High-power deep-rollback broadband multimode amplifier based on active load modulation

Abstract

The invention discloses a high-power deep-rollback broadband multimode amplifier based on active load modulation, which comprises a 3dB power divider, one output end of the 3dB power divider is connected with a CA amplifier, the other output end of the 3dB power divider is connected with a BA amplifier through a phase compensator, and the output end of the BA amplifier is connected with a rear matching network; the output of the CA amplifier is connected to the input end of an output 3dB coupler in the BA amplifier; by controlling the current amplitude and the current phase of the injection signal of the CA amplifier, active load modulation is carried out on the BA amplifier, the current amplitude and the current phase characteristics of the injection signal of the CA amplifier are changed, and the high-efficiency characteristic during deep rollback is achieved under the broadband. According to the invention, high-power output (greater than or equal to 100W) is realized, a deep rollback effect is accompanied, and the high-efficiency characteristic is realized in saturation and rollback states.

Description

Technical Field

[0001] The invention relates to a power amplifier technology, and in particular to a high-power deep back-off broadband multi-mode amplifier based on active load modulation. Background Art

[0002] Driven by the demand for future wireless communication systems, more communication modes and wider communication frequency bands will be compatible, which will pose a challenge to the performance of the RF front-end, especially the RF amplifier as a key part, which faces challenges in wideband, multi-function, integration and miniaturization.

[0003] In existing application scenarios, power amplifiers are required to have higher efficiency at different power output levels, but traditional high-efficiency power amplifiers cannot achieve this in broadband. When implementing broadband power amplifiers, efficiency is sacrificed. When traditional power amplifiers work in the back-off zone, their working efficiency is low, which increases the heat consumption in the transmission link.

[0004] In order to break the limitation of low back-off efficiency of traditional power amplifiers, a variety of high-efficiency architectures for processing multiple power modes have been proposed. In recent years, the emergence of continuous-type power amplifiers has pushed the research on broadband high-efficiency power amplifier design methods to a climax and formed an easy-to-implement development system. The high efficiency of high-power broadband multi-mode amplifiers under large back-off can reduce heat loss under high power, which is of great significance to device reliability and energy saving. The high efficiency under back-off is more in line with the most widely used high peak-to-average power ratio (PAPR) modulation signal. According to the different signal transmission forms, the peak-to-average power ratio (PAPR) improvement technology can be divided into two categories: power supply modulation technology (envelope elimination and restoration (EER), envelope tracking (ET), etc.), and active load modulation technology (outphasing technology (Outphasing), Doherty technology, load modulation balanced amplifier technology (LMBA), etc.). Active load modulation technology has a wide range of applications and a simple architecture, which is more suitable for the requirements of modern communication systems for miniaturization, broadband multi-mode high efficiency and improved back-off efficiency.

[0005] However, the traditional Doherty and inherent output matching networks have the disadvantage of narrow bandwidth, and the traditional LMBA control amplifier also has the problem of low output power limiting the deep back-off effect. Both of them are difficult to achieve the characteristics of high power, high efficiency, broadband and deep back-off. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a high-power deep back-off broadband multimode amplifier based on active load modulation, which can achieve high-power output (≥100W) accompanied by deep back-off effect, and has high efficiency characteristics in saturation and back-off states.

[0007] Technical solution: A high-power deep back-off broadband multi-mode amplifier based on active load modulation of the present invention comprises a 3dB power divider, one output end of the 3dB power divider is connected to a CA amplifier, the other output end of the 3dB power divider is connected to a BA amplifier through a phase compensator, and the output end of the BA amplifier is connected to a rear matching network;

[0008] The output of the CA amplifier is connected to the input of the output 3dB coupler in the BA amplifier;

[0009] By controlling the current amplitude and current phase of the CA amplifier injection signal, active load modulation of the BA amplifier is achieved, the current amplitude and current phase characteristics of the CA amplifier injection signal are changed, and high efficiency characteristics at deep back-off are achieved in a wide bandwidth.

[0010] Furthermore, by adjusting the input power ratio of the CA amplifier and the BA amplifier and the drain voltage of the CA amplifier, the current amplitude of the CA amplifier injection signal can be controlled.

[0011] Furthermore, according to the static phase shift method and the dynamic adjustable phase method, the current phase of the CA amplifier injection signal is controlled.

[0012] Furthermore, the CA amplifier and the BA amplifier adopt a broadband continuous-mode high-efficiency amplifier to achieve high-efficiency characteristics under saturated output and back-off.

[0013] Furthermore, the CA amplifier includes a CA amplifier input matching circuit, a CA amplifier large gate pitch GaN tube core and a CA amplifier output matching circuit arranged in series; wherein the output end of the CA amplifier output matching circuit is connected to the input end of the 3dB coupler.

