Millimeter wave radio frequency front-end circuit and radio frequency equipment

Abstract

The present application provides a millimeter wave radio frequency front-end circuit and radio frequency equipment, the front-end circuit comprising: two balanced couplers, the balanced couplers comprising a signal end, a first end, a second end and an impedance matching end, the impedance matching end being connected to a resistor of a preset resistance value; two amplifiers, respectively arranged between the first end and the second end of the two balanced couplers, forming two parallel amplifiers; wherein, during the reception or transmission of radio frequency signals, the radio frequency signal is input from the signal end of one of the balanced couplers, and after passing through the two amplifiers respectively, the outputs of the two amplifiers are synthesized into one signal by the other balanced coupler and output through the corresponding signal end. The present application can effectively increase the output power and improve the impedance matching performance.

Description

Technical Field

[0001] The present invention relates to the field of radio frequency communications, and in particular to a millimeter wave radio frequency front-end circuit and radio frequency equipment. Background Art

[0002] RF front-end circuits are widely used in electronic devices such as phased array radars and communications. They generally include low-noise amplifiers and power amplifiers, and their function is to amplify RF signals. The function of the low-noise amplifier is to amplify the weak received signal, reduce noise, and enable the system to demodulate the required information. The function of the power amplifier is to increase the radiation distance of the wireless transmitter signal. In wireless communication systems, it is necessary to realize the receiving and transmitting functions at the same time, and RF front-end circuits are often required. At present, how to achieve the optimal performance of the transmitting and receiving links at the same time in the RF front-end circuit is one of the difficulties. Summary of the invention

[0003] In view of the above problems in the prior art, the present application proposes a millimeter wave RF front-end circuit and RF device, which can significantly improve the RF performance of the RF front-end. In order to achieve the above purpose and other purposes, the technical solution adopted by the present invention is as follows.

[0004] The present application provides a millimeter wave radio frequency front-end circuit, the circuit comprising: two balanced couplers, the balanced couplers comprising a signal end, a first end, a second end and an impedance matching end, the impedance matching end being connected to a resistor with a preset resistance value; two amplifiers, respectively arranged between the first end and the second end of the two balanced couplers, forming two parallel amplifiers; wherein, during the reception or transmission of a radio frequency signal, the radio frequency signal is input from the signal end of one of the balanced couplers, passes through the two amplifiers respectively, and then the outputs of the two amplifiers are synthesized into one signal by the other balanced coupler and output through the corresponding signal end.

[0005] In one embodiment of the present application, the balanced coupler includes two groups of coils connected in parallel to each other, wherein two ends of one group of coils are respectively connected to the signal end and the first end, and the other group of coils are respectively connected to the second end and the impedance matching end, and through the electromagnetic induction of the two groups of coils, the radio frequency signal input to the signal end is output from the first end and the second end respectively, or the radio frequency signal input from the first end and the second end is synthesized into one signal output from the signal end.

[0006] In one embodiment of the present application, the amplifier includes a low-noise amplification unit and a power amplification unit, the signal input end of the low-noise amplification unit is connected to the signal output end of the power amplification unit, and the signal output end of the low-noise amplification unit is connected to the signal input end of the power amplification unit; when receiving a radio frequency signal, the low-noise amplification unit is controlled to work and the power amplification unit is disconnected; when transmitting a radio frequency signal, the power amplification unit is controlled to work and the low-noise amplification unit is disconnected.

[0007] In one embodiment of the present application, the low-noise amplifying unit includes a first bias circuit and a first amplifying circuit; a control signal is received through the first bias circuit to control the on / off state of the first amplifying circuit.

[0008] In one embodiment of the present application, the power amplification unit includes a second bias circuit and a second amplification circuit; and a control signal is received through the second bias circuit to control the on / off state of the two amplification circuits.

