF pulse transmission time, the RF power is output to the absorption load, and there is no power output at the bridge output port. The pulse rising and falling edges can reach the sub-nanosecond level.

[0030] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultrafast pre- and post-pulse narrow-pulse transmitter architecture, characterized by, include: A vector pulse modulator is used to generate phase-synchronized, phase-difference-adjustable I-channel and Q-channel signals, wherein the Q-channel signal switches between a +Q signal and a -Q signal with a phase difference. A driver amplifier, connected to the vector pulse modulator, is used to pre-amplify the I-channel signal and the Q-channel signal, respectively; A vector power amplifier, connected to the drive amplifier, is used to amplify the two pre-amplified signals separately and then combine them with a power combiner. When the Q signal is switched to -Q, the -Q signal cancels out the I signal and is output from the first output. When the Q signal is switched to +Q, the +Q signal enhances the I signal and is output from the second output, forming an ultrafast narrow pulse with leading and trailing edges.

2. The ultrafast pre- and post-pulse narrow-pulse transmitter structure according to claim 1, characterized in that, The phase of the I-channel signal remains constant, and the phase difference between the +Q and -Q signals of the Q-channel signal is 180°.

3. The ultrafast pre- and post-pulse narrow-pulse transmitter structure according to claim 1, characterized in that, In the vector pulse modulator, two signals are modulated by digital control oscillation or analog local oscillation to provide a synchronization carrier for the I-channel signal and the Q-channel signal, and to independently control the amplitude and phase of the two signals.

4. The ultrafast pre- and post-pulse narrow-pulse transmitter structure of claim 1, wherein, The vector power amplifier includes a single-stage or multi-stage power amplifier.

5. The ultrafast pre- and post-pulse narrow-pulse transmitter structure of claim 1, wherein, In the vector power amplifier, the power amplifier is a Class C power amplifier.

6. The ultrafast pre- and post-pulse narrow-pulse transmitter structure of claim 1, wherein, In the vector power amplifier, the power combiner includes a bridge or waveguide combiner.

7. The ultrafast pre- and post-pulse narrow-pulse transmitter structure according to claim 1, characterized in that, The first outlet is connected to an absorption load or energy recovery circuit, and the second outlet is a radio frequency output port.

8. The ultrafast pre- and post-amplified narrow pulse transmitter structure of claim 1, wherein, It also includes a voltage modulation circuit for reducing the operating voltage of the power amplifier during transmitter RF pulse shutdown to reduce the transmitter's noise figure.

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