[0014] Furthermore, the CA amplifier input matching circuit includes a CA input DC blocking capacitor, a CA input two-segment asymptotic microstrip line, a CA input one-segment asymptotic line and a branch circuit, a CA input matching and feeding network with a thin-film resistor, and a decoupling capacitor connected above the CA input matching and feeding network with a thin-film resistor, which are connected in series in sequence, and each component is connected by gold wire bonding; wherein the first DC blocking capacitor is connected to the output end of the 3dB power divider by gold wire bonding.

[0015] Further, the BA amplifier includes an input 3dB coupler, a first BA amplifier, a second BA amplifier and an output 3dB coupler; wherein the first BA amplifier includes a first BA amplifier input matching circuit, a first BA amplifier large-gate pitch GaN tube core and a first BA amplifier output matching circuit, and the second BA amplifier includes a second BA amplifier input matching circuit, a second BA amplifier large-gate pitch GaN tube core and a second BA amplifier output matching circuit;

[0016] The input end of the input 3dB coupler is connected to the phase compensator, the through end of the input 3dB coupler is connected to the first BA amplifier input matching circuit, the isolation end of the input 3dB coupler is connected to the second BA amplifier input matching circuit, and the coupling end of the input 3dB coupler is connected to a 50 ohm load;

[0017] The output end of the first BA amplifier input matching circuit is connected to the input end of the first BA amplifier large gate spacing GaN tube core, and the output end of the second BA amplifier input matching circuit is connected to the input end of the BA amplifier; the output end of the first BA amplifier large gate spacing GaN tube core is connected to the first BA amplifier output matching circuit, and the output end of the second BA amplifier large gate spacing GaN tube core is connected to the second BA amplifier output matching circuit, the output end of the first BA amplifier output matching circuit is connected to the through end of the output 3dB coupler, the output end of the second BA amplifier output matching circuit is connected to the isolation end of the output 3dB coupler, and the coupling end of the output 3dB coupler is connected to the rear matching network.

[0018] Furthermore, the CA amplifier output matching circuit includes a CA drain decoupling capacitor, a CA output matching and drain feeding network with a thin film resistor, a CA output two-section progressive microstrip line, a CA output one-section progressive microstrip line, and a CA output DC blocking capacitor; wherein the CA output DC blocking capacitor is directly sintered at the end of the CA output one-section progressive microstrip line, the CA output matching and drain feeding network with a thin film resistor and the CA output two-section progressive microstrip line and the CA output one-section progressive microstrip line are all bonded with gold wires, and are connected to the output 3dB coupler through gold wire bonding.

[0019] Furthermore, the input 3dB coupler adopts a broadband Lange coupler with a characteristic impedance of 50 ohms, which has a load circuit with a load of 50 ohms, and the output 3dB coupler adopts a broadband Lange coupler with a characteristic impedance of 30 ohms.

[0020] Furthermore, all circuit structures use ceramic substrate circuits, which are sintered as a whole on a molybdenum-copper carrier board with high thermal conductivity, and the ceramic substrate circuits are bonded by a gold wire bonding process to achieve internal matching of the amplifier; the CA amplifier large-gate spacing GaN tube core in the CA amplifier, the first BA amplifier large-gate spacing GaN tube core in the BA amplifier, and the second BA amplifier large-gate spacing GaN tube core all use GaN HEMT tube cores with high heat dissipation performance in combination with a high-thermal and high-efficiency carrier board to achieve 100W continuous wave output.

[0021] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows:

[0022] The present invention integrates the continuous class working mode into the Doherty-like load modulation balanced amplifier (PD-LMBA) architecture, and uses the high-efficiency amplifier of the broadband continuous class mode to act on the control amplifier and the balanced amplifier in the PD-LMBA architecture, so as to achieve the high-efficiency characteristics of saturated output and output under back-off in a wide bandwidth.

[0023] The gold wire inductor bonding process combined with the reactance-type multi-stage broadband LC matching technology is used to realize the compact broadband multi-mode matching circuit design and achieve the miniaturization characteristics of the broadband multi-mode amplifier.

[0024] Using a ceramic substrate circuit structure with low insertion loss, high dielectric constant and high thermal conductivity, combined with a high-density GaN die with a large gate spacing, the ceramic substrate circuit and the GaN die are sintered on a high thermal conductivity carrier to achieve high power output (≥100W). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the principle of a high-power deep back-off broadband multi-mode amplifier based on active load modulation disclosed in an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a high-power deep back-off broadband multi-mode amplifier based on active load modulation disclosed in an embodiment of the present invention;

[0027] Figure 3 An ideal model diagram of load modulation disclosed in an embodiment of the present invention;

[0028] Figure 4 A curve diagram of the output power of a high-power deep back-off broadband multi-mode amplifier based on active load modulation disclosed in an embodiment of the present invention at back-off and saturation;

[0029] Figure 5 It is a curve diagram of the output efficiency of the high-power deep back-off broadband multi-mode amplifier based on active load modulation disclosed in an embodiment of the present invention at back-off and saturation. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings of the specification.

