Radio frequency power amplifier and wireless signal transmitting system

Abstract

The application relates to the radio technology field, in particular to a radio frequency power amplifier and a wireless signal transmitting system. The radio frequency power amplifier comprises a first amplification branch and a second amplification branch. The first amplification branch comprises a first transistor. The gate of the first transistor is used for connecting a radio frequency output device to receive a radio frequency signal emitted by the radio frequency output device. The drain of the first transistor is used for connecting a signal transmitting device. The second amplification branch comprises a second transistor. The gate of the second transistor is used for connecting the radio frequency output device to receive the radio frequency signal emitted by the radio frequency output device. The drain of the second transistor is used for connecting the signal transmitting device. When the radio frequency power amplifier works, the working voltage of the drain of the second transistor is greater than the working voltage of the drain of the first transistor. The impedance of the first amplification branch in a backoff state, the characteristic impedance of a transmission line connected with the drain of the first transistor and the impedance of a combiner are equal, so that the bandwidth generated by the radio frequency power amplifier in the backoff state is ensured to be larger.

Description

Technical Field

[0001] This application relates to the field of radio technology, specifically to a radio frequency power amplifier and a wireless signal transmission system. Background Technology

[0002] Radio frequency (RF) power amplifiers are among the most important components in RF front-end systems, and they are widely used in existing communication systems. Generally speaking, existing RF power amplifiers use the same manufacturing process for both the first and second amplification branches, such as LDMOS, GaN, or GaAs, and the drain voltage in each amplification branch is uniform.

[0003] like Figure 1 As shown, Figure 1 This is a schematic diagram of a radio frequency (RF) power amplifier in a prior art solution. Taking an RF power amplifier with a saturated output power ratio of 1:1 for the first amplification branch 101 and the second amplification branch 102 as an example, in saturation, the impedance of the first amplification branch 101 is Ropt_M, and the characteristic impedance of the transmission line connected to it is also Ropt_M. The impedance of the second amplification branch 102 is Ropt_P. In the back-off state, the second amplification branch 102 presents an infinite open-circuit load, and the impedance of the second amplification branch 101 is RHL_M, while the combined impedance is Ropt_M2 / RHL_M.

[0004] With the advent of the 5.5G and even 6G era, bandwidth requirements are increasing. In the current technology, under backoff conditions, because the impedance of the first amplification branch 101 is not equal to the characteristic impedance at both ends of the transmission line, the impedance RHL_M of the first amplification branch 101 under backoff conditions only holds true at the center frequency. Furthermore, the greater the frequency deviates from the center frequency, the greater the drift in its characteristic impedance, thus severely limiting bandwidth. Summary of the Invention

[0005] To address one of the aforementioned technical deficiencies, this application provides a radio frequency power amplifier and a wireless signal transmission system, the technical solution of which is as follows:

[0006] According to a first aspect of the embodiments of this application, this application provides a radio frequency power amplifier, the radio frequency power amplifier comprising,

[0007] The first amplification branch comprises a first transistor, a gate of the first transistor is used for connecting a radio frequency output device to receive a radio frequency signal emitted by the radio frequency output device, and a drain of the first transistor is used for connecting a signal transmitting device; the second amplification branch comprises a second transistor, a gate of the second transistor is used for connecting the radio frequency output device to receive the radio frequency signal emitted by the radio frequency output device, and a drain of the second transistor is used for connecting the signal transmitting device; wherein, in the working process of the radio frequency power amplifier, the working voltage of the drain of the second transistor is greater than the working voltage of the drain of the first transistor.

