Open circuit compensation type biasing circuit

Abstract

The invention discloses an open-circuit compensation type bias circuit, which belongs to the technical field of solid-state microwave power amplifiers and comprises a bias line, an open-circuit compensation line, a first transmission line and a second transmission line. One end of the first transmission line, one end of the open circuit compensation line, one end of the bias line and one end of the second transmission line are connected; the other end of the first transmission line is a first microwave port, the other end of the open circuit compensation line is suspended, the other end of the bias line is a power port, and the other end of the second transmission line is a second microwave port; the physical length of the bias line and the physical length of the open-circuit compensation line meet the relational expression that the sum of the physical length of the bias line and the physical length of the open-circuit compensation line is equal to the sum of four of the central wavelength of the working frequency band of the power amplifier. Through the combination of the transmission line, the compensation line and the bias line, the parasitic inductance of the bias circuit is reduced, and compared with an existing bias circuit, the parasitic inductance is reduced by more than 1 / 4.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state microwave power amplifiers, and particularly relates to an open-circuit compensation type bias circuit. Background Art

[0002] The application of the pulse regime in microwave systems has a wide range of fields. Pulse regime radars and laser weapons, etc. all belong to such applications. Such systems require the power amplifier circuit to be able to operate stably under pulse modulation. Pulse modulation usually includes two forms: gate bias voltage modulation and drain bias voltage modulation. Fu C et al. pointed out in the article "A Wideband Bias Circuit with Low Parasitic Inductance for High-Power GaN Pulsed Power Amplifiers", IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) in 2022 that compared with gate bias voltage modulation, using drain bias voltage modulation can achieve higher efficiency and greater output power. Therefore, in the design of pulse power amplifiers, the drain bias voltage modulation method is usually preferred to optimize the overall performance of the system and improve the power amplification effect. When the pulse signal is in the working state, the drain supply current is a dynamic current I d ; while when the pulse signal is turned off, the drain supply current is a static current I q . Therefore, at the moment when the microwave signal is turned off, the drain voltage will have an overshoot V s :

[0003] In the formula, L is the parasitic inductance of the drain supply path, Δt is the current change time. Reducing the drain voltage overshoot V s is related to L , I d , I q , Δt .

[0004] With the continuous maturity of the gallium nitride technology of the third-generation semiconductor materials, the output power of power amplifiers has been significantly improved and has currently exceeded the 2kW level. For example, the paper "Design of an X-band GaN Kilowatt-level Power Amplifier" published by Hu Yansheng et al. in 2023 in Research & Progress of Solid Electronics. Therefore, the current I d 、 I q value and the difference have increased significantly. In order to improve the waveform quality, the pulse width Δt has been compressed to the nanosecond level. These factors cause a relatively small inductor L to cause a large drain voltage overshoot V s 。Furthermore, when the drain voltage overshoot V s is too large, it will cause the drain voltage amplitude to be too large, affecting the safety of the power amplifier.

[0005] In order to reduce the drain voltage overshoot of the power amplifier and improve the safety and reliability of the power amplifier, it is urgent to reduce the drain parasitic inductance of the power amplifier L 。The bias circuit of the power amplifier is an important factor affecting the drain parasitic inductance. By optimizing the design of the bias circuit and reducing its size, the parasitic inductance of the bias circuit can be effectively reduced, thereby further reducing the drain parasitic inductance.

[0006] Figure 1a and Figure 1b are two common schematic diagrams of bias circuits in the published literature. Figure 1a is a traditional bias circuit, mainly composed of transmission line 1, transmission line 2, and bias line. The characteristic impedances of transmission line 1 and transmission line 2 are 50Ω, and the electrical lengths are λ / 4. The characteristic impedance of the bias line is Z a 、and the electrical length is λ / 4; Figure 1b is an in-situ compensation type bias circuit, mainly composed of transmission line 1, transmission line 2, bias line 1, and bias line 2. The characteristic impedances of transmission line 1 and transmission line 2 are 50Ω, and the electrical lengths are λ / 4. The characteristic impedances of bias line 1 and bias line 2 are Z b 、and the electrical lengths are λ / 4. The output frequency of the power amplifier is fThe microwave, input from port 1, passes through transmission line 1 and transmission line 2 and is output from port 2; the drain supply current is input from the power supply port, passes through the bias line and transmission line 1, and provides a pulsed voltage for the drain of the power amplifier. Among them, the drain supply current of the in-situ compensation type bias circuit is input from two power supply ports. The parasitic inductance of the bias circuit is determined by the dimensions of transmission line 1 and the bias line. The smaller the width and the larger the length of transmission line 1 and the bias line, the larger the parasitic inductance of the bias circuit.