[0031] like Figure 1 Shown and Figure 2As shown, a high-power deep back-off broadband multi-mode amplifier based on active load modulation of the present invention involves the following components: a 3dB power divider 1, a phase compensator 2, a CA amplifier input matching circuit 3, a CA amplifier large gate spacing GaN tube core 4, a CA amplifier output matching circuit 5, and a 50 ohm load 6; an input 3dB coupler 7; a first BA amplifier input matching circuit 8, a second BA amplifier input matching circuit 9, a first BA amplifier large gate spacing GaN tube core 10, a first BA amplifier output matching circuit 11, a second BA amplifier output matching circuit 12, an output 3dB coupler 13, a post-matching network 14, and a second BA amplifier large gate spacing GaN tube core 15.

[0032] The CA amplifier input matching circuit 3 includes a CA input DC blocking capacitor 301 , a CA input two-segment asymptotic microstrip line 302 , a CA input one-segment asymptotic line and branch circuit 303 , a CA input matching and gate feeding network with thin film resistors 304 , and a CA gate decoupling capacitor 305 .

[0033] The CA amplifier output matching circuit 5 includes a CA drain decoupling capacitor 501 , a CA output matching and drain feeding network 502 with a thin film resistor, a CA output two-segment progressive microstrip line 503 , a CA output one-segment progressive microstrip line 504 , and a CA output DC blocking capacitor 505 .

[0034] Among them, the first BA amplifier input matching circuit 8 includes a first BA amplifier input DC blocking capacitor 801, a first BA amplifier input two-section asymptotic microstrip line 802, a first BA amplifier input one-section asymptotic line and branch circuit 803, a first BA amplifier input matching and gate feeding network 804 with thin film resistors, and a first BA amplifier input gate decoupling capacitor 805.

[0035] Among them, the second BA amplifier input matching circuit 9 includes a second BA amplifier input DC blocking capacitor 901, a second BA amplifier input two-section asymptotic microstrip line 902, a second BA amplifier input one-section asymptotic line and branch circuit 903, a second BA amplifier input matching and gate feeding network with thin film resistor 904, and a second BA amplifier input gate decoupling capacitor 905.

[0036] Among them, the first BA amplifier output matching circuit 11 includes a first BA amplifier output drain decoupling capacitor 1101, a first BA amplifier output matching and drain feeding network 1102 with a thin film resistor, a first BA amplifier output two-section asymptotic microstrip line 1103, a first BA amplifier output one-section asymptotic line and branch circuit 1104, and a first BA amplifier output DC blocking capacitor 1105.

[0037] Among them, the second BA amplifier output matching circuit 12 includes a second BA amplifier output drain decoupling capacitor 1201, a second BA amplifier output matching and drain feeding network 1202 with thin film resistors, a second BA amplifier output two-section asymptotic microstrip line 1203, a second BA amplifier output one-section asymptotic line and branch circuit 1204, and a second BA amplifier output DC blocking capacitor 1205.

[0038] like Figure 1 As shown, a high-power deep back-off broadband multi-mode amplifier based on active load modulation of the present invention includes a power divider 1, a phase compensator 2, a CA amplifier 100, a BA amplifier 200, a 50 ohm load 6, and a post-matching network 14.

[0039] The CA amplifier 100 is composed of a CA amplifier input matching circuit 3, a CA amplifier large-gate-pitch GaN tube core 4 and a CA amplifier output matching circuit 5, and its operating mode is a broadband continuous type operating mode.

[0040] Similarly, the BA amplifier 200 is composed of an input 3dB coupler 7, a first BA amplifier, a second BA amplifier and an output 3dB coupler 13, wherein the first BA amplifier is composed of a first BA amplifier input matching circuit 8, a first BA amplifier large-gate-pitch GaN die 10 and a first BA amplifier output matching circuit 11. The second BA amplifier is composed of a second BA amplifier input matching circuit 9, a second BA amplifier large-gate-pitch GaN die 15 and a second BA amplifier output matching circuit 12.

[0041] The above matching circuits are all implemented based on ceramic circuits, and are interconnected by gold wires to realize miniaturized internal matching circuits; by controlling the current amplitude and current phase of the CA amplifier injection signal, active load modulation of the BA amplifier is realized, and the current amplitude and current phase characteristics of the CA amplifier injection signal are changed, so as to achieve high power output (≥100W) in a wide bandwidth with a deep back-off effect. The control amplifier (CA) and the balanced amplifier (BA) of the present invention both use continuous class mode, so that they have high efficiency characteristics in saturated output and back-off state.