[0008] According to a second aspect of the embodiments of the present application, the present application provides a wireless signal transmitting system, which comprises:

[0009] a radio frequency output device and a signal transmitting device; a radio frequency power amplifier as described above, which is connected with the radio frequency output device and the signal transmitting device respectively

[0010] By using the radio frequency power amplifier provided in the embodiments of the present application, the radio frequency output device outputs a radio frequency signal to the first amplification branch and the second amplification branch, and the radio frequency signal is output to the signal transmitting device from the drain of the first transistor and the drain of the second transistor under the amplification of the first transistor and the second transistor. In the case that the working voltage of the drain of the second transistor is greater than the working voltage of the drain of the first transistor, the impedance of the first amplification branch in the back-off state, the characteristic impedance of the transmission line connected with the drain of the first transistor and the impedance of the combiner are equal, so that the bandwidth generated by the radio frequency power amplifier in the back-off state is ensured to be larger, and the total bandwidth generated by the radio frequency power amplifier is larger even if the bandwidth generated by the radio frequency power amplifier in the saturation state is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0011] The accompanying drawings, which are included to provide a further understanding of the present application, form a part of the present application and illustrate the illustrative embodiments of the present application and its description, and do not constitute improper limitations to the present application. In the drawings:

[0012] Figure 1 It is a schematic diagram of the radio frequency power amplifier in the prior art;

[0013] Figure 2 It is a schematic diagram of the structure of the radio frequency power amplifier of the present application;

[0014] Figure 3 It is a schematic diagram of one of the circuit principles of the radio frequency power amplifier;

[0015] Figure 4 It is another schematic diagram of the circuit principle of the radio frequency power amplifier;

[0016] Figure 5 Another circuit schematic diagram of a radio frequency power amplifier;

[0017] Figure 6 An experimental comparison chart of prior art and the technical scheme of the present application. DETAILED DESCRIPTION

[0018] In order to make the technical scheme and advantages in the embodiments of the present application more clear and explicit, the exemplary embodiments of the present application are further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and are not an exhaustive enumeration of all embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0019] Radio frequency power amplifiers (such as two-way Doherty amplifiers) play an increasingly important role in wireless communication, which can amplify radio frequency signals and then transmit them to user terminals by signal transmitting equipment. The first amplification branch and the second amplification branch of the radio frequency power amplifier can adopt the same process, and the drain voltages of the transistors are equal, such as LDMOS which is usually 28-48V, GaN which is usually 28-48V, and GaAs which is usually 5V. As shown in the figure, Figure 1 The drain voltages of the first transistor 105 and the second transistor 106 are equal, and in the saturation state, the impedance of the first amplification branch 101 is Ropt_M, and the characteristic impedance of the transmission line connected after it, such as the electrical length of 90 degrees, is also Ropt_M, and the impedance of the second amplification branch 102 is Ropt_P. In the backoff state, the second amplification branch 102 presents an infinite open circuit load, and the impedance of the first amplification branch 101 is RHL_M, and the impedance of the combiner is Ropt_M 2 Ropt_M / RHL_M. And in the backoff state, since the impedance of the first amplification branch 101 is not equal to the characteristic impedance of the transmission line at both ends, the impedance of the first amplification branch 101 in the backoff state is RHL_M, which is only true at the center frequency. And the greater the frequency deviates from the center frequency, the greater the drift of its characteristic impedance, thus severely limiting the bandwidth.

[0020] In addition, the increase in the number of channels of the active antenna system (AAS) puts more stringent requirements on the area of the radio frequency power amplifier. Common bandwidth expansion schemes, such as introducing a 180-degree electrical length transmission line in the first amplification branch to compensate for the main path impedance, are a huge pressure on the chip area.

[0021] The present application provides a radio frequency power amplifier, as shown in the figure, Figure 2 Figure 2 ​This is a schematic diagram of the structure of the radio frequency (RF) power amplifier of this application. The RF power amplifier includes a first amplification branch 101, a second amplification branch 102, a first drain bias circuit 103, and a second drain bias circuit 104. The first amplification branch 101 includes a first transistor 105. The gate of the first transistor 105 can be connected to an RF output device (not shown), and the drain of the first transistor 105 can be connected to a signal transmitting device (not shown). The RF output device can output an RF signal, so that after the RF signal passes through the first transistor 105 and is amplified by the first transistor 105, the RF signal is output to the signal transmitting device through the drain of the first transistor 105. The first terminal of the first drain bias circuit 103 is connected to the drain of the first transistor 105, and the second terminal of the first drain bias circuit 103 can be connected to a first power supply (not shown). The first power supply can supply power to the drain of the first transistor 105 through the first drain bias circuit 103 to meet the operating requirements of the first transistor 105. The first transistor 105 includes, but is not limited to, a field-effect transistor, a BJT transistor, a HEMT transistor, and an HBT transistor.

