CN117176093A

CN117176093A - low noise amplifier

Info

Publication number: CN117176093A
Application number: CN202311232340.2A
Authority: CN
Inventors: 孟少伟; 王绍权; 赵瑞华; 王鑫; 徐永祥; 汤晓东; 周子棋; 王月阳
Original assignee: San Microelectronics Technology Suzhou Co ltd
Current assignee: San Microelectronics Technology Suzhou Co ltd
Priority date: 2023-09-22
Filing date: 2023-09-22
Publication date: 2023-12-05

Abstract

The invention belongs to the technical field of amplifiers, and discloses a low-noise amplifier which comprises an input matching circuit, an amplifying circuit, a power supply circuit and an output matching circuit; the output end of the input matching circuit is connected with the input end of the amplifying circuit, the output end of the amplifying circuit is connected with the first input end of the output matching circuit, and the output end of the power supply circuit is connected with the second input end of the output matching circuit. The invention can ensure that the low noise amplifier obtains smaller noise coefficient and higher gain in the working frequency band, and effectively improves the reliability of the low noise amplifier.

Description

Low noise amplifier

Technical Field

The invention belongs to the technical field of amplifiers, and relates to a low-noise amplifier.

Background

The RF low noise amplifier is a key module in the whole RF receiver system, and directly determines the system sensitivity. The key indexes in the design of the radio frequency low noise amplifier chip are as follows: gain, noise figure, and stability coefficient. From the perspective of evaluating the performance of a radio frequency low noise amplifier chip, high gain and low noise are important goals for low noise amplifier optimization, where gain and noise are important concerns as to whether optimum performance can be achieved in the operating frequency band. From the perspective of evaluating the reliability of the radio frequency low noise amplifier, the stability coefficient is a key index for measuring whether the low noise amplifier can work normally, and the stability not only requires that the low noise amplifier chip is more than one in the working frequency band, but also must ensure that the designed low noise amplifier chip is more than one from direct current to more than four times of the working frequency, so that the low noise amplifier can be ensured to be in absolute stability.

However, in the actual chip design process, the stability of the actual low noise amplifier chip is greatly affected by the bond wire inductance. Since the signal input and output caused by the bonding wire electricity form feedback to generate oscillation, in order to ensure the reliability of the low noise amplifier chip, the influence of the input and output feedback loop caused by the bonding wire inductance must be eliminated, and the conventional scheme for improving the stability is to add a lossy network in series on the radio frequency path, but the gain and the noise are sacrificed in this way. Therefore, it is important to study the improvement of the stability of the low noise amplifier with as little sacrifice gain and noise as possible, taking the external bond wire inductance into account.

Disclosure of Invention

The invention aims to provide a low-noise amplifier so as to solve the problem that an input/output loop of a low-noise amplifier chip forms feedback due to bonding wire inductance, so that an unstable phenomenon of the low-noise amplifier occurs at a high frequency.

The technical scheme adopted by the invention for realizing the purposes is as follows:

a low noise amplifier includes an input matching circuit, an amplifying circuit, a power supply circuit, and an output matching circuit;

the output end of the input matching circuit is connected with the input end of the amplifying circuit, the output end of the amplifying circuit is connected with the first input end of the output matching circuit, and the output end of the power supply circuit is connected with the second input end of the output matching circuit.

As a limitation, the input matching circuit includes an input port INA, a first inductance L1, a second inductance L2, a third inductance L3, a fourth inductance L4, a first capacitance C1, a second capacitance C2, a blocking capacitance C3, a fourth capacitance C4, a fifth capacitance C5, a sixth capacitance C6, a first resistance R1, a bias resistance R2, a third resistance R3, a fourth resistance R4, a first bonding wire inductance LB1, a second bonding wire inductance LB2, a third bonding wire inductance LB3, and a fourth bonding wire inductance LB4;

the first inductor L1, the first capacitor C1, the second capacitor C2, the first resistor R1 and the second bonding wire inductor LB2 form a band-pass filter; the second inductor L2, the fourth capacitor C4 and the third bonding wire inductor LB3 form a resonant circuit; the third inductor L3, the fifth capacitor C5, the third resistor R3, the fourth inductor L4, the sixth capacitor C6, the fourth resistor R4 and the fourth bonding wire inductor LB4 form a first high-frequency resonance selection network;

