Power amplifier

Abstract

The embodiment of the invention provides a power amplifier. The power amplifier comprises a first transistor and at least one second transistor; the control end of the first transistor is used for receiving a radio frequency input signal; the control end of the second transistor is used for receiving bias voltage, and the first end of at least one second transistor is coupled with a power supply voltage end and a signal output end; and the first transformer is coupled between the first end of the first transistor and the second end of the second transistor.

Description

TECHNICAL FIELD

[0001] The embodiment of the present disclosure relates to the technical field of circuit, in particular to a power amplifier. BACKGROUND

[0002] The radio frequency power amplifier (PA) is an important component of the radio frequency circuit in the electronic device, which is responsible for amplifying the power of the radio frequency signal to be transmitted for communication with the base station or WiFi hotspot.

[0003] However, as the requirement of the electronic device for the communication quality is higher and higher, the requirement for the output power of the PA is also higher and higher. Specifically, the PA needs to support a higher power class, such as power class 2 (PC2) to improve the communication quality. SUMMARY

[0004] Therefore, the embodiment of the present disclosure provides a power amplifier.

[0005] The technical solution of the present disclosure is implemented as follows: The embodiment of the present disclosure provides a power amplifier, comprising: a first transistor and at least one second transistor; a control end of the first transistor is used for receiving a radio frequency input signal; a control end of the second transistor is used for receiving a bias voltage; a first end of at least one of the second transistors is coupled with a power supply voltage end and a signal output end; a first transformer coupled between a first end of the first transistor and a second end of the second transistor.

[0006] In some embodiments, the at least one second transistor includes a sub-transistor one and a sub-transistor two; a first end of the sub-transistor two is coupled with the power supply voltage end and the signal output end; the first transformer is coupled between a first end of the first transistor and a second end of the sub-transistor one; The power amplifier further comprises: a second transformer coupled between a first end of the sub-transistor one and a second end of the sub-transistor two.

[0007] In some embodiments, the at least one second transistor includes a sub-transistor three and a sub-transistor four; a first end of the sub-transistor three and a first end of the sub-transistor four are both coupled with the signal output end; the first transformer includes a first input end, a first output end and a second output end; the first input end is coupled with the first end of the first transistor, the first output end is coupled with a second end of the sub-transistor three, and the second output end is coupled with a second end of the sub-transistor four; The power amplifier further comprises: a third transformer, the third transformer comprising a second input terminal, a third input terminal and a third output terminal; the second input terminal coupled to the first terminal of the third sub-transistor, the third input terminal coupled to the first terminal of the fourth sub-transistor, the third output terminal coupled to the signal output terminal.

[0008] In some embodiments, the power amplifier further comprises: a first choke inductor and a second choke inductor, the first terminal of the third sub-transistor coupled to the power voltage terminal through the first choke inductor, the first terminal of the fourth sub-transistor coupled to the power voltage terminal through the second choke inductor; the first choke inductor, the second choke inductor and the third transformer integrated on a first substrate, the material of the first substrate comprising ceramic.

[0009] In some embodiments, the power amplifier further comprises: a capacitor, the capacitor coupled between the power voltage terminal and the signal output terminal; a load, the load coupled between the signal output terminal and a ground terminal.

[0010] In some embodiments, the capacitor comprises a first capacitor and a second capacitor; wherein the first capacitor is coupled between the first terminal of the third sub-transistor and the second input terminal; the second capacitor is coupled between the first terminal of the fourth sub-transistor and the third input terminal; the first capacitor, the second capacitor integrated on a second substrate, the material of the second substrate comprising ceramic.

[0011] In some embodiments, the first transistor comprises a silicon-on-insulator (SOI) transistor, and the second transistor comprises a heterojunction bipolar transistor (HBT).

[0012] In some embodiments, the first transformer is integrated on a third substrate, the material of the third substrate comprising ceramic.

[0013] In some embodiments, the first transformer comprises a primary coil and a secondary coil, and a turns ratio of the primary coil and the secondary coil comprises 1:1 to 3:1.

[0014] In some embodiments, the first transformer comprises a variable transformer.

