Power amplification circuit and radio frequency chip

Abstract

The utility model provides a power amplifier, a radio frequency chip and a power amplification circuit. The power amplifier comprises an input matching network, a first power amplifier, a second power amplifier, a first biasing circuit, a second biasing circuit, an isolation network and an output matching network, the output end of the input matching network is connected with the input end of the first power amplifier and the input end of the second power amplifier, the isolation network is connected between the output end of the second power amplifier and the input end of the output matching network in series, and the isolation network is used for adjusting the impedance of a second power amplifier branch to an open circuit state; the emitter area of the first power amplifier is larger than the emitter area of the second power amplifier. Compared with the prior art, the power amplification circuit provided by the utility model effectively improves the efficiency of a back-off area under the condition of ensuring enough output power, is simpler in circuit structure, and reduces the limitation on bandwidth.

Description

TECHNICAL FIELD

[0001] The utility model relates to wireless communication technical field, especially involve a kind of power amplifier circuit and radio frequency chip. BACKGROUND

[0002] With recent years, communication technology develops rapidly, especially with the emergence and rapid popularization of 5G communication, it brings great convenience to people's life.Power amplifier as the most core component of radio frequency front end of wireless communication equipment, its performance directly determines the communication distance, signal quality and standby time (or power consumption) of wireless terminal, and it is also the largest power consumption device of radio frequency front end.

[0003] However, the modulation signal applied to complex modulation technology generally has a high peak-to-average power ratio (PAPR), such as the PAPR of LTE signal can reach 10dB.The signal with high PAPR will force the power amplifier to work in the back-off area, but the efficiency peak of the traditional power amplifier is located at the power saturation point, and the efficiency at the power back-off point is very low, therefore, how to improve the efficiency of the power amplifier in the back-off area is very important to improve the performance of the power amplifier.Currently, some existing technologies can improve the efficiency of power amplifier to some extent, for example, envelope tracking technology (ET), outphasing power amplifier, etc.

[0004] Envelope tracking technology (ET) is a dynamic drain voltage modulation technology that can effectively improve the average efficiency of PA, but due to the power loss of the power supply modulation circuit itself, in addition, the bandwidth performance will be limited in the face of large output power and output voltage swing.The outphasing power amplifier (Outphasing) uses nonlinear power amplifier to achieve linear amplification technology, so theoretically it can achieve very high efficiency, but it is very sensitive to the imbalance of phase and amplitude.

[0005] Therefore, there is an urgent need for a new power amplifier circuit and radio frequency chip to solve the above technical problems. UTILITY MODEL CONTENT

[0006] The utility model provides a kind of and radio frequency chip, aims at improving the efficiency of power amplifier in the back-off area, and reducing circuit complexity and bandwidth limitation.

[0007] In the first aspect, the utility model provides a kind of power amplifier circuit, and the power amplifier circuit includes input matching network, first power amplifier, second power amplifier, first bias circuit, second bias circuit, isolation network and output matching network;

[0008] The input end of the input matching network is used for receiving a radio frequency signal, the output end of the input matching network is connected with the input end of the first power amplifier and the input end of the second power amplifier respectively, the output end of the first power amplifier and the output end of the second power amplifier are connected to the input end of the output matching network respectively, wherein the emitter area of the first power amplifier is greater than the emitter area of the second power amplifier; the isolation network is connected in series between the output end of the second power amplifier and the input end of the output matching network; the output end of the output matching network is used for outputting a radio frequency signal, the first bias circuit is used for providing a bias voltage for the first power amplifier, the second bias circuit is used for providing a bias voltage for the second power amplifier, and the isolation network is used for adjusting the impedance of the second power amplifier branch to an open circuit state.

[0009] Preferably, the isolation network comprises a first capacitor, a second capacitor and a first inductor, a first end of the first inductor is connected to the output end of the second power amplifier as the input end of the isolation network, a second end of the first inductor is connected to the input end of the output matching network as the output end of the isolation network, a first end of the first capacitor is connected with the first end of the first inductor, a second end of the first capacitor is grounded, a first end of the second capacitor is connected with the second end of the first inductor, and a second end of the second capacitor is grounded.

[0010] In a second aspect, the utility model also provides a radio frequency chip, the radio frequency chip includes the power amplifier circuit as any one of above-mentioned embodiments.