one end of the input port INA is connected with a radio frequency signal port IN of an external bonding pad through a first bonding wire inductor LB1, the other end of the input port INA is respectively connected with one end of a first inductor L1, one end of a first capacitor C1 and one end of a blocking capacitor C3, the other end of the first inductor L1 is connected with one end of a first resistor R1 through a second capacitor C2 after being connected with the other end of the first capacitor C1, the other end of the first resistor R1 is connected with one end of a first grounding port GND1, and the other end of the first grounding port GND1 is grounded through a second bonding wire inductor LB 2; the other end of the blocking capacitor C3 is respectively connected with one ends of the second inductor L2, the third inductor L3, the fourth inductor L4 and the bias resistor R2 and then is used as an output end to be connected with the input end of the amplifying circuit; the other end of the bias resistor R2 is connected with a power-on end VG 1; the other end of the second inductor L2 is connected with one end of the second grounding port GND2 through a fourth capacitor C4, and the other end of the second grounding port GND2 is grounded through a third bonding wire inductor LB 3; the other end of the third inductor L3 is connected with one end of a third resistor R3 through a fifth capacitor C5, the other end of a fourth inductor L4 is connected with one end of a fourth resistor R4 through a sixth capacitor C6, the other end of the third resistor R3 is connected with one end of a third grounding port GND3 after being connected with the other end of the fourth resistor R4, and the other end of the third grounding port GND3 is grounded through a fourth bonding wire inductor LB4.

As a second limitation, the amplifying circuit includes a first transistor M1, a second transistor M2, a seventh capacitor C7, an eighth capacitor C8, a parasitic capacitor Cds, a fifth inductance L5, a bias resistor R5, a fifth bonding wire inductance LB5, and a sixth bonding wire inductance LB6;

the grid electrode of the first transistor M1 is used as an input end to be connected with the output end of the input matching circuit, the drain electrode of the first transistor M1 is connected with one end of a fifth inductor L5, the other end of the fifth inductor L5 is respectively connected with one end of a seventh capacitor C7 and the source electrode of a second transistor M2, the grid electrode of the second transistor M2 is respectively connected with the other end of the seventh capacitor C7, an eighth capacitor C8 and one end of a bias resistor R5, the other end of the eighth capacitor C8 is connected with one end of a fifth grounding port GND5, and the other end of the fifth grounding port GND5 is grounded through a sixth bonding wire inductor LB6; the other end of the bias resistor R5 is connected with the power-on end VG 2; the source electrode of the first transistor M1 is connected to the fourth ground port GND4 and one end of the parasitic capacitance Cds, the other end of the fourth ground port GND4 is grounded through the fifth bonding wire inductor LB5, and the other end of the parasitic capacitance Cds is connected to the drain electrode of the second transistor M2 and then connected to the first input end of the output matching circuit as an output end.

As a third limitation, the power supply circuit includes a seventh inductance L7, an eighth inductance L8, a ninth capacitance C9, a tenth capacitance C10, an eleventh capacitance C11, a sixth resistance R6, a seventh resistance R7, an eighth resistance R8, a seventh bonding wire inductance LB7, and an eighth bonding wire inductance LB8;

the seventh inductor L7, the eighth inductor L8, the ninth capacitor C9, the tenth capacitor C10, the sixth resistor R6, the seventh resistor R7 and the seventh bonding wire inductor LB7 form a second high-frequency resonance selection network;

one end of the eighth resistor R8 is connected with the power supply VDD, the other end of the eighth resistor R8 is connected with one end of the seventh inductor L7, the eighth inductor L8 and the eleventh capacitor C11, and then is connected with the second input end of the output matching circuit as output ends, the other end of the seventh inductor L7 is connected with one end of the sixth resistor R6 through the ninth capacitor C9, the eighth inductor L8 is connected with one end of the seventh resistor R7 through the tenth capacitor C10, the other end of the sixth resistor R6 is connected with one end of the sixth ground port GND6 after being connected with the other end of the seventh resistor R7, and the other end of the sixth ground port GND6 is grounded through the seventh bonding wire inductor LB 7; the other end of the eleventh capacitor C11 is connected to one end of the seventh ground port GND7, and the other end of the seventh ground port GND7 is grounded through the eighth bonding wire inductor LB8.