[0007] The size of the bias line of the existing bias circuit is still relatively large, so the parasitic inductance of the existing bias circuit is large. When applied to a pulsed power amplifier with higher power, it will cause a large voltage overshoot, affecting the reliability and safety of the power amplifier. Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of low stability or low efficiency of existing high-power pulsed power amplifiers, and a open-circuit compensation type bias circuit is proposed.

[0009] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a open-circuit compensation type bias circuit, including: A bias line, an open-circuit compensation line, a first transmission line, and a second transmission line; One end of the first transmission line, one end of the open-circuit compensation line, one end of the bias line, and one end of the second transmission line are connected; The other end of the first transmission line is the first microwave port, the other end of the open-circuit compensation line is suspended, the other end of the bias line is the power supply port, and the other end of the second transmission line is the second microwave port; The physical length of the bias line and the physical length of the open-circuit compensation satisfy the relationship: physical length of the bias line + physical length of the open-circuit compensation line = center wavelength of the power amplifier operating frequency band / 4.

[0010] Further, under the action of the compensation line, the bias line is equivalent to an open circuit for the microwave signal of the power amplifier.

[0011] Further, the open-circuit compensation line is theoretically equivalent to a capacitor connected to the ground.

[0012] Further, the characteristic impedance of the bias line is the same as that of the open-circuit compensation line.

[0013] Further, the electrical length of the bias line = phase constant × physical length of the bias line; The electrical length of the open-circuit compensation line = phase constant × physical length of the open-circuit compensation line.

[0014] Further, the characteristic impedance of the first transmission line is the same as that of the second transmission line.

[0015] Further, the characteristic impedances of the first transmission line and the second transmission line are 50 Ω.

[0016] In a second aspect, the present invention provides a method for implementing an open - circuit compensation type bias circuit. Using the open - circuit compensation type bias circuit described above, the microwave of the power amplifier is input from the first microwave port, and after passing through the first transmission line and the second transmission line, it is output from the second microwave port.

[0017] Further, the drain supply current of the power amplifier is input from the power supply port, and after passing through the bias line and the first transmission line, a pulsed voltage is provided for the drain of the power amplifier.

[0018] A power amplifier includes a high - power pulsed power amplifier, which includes the open - circuit compensation type bias circuit described above.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects: The open - circuit compensation type bias circuit proposed by the present invention reduces the parasitic inductance of the bias circuit through the combination of the transmission line, the compensation line, and the bias line. Compared with the existing bias circuit, the parasitic inductance is reduced by more than 1 / 4. Therefore, when the open - circuit compensation type bias circuit is applied to a kilowatt - level high - power pulsed power amplifier, the voltage overshoot is smaller, which can improve the reliability and safety of the high - power pulsed power amplifier. The present invention has high application value in the field of high - power pulsed power amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Additionally, the shapes and proportional dimensions of the components in the figures are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1a It is a schematic diagram of an existing traditional bias circuit.

[0021] Figure 1b It is a schematic diagram of an existing in - situ compensation type bias circuit.

[0022] Figure 2 It is a schematic diagram of an open - circuit compensation type bias circuit proposed by the present invention.

[0023] Figure 3 It is an equivalent circuit schematic diagram of an open - circuit compensation type bias circuit proposed by the present invention.

[0024] Figure 4a It is the simulation result of the reflection coefficient of the open - circuit compensation type bias circuit proposed by the present invention and two existing bias circuits.