[0009] In one embodiment of the present application, the first bias circuit and the second bias circuit have the same structure, wherein the first bias circuit includes a first transistor, a first triode, a first resistor, a first inductor and a first capacitor; the gate of the first transistor is connected to a control signal, the source is respectively connected to the collector of the first triode, one end of the first inductor, one end of the first resistor and one end of the first capacitor, and is connected to a bias voltage port, and the drain is grounded; the emitter of the first triode is grounded, the base is connected to the other end of the first resistor, the other end of the first capacitor is grounded, and the other end of the first inductor serves as an output end.

[0010] In one embodiment of the present application, the first amplifier circuit includes a second capacitor, a second inductor, a second transistor, a third inductor, a third capacitor and a fourth capacitor; one end of the second capacitor is connected to one end of the second inductor as a power input end, the other end of the second capacitor is grounded, the other end of the second inductor is respectively connected to the collector of the second transistor and one end of the fourth capacitor, the emitter of the second transistor is connected to one end of the third inductor, the other end of the third inductor is grounded, the base of the second transistor is connected to one end of the third capacitor and connected to the output end of the first bias circuit, the other end of the third capacitor is used as the signal input end of the low-noise amplifier unit, and the other end of the fourth capacitor is used as the signal output end of the low-noise amplifier unit.

[0011] In one embodiment of the present application, the second amplifier circuit includes a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a fourth inductor, a fifth inductor, a third transistor, a fourth transistor and a second resistor, one end of the fifth capacitor serves as a signal input end of the power amplifier unit, and the other end is connected to the base of the third transistor and connected to the output end of the second bias circuit; the emitter of the third transistor is connected to one end of the fourth inductor, the other end of the fourth inductor is grounded, the collector of the third transistor is connected to the emitter of the fourth transistor, the base of the fourth transistor is respectively connected to one end of the sixth capacitor and one end of the second resistor, the other end of the sixth capacitor is grounded, the other end of the second resistor is respectively connected to one end of the fifth inductor and one end of the seventh capacitor, and is connected to the power input end, the other end of the seventh capacitor is grounded, the other end of the fifth inductor is respectively connected to the collector of the fourth transistor and one end of the eighth capacitor, and the other end of the eighth capacitor serves as the signal output end of the power amplifier unit.

[0012] In an embodiment of the present application, the impedance matching terminal access resistor has a resistance value of 50 ohms.

[0013] The present application also provides a radio frequency device, including the millimeter wave radio frequency front-end circuit.

[0014] As described above, the millimeter wave RF front-end circuit and RF device provided in the present application have the following beneficial effects.

[0015] The present application replaces the traditional switching circuit with two balanced couplers, which can effectively solve the problem of the switch limiting the link RF power. The outputs of the two amplifiers are synthesized by the balanced coupler to increase the output power. The balanced coupler can provide a fixed impedance, which can improve the impedance matching performance of the RF front-end circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the RF front-end circuit structure in the prior art solution 1.

[0017] Figure 2 This is a schematic diagram of the RF front-end circuit structure in the second prior art solution.

[0018] Figure 3 Schematic diagram of the structure of the millimeter wave radio frequency front-end circuit in one embodiment of the present application.

[0019] Figure 4 Schematic diagram of the structure of a balanced coupler in one embodiment of the present application.

[0020] Figure 5 This is a circuit schematic diagram of an amplifier in a receiving state in an embodiment of the present application.

[0021] Figure 6 This is a circuit schematic diagram of an amplifier in a transmitting state in an embodiment of the present application.

[0022] Figure 7 It is a structural schematic diagram of a radio frequency device in one embodiment of the present application.