[0015] The embodiment of the present disclosure provides a power amplifier, which comprises a first transistor and at least one second transistor; a control end of the first transistor is used for receiving a radio frequency input signal; a control end of the second transistor is used for receiving a bias voltage; a first end of at least one second transistor is coupled with a power supply voltage end and a signal output end; and a first transformer is coupled between a first end of the first transistor and a second end of the second transistor. In the embodiment of the present disclosure, by arranging the first transformer between the first end of the first transistor and the second end of the second transistor, the lowest voltage of the second end of the second transistor is pulled down by using the inductive characteristic of the first transformer, so that the swing of the radio frequency output signal is increased, thereby ensuring that the output power of the power amplifier is increased under the condition that the power supply voltage is unchanged. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A structure schematic diagram of the power amplifier in example one is shown; Figure 2 A structure schematic diagram of the power amplifier in example two is shown; Figure 3 A structure schematic diagram of the first power amplifier provided by the embodiment of the present disclosure is shown; Figure 4 A structure schematic diagram of the second power amplifier provided by the embodiment of the present disclosure is shown; Figure 5 A structure schematic diagram of the third power amplifier provided by the embodiment of the present disclosure is shown; Figure 6 A structure schematic diagram of the fourth power amplifier provided by the embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present disclosure will be described clearly and completely in combination with the embodiments of the present disclosure and the drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present disclosure.

[0018] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present disclosure. However, it is obvious for those skilled in the art that the present disclosure can be implemented without one or more of these details. In other examples, in order to avoid obscuring the present disclosure, some technical features known in the art are not described; that is, all the features of the actual embodiments are not described here, and the known functions and structures are not described in detail.

[0019] In the drawings, the size of layers, regions, elements, and the like can be exaggerated for clarity. Like reference numbers in different drawings can indicate like elements.

[0020] It will be understood that when an element or layer is referred to as being "on", "adjacent", "connected" or "coupled" to another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly adjacent", "directly connected" or "directly coupled" to another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure and, similarly, a second element, component, region, layer or section discussed below could be termed a first element, component, region, layer or section without departing from the teachings of the present disclosure.

[0021] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0023] To fully understand this disclosure, detailed steps and structures will be presented in the following description to illustrate the technical solutions of this disclosure. Preferred embodiments of this disclosure are described in detail below; however, other embodiments may also be implemented in addition to these detailed descriptions.

[0024] Figure 1 This is a schematic diagram of the power amplifier in Example 1. Figure 1 As shown, power amplifier 100 typically includes transistor Q, capacitor C, and load R. L In this transistor, the base of transistor Q is connected to the RF signal input terminal RFIN to receive the RF input signal. The collector of transistor Q is connected to the power supply voltage terminal to receive the power supply voltage V. CC Here, the power supply voltage V CC Typically, it is a low voltage, denoted as V1 (V1>0), for example, V1 could be 3.4V. The emitter of transistor Q is grounded. The base of transistor Q is also connected to a bias voltage ( Figure 1 (Not shown in the diagram) The bias voltage is used to turn on transistor Q. Transistor Q amplifies the received RF input signal and outputs it from its collector. Here, the amplified RF input signal is also the RF output signal, and the swing of the RF output signal is V1. Capacitor C is coupled between the power supply voltage terminal and the RF signal output terminal RFOUT to isolate the signal from the power supply voltage V1. CC The DC component. Load R L Coupled between the RF signal output terminal RFOUT and the ground terminal, the load impedance is R1. Power amplifier 100 converts the DC power supplied to it by the power supply into load R1. L The AC power of the power amplifier 100 can be expressed as P.

[0025] As electronic devices demand increasingly higher communication quality, power amplifiers are needed to meet the power requirements of PC2. In a specific example, to meet the power requirements of PC2, a higher supply voltage V can be used when designing the power amplifier. CC Powering the power amplifier. For example, a constant 4.5V or a high 5V power supply can be used. However, due to the limited voltage tolerance of individual transistors, when the supply voltage V... CC When the voltage is increased, the transistor is easily damaged.

[0026] Figure 2 The schematic diagram of the power amplifier in Example 2 is shown below. Figure 2 As shown, to prevent individual transistors from being damaged, a power amplifier 200 with a stacked transistor structure can be used to amplify the RF input signal. Specifically, the power amplifier 200 includes transistor Q', transistor Q'", capacitor C, and load R.L The base of the transistor Q' is connected to the RF input terminal RFIN for receiving the RF input signal. The collector of the transistor Q' is connected to the emitter of the transistor Q", and the emitter of the transistor Q' is grounded. The transistor Q' is used to amplify the received RF input signal and output the amplified RF input signal from the collector of the transistor Q' to the transistor Q". bias The base of the transistor Q" is connected to the bias voltage V CC The collector of the transistor Q" is connected to the power supply voltage terminal. Here, the power supply voltage V CC is a constant voltage or a high voltage, and the value of the power supply voltage V CC is represented as V2. For example, V2 is equal to 2V1. The capacitor C is coupled between the power supply voltage terminal and the RF output terminal RFOUT for isolating the DC component from the power supply voltage V L At this time, the amplified RF input signal can be output from the RF output terminal RFOUT via the transistor Q" and the capacitor C. Here, the amplified RF input signal is also the RF output signal. The swing of the RF output signal is the difference between the voltage at the collector of the transistor Q" (i.e., the value of the power supply voltage V L The load R CC is coupled between the RF output terminal RFOUT and the ground terminal. Here, the load impedance can be R1. The power amplifier 200 can convert the DC power supplied thereto into the AC power on the load R

[0027] Here, it should be noted that, compared with the power amplifier 100 in Figure 1 , the value of the power supply voltage V L connected to the power amplifier 200 in Figure 2 is doubled, so that the swing of the RF output signal thereof is also doubled.