[0025] Figure 4bInsertion loss simulation results of the open - circuit compensation type bias circuit proposed by the present invention and two existing bias circuits.

[0026] Figure 5 Parasitic inductance simulation results of the open - circuit compensation type bias circuit proposed by the present invention and two existing bias circuits. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0030] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above - mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non - exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] Embodiment 1 This embodiment proposes an open - circuit compensation type bias circuit, as Figure 2It is a schematic diagram of an open - circuit compensation type bias circuit. The open - circuit compensation type bias circuit mainly consists of a bias line, an open - circuit compensation line, transmission line 1, and transmission line 2. The characteristic impedance of the bias line is Z bias , the electrical length is θ a , and the physical length is l 1. The characteristic impedance of the open - circuit compensation line is Z bias , the electrical length is θ b , and the physical length is l 2. The characteristic impedances of transmission line 1 and transmission line 2 are 50Ω, and there is no requirement for the electrical length; the output frequency of the power amplifier is f microwave, which is input from port 1 and output from port 2 after passing through transmission line 1 and transmission line 2; the drain supply current is input from the power supply port and provides a pulsed voltage for the drain of the power amplifier after passing through the bias line and transmission line 1. The parasitic inductance of the bias circuit is determined by the dimensions of transmission line 1 and the bias line. The smaller the width and the larger the length of transmission line 1 and the bias line, the larger the parasitic inductance of the bias circuit.

[0032] Next, it is proved that the open - circuit compensation line and the bias line are equivalent to an open - circuit for microwave signals with a frequency of f , that is, the open - circuit compensation type bias circuit does not affect microwave signal transmission. Figure 3 It is a schematic diagram of the equivalent circuit of the open - circuit compensation type bias circuit proposed by the present invention. The bias line is equivalent to a lumped - element inductor L S , and the open - circuit compensation line is equivalent to a lumped - element capacitor C S . In the figure, Z 1 is the impedance seen from the end face of the transmission line towards the bias line side, Z 2 is the impedance seen from the end face of the transmission line towards the open - circuit compensation line side.

[0033] According to the transmission line theory, it can be obtained that:

[0034]

[0035] Among them, ,

[0036] In the formula, ω is the center frequency point of the working frequency band of the power amplifier, β represents the phase constant.

[0037] In order to make the open - circuit compensation line and the bias line equivalent to an open - circuit for microwaves with a frequency of f , and the open - circuit compensation type bias circuit does not affect microwave transmission. At this time, a parallel capacitor needs to be usedC S For parallel inductance L S Effective compensation is performed at the working frequency, that is:

[0038] Combining the above equations, we can get l 1. l The relationship between the 2:

[0039] In the formula, λ The center wavelength of the power amplifier operating frequency band Due to the parasitic inductance of the bias circuit and the physical length of the bias line l 1, it can be concluded from the above conclusion that the physical length of the bias line can be further shortened l 1. Thus, the parasitic inductance of the bias circuit is reduced, the reliability and safety of the high-power pulse power amplifier are improved, and the transmission of microwave signals in the circuit is not affected.

[0040] Embodiment 2 This embodiment is an open circuit compensation bias circuit in the first embodiment, with 8.5 GHz as the operating frequency. Z bias , l 1 is set to 100Ω and 1mm respectively, and simulation verification is carried out. When the physical length of the bias line is too small, the insertion loss of the circuit is large and the microwave signal cannot be efficiently transmitted. When the physical length of the bias line is too large, the parasitic inductance of the circuit will increase, resulting in reduced stability of the high-power pulse power amplifier. Therefore, it is necessary to select a suitable l 1. While ensuring signal transmission efficiency, reduce the impact of parasitic inductance on stability, so as to achieve the best working state of the power amplifier. Therefore, considering the parasitic inductance and insertion loss of the circuit, the bias line is finally selected under the condition of 8.5GHz working frequency. l The length of 1 is 1.3mm.