[0022] like Figure 2 As shown, the drain of the first transistor 105 in the first amplification branch 101 is also connected to the transmission line 1011. It should be noted that... Figure 2 Transmission line 1011 is an equivalent schematic diagram; the specific structure can appear in different forms.

[0023] The second amplification branch 102 includes a second transistor 106. The gate of the second transistor 106 can be connected to an RF output device (not shown), and the drain of the second transistor 106 can be connected to a signal transmitting device (not shown). The RF output device can output an RF signal, so that after the RF signal passes through the second transistor 106 and is amplified by the second transistor 106, it can be output to the signal transmitting device through the drain of the second transistor 106. The first terminal of the second drain bias circuit 104 is connected to the drain of the second transistor 106, and the second terminal of the second drain bias circuit 104 can be connected to a second power supply (not shown). The second power supply can supply power to the drain of the second transistor 106 through the second drain bias circuit 104 to meet the operating requirements of the second transistor 106. The second transistor 106 includes, but is not limited to, a field-effect transistor, a BJT, a HEMT, or an HBT.

[0024] When the RF power amplifier is operating, the operating voltage of the drain of the second transistor 106 is greater than the operating voltage of the drain of the first transistor 105. That is, in the saturation or fallback state of the RF power amplifier, the operating voltage supplied by the first power supply to the drain of the first transistor 105 is less than the operating voltage supplied by the second power supply to the drain of the second transistor 106.

[0025] The following asymmetric radio frequency power amplifier is taken as an example for demonstration. It is assumed that the saturated output power of the first amplification branch P1 and the saturated output power of the second amplification branch P2 in the radio frequency power amplifier are in a ratio of 1:α, and the total saturated power of the radio frequency power amplifier is Psat.

[0026] It is assumed that the working voltage of the first transistor drain is V1, and the saturated power of the first transistor is Psat / (1+α), so the impedance of the first transistor in the saturated state is Ropt_M=(1+α)*V1*V1 / (2*Psat), and the impedance of the first transistor in the back-off state is RHL_M=Ropt_M*(1+α).

[0027] It is assumed that the working voltage of the second transistor drain is V2, and the saturated power of the second transistor is Psat*α / (1+α), so the impedance of the second transistor in the saturated state is Ropt_P=(1+α)*V2*V2 / (2α*Psat), and the impedance of the second transistor in the back-off state is still infinite, that is, the second amplification branch is open in the back-off state.

[0028] In order to expand the bandwidth in the back-off state, the impedance of the first amplification branch in the back-off state needs to be the same as the characteristic impedance of the transmission line, that is, both are RHL_M. Therefore, in the saturated state, the impedance of the second amplification branch at the combining point should be Ropt_M*(1+α) 2 / α, and this value should be equal to Ropt_P, and then V1 / V2=1 / (1+α) is derived. Wherein, α is a value greater than 0, for example, α includes but is not limited to 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.1, 1.5, 2.0, 2.5 and 3.0.

[0029] From the above derivation, in order to make the impedance of the first amplification branch in the back-off state equal to the characteristic impedance of the transmission line connected to the first transistor drain, it is necessary to make the working voltage of the second transistor drain greater than the working voltage of the first transistor drain when the radio frequency power amplifier is working.

[0030] In the above embodiment, the radio frequency output device outputs the radio frequency signal to the first amplification branch and the second amplification branch, and the radio frequency signal is amplified by the first transistor and the second transistor, and then output from the drain of the first transistor and the drain of the second transistor to the signal transmitting device. In the case where the working voltage of the second transistor drain is greater than the working voltage of the first transistor drain, the impedance of the first amplification branch in the back-off state, the characteristic impedance of the transmission line connected to the first transistor drain, and the impedance of the combining point can be equal, so as to ensure that the bandwidth generated by the radio frequency power amplifier in the back-off state is larger, that is, although the bandwidth generated by the radio frequency power amplifier in the saturated state is reduced, the total bandwidth generated by the radio frequency power amplifier is larger.