[0023] Description of Figure Numbers:

[0024] C1-first capacitor; C2-second capacitor; C3-third capacitor; C4-fourth capacitor; C5-fifth capacitor; C6-sixth capacitor; C7-seventh capacitor; C8-eighth capacitor; R1-first resistor; R2-second resistor; M1-first transistor; Q1-first triode; Q2-second triode; Q3-third triode; Q4-fourth triode; L1-first inductor; L2-second inductor; L3-third inductor; L4-fourth inductor; L5-fifth inductor. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0026] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0027] The inventors have found that:

[0028] Figure 1 The figure is a schematic diagram of the RF front-end circuit structure in the prior art solution 1. The RF front-end circuit of the prior art solution 1 is composed of two amplifiers (LNA and PA) and two single-pole double-throw switches (SPDT), and its principle is to switch the switch to the receiving path or the transmitting path. The bidirectional RF amplifier circuit of the prior art solution 1 has high isolation and stable circuit performance, but has the following disadvantages: 1) The switch insertion loss is large, the single-pole double-throw switch loss of the receiving channel will increase the noise coefficient of the receiving channel, and the transmitting channel switch will cause power loss of the power amplifier; 2) The linearity is low. For a power amplifier with a large power output, the switch will limit the output power of the power amplifier.

[0029] Figure 2 The figure is a schematic diagram of the RF front-end circuit structure in the second technical solution. The RF front-end circuit of the second technical solution consists of a power amplifier (PA), a low noise amplifier (PA), a transformer and a microstrip line, which omits the switch and has certain advantages in improving linearity. Although the second technical solution omits the switch and has certain advantages in improving linearity, it has the following disadvantages: 1) poor impedance performance, which will lead to serious signal reflection; 2) poor load mismatch resistance.

[0030] Based on the problems existing in the above-mentioned existing technical solutions, the present application proposes a millimeter-wave RF front-end circuit and RF equipment. A miniaturized balancer is used to replace the traditional switching circuit at the input and output ports of the amplifier, which can effectively solve the problem of the switch limiting the link RF power. The balanced coupler at the output port can synthesize the output signals of the two internal amplifiers to increase the output power by 3dBm. The port impedance of the balanced coupler is always 50 ohms, which can effectively improve the impedance performance of the RF front-end circuit. The silicon-based millimeter-wave RF front-end circuit can not only realize the functions of the traditional RF front-end circuit, but also realize the function of a bidirectional amplifier. For some RF circuits with specific functions, the same RF channel can realize both the receiving function and the transmitting function, which can greatly simplify the circuit structure. The technical solution of the present application is described in detail below in conjunction with specific embodiments.

[0031] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of the millimeter wave RF front-end circuit in an embodiment of the present application. The millimeter wave RF front-end circuit in the embodiment of the present application includes: two balanced couplers, the balanced couplers include a signal end, a first end, a second end and an impedance matching end, and the impedance matching end is connected to a resistor with a preset resistance value; two amplifiers are respectively arranged between the first end and the second end of the two balanced couplers to form two parallel amplifiers; wherein, during the reception or transmission of the RF signal, the RF signal is input from the signal end of one of the balanced couplers, and after passing through the two amplifiers respectively, the outputs of the two amplifiers are synthesized into one signal by the other balanced coupler and output through the corresponding signal end.

[0032] In one embodiment, the two balanced couplers have the same structure, and the two amplifiers also have the same structure. The two amplifiers are connected between the two balanced couplers, respectively. Specifically, the two balanced couplers are denoted as 1 and 2, one amplifier is connected between the first end of the balanced coupler 1 and the second end of the balanced coupler 2, and the other amplifier is connected between the second end of the balanced coupler 1 and the first end of the balanced coupler 2, thereby forming a two-way parallel amplifier connection structure.