[0042] like Figure 1 As shown, one output end of the 3dB power divider 1 is connected in series with a CA amplifier input matching circuit 3, a CA amplifier large gate pitch GaN tube core 4 and a CA amplifier output matching circuit 5, and the other output end of the 3dB power divider 1 is connected to the input end of the input 3dB coupler 7 through a phase compensator 2. The through end of the input 3dB coupler 7 is connected to the first BA amplifier input matching circuit 8, the isolation end of the input 3dB coupler 7 is connected to the second BA amplifier input matching circuit 9, and the coupling end of the input 3dB coupler 7 is connected to a 50 ohm load 6.

[0043] The output end of the first BA amplifier input matching circuit 8 is connected to the input end of the first BA amplifier large gate pitch GaN tube core 10, and the output end of the second BA amplifier input matching circuit 9 is connected to the input end of the second BA amplifier large gate pitch GaN tube core 15; the output end of the first BA amplifier large gate pitch GaN tube core 10 is connected to the first BA amplifier output matching circuit 11, and the output end of the second BA amplifier large gate pitch GaN tube core 15 is connected to the second BA amplifier output matching circuit 12, the output end of the first BA amplifier output matching circuit 11 is connected to the through end of the output 3dB coupler 13, the output end of the second BA amplifier output matching circuit 12 is connected to the isolation end of the output 3dB coupler 13, the coupling end of the output 3dB coupler 13 is connected to the rear matching network 14, and the output end of the CA amplifier output matching circuit 5 is connected to the input end of the output 3dB coupler 13.

[0044] The RF signal enters from the input end and is divided into two outputs through the 3dB power divider 1. One path passes through the CA amplifier input matching circuit 3, and after impedance matching through the CA amplifier input matching circuit 3, it enters the CA amplifier large-gate spacing GaN tube core 4 for signal amplification. The amplified signal enters the CA amplifier output matching circuit 5 for signal output matching, and the output signal reaches the output 3dB coupler 13; the other path is input into the first BA amplifier input matching circuit 8 and the second BA amplifier input matching circuit 9 of the BA amplifier 200 through the input 3dB coupler 7, and after impedance matching through the first BA amplifier input matching circuit 8 and the second BA amplifier input matching circuit 9, they enter the first BA amplifier large-gate spacing GaN tube core 10 and the second BA amplifier large-gate spacing GaN tube core 15 for signal amplification respectively. The amplified signal enters the first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12 for signal output matching, and the output signal reaches the output 3dB coupler 13.

[0045] like Figure 2 As shown, in this embodiment, the 3dB power divider 1 selects the Wilkinson power divider to make the two-way power distribution of the power divider even and the phase output consistent. The designed operating frequency is 1.3-2GHz and the transmission loss is 0.3dBm. The phase compensator 2 uses a microstrip line, and the phase difference between the control path and the balanced path amplifier is 90°. The 3dB power divider 1 is implemented using ceramic technology and has the characteristics of miniaturization and high temperature resistance. A multi-stage ceramic base shifter is added behind the 3dB power divider 1 to debug the phase difference of the two paths in the PD-LMBA architecture and realize load traction.

[0046] In this example, the CA amplifier 100 uses a continuous operation mode, and the selected transistor is a 14.4mm GaN HEMT independently developed by the Nanjing Institute of Electronic Devices based on a 0.35μm process. The CA amplifier output matching circuit 5 uses a harmonic matching network to load a multi-branch matching circuit and is matched to 30 ohms. The CA amplifier 4 is matched to 50 ohms through the CA amplifier input matching circuit 3.

[0047] The CA amplifier input matching circuit 3 includes a CA input DC blocking capacitor 301, a CA input two-stage asymptotic microstrip line 302, a CA input one-stage asymptotic line and a branch circuit 303, a CA input matching and gate feeding network 304 with a thin film resistor, and a CA gate decoupling capacitor 305; wherein the CA input DC blocking capacitor 301, the CA input two-stage asymptotic microstrip line 302, the CA input one-stage asymptotic line and a branch circuit 303, and the CA input matching and gate feeding network 304 with a thin film resistor are sequentially connected in series, and the CA gate decoupling capacitor 305 is connected above the CA input matching and gate feeding network 304 with a thin film resistor, and each component is connected by gold wire bonding. The CA input DC blocking capacitor 301 is connected to the output end of the 3dB power divider 1 by gold wire bonding. The output end of the CA input matching and gate feeding network 304 with a thin film resistor is connected to the input end of the CA amplifier 4 by gold wire bonding. For the CA amplifier input matching circuit, the length and width of the three microstrip lines are 6810um long / 240um wide, 7800um long / 825um wide, and 2700um long / 700um wide. The parallel branch is 3000um long / 1450um wide, and the DC blocking capacitor has a capacitance of 6pF.

[0048] In this embodiment, the CA amplifier 100 and the BA amplifier 200 are both high-efficiency amplifiers in a broadband continuous-mode operation mode, achieving high-efficiency characteristics under saturation and back-off.