[0031] According to the above derivation, the ratio of the working voltage of the second transistor drain to the working voltage of the first transistor drain is:

[0032]

[0033]

[0034] Wherein, the V1 represents the working voltage of the first transistor drain, the V2 represents the working voltage of the second transistor drain, the P1 represents the saturated output power of the first amplification branch, and the P2 represents the saturated output power of the second amplification branch.

[0035] In one or more embodiments, the working voltage of the second transistor drain is at least 2 times the working voltage of the first transistor drain, for example, the working voltage of the second transistor drain is 3 times, 3.5 times, 5 times, 6.5 times, 7 times, 8 times, 10 times, 12.5 times, 13 times, 15 times, 17 times, 18.5 times, 20 times, 22 times, 24.5 times, 25.8 times, 27 times, 28.4 times, 29.5 times and 30 times the working voltage of the first transistor drain. In some embodiments, the ratio of the working voltage of the second transistor drain to the working voltage of the first transistor drain is between 2 to 20 times. Setting the saturated output power of the first amplification branch to be less than 1:1 of the saturated output power of the second amplification branch, i.e. the saturated output power of the second amplification branch α is greater than 1, can improve the efficiency of the radio frequency power amplifier.

[0036] For example, the first amplification branch is a 28V LDMOS matched with a second amplification branch of 48V GaN, the first amplification branch is a 12V LDMOS matched with a second amplification branch of 28V LDMOS, the first amplification branch is a 5V GaAs matched with a second amplification branch of 12V LDMOS, and so on.

[0037] In one or more embodiments, as shown in Figure 3 , the first transistor 105 and the second transistor 106 can be active device packages in a package, connected to the pins of the package through bonding wires. The radio frequency output device can be delivered to the first amplification branch 101 and the second amplification branch 102 through the radio frequency signal input end 301, respectively, and then delivered to the signal transmitting device through the radio frequency signal output end 302. Figure 3 Figure 3

[0038] ​​The first drain bias circuit 103 comprises a first microstrip line 1031 and a first filter capacitor 1032, a first end of the first microstrip line 1031 is connected with the drain of the first transistor 105, a second end of the first microstrip line 1031 is connectable with the first power supply 303, a first end of the first filter capacitor 1032 is connected with the first microstrip line 1031, and a second end of the first filter capacitor is grounded. The first filter capacitor 1032 can be a parallel-to-ground capacitor, which is equivalent to be connected to ground at radio frequency, but not connected to ground at direct current, and can provide a path for radio frequency signals to ground, so as to ensure that subsequent circuit devices and direct current voltage sources do not affect the operation of radio frequency signals. In some embodiments, the first filter capacitor 1032 can comprise a plurality of first filter capacitors 1032, which are connected in parallel and have first ends connected with the first microstrip line 1031, and second ends grounded.

[0039] The second drain bias circuit 104 comprises a second microstrip line 1041 and a second filter capacitor 1042, a first end of the second microstrip line 1041 is connected with the drain of the second transistor 106, a second end of the second microstrip line 1041 is connectable with the second power supply 304, a first end of the second filter capacitor 1042 is connected with the second microstrip line 1041, and a second end of the second filter capacitor 1042 is grounded. The second filter capacitor 1042 can be a parallel-to-ground capacitor, which is equivalent to be connected to ground at radio frequency, but not connected to ground at direct current, and can provide a path for radio frequency signals to ground, so as to ensure that subsequent circuit devices and direct current voltage sources do not affect the operation of radio frequency signals. In some embodiments, the second filter capacitor 1042 can comprise a plurality of second filter capacitors 1042, which are connected in parallel and have first ends connected with the second microstrip line 1041, and second ends grounded.

