A broadband and high-efficiency GaN internally matched power tube

Abstract

The present invention relates to a novel broadband, high-efficiency GaN internally matched power tube, whose input and output both utilize a bandpass matching network in the form of a multi-stage impedance transformation. The matching elements are fabricated on a ceramic substrate. A parallel resonant network is formed near the gate terminal of the GaN HEMT tube core by connecting a series circuit of an inductor, capacitor, and resistor to ground and the GaN HEMT's Cgs series resistor Rin. Through optimization, the network forms a parallel resonance within the fundamental frequency band, achieving efficient input impedance matching within a wider frequency band. At the same time, the network introduces a certain amount of loss, reducing low-frequency gain, effectively improving amplifier stability, improving standing waves, and expanding bandwidth. The introduction of the series resistor Rin can increase the input impedance, and the increased impedance facilitates broadband impedance matching for high-power GaN HEMT devices. The present invention effectively reduces the difficulty of achieving broadband matching for GaN HEMT devices, making the use of broadband, high-efficiency GaN power tubes more widespread.

Description

Technical Field

[0001] The invention relates to a broadband and high-efficiency GaN internally matched power tube, belonging to the technical field of microwave power amplifiers. Background Art

[0002] As wireless systems such as radar and communications increasingly demand multifunctionality, fast response, interference resistance, high reliability, and mobility in front-end modules, miniaturized, high-efficiency, and broadband microwave power amplifiers are becoming a research trend. First-generation semiconductors such as Ge and Si, and second-generation semiconductors such as GaAs, no longer fully meet these power amplifier requirements. Third-generation semiconductor materials such as GaN offer wide band gaps, high electron mobility, high electron saturation velocity, high breakdown voltage, high thermal conductivity, excellent chemical stability, and strong radiation resistance. High electron mobility transistor (GaN HEMT) power devices, with their high operating frequency, high power density, high breakdown voltage, and high efficiency, are becoming an ideal device for microwave power devices and microwave monolithic integrated circuits.

[0003] As a next-generation solid-state microwave power device, GaN HEMT microwave power devices have garnered significant attention and development attention in Europe, the United States, Japan, and other countries since their introduction. Western countries have prioritized GaN microwave power devices and MMIC circuit research within their strategic technology plans. In recent years, the development of GaN HEMT technology abroad has surpassed expectations, with device performance continuously improving and their engineering applications expanding. The International Technology Roadmap for Semiconductors (ITRS-2009), released in 2009, further clarified that GaN HEMTs will replace GaAs in power applications below the Ka-band between 2013 and 2017. Currently, several companies, including Cree, Qorvo, and Macom in the United States, and Fujitsu in Japan, offer GaN HEMT power tube products, primarily targeting L- and S-band basestation applications, but also expanding into other frequency bands including the Ku-band. While Macom and other companies are focusing on GaN HEMT technology based on Si substrates, all other companies utilize semi-insulating SiC substrates. Compared to Si and GaAs microwave power devices, GaN HEMTs offer significant performance advantages. For example, top-of-the-line products from the US company CREE reach 1000W in the L-band, 500W in the S-band, and 200-300W in the C- and X-bands. Their maximum operating voltages range from 50V to 65V. Integra has reported laboratory-grade high-voltage products, with a single transistor operating in the P-band achieving 1.1kW output at 145V.

[0004] In recent years, wireless systems have become increasingly integrated and complex, yet both power consumption and size have decreased. This has created new demands for high-efficiency and miniaturized components. Microwave power amplifiers are a crucial component of the system's transmit path, often accounting for the majority of the component's power consumption. High-efficiency output from a single power device can effectively reduce the system's total power consumption. The size of the power amplifier, especially the final stage, is typically large. Internally matched amplifiers, by using high-dielectric-constant ceramic substrates, effectively reduce the amplifier circuit area, thereby minimizing system size. Summary of the Invention

[0005] The present invention proposes a broadband, high-efficiency GaN internally matched power tube. Its purpose is to address the shortcomings of the existing technology and propose a new broadband, high-efficiency GaN internally matched power tube that can achieve efficient output of a single power device within a wider operating frequency range. The internally matched power device effectively reduces the size of the amplifier and meets the requirements of miniaturization of microwave systems.