[0033] In one embodiment, the balanced coupler includes two sets of coils in parallel, wherein two ends of one set of coils are respectively connected to the signal end and the first end, and the other set of coils are respectively connected to the second end and the impedance matching end, and the RF signal input to the signal end is output from the first end and the second end respectively through electromagnetic induction of the two sets of coils, or the RF signal input from the first end and the second end is synthesized into one signal output from the signal end. Figure 4 , Figure 4 The schematic diagram of the structure of a balanced coupler in one embodiment of the present application. The signal end of the balanced coupler is denoted as IN, the first end is denoted as COU, the second end is denoted as TRH, and the impedance matching end is denoted as ISO. TRH and COU are respectively connected to an amplifier, and the signal end serves as the input or output port of the RF signal. ISO is connected to a resistor with a preset resistance value. For example, ISO can be grounded through a 50 ohm resistor to provide a constant impedance for the balanced coupler. Among them, the routing of IN and TRH is parallel to each other to form a coupling coil, one coil connects IN and COU, and the other coil connects TRH and ISO. When an RF signal is input at the IN end, a RF signal is also generated at the TRH end through coil induction, and is respectively input into the amplifier of the corresponding link through the TRH end and the COU end; when a signal is input at the TRH end and the COU end, the two input signals are synthesized into one and output from the IN end.

[0034] In one embodiment, the amplifier includes a low-noise amplifier unit and a power amplifier unit, the signal input end of the low-noise amplifier unit is connected to the signal output end of the power amplifier unit, and the signal output end of the low-noise amplifier unit is connected to the signal input end of the power amplifier unit; when receiving a radio frequency signal, the low-noise amplifier unit is controlled to work and the power amplifier unit is disconnected; when transmitting a radio frequency signal, the power amplifier unit is controlled to work and the low-noise amplifier unit is disconnected. Specifically, the amplifier adopts a bidirectional amplification structure, and in the radio frequency signal receiving state, only the low-noise amplifier unit works and the power amplifier unit is disconnected.

[0035] The low noise amplifier unit includes a first bias circuit and a first amplifier circuit; the first bias circuit receives a control signal to control the on / off state of the first amplifier circuit; the power amplifier unit includes a second bias circuit and a second amplifier circuit; the second bias circuit receives a control signal to control the on / off state of the two amplifier circuits. Figure 5 , Figure 5The schematic diagram of the circuit of the amplifier in the receiving state in one embodiment of the present application. The structures of the first bias circuit and the second bias circuit are the same. The structure of the first bias circuit (i.e., the bias circuit 1 in the figure) is only described in detail below. The first bias circuit includes a first transistor M1, a first triode Q1, a first resistor R1, a first inductor L1, and a first capacitor C1; the gate of the first transistor M1 is connected to the control signal as the PD1 port, the source is respectively connected to the collector of the first triode Q1, one end of the first inductor L1, one end of the first resistor R1, and one end of the first capacitor C1, and is connected to the bias voltage port Ibl, and the drain is grounded; the emitter of the first triode Q1 is grounded, the base is connected to the other end of the first resistor R1, the other end of the first capacitor C1 is grounded, and the other end of the first inductor L1 is used as the output end.

[0036] In one embodiment, the first amplifier circuit includes a second capacitor C2, a second inductor L2, a second transistor Q2, a third inductor L3, a third capacitor C3 and a fourth capacitor C4; one end of the second capacitor C2 is connected to one end of the second inductor L2 as a power input end, the other end of the second capacitor C2 is grounded, the other end of the second inductor L2 is respectively connected to the collector of the second transistor Q2 and one end of the fourth capacitor C4, the emitter of the second transistor Q2 is connected to one end of the third inductor L3, the other end of the third inductor L3 is grounded, the base of the second transistor Q2 is connected to one end of the third capacitor C3 and connected to the output end of the first bias circuit, the other end of the third capacitor C3 is used as the signal input end of the low-noise amplifier unit, and the other end of the fourth capacitor C4 is used as the signal output end of the low-noise amplifier unit.