[0040] In one or more embodiments, the radio frequency power amplifier can further comprise a third microstrip line 201, a first direct current blocking capacitor 202, and a fourth microstrip line 203, a first end of the third microstrip line 201 is connected with the drain of the first transistor 105, a second end of the third microstrip line 201 is connected with a first end of the first direct current blocking capacitor 202, a first end of the fourth microstrip line 203 is connected with a second end of the first direct current blocking capacitor 202, and a second end of the fourth microstrip line 203 is connectable with a signal transmitting device. That is, the third microstrip line 201, the first direct current blocking capacitor 202, and the fourth microstrip line 203 are connected in series, and the opposite end of the third microstrip line 201 and the first direct current blocking capacitor 202 is connected with the drain of the first transistor 105, and the opposite end of the fourth microstrip line 203 and the first direct current blocking capacitor 202 is connected with the signal transmitting device. Among them, the third microstrip line 201 and the fourth microstrip line 203 constitute Figure 2 part of the transmission line 1011.

[0041] Since the voltage provided by the first drain biasing circuit 103 to the drain of the first transistor 105 is less than the voltage provided by the second drain biasing circuit 104 to the drain of the second transistor 106, voltage confusion between the two can occur, which can affect the final bandwidth size. The first DC blocking capacitor 202 can isolate the voltage at both ends, ensuring the stability of the drain voltage of the first transistor 105 and the drain voltage of the second transistor 106, and preventing confusion.

[0042] In one or more embodiments, as shown in Figure 4 and Figure 5 , Figure 4 is another circuit schematic diagram of a radio frequency power amplifier, Figure 5 is still another circuit schematic diagram of a radio frequency power amplifier. Figure 4 In the first transistor 105 and the second transistor 106 in the first transistor 105 and the second transistor 106 can be active devices, and the input and output circuits of the first transistor 105 and the second transistor 106 can be passive integrated devices. The active devices and passive devices are assembled in one package, and the device interconnection and the interconnection with the package pins are performed by bonding wires. Figure 5 In the first transistor 104 and the second transistor 106 in the first transistor 104 and the second transistor 106 can be active devices assembled in one substrate, and the interconnection of the active devices to the substrate is performed by bonding wires. The radio frequency output device can be delivered to the first amplification branch 101 and the second amplification branch 102 through the radio frequency signal input end 301, and then delivered to the signal transmitting device through the radio frequency signal output end 302.

[0043] The first drain biasing circuit 103 includes a first inductor 1033 and a third filter capacitor 1034. The first end of the first inductor 1033 is connected to the drain of the first transistor 105, and the second end of the first inductor 1033 can be connected to the first power supply 303. The first end of the third filter capacitor 1034 is connected to the second end of the first inductor 1033, and the second end of the third filter capacitor 1034 is grounded. The third filter capacitor 1034 can be a parallel-to-ground capacitor, which is equivalent to being connected to the ground at radio frequency, but the direct current signal is not connected to the bottom, which can provide a path for the radio frequency signal to the ground, ensuring that the subsequent circuit devices and direct current voltage sources do not affect the operation of the radio frequency signal. In some embodiments, the third filter capacitor 1034 can include multiple third filter capacitors 1034 connected in parallel, and the first ends of the multiple third filter capacitors 1034 are connected to the first inductor 1033. The second ends of the multiple third filter capacitors 1034 are grounded.

[0044] The second drain bias circuit 104 includes a second inductor 1043 and a fourth filter capacitor 1044. The first end of the second inductor 1043 is connected to the drain of the second transistor 106, and the second end of the second inductor 1043 can be connected to the second power supply 304. The first end of the fourth filter capacitor 1044 is connected to the second end of the second inductor 1043, and the second end of the fourth filter capacitor 1044 is grounded. The fourth filter capacitor 1044 can be a parallel-to-ground capacitor, which is equivalent to a radio frequency connection to ground, but a direct current signal is not connected to the bottom, which can provide a radio frequency signal path to ground and ensure that subsequent circuit devices and direct current voltage sources do not affect the operation of the radio frequency signal. In some embodiments, the fourth filter capacitor 1044 can include multiple fourth filter capacitors 1044 connected in parallel, with the first ends connected to the second inductor 1043 and the second ends grounded.