[0006] The technical solution of the present invention is as follows: The present invention proposes a novel broadband high-power GaN internally matched power tube. This power tube is synthesized by a twin GaN HEMT tube core to achieve output. The larger the gate width of the tube core, the lower the input and output impedance of the GaN HEMT device, and the more difficult it is to perform impedance matching. The input and output matching networks of the present invention adopt distributed element matching, and the matching elements are made on an alumina ceramic substrate; the input matching network adopts a resonant network matching form, and an inductor L1 and a resistor R1 are used near the gate end of the GaN HEMT tube core to connect with the C of the GaN HEMT. gs Capacitor, series resistor R in Form a parallel resonant network by optimizing L1, R1, R in The value of realizes parallel resonance within the fundamental frequency band, making the input impedance close to the optimal efficiency point within a wider frequency band, and at the same time improving the device stability and the GaN HEMT input impedance. The impedance improvement is conducive to achieving broadband impedance matching for large gate width GaN HEMT devices, realizing higher performance microwave power devices.

[0007] The input matching network includes a gate feed part, which uses a distributed parameter circuit for matching, including L1 parallel inductor, L in1 The first-stage inductor, L in2 Second-stage inductor, Rin series resistor, C in capacitor, R1 resistor and C1 capacitor, forming R in -L1-L in1 -C in -L in2 In the T-type matching network, the other end of the L1 parallel inductor is connected in series with the R1 resistor and the C1 capacitor, and the C1 capacitor is grounded. in1The first-stage inductor, L in2 The second-level inductor is made of low dielectric constant ceramic with a dielectric constant of less than 20. in The capacitor is made of high dielectric constant ceramic with a dielectric constant greater than 70.

[0008] The output matching network includes a leakage feed part, which uses a distributed parameter circuit for matching, including L2 parallel inductor, L out1 The first-stage inductor, L out2 The second-stage inductor, C out Capacitor, C2 capacitor, forming L2-L out1 -C out -L out2 In the T-type matching network, the other end of the L2 parallel inductor is connected in series with the C2 capacitor, and the C2 capacitor is grounded. out1 The first-stage inductor, L out2 The second-level inductor is made of low dielectric constant ceramic with a dielectric constant of less than 20. out The capacitor is made of high dielectric constant ceramic with a dielectric constant greater than 70.

[0009] The low dielectric constant ceramic is alumina ceramic.

[0010] The matching networks all adopt a microstrip structure and are distributed components.

[0011] The L1 parallel inductor is equivalent to a microstrip line, and the gate end is fed through the L1 parallel inductor; the gate end R1 resistor, R in The resistor is a lumped resistor; the drain end L2 parallel inductor is equivalent to a microstrip line, and the drain end is fed through the L2 parallel inductor.

[0012] The input matching network, GaN HEMT die and output matching network are manufactured on a SiC substrate.

[0013] The C1 capacitor and C2 capacitor are drain bias circuit decoupling capacitors to prevent DC power supply from reaching the ground. They use lumped element MIM capacitors. The R1 resistor and R in The resistors are thin film resistors.

[0014] Beneficial effects of the present invention:

[0015] Because the input and output matching networks utilize distributed element matching, with the matching elements fabricated on an alumina ceramic substrate, the matching networks all employ parallel resonant matching. A parallel resonant network is formed near the gate end of the GaN HEMT die through inductor L1 and resistor R1, along with the GaN HEMT's Cgs capacitor and series resistor Rin. A parallel resonant network is also formed near the drain end of the GaN HEMT die through microstrip inductor L2 and the GaN HEMT's Cds capacitor. This internal matching network directly matches the GaN HEMT device to an output impedance of approximately 50 ohms, significantly reducing the area of ​​the RF amplifier and enhancing its ease of use.

[0016] As can be seen from the above, this new broadband, high-efficiency GaN power tube utilizes a distributed resonant network for both gate and drain matching, enabling high-efficiency output across a single power device over a wide bandwidth. This broadband, high-efficiency, internally matched GaN power tube effectively reduces system size and power consumption while maintaining the same output power, achieving system miniaturization and low power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram showing the internal structure of a novel broadband and high-efficiency GaN internally matched power tube according to the present invention;

[0018] Figure 2 This is a diagram of the internal amplification structure of a novel broadband and high-efficiency GaN internally matched power tube of the present invention;

[0019] Figure 3 This is a schematic diagram of a novel broadband and high-efficiency GaN internally matched power tube circuit of the present invention;

[0020] Figure 4 The following are the test results of the output characteristics of a new broadband high-efficiency internally matched power tube of the present invention.

[0021] In the figure, L is the inductor, R is the resistor, and C is the capacitor. DETAILED DESCRIPTION

[0022] A new broadband, high-efficiency GaN internally matched power transistor achieves efficient output from a single power device across a wide operating frequency range. This internally matched power device effectively reduces amplifier size, meeting the miniaturization requirements of microwave systems. To achieve broadband, high-efficiency output, the present invention utilizes GaN HEMT devices, which offer advantages such as high breakdown electric field and high thermal conductivity. This power device can operate at higher voltages (≥28V), offering higher power density, improved heat dissipation, and higher drain impedance, ensuring broadband, high-efficiency output.

