CN116317968A

CN116317968A - Low noise amplifier and radio frequency transceiver

Info

Publication number: CN116317968A
Application number: CN202211560781.0A
Authority: CN
Inventors: 谢婷婷; 张博涛; 周德杭; 夏小辉; 倪文海; 徐文华
Original assignee: Canaantek Co ltd
Current assignee: Canaantek Co ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-06-23

Abstract

The application relates to a low noise amplifier and a radio frequency transceiver, comprising an input matching circuit; the amplifying circuit is provided with a first end and a second end which are connected with each other, and the first end is connected with the input matching circuit; the two mutually coupled first inductors and the second inductor are connected with one end of the first inductor and one end of the second inductor to form a connecting end, the other end of the first inductor is connected with a power supply, and the other end of the second inductor is connected with the second end; and the output matching circuit is connected with the connecting end. The first inductor and the second inductor form a T-coil inductor structure together, and the bandwidth can be widened through the T-coil inductor structure according to the transfer function of the T-coil inductor structure. Meanwhile, after the bandwidth is expanded, the load impedance changes little in a wider frequency band, and the load can be considered to be constant. When the load is constant, the low noise amplifier is a broadband amplifier, and the gain curve of the low noise amplifier has little change and high gain flatness in a wider working frequency band.

Description

Low noise amplifier and radio frequency transceiver

Technical Field

The present disclosure relates to the field of power devices, and in particular, to a low noise amplifier and a radio frequency transceiver.

Background

An amplifier is an electronic device that is capable of modulating a power supply such that an output signal is stronger than an input signal. The low noise amplifier is one of the important modules in the radio frequency transceiver, and is mainly used for amplifying the signal received from the antenna in the communication system, so as to facilitate the processing of the receiver circuit at the lower level.

In general, a low noise amplifier has a cascode structure including two transistors: a common source tube and a common grid tube. The drain electrode of the common source tube is connected with the source electrode of the common grid tube. Meanwhile, the low noise amplifier is often connected in series with an inductor at the load end, and in particular, the inductor is connected with the drain electrode of the common grid tube. The total series impedance is also increased with frequency due to the influence of the increase of the inductance and inductance with frequency, so that a large amount of current is forced to flow through the load capacitor, gain bandwidth consistency is realized, and the working bandwidth is improved. However, this solution has a significant impedance discontinuity problem at high frequencies, indirectly pulling down the operating bandwidth of the low noise amplifier, and thus the bandwidth improvement is still insufficient.

Disclosure of Invention

Based on this, it is necessary to provide a low noise amplifier and a radio frequency transceiver that widen the bandwidth in response to the problem of insufficient bandwidth of the conventional low noise amplifier.

A low noise amplifier, the low noise amplifier comprising:

an input matching circuit;

the amplifying circuit is provided with a first end and a second end which are connected with each other, and the first end is connected with the input matching circuit;

the two mutually coupled first inductors and second inductors, one end of the first inductor is connected with one end of the second inductor to form a connecting end, the other end of the first inductor is connected with a power supply, and the other end of the second inductor is connected with the second end;

and the output matching circuit is connected with the connecting end.

In one embodiment, the first inductor and the second inductor are symmetrically arranged with the connection end as a reference.

In one embodiment, the input matching circuit includes a third inductor and a first capacitor connected in series, and the first capacitor is connected to the first end.

In one embodiment, the input matching circuit further includes a first resistor, one end of the first resistor is connected to the first capacitor and the first end, and the other end of the first resistor is connected to a power supply.

In one embodiment, the amplifying circuit includes a first transistor and a second transistor, the first transistor and the second transistor form a cascode structure, a gate of the first transistor forms the first end, and a drain of the second transistor forms the second end.

In one embodiment, the low noise amplifier further includes a fourth inductor, one end of the fourth inductor is connected to the source electrode of the first transistor, and the other end of the fourth inductor is grounded.

In one embodiment, the low noise amplifier further includes an array resistor, one end of the array resistor is connected to the second end, and the other end of the array resistor is connected to the other end of the first inductor.

In one embodiment, the output matching circuit includes an attenuator connected to the connection terminal.

In one embodiment, the output matching circuit further includes a second capacitor, and the second capacitor is serially connected between the connection end and the attenuator.

A radio frequency transceiver comprising a low noise amplifier as described above.

According to the low-noise amplifier and the radio frequency transceiver, the low-noise amplifier comprises the first inductor and the second inductor which are mutually coupled, namely, the first inductor and the second inductor form the T-coil inductor structure together, and according to the transfer function of the T-coil inductor structure, the bandwidth can be widened through the T-coil inductor structure. Meanwhile, after the bandwidth is expanded, the load impedance changes little in a wider frequency band, and the load can be considered to be constant. When the load is constant, the low noise amplifier is a broadband amplifier, and the gain curve of the low noise amplifier has little change and high gain flatness in a wider working frequency band. Compared with the prior art that an inductor is connected in series with the load end, the occupied area of the load end is not increased greatly.