As a fourth limitation, the output matching circuit includes a sixth inductance L6, a twelfth capacitance C12, and a ninth bond wire inductance LB9;

one end of the sixth inductor L6 is connected with the output end of the power circuit as a second input end, the other end of the sixth inductor L6 is connected with one end of the twelfth capacitor C12 and then is connected with the output end of the amplifying circuit as a first input end, the other end of the twelfth capacitor C12 is connected with one end of the output port OUT1, and the other end of the output port OUT1 is connected with the external output end OUT2 through a ninth bonding wire inductor LB 9.

Compared with the prior art, the technical proposal adopted by the invention has the following technical progress:

(1) The invention not only can remarkably improve the stability of the low-noise amplifier, but also can effectively improve the noise and gain of the low-noise amplifier;

(2) The invention adopts the band-pass filter, the resonant circuit and the first high-frequency resonance selection network in the input matching circuit, and adds the second high-frequency resonance selection network in the power circuit, thereby ensuring that the low-noise amplifier realizes lower noise coefficient and higher gain in the working frequency band, simultaneously ensuring that the low-noise amplifier keeps stable in the whole passband, and effectively improving the reliability of the low-noise amplifier.

By integrating the above, the invention can ensure that the low noise amplifier obtains smaller noise coefficient and higher gain in the working frequency band.

Drawings

FIG. 1 is a schematic circuit diagram of an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of a first comparative example in accordance with an embodiment of the present invention;

FIG. 3 is a schematic circuit diagram of a second comparative example in accordance with an embodiment of the present invention;

FIG. 4 is a graph showing comparison of stability coefficients for the first and second comparative schemes according to an embodiment of the present invention;

FIG. 5 is a graph showing the minimum noise figure of the first and second comparison schemes according to the embodiment of the present invention;

fig. 6 shows a graph of the maximum available gain versus the first and second comparison schemes of the present invention.

Detailed Description

The invention will be better explained by the following detailed description of the embodiments with reference to the drawings.

Embodiments are low noise amplifiers

As shown in fig. 1, the present embodiment fully considers the influence of external practical situations on a low noise amplifier, and proposes a low noise amplifier, which includes an input matching circuit, an amplifying circuit, a power supply circuit, and an output matching circuit; the output end of the input matching circuit is connected with the input end of the amplifying circuit, the output end of the amplifying circuit is connected with the first input end of the output matching circuit, and the output end of the power supply circuit is connected with the second input end of the output matching circuit.

In this embodiment, the input matching circuit includes an input port INA, a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a first capacitor C1, a second capacitor C2, a blocking capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a first resistor R1, a bias resistor R2, a third resistor R3, a fourth resistor R4, a first bonding wire inductor LB1, a second bonding wire inductor LB2, a third bonding wire inductor LB3, and a fourth bonding wire inductor LB4.

The first inductor L1, the first capacitor C1, the second capacitor C2, the first resistor R1 and the second bonding wire inductor LB2 form a band-pass filter, and the band-pass filter can ensure that signals only pass through the working frequency band of the low-noise amplifier. The second inductor L2, the fourth capacitor C4 and the third bonding wire inductor LB3 form a resonant circuit; the third inductor L3, the fifth capacitor C5, the third resistor R3, the fourth inductor L4, the sixth capacitor C6, the fourth resistor R4 and the fourth bonding wire inductor LB4 form a first high-frequency resonance selection network, feedback of signals at high frequency can be effectively isolated through the first high-frequency resonance selection network, and the third inductor L3, the fifth capacitor C5, the fourth inductor L4 and the sixth capacitor C6 in the first high-frequency resonance selection network are used for resonating at the high frequency, so that flatness is improved.

In this embodiment, the amplifying circuit includes a first transistor M1, a second transistor M2, a seventh capacitor C7, an eighth capacitor C8, a parasitic capacitor Cds, a fifth inductor L5, a bias resistor R5, a fifth bonding wire inductor LB5, and a sixth bonding wire inductor LB6.

The gate of the first transistor M1 is connected to the bias resistor R2, and the power-on terminal VG1 can provide dc bias for the first transistor M1 through the bias resistor R2; the grid electrode of the second transistor M2 is connected with the bias resistor R5, and the power-on end VG2 can provide direct current bias for the transistor M2 through the bias resistor R5; the fifth inductor L5 is an inter-stage inductor, and mainly functions to increase gain and reduce noise, and the eighth capacitor C8 is a bypass capacitor, and mainly functions to provide a sufficient output swing for the circuit. Since the sixth bonding wire inductor LB6 is connected to the gate of the second transistor M2 through the eighth capacitor C8, the sixth bonding wire inductor LB6 may cause the gate of the second transistor M2 to be connected in series with an inductor, which is very easy to form negative resistance at the source of the second transistor M2, so as to generate oscillation, and conventionally, the resistor is generally connected in series with the gate of the second transistor M2, but this way will deteriorate noise and reduce gain, so that this embodiment connects the seventh capacitor C7 in series between the gate and the source of the second transistor M2, and by connecting the seventh capacitor C7 in series, stability can be improved, and the balance between gain and noise can be also improved.