[0023] Secondly, a new matching network is selected to achieve broadband matching of the power tube. The input internal matching network adopts distributed component matching, the matching components are made on the ceramic substrate, and a broadband resonant network is introduced. The distributed inductor L1 and the resistor R1 are connected to the C of the GaN HEMT near the gate end of the GaN HEMT. gs Capacitor, series resistor R in Form a parallel resonant network by optimizing L1, R1, R in The value of makes the parallel resonance in the fundamental frequency band, making the input matching close to the efficiency matching in a wider frequency band, and at the same time improving the device stability and the input impedance of GaN HEMT. The impedance improvement is conducive to the realization of broadband impedance matching for large gate width GaN HEMT devices; the output matching network also adopts a similar matching form, and the distributed inductor L2 is connected to the C of GaN HEMT near the drain end of GaN HEMT tube core. ds The capacitors form a parallel resonant network. By optimizing the value of L2, parallel resonance is achieved within the fundamental frequency band, increasing the GaN HEMT output impedance and facilitating broadband matching. Here, C1 and C2 are drain bias circuit decoupling capacitors, preventing DC power from reaching ground.

[0024] In addition, the input matching circuit adopts a multi-stage impedance transformation structure to achieve broadband matching, and the input impedance matching network adopts R in -L in1 -C in -L in2 T-type matching network, the Q value of this matching network in the Smith chart is low, which effectively expands the matching bandwidth. Input matching network inductor L in1 , L in2 Using relatively low dielectric constant alumina ceramic equivalent, capacitor C in The use of ceramic equivalents with relatively high dielectric constants can effectively reduce the size of the matching circuit and facilitate miniaturization.

[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings.

[0026] The present invention is a new broadband high-efficiency GaN internal matching power tube, the internal structure of which is shown in Figure 1 As shown, Figure 2 To enlarge the structure diagram near the GaN internal matching power tube die. The input matching network uses a distributed resonant matching network for matching. The matching components are made on an alumina ceramic substrate. The distributed inductor L1 and resistor R1 are connected to the C of the GaN HEMT near the gate end of the two-cell GaN HEMT die. gs Capacitor, input resistance R in Form a resonant network by optimizing L1, R1, R inThe value of makes parallel resonance form within the fundamental frequency band, which can increase the circuit bandwidth, improve the input standing wave, improve the circuit stability, and increase the output impedance of the GaN HEMT gate. The impedance increase is conducive to achieving broadband impedance matching for large gate width GaN HEMT devices. Similarly, the output matching network also uses a distributed resonant matching network for matching. Near the drain end of the two-cell GaN HEMT die, a distributed inductor L2 is connected to the GaN HEMT's C ds The capacitors form a parallel resonant network. By optimizing the value of L2, parallel resonance is formed within the fundamental frequency band, thereby improving the output impedance of the GaN HEMT drain end. Figure 3 This is the electrical schematic diagram of the internal matching power tube.

[0027] To achieve broadband high-power output, this example uses a twin-cell GaN HEMT die with a gate width of 50mm per die. Under a drain operating voltage of 50V, the chip achieves an output power density of 6W / mm. Therefore, the output impedance of the GaN HEMT die is very small, only a few tenths of an ohm. Directly matching it to 50 ohms is very difficult, and the circuit is extremely unstable. Therefore, in the present invention, a distributed inductor L1, a resistor R1, and a C resistor are connected near the gate ends of the two GaN HEMT dies. gs Capacitor, series resistor R in The formation of a resonant network effectively increases the circuit bandwidth, improves the circuit stability, improves the circuit standing wave, and increases the GaN HEMT gate terminal impedance, which is conducive to further matching low impedance to high impedance.

[0028] like Figure 4 The figure shows the output power and added efficiency characteristic test curve of the device of the present invention when the drain voltage VD is equal to 50V. It can be seen from the figure that the output power is greater than 600W (58dBm) in the frequency band of 1.0GHz~1.5GHz, and the added efficiency is greater than 60%.