[0028] Specifically, reference can be made to the calculation formula (1) of the output power of the power amplifier:

[0029] wherein V represents the swing of the RF output signal, and R represents the load impedance.

[0030] As can be seen from the above formula, in the case where the load impedance of the load R L remains unchanged, if the swing of the RF output signal is doubled, the output power of the power amplifier 200 becomes 4 times of the original output power. Therefore, the output power of the power amplifier 200 in Figure 2 is 4 times of the output power of the power amplifier 100 in Figure 1 . That is, the output power of the power amplifier 200 in Figure 2 is 4P.

[0031] As can be seen from the preceding text, Figure 2 The power amplifier 200 shown has higher output power, which can effectively improve communication quality. However, Figure 2 The power amplifier 200 in the middle uses a higher power supply voltage V. CC The power supply voltage V CC It requires an additional boost chopper circuit, which is expensive and increases the cost of the entire RF system.

[0032] In view of this, embodiments of the present disclosure provide a power amplifier. This power amplifier can operate using a power supply voltage V with a lower voltage value. CC At the same time, it outputs higher power. This eliminates the need for a boost circuit at the RF system level and improves compatibility.

[0033] This disclosure provides a power amplifier, including: a first transistor and at least one second transistor; a control terminal of the first transistor is used to receive a radio frequency input signal; a control terminal of the second transistor is used to receive a bias voltage; a first terminal of the at least one second transistor is coupled to a power supply voltage terminal and a signal output terminal; and a first transformer is coupled between the first terminal of the first transistor and the second terminal of the second transistor.

[0034] Figure 3 This is a schematic diagram of the structure of a first power amplifier provided in an embodiment of this disclosure. Figure 3 As shown, the power amplifier 300 includes a first transistor Q1, a second transistor Q2, and a first transformer 301. The control terminal 302 of the first transistor Q1 is connected to the radio frequency signal input terminal RFIN for receiving radio frequency input signals. The control terminal 302 of the first transistor Q1 is also connected to a bias voltage (…). Figure 3 (Not shown in the diagram) The bias voltage is used to turn on the first transistor Q1. The first terminal 303 of the first transistor Q1 is connected to the first transformer 301, and the second terminal 304 of the first transistor Q1 is grounded. The first transformer 301 includes an input terminal 305 and an output terminal 306, wherein the input terminal 305 of the first transformer 301 is connected to the first terminal 303 of the first transistor Q1, and the output terminal 306 of the first transformer 301 is connected to the second terminal 307 of the second transistor Q2. The control terminal 308 of the second transistor Q2 is connected to the bias voltage V. bias Connection, bias voltage V bias This is used to turn on the second transistor Q2. The first terminal 309 of the second transistor Q2 is coupled to both the power supply voltage terminal and the signal output terminal RFOUT. Here, the power supply voltage terminal is used to output a low-voltage power supply voltage V. CC Power supply voltage V CC The value can be V1.

[0035] In some embodiments, the power amplifier 300 further comprises a load R L , the load R L is coupled between the signal output end RFOUT and the ground end. Here, the load impedance can be R1.

[0036] In some embodiments, the power amplifier 300 further comprises a capacitor C. Wherein, the capacitor C is coupled between the power supply voltage end and the signal output end RFOUT, the capacitor C can be used to isolate the direct current component from the power supply voltage V CC in the radio frequency output signal.

[0037] Figure 3 In the power amplifier 300, the first transistor Q1 is used to amplify the received radio frequency input signal and output the amplified radio frequency input signal from the first end 303 to the input end 305 of the first transformer 301, the first transformer 301 is used to output a second radio frequency signal to the second transistor Q2 according to the input first radio frequency signal (i.e. the amplified radio frequency input signal described above), and the second transistor Q2 is used to output the second radio frequency signal from the radio frequency signal output end RFOUT. Here, the second radio frequency signal is also the radio frequency output signal. It should be noted that under the action of the first transformer 301, the lowest voltage of the voltage node at the output end 306 of the first transformer 301 can be reduced to 0V or below, that is, the lowest voltage at the second end 307 of the second transistor Q2 is reduced to 0V or below. Specifically, the value of the lowest voltage at the second end 307 of the second transistor Q2 can be reduced to -V1. At this time, the voltage difference between the first end 309 and the second end 307 of the second transistor Q2 is 2V1, that is, the swing of the radio frequency output signal is 2V1. According to formula (1), under the condition that the load impedance is unchanged, if the swing of the radio frequency output signal is doubled, the output power of the power amplifier 300 becomes 4 times the original. Therefore, Figure 3 In the power amplifier 300, the output power is increased to Figure 1 4 times the output power of the power amplifier 100. That is, Figure 3 In the power amplifier 300, the size of the output power is 4P.