In this embodiment, the power supply circuit includes a seventh inductor L7, an eighth inductor L8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a seventh bonding wire inductor LB7, and an eighth bonding wire inductor LB8. The seventh inductor L7, the eighth inductor L8, the ninth capacitor C9, the tenth capacitor C10, the sixth resistor R6, the seventh resistor R7, and the seventh bonding wire inductor LB7 form a second high-frequency resonance selection network, the eighth inductor L8, the tenth capacitor C10, the seventh inductor L7, and the ninth capacitor C9 are configured to resonate at a high frequency, and the sixth resistor R6 and the seventh resistor R7 function to increase flatness, to attenuate a high-frequency signal in an output signal, and to reduce coupling of the high-frequency signal to an ideal.

One end of the eighth resistor R8 is connected to the power supply VDD, the other end of the eighth resistor R8 is connected to one end of the seventh inductor L7, the eighth inductor L8, and one end of the eleventh capacitor C11, and then is connected to the second input end of the output matching circuit as an output end, the other end of the seventh inductor L7 is connected to one end of the sixth resistor R6 through the ninth capacitor C9, the eighth inductor L8 is connected to one end of the seventh resistor R7 through the tenth capacitor C10, the other end of the sixth resistor R6 is connected to one end of the sixth ground port GND6 after being connected to the other end of the seventh resistor R7, and the other end of the sixth ground port GND6 is grounded through the seventh bonding wire inductor LB 7; the other end of the eleventh capacitor C11 is connected to one end of the seventh ground port GND7, and the other end of the seventh ground port GND7 is grounded through the eighth bonding wire inductor LB8. The eleventh capacitor C11 is a bypass capacitor, and is mainly used for providing enough output swing for the circuit; the power supply VDD is connected with the eighth resistor R8 in series, so that the circuit can be effectively ensured to be stable under low frequency.

In this embodiment, the output matching circuit includes a sixth inductor L6, a twelfth capacitor C12, and a ninth bonding wire inductor LB9; one end of a sixth inductor L6 is used as a second input end to be connected with the output end of the power circuit, the other end of the sixth inductor L6 is connected with one end of a twelfth capacitor C12 and then is used as a first input end to be connected with the output end of the amplifying circuit, the other end of the twelfth capacitor C12 is connected with one end of an output port OUT1, and the other end of the output port OUT1 is connected with an external output end OUT2 through a ninth bonding wire inductor LB 9.

Since the low noise amplifier is ideally connected to the outside by means of external bonding via bond wire inductance, the crosstalk between signals is very serious. The parasitic capacitance Cds is connected in series between the source of the first transistor M1 and the drain of the second transistor M2, the output signal is coupled to the ideal ground through the parasitic capacitance Cds and the eleventh capacitance C11, and the output signal is coupled to the input through the second bonding wire inductance LB2, the third bonding wire inductance LB3 and the fourth bonding wire inductance LB4 due to the non-ideal ground, so as to generate oscillation. By adding a first high frequency resonant selection network in the input matching circuit, the effect of the output signal on the input through ideal can be effectively reduced,

the working principle of the embodiment is as follows:

the signal enters an input port INA of an input matching circuit through a radio frequency signal port IN of an external bonding pad, and the input matching of the low-noise amplifier is realized through the input matching circuit consisting of a band-pass filter, a resonant circuit and a first high-frequency resonance selection network; and then the signal is amplified by a first transistor M1 and a second transistor M2 in the amplifying circuit and enters the output matching circuit to realize the output matching of the low-noise amplifier.

In the input matching circuit of the embodiment, the first bonding wire inductor LB1, the second bonding wire inductor LB2, the third bonding wire inductor LB3 and the fourth bonding wire inductor LB4 are bonding grounding inductors, and due to the existence of the first bonding wire inductor LB1 to the fourth bonding wire inductor LB4, a feedback loop outputting an input signal exists, and an unstable phenomenon is easy to occur at a certain high-frequency band. The input matching circuit is only composed of a band-pass filter, a resonant circuit and the first high-frequency resonance selection network, so that the signal stability at high frequency can be ensured, and the signal stability at a working frequency band can be ensured, and the noise and the gain at the working frequency band are lower.