[0049] The CA amplifier output matching circuit 5 includes a CA drain decoupling capacitor 501, a CA output matching and drain feeding network 502 with a thin film resistor, a CA output two-segment progressive microstrip line 503, a CA output one-segment progressive microstrip line 504 and a CA output DC blocking capacitor 505. The CA output DC blocking capacitor 505 is directly sintered at the end of the CA output one-segment progressive microstrip line 504, the CA output matching and drain feeding network 502 with a thin film resistor and the CA output two-segment progressive microstrip line 503 and the CA output one-segment progressive microstrip line 504 are all bonded by gold wires, and are connected to the output 3dB coupler 13 by gold wire bonding, the length and width of the three-segment microstrip line are respectively 4300um long / 800um wide, 7300um long / 600um wide, and 9500um long / 600um wide, and the capacitance of the CA output DC blocking capacitor 505 is 6pF.

[0050] In this embodiment, the input 3dB coupler 7 adopts a broadband Lange coupler with a characteristic impedance of 50 ohms, wherein the built-in load is a 50 ohm load circuit, the coupling line width is 60um, the line spacing is 65um, and the line length is 19000um.

[0051] To ensure phase consistency between the CA circuit and the BA circuit, the components of the first BA amplifier input matching circuit 8 and the second BA amplifier input matching circuit 9 are the same as those of the CA amplifier input matching circuit 3. Considering the different layout positions between the two circuits, the folding method used by the first BA amplifier input matching circuit 8 and the second BA amplifier input matching circuit 9 is different from the folding method used by the CA amplifier input matching circuit 3.

[0052] The first BA amplifier input matching circuit 8 includes a first BA amplifier input DC blocking capacitor 801, a first BA amplifier input two-section asymptotic microstrip line 802, a first BA amplifier input one-section asymptotic line and branch circuit 803, a first BA amplifier input matching and gate feeding network 804 with thin film resistors, and a first BA amplifier input gate decoupling capacitor 805.

[0053] The second BA amplifier input matching circuit 9 includes a second BA amplifier input DC blocking capacitor 901, a second BA amplifier input two-section asymptotic microstrip line 902, a second BA amplifier input one-section asymptotic line and branch circuit 903, a second BA amplifier input matching and gate feeding network 904 with thin film resistors, and a second BA amplifier input gate decoupling capacitor 905.

[0054] The first BA amplifier large-gate-pitch GaN die 10 and the second BA amplifier large-gate-pitch GaN die 15 use a 0.35μmGaN HEMT process, with a die breakdown voltage greater than 200V, a saturation current exceeding 1A / mm, a saturated output power density of 4W / mm at a working voltage of 28V, and a die saturated output power of 50W. The output impedance of the die in the specific implementation of the present invention is obtained using a load-pull method.

[0055] The components of the first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12 are the same as those of the CA amplifier output matching circuit 5 , but the folding method used by the first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12 is different from the folding method used by the CA amplifier output matching circuit 5 .

[0056] The first BA amplifier output matching circuit 11 includes a first BA amplifier output drain decoupling capacitor 1101, a first BA amplifier output matching and drain feeding network 1102 with a thin film resistor, a first BA amplifier output two-segment asymptotic microstrip line 1103, a first BA amplifier output one-segment asymptotic line and branch circuit 1104, and a first BA amplifier output DC blocking capacitor 1105.

[0057] The second BA amplifier output matching circuit 12 includes a second BA amplifier output drain decoupling capacitor 1201, a second BA amplifier output matching and drain feeding network 1202 with a thin film resistor, a second BA amplifier output two-section asymptotic microstrip line 1203, a second BA amplifier output one-section asymptotic line and branch circuit 1204, and a second BA amplifier output DC blocking capacitor 1205.

[0058] The BA amplifier 200 uses a deep class C bias, and the output end is matched to 30 ohms through the first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12, and the input end is matched to 50 ohms through the first BA amplifier input matching circuit 8 and the second BA amplifier input matching circuit 9. The first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12 have the same structure. From the input end coupler straight-through end (coupling end), the DC blocking capacitor, four sections of microstrip lines and a parallel open-circuit branch are connected through gold wire bonding. The length and width of the three sections of microstrip lines are 6780um long / 240um wide, 8850um long / 825um wide, 3.21um long / 700um wide, and 2090um long / 1000um wide, respectively. The parallel branch is 3000um long / 1450um wide, and the capacitance of the DC blocking capacitor is 5pF; the first BA amplifier output matching circuit 11 and the second BA amplifier output matching circuit 12 have the same structure. The first BA amplifier output matching circuit 11 includes a harmonic matching network, two sections of microstrip lines and a DC blocking capacitor, and is connected to the output 3dB coupler 13 through gold wire bonding. The length and width of the two sections of microstrip lines are 5350um long / 800um wide, and 6600um long / 600um wide, respectively, and the capacitance of the DC blocking capacitor is 6pF.