[0037] See also Figure 6 , Figure 6The schematic diagram of the circuit of the amplifier in the transmitting state in one embodiment of the present application. The second amplifier circuit includes a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a fourth inductor L4, a fifth inductor L5, a third transistor Q3, a fourth transistor Q4 and a second resistor R2, one end of the fifth capacitor C5 is used as the signal input end of the power amplifier unit, and the other end is connected to the base of the third transistor Q3 and connected to the output end of the second bias circuit; the emitter of the third transistor Q3 is connected to one end of the fourth inductor L4, the other end of the fourth inductor L4 is grounded, and the collector of the third transistor Q3 is connected to the fourth transistor The emitter of the fourth triode Q4, the base of the fourth triode Q4 are respectively connected to one end of the sixth capacitor C6 and one end of the second resistor R2, the other end of the sixth capacitor C6 is grounded, the other end of the second resistor R2 is respectively connected to one end of the fifth inductor L5 and one end of the seventh capacitor C7, and is connected to the power input terminal, the other end of the seventh capacitor C7 is grounded, the other end of the fifth inductor L5 is respectively connected to the collector of the fourth triode Q4 and one end of the eighth capacitor C8, and the other end of the eighth capacitor C8 serves as the signal output terminal of the power amplification unit.

[0038] The working principle of the amplifier of the embodiment of the present application is as follows: when in the receiving state, the PD2 port is connected to a high level, the Ib2 port of the bias circuit 2 is pulled down to the ground, and the DC operating point of the transistor Q3 is turned off, thereby achieving the purpose of turning off the PA amplifier. The PD1 port of the bidirectional amplifier is connected to a low level, the bias circuit 1 works normally, and the bias circuit 1 can provide a DC operating point for the transistor Q1. The signal enters from the port P1, passes through the DC blocking capacitor C1, and enters the LNA for amplification. Finally, it passes through a DC blocking capacitor C4 and outputs the amplifier from the port P2; when in the transmitting state, the PD1 port is connected to a high level, the Ib2 port of the bias circuit 1 is pulled down to the ground, and the DC operating point of the transistor Q1 is turned off, thereby achieving the purpose of turning off the LNA amplifier. The PD2 port of the bidirectional amplifier is connected to a low level, the bias circuit 2 works normally, and the bias circuit 2 can provide a DC operating point for the transistor Q3. The signal enters from the port P2, passes through the DC blocking capacitor C5, and enters the common emitter and common base amplifier composed of transistors Q3 and Q4 for amplification. Finally, it passes through a DC blocking capacitor C2 and outputs the amplifier from the port P1. Capacitor C7 can provide filtering for the power supply, and the RC circuit composed of resistor R2 and capacitor C6 can provide a DC bias point for the operation of transistor Q4.

[0039] Based on the above technical solution of the present application, the output signals of the two amplifiers can be synthesized through a balanced coupler, so that the output power of the developed device is increased by 3dBm, which is beneficial to improving the RF performance of the link. The impedance of the impedance matching end of the balanced coupler is always a constant value, and there is no need for complex impedance matching. It can effectively reduce the complexity of the circuit structure and improve the port impedance characteristics.

[0040] See also Figure 7 , Figure 7 This is a schematic diagram of the structure of the radio frequency device in an embodiment of the present application. The radio frequency device includes the aforementioned millimeter wave radio frequency front-end circuit. The specific location of the millimeter wave front-end circuit can be adjusted according to actual application requirements and is not limited here. The radio frequency device can be a mobile communication terminal such as a mobile phone, a tablet, etc. The specific type of radio frequency device can be configured and selected according to actual application requirements and is not limited here.