[0041] According to the above analysis, the reflection coefficient, insertion loss and parasitic inductance of the open circuit compensation bias circuit, the existing traditional bias circuit and the in-situ compensation bias circuit are simulated and compared. The simulation results are shown in Figure 4. Figure 5 S11 and S21 are the reflection coefficient and insertion loss of the open-circuit compensation bias circuit. The simulation results show that the open-circuit compensation bias circuit has almost no effect on the transmission of microwave signals compared with the two existing bias circuits. According to the characteristics of the microwave pulse modulator, it is assumed that the time for the microwave signal to be turned on and off is 3ns, that is, the current change frequency is about 333MHz. Therefore, when comparing the parasitic inductance, focus on Figure 5Parasitic inductance of the center-biased circuit at 333 MHz frequency.

[0042] The physical length of the bias line of the open-circuit compensation type bias circuit proposed by the present invention is about 1 / 30 λ , which is only 1 / 5 of the physical length of the bias lines of the existing two types of bias circuits, and the corresponding parasitic inductance is also only 1 / 5. Considering the change in the parasitic inductance of the bias line and transmission line 1 comprehensively, the parasitic inductance of the open-circuit compensation type bias circuit proposed by the present invention is reduced by more than 1 / 4 compared with that of the existing bias circuits.

[0043] Upon reading the above description, many embodiments and many applications beyond the provided examples will be apparent to those skilled in the art. Therefore, the scope of this teaching should not be determined with reference to the above description, but should be determined with reference to the full scope of the foregoing claims and the equivalents thereof. For the sake of completeness, all articles and references including patent applications and published announcements are incorporated herein by reference. Omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to abandon such subject matter, nor should the applicant be regarded as not considering such subject matter as part of the disclosed inventive subject matter.

[0044] The above content is a further detailed description of the present invention. It cannot be determined that the specific implementation of the present invention is limited thereto. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope determined by the claims submitted for the present invention.

Claims

1. An open circuit compensation type bias circuit, characterized in that: include: a bias line, an open circuit compensation line, a first transmission line, and a second transmission line; One end of the first transmission line, one end of the open circuit compensation line, one end of the bias line, and one end of the second transmission line are connected; The other end of the first transmission line is a first microwave port, the other end of the open compensation line is suspended, the other end of the bias line is a power port, and the other end of the second transmission line is a second microwave port; The physical length of the bias line and the physical length of the open-circuit compensation line satisfy the relationship: the physical length of the bias line+the physical length of the open-circuit compensation line=the central wavelength of the power amplifier operating frequency band / 4.

2. The open circuit compensation bias circuit according to claim 1, characterized in that: Under the action of the compensation line, the bias line is equivalent to an open circuit for the microwave signal of the power amplifier.

3. The open circuit compensation bias circuit according to claim 1, characterized in that: The other end of the open-circuit compensation line is suspended, which is theoretically equivalent to connecting a capacitor to the ground.

4. The open circuit compensation bias circuit according to claim 1, characterized in that: The characteristic impedance of the bias line is the same as the characteristic impedance of the open compensation line.

5. The open circuit compensation bias circuit according to claim 1, characterized in that: The electrical length of the bias line = phase constant × physical length of the bias line; The electrical length of the open compensation line=phase constant×physical length of the open compensation line.

6. The open circuit compensation bias circuit according to claim 1, characterized in that: The first transmission line and the second transmission line have the same characteristic impedance.

7. The open circuit compensation bias circuit according to claim 6, characterized in that: The characteristic impedance of the first transmission line and the second transmission line is 50Ω.

8. A method for implementing an open circuit compensation bias circuit, using an open circuit compensation bias circuit as claimed in any one of claims 1 to 7, characterized in that: The microwave signal of the power amplifier is inputted from the first microwave port, and is outputted from the second microwave port after passing through the first transmission line and the second transmission line.

9. The method for implementing an open circuit compensation bias circuit according to claim 8, characterized in that: The drain power supply current of the power amplifier is input from the power supply port, and provides a pulse voltage for the drain of the power amplifier after passing through the bias line and the first transmission line.

10. A power amplifier, comprising a high-power pulse power amplifier, characterized in that: An open circuit compensation bias circuit comprising any one of claims 1-7.

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