[0038] In the embodiments of the present disclosure, by setting the first transformer 301 between the first end 303 of the first transistor Q1 and the second end 307 of the second transistor Q2, and using the inductive characteristic of the first transformer 301 to reduce the lowest voltage at the second end 307 of the second transistor Q2, the voltage swing of the radio frequency output signal is increased, and the output power of the power amplifier 300 is increased under the condition that the power supply voltage V CC is unchanged.

[0039] In this embodiment, the load impedance of the power amplifier 300 can be adjusted to approach 50Ω, thereby increasing the bandwidth of the power amplifier 300. For example, the load impedance can be increased from a smaller R1 to a larger 4R1 to bring the load impedance closer to 50Ω. In this case, the bandwidth of the power amplifier 300 increases. However, the output power of the power amplifier 300 will decrease to P. Therefore, in practical applications, the load impedance of the power amplifier 300 can be adjusted according to specific needs to balance output power and bandwidth.

[0040] In some embodiments, the first transistor Q1 and the second transistor Q2 can be transistors of the same type, such as heterojunction bipolar transistors (HBTs). In this case, the control terminal 302 of the first transistor Q1 is its base, the first terminal 303 of the first transistor Q1 is its collector, and the second terminal 304 of the first transistor Q1 is its emitter.

[0041] Figure 4 This is a schematic diagram of the structure of a second power amplifier provided in an embodiment of this disclosure. Figure 4 As shown, in some embodiments, depending on the voltage withstand capability of each transistor, the first transistor Q1 and the second transistor Q2 in the power amplifier 400 can be different types of transistors. For example, the first transistor Q1 can be a transistor with a lower voltage withstand capability, and the second transistor Q2 can be a transistor with a higher voltage withstand capability. Specifically, the first transistor Q1 includes a silicon-on-insulator (SOI) transistor, and the second transistor Q2 includes a heterojunction bipolar transistor (HBT). In this case, the control terminal 402 of the first transistor Q1 is its gate, the first terminal 403 of the first transistor Q1 is its drain, and the second terminal 404 of the first transistor Q1 is its source. Here, compared to an HBT, the SOI transistor is less expensive; therefore, using an SOI transistor for the first transistor Q1 can further reduce costs.

[0042] In some embodiments, the first transformer 301 is integrated on a third substrate, the third substrate being made of ceramic. In a specific embodiment, the third substrate is made of LMT ceramic, such as Li2MgTi3O8. It should be noted that, since LMT ceramics are inexpensive and suitable for the integration of passive devices, the first transformer 301 can be integrated on an LMT ceramic substrate instead of a semiconductor chip, thereby saving chip area and further reducing costs.

[0043] In this embodiment of the disclosure, the first transformer 301 includes a balun. For example... Figure 4 As shown, in some embodiments, the first transformer 301 includes a primary coil L1 and a secondary coil L2, the turns ratio of the primary coil L1 to the secondary coil L2 including 1:1 to 3:1.

[0044] In the embodiments of the present disclosure, the first transformer 301 can participate in impedance matching of the power amplifier 400. Specifically, Figure 4 The impedance Z1 located at the input end 305 side of the first transformer 301 (i.e., the impedance of the first transistor Q1) is different from the impedance Z2 located at the output end 306 side of the first transformer 301 (i.e., the impedance of the second transistor Q2). At this time, the impedance at both ends of the first transformer 301 needs to be matched to improve the working efficiency of the power amplifier 400. Here, there is a specific relationship between the impedance ratio at both ends of the first transformer 301 and the turn ratio N of the primary coil L1 and the secondary coil L2 of the first transformer 301, as shown in formula (2):

[0045] As can be seen from the above formula, the ratio of the impedance Z1 located at the input end 305 side of the first transformer 301 and the impedance Z2 located at the output end 306 side of the first transformer 301 is equal to the square of the turn ratio N of the primary coil L1 and the secondary coil L2 of the first transformer 301. Therefore, the impedance matching in the power amplifier 400 can be realized by adjusting the turn ratio N of the primary coil L1 and the secondary coil L2 of the first transformer 301.