[0041] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A millimeter wave radio frequency front-end circuit, characterized in that: The circuit comprises: Two balanced couplers, the balanced couplers include a signal end, a first end, a second end and an impedance matching end, the impedance matching end is connected to a resistor with a preset resistance value; the balanced couplers include two groups of coils in parallel with each other, wherein two ends of one group of coils are respectively connected to the signal end and the first end, and the other group of coils are respectively connected to the second end and the impedance matching end, and through electromagnetic induction of the two groups of coils, the radio frequency signal input to the signal end is output by the first end and the second end respectively, or the radio frequency signals input from the first end and the second end are synthesized into one signal output by the signal end; the impedance matching end is connected to a resistor with a resistance of 50 ohms; Two amplifiers are respectively arranged between the first end and the second end of the two balanced couplers to form two parallel amplifiers; the amplifier includes a low-noise amplifier unit and a power amplifier unit, the signal input end of the low-noise amplifier unit is connected to the signal output end of the power amplifier unit, and the signal output end of the low-noise amplifier unit is connected to the signal input end of the power amplifier unit; when receiving a radio frequency signal, the low-noise amplifier unit is controlled to work and the power amplifier unit is disconnected; when transmitting a radio frequency signal, the power amplifier unit is controlled to work and the low-noise amplifier unit is disconnected; the low-noise amplifier unit includes a first bias circuit and a first amplifier circuit; a control signal is received through the first bias circuit to control the on / off state of the first amplifier circuit; the power amplifier unit includes a second bias circuit and a second amplifier circuit; a control signal is received through the second bias circuit to control the on / off state of the two amplifier circuits; In the process of receiving or transmitting the RF signal, the RF signal is input from the signal end of one of the balanced couplers, passes through the two amplifiers respectively, and then the outputs of the two amplifiers are combined into one signal by the other balanced coupler and output through the corresponding signal end.

2. The millimeter wave RF front-end circuit according to claim 1, characterized in that: The first bias circuit and the second bias circuit have the same structure, wherein the first bias circuit comprises a first transistor, a first triode, a first resistor, a first inductor and a first capacitor; the gate of the first transistor is connected to a control signal, the source is respectively connected to the collector of the first triode, one end of the first inductor, one end of the first resistor and one end of the first capacitor, and is connected to a bias voltage port, and the drain is grounded; the emitter of the first triode is grounded, the base is connected to the other end of the first resistor, the other end of the first capacitor is grounded, and the other end of the first inductor serves as an output end.

3. The millimeter wave RF front-end circuit according to claim 2, characterized in that: The first amplifier circuit includes a second capacitor, a second inductor, a second transistor, a third inductor, a third capacitor and a fourth capacitor; one end of the second capacitor is connected to one end of the second inductor as a power input end, the other end of the second capacitor is grounded, the other end of the second inductor is respectively connected to the collector of the second transistor and one end of the fourth capacitor, the emitter of the second transistor is connected to one end of the third inductor, the other end of the third inductor is grounded, the base of the second transistor is connected to one end of the third capacitor and connected to the output end of the first bias circuit, the other end of the third capacitor is used as the signal input end of the low-noise amplifier unit, and the other end of the fourth capacitor is used as the signal output end of the low-noise amplifier unit.

4. The millimeter wave RF front-end circuit according to claim 2, characterized in that: The second amplifier circuit includes a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a fourth inductor, a fifth inductor, a third transistor, a fourth transistor and a second resistor. One end of the fifth capacitor serves as a signal input end of the power amplifier unit, and the other end is connected to the base of the third transistor and connected to the output end of the second bias circuit; the emitter of the third transistor is connected to one end of the fourth inductor, and the other end of the fourth inductor is grounded; the collector of the third transistor is connected to the emitter of the fourth transistor, and the base of the fourth transistor is respectively connected to one end of the sixth capacitor and one end of the second resistor, and the other end of the sixth capacitor is grounded; the other end of the second resistor is respectively connected to one end of the fifth inductor and one end of the seventh capacitor, and is connected to the power input end; the other end of the seventh capacitor is grounded; the other end of the fifth inductor is respectively connected to the collector of the fourth transistor and one end of the eighth capacitor, and the other end of the eighth capacitor serves as the signal output end of the power amplifier unit.

5. A radio frequency device, characterized in that: It comprises a millimeter wave radio frequency front-end circuit as described in any one of claims 1 to 4.

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