To further verify the effect of the low noise amplifier proposed in this embodiment, this embodiment is compared with the low noise amplifier without any network (denoted as a first comparison scheme) shown in fig. 2 and the low noise amplifier circuit with a series lossy device in the conventional scheme (denoted as a second comparison scheme) shown in fig. 3, to obtain the stability factor, the minimum noise factor, and the maximum available gain comparison diagrams shown in fig. 4 to 6.

As shown in fig. 4, which is a graph comparing the stability coefficients of the embodiment with those of the first and second comparison schemes, when the operating frequency band of the low noise amplifier is 5-6 ghz, as shown in fig. 4, the first comparison scheme is a low noise amplifier circuit without any attenuation network, and in the operating frequency band, the stability coefficients of the low noise amplifier are all smaller than 1, but the circuit of the first comparison scheme has self-oscillation, which causes damage to the actual chip, so that the first comparison scheme is not feasible. The second comparison scheme is to add a low noise amplifier circuit with serially connected lossy devices, so that the stability coefficient in the working frequency band is ensured to be more than 1, and the self-oscillation of the chip can be ensured not to occur. The low noise amplifier circuit of the present embodiment has higher stability in the operating frequency band than the second embodiment. The low noise amplifier of the embodiment not only realizes that the stability in the full frequency band is more than 1, but also has higher stability at high frequency, so the low noise amplifier of the embodiment can remarkably improve the stability.

As shown in fig. 5, which is a graph comparing the minimum noise coefficients of the present embodiment with those of the first and second comparison schemes, the low noise amplifier of the present embodiment has lower noise than the structure of the second comparison scheme in the operating frequency range.

As shown in fig. 6, which is a graph of the maximum available gain of the embodiment and the comparison schemes one and two, the low noise amplifier of the embodiment has a higher gain than the comparison scheme two.

Therefore, in order to ensure the reliability of the circuit, as can be seen from fig. 4 to 6, the first comparison scheme has a higher gain and a lower stability factor, but the first comparison scheme has self-oscillation, which causes damage to the actual chip, and the first comparison scheme is not feasible, so that the first comparison scheme circuit is not selected in practice. The circuit stability of the second comparison scheme meets the requirement of an actual circuit, but the low-noise amplifier of the second comparison scheme has lower gain and poorer noise coefficient, and the low-noise amplifier circuit of the embodiment has higher gain and lower noise coefficient compared with the second comparison scheme on the basis of ensuring the stability in the whole frequency band. Therefore, the first comparative scheme is not preferable, and the low noise amplifier of the present embodiment has the advantages of high stability, low noise figure and high gain compared to the second comparative scheme.

It should be noted that the foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but the present invention is described in detail with reference to the foregoing embodiment, and it will be apparent to those skilled in the art that modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some of the technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The low noise amplifier is characterized by comprising an input matching circuit, an amplifying circuit, a power supply circuit and an output matching circuit;

2. The low noise amplifier of claim 1, wherein the input matching circuit comprises an input port INA, a first inductance L1, a second inductance L2, a third inductance L3, a fourth inductance L4, a first capacitance C1, a second capacitance C2, a blocking capacitance C3, a fourth capacitance C4, a fifth capacitance C5, a sixth capacitance C6, a first resistance R1, a bias resistance R2, a third resistance R3, a fourth resistance R4, a first bond wire inductance LB1, a second bond wire inductance LB2, a third bond wire inductance LB3, and a fourth bond wire inductance LB4;

3. The low noise amplifier of claim 1, wherein the amplifying circuit comprises a first transistor M1, a second transistor M2, a seventh capacitor C7, an eighth capacitor C8, a parasitic capacitor Cds, a fifth inductance L5, a bias resistor R5, a fifth bond wire inductance LB5, and a sixth bond wire inductance LB6;

4. The low noise amplifier of claim 1, wherein the power supply circuit comprises a seventh inductor L7, an eighth inductor L8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a seventh bond wire inductor LB7, an eighth bond wire inductor LB8;

5. The low noise amplifier of claim 1, wherein the output matching circuit comprises a sixth inductance L6, a twelfth capacitance C12, and a ninth bond wire inductance LB9;