[0046] In a specific embodiment, the ratio of the impedance Z1 located at the input end 305 side of the first transformer 301 and the impedance Z2 located at the output end 306 side of the first transformer 301 is 4:1. At this time, the turn ratio N of the primary coil L1 and the secondary coil L2 of the first transformer 301 needs to be adjusted to 2:1, so as to realize the impedance matching in the power amplifier 400.

[0047] In other embodiments, the turn ratio N of the primary coil L1 and the secondary coil L2 of the first transformer 301 can be greater than 3:1. Moreover, the turn ratio N of the primary coil L1 and the secondary coil L2 can be adjusted according to actual design requirements.

[0048] In some embodiments, the first transformer 301 includes an adjustable transformer. The adjustable transformer can realize different voltage conversion ratios, so as to adjust the swing of the radio frequency output signal according to the power supply voltage V CC The voltage conversion ratio of the adjustable transformer can also be adjusted according to the actual required output power.

[0049] In some embodiments, the at least one second transistor includes a sub-transistor one and a sub-transistor two, a first end of the sub-transistor two is coupled with a power supply voltage end and a signal output end; the first transformer is coupled between the first end of the first transistor and a second end of the sub-transistor one; the power amplifier further includes: a second transformer coupled between the first end of the sub-transistor one and a second end of the sub-transistor two.

[0050] Figure 5 This is a schematic diagram of the structure of a third power amplifier provided in an embodiment of this disclosure. Figure 5 As shown, the power amplifier 500 includes a first transistor Q1, two second transistors Q2, a first transformer 301, a second transformer 501, a capacitor C, and a load R. L Among them, the two second transistors Q2 are respectively sub-transistors Q1 and Q2. 21 Q-type transistor 22 The control terminal 402 of the first transistor Q1 is connected to the RF signal input terminal RFIN to receive the RF input signal. The control terminal 402 of the first transistor Q1 is also connected to the bias voltage (…). Figure 5 (Not shown in the diagram) A bias voltage is used to turn on the first transistor Q1. The first terminal 403 of the first transistor Q1 is connected to the first transformer 301, and the second terminal 404 of the first transistor Q1 is grounded. The first transformer 301 includes an input terminal 305 and an output terminal 306, wherein the input terminal 305 of the first transformer 301 is connected to the first terminal 403 of the first transistor Q1, and the output terminal 306 of the first transformer 301 is connected to the sub-transistor Q1. 21 The second terminal 502 is connected. Sub-transistor Q 21 Control terminal 503 and bias voltage V bias Connection, bias voltage V bias Used for the conduction transistor Q 21 The second transformer 501 includes an input terminal 505 and an output terminal 506. The input terminal 505 of the second transformer 501 is connected to the sub-transistor Q. 21 The first terminal 504 is connected, and the output terminal 506 of the second transformer 501 is connected to the sub-transistor Q. 22 The second terminal is connected to 507. Sub-transistor Q... 22 Control terminal 508 and bias voltage V bias Connection, bias voltage V bias Used for the conduction transistor Q2 22 Sub-transistor Q 22 The first terminal 509 is coupled to both the power supply voltage terminal and the signal output terminal RFOUT. Here, the power supply voltage V... CC For low voltage, its value can be V1. The load impedance can be R1.

[0051] Figure 5 In this circuit, the first transistor Q1 amplifies the received radio frequency input signal and outputs it from its first terminal 403 to the input terminal 305 of the first transformer 301. The first transformer 301 outputs a second radio frequency signal to the sub-transistor Q1 based on the input first radio frequency signal (i.e., the amplified radio frequency input signal mentioned above). 21It should be noted here that, under the transformation effect of the first transformer 301, the minimum voltage of the voltage node located at the output terminal 306 of the first transformer 301 can be reduced to below 0V. That is to say, the voltage at the sub-transistor Q... 21 The minimum voltage at the second terminal 502 is reduced to below 0V. Specifically, located at sub-transistor Q... 21 The minimum voltage at the second terminal 502 can be reduced to -V1. At this point, the swing of the second RF signal increases compared to the first RF signal. Sub-transistor Q 21 The second radio frequency (RF) signal is output from its first terminal 504 to the input terminal 505 of the second transformer 501. The second transformer 501 outputs a third RF signal to the signal output terminal RFOUT based on the input second RF signal. Here, the third RF signal is also known as the RF output signal.

[0052] It should be noted that, under the transformation effect of the second transformer 501, the minimum voltage of the voltage node located at the output terminal 506 of the second transformer 501 can be reduced to a level lower than the minimum voltage of the voltage node located at the output terminal 306 of the first transformer 301. In other words, the voltage at the sub-transistor Q... 22 The minimum voltage at the second terminal 507 is further reduced. At this point, the swing of the third radio frequency signal is further increased compared to the second radio frequency signal. Thus, compared to... Figure 4 , Figure 5 The output power of the power amplifier 500 in the middle is further improved.