[0045] In one or more embodiments, as shown in Figure 4 and Figure 5 The radio frequency power amplifier further includes a second DC blocking capacitor 204 and a third inductor 205. The first end of the second DC blocking capacitor 204 is connected to the drain of the first transistor 105, and the second end of the second DC blocking capacitor 204 is connected to the first end of the third inductor 205. The second end of the third inductor 205 can be connected to a signal transmitting device. That is, the second DC blocking capacitor 204 and the third inductor 205 are connected in series, the end opposite the second DC blocking capacitor 204 is connected to the drain of the first transistor 105, and the end opposite the third inductor 205 is connected to the signal transmitting device. Among them, the third inductor 205, the parasitic capacitance of the first transistor 105, and the parasitic capacitance of the second transistor 106 constitute at least part of the transmission line 1011 in Figure 2 .

[0046] Because the voltage provided by the first drain bias circuit 103 to the drain of the first transistor 105 is less than the voltage provided by the second drain bias circuit 104 to the drain of the second transistor 106, it can cause voltage confusion between the two, thereby affecting the final bandwidth size. The second DC blocking capacitor 204 can isolate the voltage at both ends, ensuring the stability of the drain voltage of the first transistor 105 and the drain voltage of the second transistor 106, and preventing confusion.

[0047] In one or more embodiments, as shown in Figures 3 to 5As shown in FIG. 1, the radio frequency power amplifier further comprises a power divider 210, an input end of the power divider 210 is connected with the radio frequency output device, a first output end of the power divider 210 is connected with the gate of the first transistor 105, and a second output end of the power divider 210 is connected with the gate of the second transistor 106. The radio frequency output device can be connected with the radio frequency signal input end 301, and after outputting the radio frequency signal, the radio frequency signal is divided at the power divider 210 to transmit the radio frequency signal to the first amplification branch 101 and the second amplification branch 102 to process the radio frequency signal in the first amplification branch 101 and the second amplification branch 102. The source of the first transistor 105 is grounded, and the source of the second transistor 106 is grounded.

[0048] In one or more embodiments, as shown in FIG. 1, Figure 4 and Figure 5 As shown in FIG. 1, the radio frequency power amplifier further comprises a first gate bias circuit and a second gate bias circuit, a first end of the first gate bias circuit is connected with the gate of the first transistor 105, and a second end of the first gate bias circuit is connected with the third power supply 305; a first end of the second gate bias circuit is connected with the gate of the second transistor 106, and a second end of the second gate bias circuit is connected with the fourth power supply 306. The third power supply 305 can provide voltage to the gate of the first transistor 105 through the first gate bias circuit, and the fourth power supply 306 can provide voltage to the gate of the second transistor 106 through the second gate bias circuit.

[0049] In one or more embodiments, as shown in FIG. 1, Figure 4 and Figure 5 As shown in FIG. 1, the radio frequency power amplifier further comprises a third DC blocking capacitor 206 and a fourth DC blocking capacitor 207, a first end of the third DC blocking capacitor 206 is connected with the first output end of the power divider 210, and a second end of the third DC blocking capacitor 206 is connected with the gate of the first transistor 105 and the first end of the first gate bias circuit respectively; a first end of the fourth DC blocking capacitor 207 is connected with the second output end of the power divider 210, and a second end of the fourth DC blocking capacitor 207 is connected with the gate of the second transistor 106 and the first end of the second gate bias circuit respectively. Since the third power supply 305 supplies power to the gate of the first transistor 105 and the fourth power supply 306 supplies power to the gate of the second transistor 106, it is possible to be chaotic through the power divider 210, and the third DC blocking capacitor 206 and / or the fourth DC blocking capacitor 207 can be set to isolate different gate voltages.

[0050] In one or more embodiments, as shown in FIG. 1, Figure 5As shown, the first gate bias circuit includes a fourth inductor 2081 and a first resistor 2082, one end of the fourth inductor 2081 is connected with the third power supply 305, the other end of the fourth inductor 2081 is connected with one end of the first resistor 2082, the other end of the first resistor 2082 is connected with the gate of the first transistor 105. The second gate bias circuit includes a fifth inductor 2091 and a second resistor 2092, one end of the fifth inductor 2091 is connected with the fourth power supply 306, the other end of the fifth inductor 2091 is connected with one end of the second resistor 2092, the other end of the second resistor 2092 is connected with the gate of the second transistor 106.