[0011] Compared with the prior art, the utility model discloses a power amplifier circuit, comprising an input matching network, a first power amplifier, a second power amplifier, a first bias circuit, a second bias circuit, an isolation network and an output matching network; the input end of the input matching network is used for receiving a radio frequency signal, the output end of the input matching network is connected with the input end of the first power amplifier and the input end of the second power amplifier respectively, the input end of the isolation network is connected in series between the output end of the second power amplifier and the input end of the output matching network, the output end of the output matching network is used for outputting a radio frequency signal, the first bias circuit is used for providing a bias voltage for the first power amplifier, the second bias circuit is used for providing a bias voltage for the second power amplifier, and the isolation network is used for adjusting the impedance of the second power amplifier branch to an open circuit state; the emitter area of the first power amplifier is greater than the emitter area of the second power amplifier. In this way, the power amplifier circuit of the utility model effectively improves the efficiency of the back-off zone under the condition of guaranteeing sufficient output power, and simultaneously the circuit structure is simpler, and the limitation on bandwidth is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0012] The utility model discloses below in conjunction with the drawings. The above or other aspects of the utility model will become more clear and more easily understood through the following detailed description made in conjunction with the accompanying drawings. In the drawings,

[0013] Figure 1 It is the structural schematic diagram of power amplifier circuit that the utility model provides embodiment provides;

[0014] Figure 2 It is the structural schematic diagram of the output matching network part of power amplifier circuit that the utility model provides embodiment provides. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantage of the utility model more clear and obvious, the following is in conjunction with the drawings and embodiment, and the utility model is further detailed. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model.

[0016] Embodiment one

[0017] Please refer to Figure 1 The utility model provides a kind of power amplifier circuit 100, the power amplifier circuit 100 includes input matching network 1, first power amplifier 2, second power amplifier 3, first bias circuit 4, second bias circuit 5, isolation network 6 and output matching network 7;

[0018] The input end of the input matching network 1 is used to receive radio frequency signal, the output end of the input matching network 1 is connected with the input end of the first power amplifier 2 and the input end of the second power amplifier 3 respectively, the isolation network 6 is connected between the output end of the second power amplifier 3 and the input end of the output matching network 7, the output end of the output matching network 7 is used to output radio frequency signal, the first bias circuit 4 is used to provide bias voltage for the first power amplifier 2, the second bias circuit 5 is used to provide bias voltage for the second power amplifier 3, the isolation network 6 is used to adjust the impedance of the second power amplifier 3 branch to open circuit state.

[0019] The emitter area of the first power amplifier 2 is greater than the emitter area of the second power amplifier 3.

[0020] Specifically, the first power amplifier 2 is a high-power power amplifier, and its emitter area needs to be designed to ensure sufficient radio frequency power output. When the first power amplifier 2 is working normally, the first bias circuit 4 is in a high bias state. The second power amplifier 3 is a low-power power amplifier, and its emitter area is significantly smaller than that of the first power amplifier 2. When the second power amplifier 3 is working normally, the second bias circuit 5 is in a low bias state. When the power amplifier circuit 100 is close to saturation, the second power amplifier 3 is not turned on, and only the first power amplifier 2 is working. At this time, the first power amplifier 2 with sufficient emitter area can output sufficient saturated radio frequency power in the high bias state. When the power is low, the first power amplifier 2 is not turned on, and only the second power amplifier 3 is working. The emitter area of the second power amplifier 3 is small and in a low bias state, so it will not generate excess direct current power consumption. The switching between the two working modes of the first power amplifier 2 and the second power amplifier 3 is realized only by setting the size of the bias voltage of the corresponding branch (that is, when the first power amplifier 2 is working, the bias voltage of the second power amplifier 3 is set to 0, and vice versa), so there will be no excessive additional power consumption.

[0021] In the specific implementation process, first, a power threshold (referred to as P0) is needed to divide the high-power area and the low-power area of the power amplifier circuit 100. When the input power is in the high-power area (greater than P0), the bias voltage of the second power amplifier 3 is set to 0, and at this time the second power amplifier 3 is in the off state, and the first power amplifier 2 works normally to output sufficient saturated power. When the input power is in the low-power area (less than P0), in order to improve the efficiency in this power range, the bias voltage of the first power amplifier 2 is set to 0, and at this time the first power amplifier 2 is in the off state, and only the second power amplifier 3 works normally under low bias. By switching the two working modes in different power ranges, the power amplifier circuit 100 can have sufficient output power in the high-power area, and at the same time can effectively improve the average efficiency of the power amplifier circuit 100 in the low-power area.

[0022] In the embodiment, the isolation network 6 includes a first capacitor C1, a second capacitor C2, and a first inductor L1. A first end of the first inductor L1 is connected to an output end of the second power amplifier 3 as an input end of the isolation network 6. A second end of the first inductor L1 is connected to an input end of the output matching network 7 as an output end of the isolation network 6. A first end of the first capacitor C1 is connected to the first end of the first inductor L1, and a second end of the first capacitor C1 is grounded. A first end of the second capacitor C2 is connected to the second end of the first inductor L1, and a second end of the second capacitor C2 is grounded.