[0029] In summary, the present invention designs a novel broadband, high-efficiency GaN internally matched power tube. The input and output networks of this novel broadband, high-efficiency GaN internally matched power tube adopt distributed component matching. The matching components are fabricated on an alumina ceramic substrate. The input matching network adopts a novel resonant network. The gate end improves the gate end output impedance by introducing an LRC resonant network. At the same time, the stability of the tube core is further improved, the bandwidth is expanded, and stable output within a wide bandwidth of a single power device is achieved.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in the technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

[0031] Example 1

[0032] Among them, L1 uses a distributed parameter inductor with a single-side inductance of about 0.465nH, the single-side resistor R1 has a resistance of 0.75Ω, and C1 is a ceramic capacitor with a capacitance of 1000pF, which has a decoupling function. gs The gate-source capacitance of the die is 1.2pF / mm, and the capacitance of a single die is 66pF. The corresponding resonant frequency can be calculated as shown in Equation 1:

[0033] Formula 1

[0034] Its resonant frequency is 1.28 GHz.

[0035] The quality factor is calculated as shown in formula 2:

[0036] Formula 2

[0037] Its quality factor is 5, which corresponds to a relative bandwidth of approximately 1 / Q, or 20%. Reducing the quality factor can effectively increase the bandwidth, but too low a quality factor will reduce the gain. Choose according to the bandwidth.

Claims

1. A broadband and high-efficiency GaN internally matched power tube, characterized by The invention comprises an input matching network, a GaN HEMT die, and an output matching network. The GaN HEMT die has two cells, which are arranged in parallel. The input matching network and the output matching network adopt a resonant network matching form and adopt distributed component matching. A parallel resonant network is formed by distributed inductors and resistors near the gate or drain end of each GaN HEMT die and the capacitors and resistors in the GaN HEMT die. Parallel resonance is formed within the fundamental frequency band, so that the input impedance approaches the optimal efficiency point within a wide band, while improving the input impedance of the GaN HEMT. The quality factor Q of the parallel resonant network is 5, corresponding to a relative bandwidth of 20%; The input matching network includes a gate feed part, which uses a distributed parameter circuit for matching, including L1 parallel inductor, L in1 The first-stage inductor, L in2 Second-stage inductor, Rin series resistor, C in capacitor, R1 resistor and C1 capacitor, forming R in -L1-L in1 -C in -L in2 In the T-type matching network, the other end of the L1 parallel inductor is connected in series with the R1 resistor and the C1 capacitor, and the C1 capacitor is grounded. in1 The first-stage inductor, L in2 The second-level inductor is made of low dielectric constant ceramic with a dielectric constant of less than 20. in The capacitor is made of high dielectric constant ceramic with a dielectric constant greater than 70; The L1 parallel inductor uses a distributed parameter inductor with a single-side inductance of approximately 0.465nH. The R1 resistor is 0.75Ω. C1 is a ceramic capacitor with a capacitance of 1000pF, which has a decoupling function. Cgs is the gate-source capacitance of the tube core. The capacitance corresponding to the impedance at the optimal efficiency is approximately 1.2pF / mm, and the single-die capacitance is 66pF. The output matching network includes a leakage feed part, which uses a distributed parameter circuit for matching, including L2 parallel inductor, L out1 The first-stage inductor, L out2 The second-stage inductor, C out Capacitor, C2 capacitor, forming L2-L out1 -C out -L out2 In the T-type matching network, the other end of the L2 parallel inductor is connected in series with the C2 capacitor, and the C2 capacitor is grounded. out1 The first-stage inductor, L out2 The second-level inductor is made of low dielectric constant ceramic with a dielectric constant of less than 20. out The capacitor is made of high dielectric constant ceramic with a dielectric constant greater than 70.

2. A broadband high-efficiency GaN internally matched power tube according to claim 1, characterized in that The low dielectric constant ceramic is alumina ceramic.

3. The broadband high-efficiency GaN internally matched power tube according to claim 1, characterized in that The matching networks all adopt a microstrip structure and are distributed components.

4. The broadband high-efficiency GaN internally matched power tube according to claim 1, characterized in that The L1 parallel inductor is equivalent to a microstrip line, and the gate end is fed through the L1 parallel inductor; the gate end R1 resistor, R in The resistor is a lumped resistor; the drain end L2 parallel inductor is equivalent to a microstrip line, and the drain end is fed through the L2 parallel inductor.

5. The broadband high-efficiency GaN internally matched power tube according to claim 1, characterized in that The input matching network, GaN HEMT die and output matching network are manufactured on a SiC substrate.

6. The broadband high-efficiency GaN internally matched power tube according to claim 1, characterized in that The C1 capacitor and C2 capacitor are drain bias circuit decoupling capacitors to prevent DC power supply from reaching the ground. They use lumped element MIM capacitors. The R1 resistor and R in The resistors are thin film resistors.

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