[0059] In the specific implementation of the present invention, the matching of the CA input with thin film resistor and the gate feed network 304 use an RC series network, and are connected to the short-circuited microstrip line in the input matching network. The loading of large resistance resistors can not only be used to eliminate low-frequency oscillations, but also to achieve radio frequency isolation and reduce the impact of the bias circuit on the bandwidth; the series connection of decoupling capacitors can filter out interference signals within a wide frequency band and enhance stability. The drain bias circuit is an LC series network, consisting of a DC feed line and a decoupling capacitor.

[0060] In this embodiment, the output 3dB coupler 13 uses a broadband Lange coupler with a characteristic impedance of 30 ohms. The line width and line spacing of the Lange bridge with a characteristic impedance of 50 ohms are too small to effectively carry the output power of 100W. At the same time, the manufacturing accuracy is too sensitive to the parameters, which is not conducive to engineering error control and consistency control. The coupling line width is 320um, the line spacing is 40um, and the line length is 19000um.

[0061] The control circuit and the auxiliary circuit use the same amplifier input matching structure and the same GaN HEMT to ensure the consistency of the phase in the input matching circuit.

[0062] The control amplifier works in class AB and undervoltage drive, ensuring that the broadband multi-mode amplifier works in an oversaturated state without damage when the output is saturated. The output matching circuit of the control amplifier uses a reactive multi-stage LC matching circuit, and combined with the continuous class working mode, the multi-mode amplifier has high efficiency characteristics at deep back-off. The balanced amplifier (auxiliary path) uses the same output matching circuit and works in deep class C, ensuring that the balanced amplifier does not turn on at deep back-off, and turns on when the input power gradually increases.

[0063] The matching circuit uses a multi-stage reactance LC matching circuit. The 3dB power divider 1, the input 3dB coupler 7, the output 3dB coupler 13, and each level of matching circuits all use ceramic-based technology. The CA amplifier large gate spacing GaN core 4, the first BA amplifier large gate spacing GaN core 10, and the second BA amplifier large gate spacing GaN core 15 use high power density cores with large gate spacing.

[0064] The post-matching network 14 is composed of four-level gradient microstrip lines to achieve matching from 30 ohm impedance to 50 ohm impedance. The length and width of the four-level microstrip lines are respectively 2000um long / 800um wide, 2200um long / 160um wide, 2800um long / 260um wide, and 5600um long / 400um wide.

[0065] This solution adopts ceramic substrate processing technology, combined with gold wire bonding technology and multi-stage broadband LC matching technology to realize a compact broadband multi-mode matching circuit design. The overall design is realized in the form of internal matching and has the characteristics of miniaturization.

[0066] The technical solution of the present invention combines the PD-LMBA architecture of the load modulation balanced amplifier and the Doherty architecture technology, and combines the high power density tube core with a large gate spacing and combines the internal matching sintering and gold wire bonding process, combines the gold wire inductor resonance technology and the multi-stage broadband LC matching technology to realize a compact broadband multi-mode matching circuit design, achieving high power output (≥100W) with a deep back-off effect.

[0067] In this embodiment, the CA amplifier 100 and the BA amplifier 200 are simultaneously loaded in lange mode and combined with the phase compensator 2 to form a broadband multi-mode amplifier.

[0068] The active load modulation method of the broadband multi-mode amplifier is still based on the input 3dB coupler 7, and is based on the dual-input power amplifier system of the BA that injects a control signal at the isolation port of the input 3dB coupler 7. This architecture can perform active load modulation on the BA by controlling the amplitude and phase of the signal injected into the control amplifier.

[0069] By controlling the current amplitude and current phase of the CA amplifier 100 injection signal, active load modulation of the BA amplifier 200 is achieved, the current amplitude and current phase characteristics of the CA amplifier 4 injection signal are changed, and high efficiency characteristics at deep back-off are achieved in a wide bandwidth.

[0070] The load impedance of the BA amplifier 200 is related to the amplitude and phase of the current of the CA amplifier 100. It can be seen that the broadband multi-mode amplifier designed in this scheme realizes load modulation depending on the following two aspects: 1) The current amplitude control of the CA amplifier 100 injection signal can be achieved by adjusting the input power ratio of the CA amplifier B and the BA amplifier 200 and the drain voltage of the CA amplifier 100. 2) The current phase control of the CA amplifier 100 injection signal can be achieved according to the static phase shift method (microstrip phase shifter) and the dynamic adjustable phase method.

[0071] The load modulation process of a high-power deep back-off broadband multimode amplifier based on active load modulation is analyzed as follows. The three active devices (amplifiers) of BA and CA are assumed to be ideal current sources, the amplifier that generates the control signal is set as the carrier amplifier, and BA is set as the peak amplifier. This method expands the design space of the power back-off range and improves the back-off efficiency. The load modulation behavior will be theoretically analyzed from three areas, such as Figure 3 shown.