[0053] In this embodiment, the second transformer 501 includes a balun. Both the second transformer 501 and the first transformer 301 can be integrated onto a third substrate.

[0054] In some embodiments, at least one second transistor includes sub-transistor three and sub-transistor four; a first terminal of sub-transistor three and a first terminal of sub-transistor four are both coupled to a signal output terminal; a first transformer includes a first input terminal, a first output terminal, and a second output terminal; the first input terminal is coupled to the first terminal of the first transistor, the first output terminal is coupled to the second terminal of sub-transistor three, and the second output terminal is coupled to the second terminal of sub-transistor four; the power amplifier further includes a third transformer, the third transformer including a second input terminal, a third input terminal, and a third output terminal; the second input terminal is coupled to the first terminal of sub-transistor three, the third input terminal is coupled to the first terminal of sub-transistor four, and the third output terminal is coupled to a signal output terminal.

[0055] Figure 6 This is a schematic diagram of the structure of a fourth power amplifier provided in an embodiment of this disclosure. Figure 6As shown, the power amplifier 600 includes a first transistor Q1, two second transistors Q2, a first transformer 601, a third transformer 602, a capacitor, and a load R. L Among them, the two second transistors Q2 are respectively sub-transistors Q3. 23 Harmony transistor quad Q 24 The control terminal 402 of the first transistor Q1 is connected to the RF signal input terminal RFIN for receiving RF input signals. The control terminal 402 of the first transistor Q1 is also connected to the bias voltage ( Figure 6 (Not shown in the diagram) A bias voltage is used to turn on the first transistor Q1. The first terminal 403 of the first transistor Q1 is connected to the first transformer 601, and the second terminal 404 of the first transistor Q1 is grounded. The first transformer 601 includes an input terminal and an output terminal; specifically, the first transformer 601 includes a first input terminal 603, a first output terminal 604, and a second output terminal 605. The first input terminal 603 of the first transformer 601 is connected to the first terminal 403 of the first transistor Q1, and the first output terminal 604 of the first transformer 601 is connected to the third transistor Q1. 23 The second terminal 606 is connected to the second output terminal 605 of the first transformer 601 and the sub-transistor quad Q. 24 The second terminal is connected to 607. Sub-transistor three Q 23 Control terminal 608 and sub-transistor quad Q 24 The control terminal 609 is connected to the bias voltage V. bias Connection. Sub-transistor three Q 23 The first terminal 610 and the sub-transistor quad Q 24 The first terminal 611 is coupled to the signal output terminal RFOUT and to the power supply voltage terminal. Here, the power supply voltage V output from the power supply voltage terminal... CC For low voltage, its value can be V1. The third transformer 602 includes a second input terminal 612, a third input terminal 613, and a third output terminal 614. The second input terminal 612 is connected to the sub-transistor Q. 23 The first input terminal 610 is coupled to the third input terminal 613 and the sub-transistor quad Q. 24 The first terminal 611 is coupled, and the third output terminal 614 is coupled to the signal output terminal RFOUT. The load impedance can be R1.

[0056] In some embodiments, the capacitor includes a first capacitor C1 and a second capacitor C2; wherein the first capacitor C1 is coupled to the sub-transistor 3Q. 23 Between the first input terminal 610 and the second input terminal 612; the second capacitor C2 is coupled to the sub-transistor quad Q. 24 Between the first input terminal 611 and the third input terminal 613. The first capacitor C1 and the second capacitor C2 can be used to isolate the DC component from the power supply voltage in the RF output signal.

[0057] In this embodiment of the disclosure, the third transformer 602 includes a balun.

[0058] Figure 6 In this circuit, the first transistor Q1 amplifies the received radio frequency input signal and outputs it from its first terminal 403 to the first input terminal 603 of the first transformer 601. The first transformer 601 outputs a differential second radio frequency signal to the sub-transistor Q1 based on the input single-ended first radio frequency signal (i.e., the amplified radio frequency input signal mentioned above). 23 Harmony transistor quad Q 24 .