[0051] As shown in Figure 6 , Figure 6 The figure is an experimental comparison chart of prior art and the technical scheme of the present application, which reflects the reflection coefficient of the impedance of the first amplification branch in the back-off state and the insertion loss of the first amplification branch to the transmission line. The first curve 401 is the experimental result curve of the technical scheme of the present application, and the second curve 402 is the experimental result curve of the prior art. The smaller the absolute value of the insertion loss is, the greater the bandwidth is, and the Figure 6 It can be obviously seen that the bandwidth performance of the technical scheme of the present application in the back-off state is obviously better than that of the prior art.

[0052] Taking a radio frequency power amplifier with a center frequency of 2.0 GHz, a total saturated power of 40 W and a ratio of the saturated output power of the first amplification branch to the saturated output power of the second amplification branch of 1:1 as an example, the advantages of the prior art and the present application are compared:

[0053] For the prior art:

[0054] If the ratio of the saturated output power of the first amplification branch to the saturated output power of the second amplification branch is 1:1, then α=1; the saturated output power of the first amplification branch and the saturated output power of the second amplification branch are both 20 W; assuming that the first amplification branch and the second amplification branch both use a 28V LDMOS; then:

[0055] The impedance Ropt_M of the first amplification branch in the saturated state is 28*28 / 2 / 20=19.6Ω;

[0056] The impedance Ropt_P of the second amplification branch in the saturated state is 28*28 / 2 / 20=19.6Ω;

[0057] The impedance RHL_M of the first amplification branch in the back-off state is 19.6*2=39.2Ω;

[0058] The characteristic impedance of the transmission line is 19.6Ω; the impedance of the combiner is 9.8Ω.

[0059] For the technical scheme of the present application:

[0060] If the ratio of the saturated output power of the first amplification branch to the saturated output power of the second amplification branch is 1:1, then α = 1; the saturated output power of the first amplification branch and the saturated output power of the second amplification branch are both 20W; the voltage V1 of the drain of the first transistor / the voltage V2 of the drain of the second transistor = 1 / 2; it is assumed that the first amplification branch adopts a 28V LDMOS and the second amplification branch adopts a 48V GaN process; the first amplification branch is stepped down to 24V and the second amplification branch is kept at 48V; then:

[0061] The impedance Ropt_M of the first amplification branch in the saturated state is 24*24 / 2 / 20 = 14.4Ω;

[0062] The impedance Ropt_P of the second amplification branch in the saturated state is 48*48 / 2 / 20 = 57.6Ω;

[0063] The impedance RHL_M of the first amplification branch in the backoff state is 14.4*2 = 28.8Ω;

[0064] The characteristic impedance of the transmission line is 28.8Ω; and the impedance of the combiner is 28.8Ω.

[0065] It can be known from the above comparison that the bandwidth performance of the technical solution of the present application in the backoff state is obviously superior to that of the prior art.

[0066] The present application also provides a wireless signal transmitting system, which comprises the aforementioned radio frequency power amplifier, a radio frequency output device (not shown) and a signal transmitting device (not shown). The radio frequency power amplifier is connected with the radio frequency output device and the signal transmitting device respectively, the radio frequency output device outputs a radio frequency signal to the radio frequency power amplifier, the radio frequency power amplifier amplifies the received signal and then outputs the signal to the signal transmitting device, and the signal transmitting device transmits the signal to a user terminal.