[0072] 1) Low power area: When the output power of PA is lower than the saturation power of CA, BA is in the off state and no current is output, that is, I b =0. The output impedance of BA is ∞, and the total current output by LMBA is I1=jI3. According to the impedance matrix of the coupler, the impedance of CA is calculated to be Z0.

[0073]

[0074] When the LMBA operates in this region, the total power and efficiency it outputs are equal to the output power and efficiency of the CA, and the maximum efficiency is achieved when the CA reaches saturation (i.e., the OBO target of the LMBA).

[0075] 2) OBO region: When CA reaches saturation, its current reaches the maximum I C,MAX When the input power is further increased, BA starts to work and its current will increase from 0 to I b,MAX In this region, the impedance of CA remains unchanged and is still Z0. According to the impedance matrix of the coupler, the impedance of BA under modulation behavior can be obtained.

[0076]

[0077] It can be seen from formula (2) that at this time CA reaches saturation and has maximum efficiency output. When BA is turned on, CA will load modulate BA, thereby improving the efficiency of BA to achieve active load modulation behavior.

[0078] 3) Saturation region: As the input power increases, when BA reaches saturation, the current reaches the maximum value I b,MAX At the same time, CA also reaches saturation, and the impedance of BA and CA is as follows:

[0079]

[0080] In this region, LMBA will achieve maximum output power and efficiency. According to formula (3), the current ratio of CA to BA is I C,MAX / I b,MAX Determines the power fallback range of the LMBA.

[0081] The load modulation behavior of LMBA is determined by the current amplitude ratio and phase difference between CA and BA. In order to make the load modulation behavior of LMBA more intuitive, the output power expression of CA and BA is:

[0082]

[0083] For example, the output current expression of LMBA can be used to deduce the output power when load modulation is achieved.

[0084]

[0085] It can be seen that the total output power of LMBA is equal to the sum of the output powers of CA and BA, that is, the power of the control amplifier CA is theoretically converted into the output power. In order to illustrate the relationship between the back-off power range and the CA and BA currents, the ratio of the CA current to the BA current is defined as α.

[0086]

[0087] From this we can conclude

[0088]

[0089] When OBO is set to 8dB, assuming that the current of CA reaches its maximum value, the value of α can be obtained

[0090] α=0.94 (9)

[0091] At this time, the reflection coefficient corresponding to BA at saturation of LMBA can be calculated.

[0092]

[0093] From (9, 10), we can see that the reflection coefficient of the output impedance of BA reflected on the impedance original diagram is a constant. In the actual circuit, the amplitude modulation can be controlled by the input power distribution of CA and BA and adjusting the drain bias voltage of CA. The input power of CA and BA is the same. Here, the value of α is adjusted by changing the drain bias voltage of CA. When the value of α is determined, it means that the back-off range of LMBA is determined. However, the reflection coefficient of BA will change with the phase difference between CA and BA currents. Due to the difference in φ, they have different positions on the Smith chart. When BA is turned on, φ has a great influence on the efficiency of BA.

[0094] The broadband multimode amplifier works in a deep back-off state, with an output power of 42dBm at 1.3-2GHz and an efficiency of more than 44%. The entire BA amplifier works in a deep pinch-off state (gate voltage -3.5V), so that it works later than the CA circuit when RFin increases. When CA and BA are loaded in lange at the same time, a broadband multimode amplifier is formed in combination with a phase compensation structure. Figure 4 and Figure 5 The simulation results of the high-power deep back-off broadband multi-mode amplifier are shown in the figure, which are the output power and drain efficiency curves. In the 1.3-2GHz frequency range, the output power of 1.3GHz-2GHz in the saturated state is greater than 50dBm, and the efficiency is greater than 54%.

[0095] In the specific implementation of the present invention, the matching circuit is made of a high dielectric constant dielectric plate and combined with the GaN process to achieve miniaturization and high performance of the amplifier. The broadband multi-mode high-power amplifier uses a continuous wave mode, which has a large heat loss and a significant thermal deposition effect. Considering that the performance of the tube core is closely related to the temperature, excessive temperature will seriously affect its reliability. Therefore, a molybdenum-copper CPC material with a thermal conductivity of 260K / m is used to make a carrier heat support.

Claims

1. A high-power deep back-off broadband multimode amplifier based on active load modulation, characterized in that: It comprises a 3dB power divider (1), one output end of the 3dB power divider (1) is connected to a CA amplifier (100), the other output end of the 3dB power divider (1) is connected to a BA amplifier (200) via a phase compensator (2), and the output end of the BA amplifier (200) is connected to a rear matching network (14); The output of the CA amplifier (100) is connected to the input of the output 3dB coupler (13) in the BA amplifier (200); By controlling the current amplitude and current phase of the CA amplifier (100) injection signal, active load modulation of the BA amplifier (200) is achieved, the current amplitude and current phase characteristics of the CA amplifier (100) injection signal are changed, and high efficiency characteristics at deep back-off are achieved in a wide bandwidth.

2. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: By adjusting the input power ratio of the CA amplifier (100) and the BA amplifier (200) and the drain voltage of the CA amplifier (100), the current amplitude of the signal injected by the CA amplifier (100) is controlled.

3. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: According to the static phase shift method and the dynamic adjustable phase method, the current phase of the CA amplifier (4) injection signal is controlled.

4. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: The CA amplifier (100) and the BA amplifier (200) adopt a broadband continuous-mode high-efficiency amplifier to achieve high-efficiency characteristics under saturated output and back-off.

5. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: The CA amplifier (100) comprises a CA amplifier input matching circuit (3), a CA amplifier large-gate-pitch GaN tube core (4) and a CA amplifier output matching circuit (5) which are arranged in series; wherein the output end of the CA amplifier output matching circuit (5) is connected to the input end of a 3dB coupler (13).

6. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 5, characterized in that: The CA amplifier input matching circuit (3) comprises a CA input DC blocking capacitor (301), a CA input two-segment asymptotic microstrip line (302), a CA input one-segment asymptotic line and a branch circuit (303), a CA input matching and feeding network with a thin film resistor (304), and a CA gate decoupling capacitor (305) connected above the CA input matching and feeding network with a thin film resistor (304) which are sequentially connected in series, and each component is connected by gold wire bonding; wherein the CA input DC blocking capacitor (301) is connected to the output end of the 3dB power divider (1) by gold wire bonding.

7. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: The BA amplifier (200) comprises an input 3dB coupler (7), a first BA amplifier, a second BA amplifier and an output 3dB coupler (13); wherein the first BA amplifier comprises a first BA amplifier input matching circuit (8), a first BA amplifier large-gate-pitch GaN tube core (10) and a first BA amplifier output matching circuit (11); and the second BA amplifier comprises a second BA amplifier input matching circuit (9), a second BA amplifier large-gate-pitch GaN tube core (15) and a second BA amplifier output matching circuit (12); The input end of the input 3dB coupler (7) is connected to the phase compensator (2), the through end of the input 3dB coupler (7) is connected to the first BA amplifier input matching circuit (8), the isolation end of the input 3dB coupler (7) is connected to the second BA amplifier input matching circuit (9), and the coupling end of the input 3dB coupler (7) is connected to a 50 ohm load (6); The output end of the first BA amplifier input matching circuit (8) is connected to the input end of the first BA amplifier large-gate-pitch GaN tube core (10), and the output end of the second BA amplifier input matching circuit (9) is connected to the input end of the BA amplifier (15); the output end of the first BA amplifier large-gate-pitch GaN tube core (10) is connected to the first BA amplifier output matching circuit (11), the output end of the second BA amplifier large-gate-pitch GaN tube core (15) is connected to the second BA amplifier output matching circuit (12), the output end of the first BA amplifier output matching circuit (11) is connected to the through end of the output 3dB coupler (13), the output end of the second BA amplifier output matching circuit (12) is connected to the isolation end of the output 3dB coupler (13), and the coupling end of the output 3dB coupler (13) is connected to the rear matching network (14).

8. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 5, characterized in that: The CA amplifier output matching circuit (5) comprises a CA drain decoupling capacitor (501), a CA output matching and drain feeding network with thin film resistors (502), a CA output two-section progressive microstrip line (503), a CA output one-section progressive microstrip line (504), and a CA output DC blocking capacitor (505); wherein the CA output DC blocking capacitor (505) is directly sintered at the end of the CA output one-section progressive microstrip line (504), and the CA output matching and drain feeding network with thin film resistors (502) and the CA output two-section progressive microstrip line (503) and the CA output one-section progressive microstrip line (504) are all bonded by gold wires, and are connected to an output 3dB coupler (13) by gold wire bonding.

9. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 7, characterized in that: The input 3dB coupler (7) adopts a broadband Lange coupler with a characteristic impedance of 50 ohms, and its own load circuit is a 50 ohm load. The output 3dB coupler (13) adopts a broadband Lange coupler with a characteristic impedance of 30 ohms.

10. The high-power deep back-off broadband multi-mode amplifier based on active load modulation according to claim 1, characterized in that: All circuit structures use ceramic substrate circuits, which are integrally sintered on a molybdenum-copper carrier board with high thermal conductivity, and the ceramic substrate circuits are bonded by a gold wire bonding process to achieve an amplifier internal matching form; the CA amplifier large-gate-pitch GaN tube core 4 in the CA amplifier (100), the first BA amplifier large-gate-pitch GaN tube core (10) and the second BA amplifier large-gate-pitch GaN tube core (15) in the BA amplifier (200) all use GaN HEMT tube cores with high heat dissipation performance in combination with a high-heat and high-efficiency carrier board to achieve a 100W continuous wave output.

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