[0059] It should be noted here that, under the transformer action of the first transformer 601, the minimum voltage at the voltage node located at the first output terminal 604 of the first transformer 601 and the voltage node located at the second output terminal 605 of the first transformer 601 can be reduced to below 0V. That is to say, the voltage at the voltage node located at the sub-transistor Q... 23 The lowest voltage at the second terminal 606 and located in the sub-transistor quad Q 24 The minimum voltage at the second terminal 607 is reduced to below 0V. Specifically, located at the sub-transistor Q... 23 The lowest voltage at the second terminal 606 and located in the sub-transistor quad Q 24 The minimum voltage at the second terminal 607 can be reduced to -V1. At this point, the swing of the second RF signal increases compared to the first RF signal. Specifically, the swing of the second RF signal increases to 2V1. (Sub-transistor three Q) 23 The sub-transistor quad-Q is used to output the second radio frequency signal from its first terminal 610 to the second input terminal 612 of the third transformer 602. 24 This is used to output the second radio frequency signal from its first terminal 611 to the third input terminal 613 of the third transformer 602. The third transformer 602 is used to output a single-ended third radio frequency signal from its third output terminal 614 to the signal output terminal RFOUT based on the input differential second radio frequency signal. Here, the third radio frequency signal is also the radio frequency output signal.

[0060] According to formula (1), if the swing of the RF output signal doubles while the load impedance remains constant, the output power of power amplifier 600 will become four times the original value. Therefore, Figure 6 The output power of the medium power amplifier 600 is increased to Figure 1 Four times the output power of the medium-power amplifier 100. That is, Figure 6 The output power of the medium power amplifier 600 is 4P.

[0061] It's important to note that in high-power applications, single-ended power amplifiers typically have low load impedance. This low load impedance leads to a high impedance slew rate, limiting the amplifier's bandwidth. Differential amplifiers, on the other hand, have a higher load impedance (approximately four times that of a single-ended amplifier), resulting in lower insertion loss for output matching and a relatively lower impedance slew rate, thus enabling a wider bandwidth. Furthermore, due to the efficient CL in a differential amplifier... bc The parasitic capacitance (i.e., the parasitic capacitance between the transistor control terminal and the first terminal) is approximately C, which is equivalent to that in a single-ended circuit. bc With half the parasitic capacitance and a higher input impedance compared to a single-ended circuit, a differential circuit power amplifier exhibits lower inter-stage matching insertion loss compared to a single-ended power amplifier, assuming a constant Q value for the impedance matching structure (e.g., a transformer). This allows for higher gain in differential circuit power amplifiers. Furthermore, since transformer-based differential output matching theoretically suppresses all even-order harmonics, differential circuit power amplifiers can effectively improve the quality of the RF output signal.

[0062] In this embodiment of the disclosure, the power amplifier 600 is designed as a differential circuit, which allows the power amplifier 600 to have lower output matching insertion loss, greater bandwidth, higher gain, and higher signal quality.

[0063] like Figure 6 As shown, in some embodiments, the power amplifier 600 further includes: a first choke inductor L3 and a second choke inductor L4, and a sub-transistor Q. 23 The first terminal 610 is coupled to the power supply voltage terminal via the first choke inductor L3, and the sub-transistor Q4 24 The first terminal 611 is coupled to the power supply voltage terminal via the second choke inductor L4. Here, the first choke inductor L3 and the second choke inductor L4 are not coupled to the DC power supply voltage V. CC It has an impact, but exhibits high impedance for AC radio frequency signals. Therefore, the power supply voltage V output from the power supply voltage terminal... CC It can be transmitted to the sub-transistor Q via the first choke inductor L3 and the second choke inductor L4 respectively. 23 The first terminal 610 and the sub-transistor quad Q 24 The first terminal 611, while the radio frequency signal output by the second transistor Q2 is suppressed and cannot pass through the first choke inductor L3 and the second choke inductor L4.

[0064] In other embodiments, the power supply voltage terminal can also be connected to the third transformer 602, enabling the sub-transistor Q to... 23 The first terminal 610 is coupled to the power supply voltage terminal via the third transformer, and the sub-transistor is Q4.24 The first end 611 of the third transformer is coupled to a power supply voltage end via the third transformer.

[0065] In the embodiments of the present disclosure, some of the devices in the power amplifier 600 can be integrated on an external substrate instead of a semiconductor chip, thereby saving the area of the semiconductor chip and reducing the cost. For example, the first choke inductor L3, the second choke inductor L4 and the third transformer 602 in the power amplifier 600 are integrated on a first substrate, and the material of the first substrate includes ceramic. The first capacitor C1 and the second capacitor C2 are integrated on a second substrate, and the material of the second substrate includes ceramic. The first transformer 601 is integrated on a third substrate, and the material of the third substrate includes ceramic.

[0066] In some embodiments of the present disclosure, the first substrate, the second substrate and the third substrate can be the same substrate. In other embodiments of the present disclosure, the first substrate, the second substrate and the third substrate can be different substrates. In still other embodiments of the present disclosure, any two of the first substrate, the second substrate and the third substrate can be the same substrate, and the remaining one can be another substrate.

[0067] In the embodiments of the present disclosure, the materials of the first substrate, the second substrate and the third substrate can be the same, for example, all being LMT ceramic.