[0067] In the description of the present application, it should be understood that the terms "first", "second", "third" and the like are only used for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0068] In this application, unless otherwise clearly indicated and limited, the terms "connected", "connecting", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection; can be directly connected, can also be indirectly connected through intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0069] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A radio frequency power amplifier, characterized by, The radio frequency power amplifier comprises, a first amplification branch comprising a first transistor, a gate of the first transistor being configured to be connected to a radio frequency output device to receive a radio frequency signal from the radio frequency output device, and a drain of the first transistor being configured to be connected to a signal transmitting device; a second amplification branch comprising a second transistor, a gate of the second transistor being configured to be connected to the radio frequency output device to receive the radio frequency signal from the radio frequency output device, and a drain of the second transistor being configured to be connected to the signal transmitting device; wherein, during operation of the radio frequency power amplifier, a working voltage of the drain of the second transistor is greater than a working voltage of the drain of the first transistor, a ratio of the working voltage of the drain of the second transistor to the working voltage of the drain of the first transistor is 2 to 20, and the ratio of the working voltage of the drain of the second transistor to the working voltage of the drain of the first transistor is: wherein, V1 represents the working voltage of the drain of the first transistor, V2 represents the working voltage of the drain of the second transistor, P1 represents a saturated output power of the first amplification branch, and P2 represents a saturated output power of the second amplification branch; a first drain biasing circuit comprising: a first microstrip line, a first end of the first microstrip line being connected to the drain of the first transistor, and a second end of the first microstrip line being configured to be connected to a first power supply; a first filter capacitor, a first end of the first filter capacitor being connected to the first microstrip line, and a second end of the first filter capacitor being grounded; and / or, a second drain biasing circuit comprising: a second microstrip line, a first end of the second microstrip line being connected to the drain of the second transistor, and a second end of the second microstrip line being configured to be connected to a second power supply; a second filter capacitor, a first end of the second filter capacitor being connected to the second microstrip line, and a second end of the second filter capacitor being grounded.

2. The radio frequency power amplifier of claim 1, wherein, The radio frequency power amplifier further comprises: a third microstrip line, a first end of the third microstrip line being connected to the drain of the first transistor; a first DC blocking capacitor, a first end of the first DC blocking capacitor being connected to a second end of the third microstrip line; a fourth microstrip line, a first end of the fourth microstrip line being connected to a second end of the first DC blocking capacitor, and a second end of the fourth microstrip line being configured to be connected to the signal transmitting device.

3. The radio frequency power amplifier of claim 2, wherein, The first drain biasing circuit comprises: a first inductor, a first end of the first inductor being connected to the drain of the first transistor, and a second end of the first inductor being configured to be connected to the first power supply; a third filter capacitor, a first end of the third filter capacitor being connected to the second end of the first inductor, and a second end of the third filter capacitor being grounded; and / or, The second drain biasing circuit comprises: a second inductor, a first end of the second inductor being connected to the drain of the second transistor, and a second end of the second inductor being configured to be connected to the second power supply; a fourth filter capacitor, a first end of the fourth filter capacitor being connected to the second end of the second inductor, and a second end of the fourth filter capacitor being grounded.

4. The radio frequency power amplifier of claim 3, wherein, The radio frequency power amplifier further comprises: a second DC blocking capacitor, a first end of the second DC blocking capacitor being connected to the drain of the first transistor; a third inductor, a first end of the third inductor being connected to a second end of the second DC blocking capacitor, and a second end of the third inductor being configured to be connected to the signal transmitting device.

5. The radio frequency power amplifier of any one of claims 1 to 4, wherein, The radio frequency power amplifier further comprises, a power divider, an input end of the power divider being connected to the radio frequency output device, a first output end of the power divider being connected to the gate of the first transistor, and a second output end of the power divider being connected to the gate of the second transistor.

6. The radio frequency power amplifier of claim 5, wherein, The radio frequency power amplifier further comprises: a first gate biasing circuit, a first end of the first gate biasing circuit being connected to the gate of the first transistor, and a second end of the first gate biasing circuit being configured to be connected to a third power supply; A second gate bias circuit, a first end of which is connected to the gate of the second transistor, and a second end of which is used for connecting to a fourth power supply.

7. The radio frequency power amplifier of claim 6, wherein, The radio frequency power amplifier further comprises: A third DC blocking capacitor, a first end of which is connected to the first output end of the power divider, and a second end of which is connected to the gate of the first transistor and the first end of the first gate bias circuit respectively; And / or a fourth DC blocking capacitor, a first end of which is connected to the second output end of the power divider, and a second end of which is connected to the gate of the second transistor and the first end of the second gate bias circuit respectively.

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