Drawings

FIG. 1 is a circuit diagram of a low noise amplifier according to an embodiment of the present application;

FIG. 2 is a schematic diagram of the T-coil inductor structure of the low noise amplifier shown in FIG. 1;

the rectangular frame of fig. 3 is a circuit diagram of a T-coil inductor structure.

Reference numerals illustrate:

100. a low noise amplifier; 10. an input matching circuit; 11. a radio frequency input; 12. a third inductance; 13. a first capacitor; 14. a first resistor; 20. an amplifying circuit; 21. a first transistor; 22. a second transistor; 30. an output matching circuit; 31. an attenuator; 32. a second capacitor; 33. a radio frequency output; 40. t-coil inductance structure; 41. a first inductance; 42. a second inductor; 50. a fourth inductance; 60. array resistance.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Referring to fig. 1, one embodiment of the present application provides a low noise amplifier 100 for use in a radio frequency receiver for amplifying signals received from an antenna in a communication system for processing by a receiver circuit at a lower level.

The low noise amplifier 100 includes an input matching circuit 10, an amplifying circuit 20, and an output matching circuit 30. The amplifying circuit 20 has a first end and a second end connected to each other, the first end being connected to the input matching circuit 10, and the second end being connected to the output matching circuit 30. The radio frequency signal is input through the radio frequency input terminal 11 of the input matching circuit 10, amplified by the amplifying circuit 20, and output through the radio frequency output terminal 33 of the output matching circuit 30.

Further, the low noise amplifier 100 further includes a first inductor 41 and a second inductor 42 that are coupled to each other, where one end of the first inductor 41 is connected to one end of the second inductor 42 to form a connection terminal, the other end of the first inductor 41 is connected to the power supply Vdd, the other end of the second inductor 42 is connected to the second end, and the output matching circuit 30 is connected to the connection terminal. That is, the output matching circuit 30 is connected to the second terminal through the second inductor 42.

In the above arrangement, since the low noise amplifier 100 includes the first inductor 41 and the second inductor 42 coupled to each other, that is, the first inductor 41 and the second inductor 42 together form the T-coil inductor structure 40 (refer to fig. 2), according to the transfer function of the T-coil inductor structure 40, the bandwidth can be widened by the T-coil inductor structure 40. Meanwhile, after the bandwidth is expanded, the load impedance changes little in a wider frequency band, and the load can be considered to be constant. When the load is constant, the low noise amplifier 100 is a broadband amplifier, and the gain curve has little variation and high gain flatness in a wide operating band. In addition, the area occupied by the load end of the T-coil inductor structure 40 is not increased much compared with the prior art in which an inductor is connected in series to the load end.

It should be noted that the transfer function of the T-coil inductance structure 40 is:

(in conjunction with FIG. 3), wherein R _T Parasitic resistance of T-coil inductance structure, C _L The load capacitance is represented by S, the complex parameter of Laplace, and k is the coupling coefficient of the T-coil inductance structure. When k=1/2 is set, it can be derived from this transfer function that the bandwidth can be widened by a factor of 2.72 by the T-coil inductance structure 40.

Specifically, the first inductor 41 and the second inductor 42 are symmetrically disposed with respect to the connection end. The T-coil inductor structure 40 is an inductor with three ports, one end of the inductor is connected to the amplifying circuit 20, the other end of the inductor is connected to the power supply Vdd, and the central tap end of the inductor forms a connection end and is connected to the output matching circuit 30. Wherein R in fig. 1 is the series parasitic resistance of the T-coil inductor structure 40.

Of course, in other embodiments, the first inductor 41 and the second inductor 42 may be disposed asymmetrically.

With continued reference to fig. 1, the input matching circuit 10 includes a third inductor 12 and a first capacitor 13 connected in series, and the first capacitor 13 is connected to the first end. The first capacitor 13 is used for isolating an external dc voltage from an internal voltage, and the third inductor 12 is used for providing an input impedance. Specifically, the third inductor 12 is capable of providing an input impedance of 50 ohms.

The amplifying circuit 20 includes a first transistor 21 and a second transistor 22, the first transistor 21 and the second transistor 22 form a cascode structure, a gate of the first transistor 21 forms a first terminal, and a drain of the second transistor 22 forms a second terminal.

The input matching circuit 10 further includes a first resistor 14, one end of the first resistor 14 is connected to the first capacitor 13 and the first end, and the other end of the first resistor 14 is connected to the power source Vb 1. The power supply Vb1 supplies a dc bias to the first transistor 21 via the first resistor 14 to the supply gate, which dc bias can be chosen according to the actual need. The power supply Vb2 provides a dc bias to the second transistor 22, which dc bias may also be chosen according to actual needs.