[0023] Specifically, referring to the output end of the second power amplifier 3 as an example, the isolation network 6 is arranged at the output end of the second power amplifier 3 Figure 2 , Figure 2 is a partial structure schematic diagram of the output matching network 7 of the power amplification circuit 100 provided by the embodiment of the utility model. In the case that the power amplification circuit 100 is in a high-power state, the output impedance state of the first power amplifier 2 when working is as follows: wherein Zload is the resistance value of the load at the output end of the first power amplifier 2 to the output matching network 7, that is, the impedance value viewed from the load end (the circuit connected behind the output end of the output matching network 7), which is matched to the vicinity of Zout (that is, the optimal load) through load pull, and at the same time, in order to avoid the influence of the branch of the second power amplifier 3 on the output impedance of the first power amplifier 2, an isolation network 6 is designed at the output end of the second power amplifier 3, and the isolation network 6 can be equivalent to a quarter-wavelength microstrip line (that is, the matching between the input impedance and the load impedance can be realized, so as to reduce the reflection and improve the signal transmission efficiency), and the purpose is to pull the impedance of the branch of the second power amplifier 3 to a state close to open circuit, so as to hardly affect the first power amplifier 2.

[0024] Load pull refers to measuring and analyzing the performance parameters of the power amplifier under large signal conditions by changing the load impedance of the output end. These parameters include but are not limited to output power, efficiency, linearity and compression ratio, etc. Through load pull test, the performance of the amplifier under different load conditions can be understood, so as to find the optimal matching impedance to improve the performance of the amplifier.

[0025] Compared with the prior art, the utility model discloses a power amplification circuit, including input matching network, first power amplifier, second power amplifier, first bias circuit, second bias circuit, isolation network and output matching network, the input end of input matching network is used to receive radio frequency signal, the output end of input matching network is connected with the input end of first power amplifier and the input end of second power amplifier respectively, the input end of isolation network is connected between the output end of second power amplifier and the input end of output matching network in series, the output end of output matching network is used for output radio frequency signal, first bias circuit is used for providing bias voltage for first power amplifier, second bias circuit is used for providing bias voltage for second power amplifier, and isolation network is used for adjusting the impedance of the branch of second power amplifier to open circuit state, and the emitter area of first power amplifier is greater than the emitter area of second power amplifier. In this way, the power amplification circuit of the utility model improves the efficiency of the backoff region effectively under the condition of guaranteeing sufficient output power, and the circuit structure is simpler, and the limitation on bandwidth is reduced.

[0026] Embodiment two

[0027] The utility model embodiment further provides a kind of radio frequency chip, the radio frequency chip includes the power amplifier circuit 100 as described in above embodiment, and can realize same technical effect, refer to the description in above embodiment, here no longer repeat.

[0028] It should be noted that in this document, the terms "comprise", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, so that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] The embodiments of the utility model are described above in combination with the drawings, and the disclosed is only the preferred embodiment of the utility model, but the utility model is not limited to the above specific implementation, and the above specific implementation is only illustrative, not restrictive, and those skilled in the art can make many equivalent changes without departing from the purpose of the utility model and the scope of protection of the claims under the inspiration of the utility model, which are all within the protection of the utility model.

Claims

1. A power amplification circuit, characterized by, The power amplification circuit comprises an input matching network, a first power amplifier, a second power amplifier, a first bias circuit, a second bias circuit, an isolation network and an output matching network; An input end of the input matching network is configured to receive a radio frequency signal, output ends of the input matching network are connected to input ends of the first power amplifier and the second power amplifier respectively, output ends of the first power amplifier and the second power amplifier are connected to an input end of the output matching network respectively, wherein an emitter area of the first power amplifier is greater than an emitter area of the second power amplifier, the isolation network is connected in series between the output end of the second power amplifier and the input end of the output matching network, an output end of the output matching network is configured to output a radio frequency signal, the first bias circuit is configured to provide a bias voltage for the first power amplifier, the second bias circuit is configured to provide a bias voltage for the second power amplifier, and the isolation network is configured to adjust an impedance of a branch of the second power amplifier to an open circuit state.

2. The power amplification circuit of claim 1, wherein, The isolation network comprises a first capacitor, a second capacitor and a first inductor, a first end of the first inductor is connected to the output end of the second power amplifier as an input end of the isolation network, a second end of the first inductor is connected to the input end of the output matching network as an output end of the isolation network, a first end of the first capacitor is connected to the first end of the first inductor, a second end of the first capacitor is grounded, a first end of the second capacitor is connected to the second end of the first inductor, and a second end of the second capacitor is grounded.

3. A radio frequency chip, characterized by The radio frequency chip comprises the power amplification circuit according to any one of claims 1-2.

Images