[0068] The embodiments of the present disclosure provide a power amplifier, which comprises: a first transistor and at least one second transistor; a control end of the first transistor is configured to receive a radio frequency input signal; a control end of the second transistor is configured to receive a bias voltage; a first end of the at least one second transistor is coupled to a power supply voltage end and a signal output end; and a first transformer is coupled between a first end of the first transistor and a second end of the second transistor. In the embodiments of the present disclosure, by arranging the first transformer between the first end of the first transistor and the second end of the second transistor, the lowest voltage of the second end of the second transistor is pulled down by the inductive characteristic of the first transformer, so that the swing of the radio frequency output signal is increased, thereby ensuring that the output power of the power amplifier is increased without changing the power supply voltage.

[0069] It should be understood that the term "in one embodiment" or "in an embodiment" as used throughout this specification means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosure. Therefore, appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that the sequence of the above-mentioned processes does not mean the execution order, and the execution order of the processes should be determined according to the functions and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the disclosure. The sequence of the above-mentioned embodiments of the disclosure is only for description, and does not represent the advantages or disadvantages of the embodiments.

[0070] The preferred embodiments of the disclosure are described above, and the patent scope of the disclosure is not limited by the above description. Any equivalent structure transformation made according to the disclosure, or direct / indirect application in other related technical fields within the concept of the disclosure is included in the patent protection scope of the disclosure.

Claims

1. A power amplifier, characterized by, The power amplifier comprises: a first transistor and at least one second transistor; a control terminal of the first transistor is configured to receive a radio frequency input signal; a control terminal of the second transistor is configured to receive a bias voltage, and a first terminal of at least one of the second transistors is coupled to a power voltage terminal and a signal output terminal; a first transformer is coupled between a first terminal of the first transistor and a second terminal of the second transistor.

2. The power amplifier of claim 1, wherein, The at least one second transistor comprises a sub-transistor one and a sub-transistor two, a first terminal of the sub-transistor two is coupled to the power voltage terminal and the signal output terminal; the first transformer is coupled between the first terminal of the first transistor and a second terminal of the sub-transistor one; The power amplifier further comprises: a second transformer is coupled between a first terminal of the sub-transistor one and a second terminal of the sub-transistor two.

3. The power amplifier of claim 1, wherein, The at least one second transistor comprises a sub-transistor three and a sub-transistor four; a first terminal of the sub-transistor three and a first terminal of the sub-transistor four are both coupled to the signal output terminal; the first transformer comprises a first input terminal, a first output terminal and a second output terminal; the first input terminal is coupled to the first terminal of the first transistor, the first output terminal is coupled to a second terminal of the sub-transistor three, and the second output terminal is coupled to a second terminal of the sub-transistor four; The power amplifier further comprises: a third transformer, the third transformer comprises a second input terminal, a third input terminal and a third output terminal; the second input terminal is coupled to the first terminal of the sub-transistor three, the third input terminal is coupled to the first terminal of the sub-transistor four, and the third output terminal is coupled to the signal output terminal.

4. The power amplifier of claim 3, wherein, The power amplifier further comprises: a first choke inductor and a second choke inductor, the first terminal of the sub-transistor three is coupled to the power voltage terminal through the first choke inductor, and the first terminal of the sub-transistor four is coupled to the power voltage terminal through the second choke inductor; the first choke inductor, the second choke inductor and the third transformer are integrated on a first substrate, and a material of the first substrate comprises ceramic.

5. The power amplifier of claim 3, wherein, The power amplifier further comprises: a capacitor, the capacitor is coupled between the power voltage terminal and the signal output terminal; a load, the load is coupled between the signal output terminal and a ground terminal.

6. The power amplifier of claim 5, wherein, The capacitor comprises a first capacitor and a second capacitor; wherein the first capacitor is coupled between the first terminal of the sub-transistor three and the second input terminal; and the second capacitor is coupled between the first terminal of the sub-transistor four and the third input terminal; The first capacitor and the second capacitor are integrated on a second substrate, and a material of the second substrate comprises ceramic.

7. The power amplifier of any one of claims 1 to 4, wherein, The first transistor comprises a silicon-on-insulator (SOI) transistor, and the second transistor comprises a heterojunction bipolar transistor (HBT).

8. The power amplifier of any one of claims 1 to 4, wherein, The first transformer is integrated on a third substrate, and a material of the third substrate comprises ceramic.

9. The power amplifier of any one of claims 1 to 4, wherein, The first transformer comprises a primary coil and a secondary coil, and a turns ratio of the primary coil and the secondary coil comprises 1:1 to 3:

1.

10. The power amplifier of any one of claims 1 to 4, wherein, The first transformer comprises an adjustable transformer.

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