In one embodiment, the low noise amplifier 100 further includes a fourth inductor 50, one end of the fourth inductor 50 is connected to the source of the first transistor 21, and the other end of the fourth inductor 50 is grounded. The fourth inductor 50 is capable of providing an actual impedance to the input to match the source impedance of the first transistor 21 and reduce the input energy reflection. Since the fourth inductor 50 (source degeneration inductor) has no resistor added, the structure has minimal influence on noise figure and good noise performance. In particular, the fourth inductance 50 is capable of providing an input impedance of 50 ohms.

Further, with continued reference to fig. 1, the low noise amplifier 100 further includes an array resistor 60, where one end of the array resistor 60 is connected to the second end, that is, one end of the array resistor 60 is connected to the drain of the second transistor 22, and the other end of the array resistor 60 is connected to the other end of the first inductor 41. By setting the array resistor 60, the gain of the low noise amplifier 100 can be adjusted to reduce the gain of the low noise amplifier 100 to realize gain controllability.

The output matching circuit 30 further includes an attenuator 31, and the radio frequency signal passes through the attenuator 31 and then is output to a radio frequency output terminal 33. The attenuator 31 is matched with the array resistor 60, so that the gain of the low noise amplifier 100 can be further reduced, and the gain is controllable.

In some embodiments, the output matching circuit 30 further includes a second capacitor 32, the second capacitor 32 being serially connected between the T-coil inductance structure 40 and the attenuator 31 to cooperate with the T-coil inductance structure 40 to provide suitable output impedance matching.

Another embodiment of the present application also provides a radio frequency transceiver including the low noise amplifier 100 described above.

The working principle of the low noise amplifier 100 and the radio frequency transceiver provided in the present application is as follows:

the rf signal is received via the rf input 11 and enters the gate of the first transistor 21 (main amplifying transistor) via the dc blocking first capacitor 13, the dc bias voltage of the first transistor 21 being provided by the power supply Vb1 and the dc bias of the second transistor 22 being provided by the power supply Vb 2. Wherein the third inductor 12 and the fourth inductor 50 provide an input impedance of 50 ohms. After the radio frequency signal is amplified by the amplifying circuit 20, the radio frequency signal is output from the drain electrode of the second transistor 22, and the array resistor 60 and the attenuator 31 reduce the gain of the low noise amplifier 100, so as to realize the gain controllability. The T-coil inductor structure 40 and the second capacitor 32 provide suitable output impedance matching, and finally the rf signal is output through the rf output 33.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.

Claims

1. A low noise amplifier, the low noise amplifier comprising:

an input matching circuit (10);

an amplifying circuit (20) having a first end and a second end connected to each other, the first end being connected to the input matching circuit (10);

the two mutually coupled first inductors (41) and second inductors (42), one end of each first inductor (41) is connected with one end of each second inductor (42) to form a connecting end, the other end of each first inductor (41) is connected with a power supply, and the other end of each second inductor (42) is connected with the second end;

and the output matching circuit (30) is connected with the connecting end.

2. A low noise amplifier according to claim 1, characterized in that the first inductance (41) and the second inductance (42) are symmetrically arranged with respect to the connection terminal.

3. The low noise amplifier according to claim 1, wherein the input matching circuit (10) comprises a third inductor (12) and a first capacitor (13) connected in series with each other, the first capacitor (13) being connected to the first terminal.

4. A low noise amplifier according to claim 3, wherein the input matching circuit (10) further comprises a first resistor (14), one end of the first resistor (14) is connected to the first capacitor (13) and the first end, and the other end of the first resistor (14) is connected to a power supply.

5. The low noise amplifier according to claim 1, wherein the amplifying circuit (20) comprises a first transistor (21) and a second transistor (22), the first transistor (21) and the second transistor (22) forming a cascode structure, a gate of the first transistor (21) forming the first terminal and a drain of the second transistor (22) forming the second terminal.

6. The low noise amplifier according to claim 5, further comprising a fourth inductor (50), one end of the fourth inductor (50) being connected to the source of the first transistor (21), the other end of the fourth inductor (50) being grounded.

7. A low noise amplifier according to any of claims 1-6, further comprising an array resistor (60), one end of the array resistor (60) being connected to the second end, the other end of the array resistor (60) being connected to the other end of the first inductance (41).

8. A low noise amplifier according to claim 1, characterized in that the output matching circuit (30) comprises an attenuator (31) connected to the connection terminal.

9. The low noise amplifier according to claim 8, wherein the output matching circuit (30) further comprises a second capacitor (32), the second capacitor (32) being arranged in series between the connection terminal and the attenuator (31).

10. A radio frequency transceiver comprising a low noise amplifier as claimed in any one of claims 1 to 9.