Radio frequency low-noise amplifier based on phase inverter structure

Abstract

The invention discloses a radio frequency low-noise amplifier based on an inverter structure. The radio frequency low-noise amplifier comprises a PMOS (P-channel Metal Oxide Semiconductor) transistor TP and an NMOS (N-channel Metal Oxide Semiconductor) transistor TN, the source electrode of the PMOS transistor TP is connected to a power supply VDD, the grid electrode of the PMOS transistor TP receives an input signal v1, the drain electrode of the PMOS transistor TP is connected with the drain electrode of the NMOS transistor TP, and an output signal vO is taken out from the drain electrode connecting part; the source electrode of the NMOS transistor TN is grounded, and the grid electrode of the NMOS transistor TN receives an input signal v1. According to the invention, the PMOS transistor and the NMOS transistor are paired, so that the PMOS transistor and the NMOS transistor are mutually loaded to form a closed loop structure, higher gain is realized, and linearity and stability of signals and suppression capability of common-mode interference can be further enhanced by adding a linear voltage regulator to a differential structure and a power line.

Description

Technical Field

[0001] The present invention relates to the technical field of amplifiers, and in particular to a radio frequency low noise amplifier based on an inverter structure. Background Art

[0002] RF low noise amplifier is an electronic device used to amplify weak RF signals. It is used in the front end of wireless communication systems. Its main purpose is to increase the strength of the received signal while reducing the introduction of additional noise, thereby improving the signal-to-noise ratio and the overall performance of the system.

[0003] Most of the existing RF low-noise amplifier structures are based on an amplifier tube + load structure, and are usually made into a differential structure to suppress common-mode interference; the two input signals are connected to the gates of the two transistors respectively, and each input signal is amplified by a field-effect transistor. The load network is composed of an inductor and a capacitor, which is used to provide suitable impedance matching and can form a resonant circuit to enhance the gain at a specific frequency. The bottom transistor is used to provide a bias current to ensure that the amplifier tube operates at a suitable DC operating point. The main advantage of the structure of the prior art is that it can effectively suppress common-mode interference and improve the signal-to-noise ratio.

[0004] However, the prior art also has corresponding defects: under the constraints of given power consumption / current, the gain of the circuit is mainly determined by the transconductance or current gain of the main amplifier tube multiplied by the load; these parameters are closely related to the size and structure of the transistor, and in order to obtain higher gain, the size of the transistor needs to be increased; however, too large a transistor size will limit the maximum operating frequency, because the parasitic capacitance of a large-size transistor will increase, thereby reducing high-frequency performance; if a resistor is used as a load, the resistance value cannot be too large, otherwise it will limit the output voltage range, because the resistive load will affect the amplitude of the output signal.

[0005] Therefore, it is necessary to improve a radio frequency low noise amplifier based on an inverter structure in the prior art to solve the above problems. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a radio frequency low noise amplifier based on an inverter structure, aiming to solve the problem in the prior art that under given power consumption or current limiting conditions, the maximum operating frequency of traditional radio frequency low noise amplifiers is limited due to the increase in transistor size, and the gain and output voltage range are limited due to the use of resistive or inductive loads.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a radio frequency low noise amplifier based on an inverter structure, comprising: a PMOS transistor T P and an NMOS transistor T N , characterized in that;

[0008] The PMOS transistor T P The source is connected to the power supply V DD , the PMOS transistor T P The gate of the PMOS transistor T receives the input signal v1. P The drain of the NMOS transistor T P The output signal v is taken from the drain connection O ;

[0009] The NMOS transistor T N The source is grounded, and the NMOS transistor T N The gate receives the input signal v1.

[0010] In a preferred embodiment of the present invention, the PMOS transistor T P and the NMOS crystal T N The tubes are connected to each other through a cascode configuration to form a closed loop structure.

[0011] In a preferred embodiment of the present invention, the PMOS transistor and the NMOS transistor provide transconductance simultaneously.

[0012] In a preferred embodiment of the present invention, the drain of the PMOS transistor serves as the load of the NMOS transistor, and the drain of the NMOS transistor also serves as the load of the PMOS transistor, and each transistor provides a dynamic load for the other.

[0013] The present invention provides a low noise amplifier based on an inverter structure and a differential structure, comprising:

[0014] Two NMOS transistors M1a, M1b and two PMOS transistors M2a, M2b, and two bias current sources I B1 , I B2 ;

[0015] The sources of the NMOS transistors M1a and M1b are connected to the ground, and the gates of the NMOS transistors M1a and M1b receive input signals respectively. and

[0016] The sources of the PMOS transistors M2a, M2b are connected to V DD , the gates of the PMOS transistors M2a and M2b are connected to the gates of the NMOS transistors M1a and M1b;

[0017] The drains of the PMOS transistors M2a and M2b are connected to the drains of the NMOS transistors M1a and M1b to extract the output signal and

[0018] In a preferred embodiment of the present invention, the bias current source I B1 Provides bias current for NMOS transistors M1a and M1b; bias current source I B2 Provides bias current for PMOS transistors M2a, M2b.

[0019] In a preferred embodiment of the present invention, M1a, M2a and M1b, M2b form a pair of complementary signal paths, and together constitute a differential pair.

[0020] In a preferred embodiment of the present invention, the gain A of the RF low noise amplifier is v It can be estimated by the formula: A v =g m R L , where R L is the load resistance or equivalent impedance.

[0021] In a preferred embodiment of the present invention, the performance of the radio frequency low noise amplifier is measured by calculating the noise factor, and the noise factor is Where k is the Boltzmann constant, T is the absolute temperature, and R s is the source resistance.

[0022] In a preferred embodiment of the present invention, a linear voltage regulator is added to the power supply.

[0023] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0024] (1) The present invention provides a radio frequency low noise amplifier based on an inverter structure, which achieves higher gain by pairing a PMOS transistor and an NMOS transistor so that the two serve as loads for each other to form a closed-loop structure. The linearity and stability of the signal, as well as the ability to suppress common-mode interference, can be further enhanced by adding a linear regulator to the differential structure and the power line.

[0025] (2) The present invention combines the PMOS and NMOS transistors by designing them as mutual loads. The drain of the PMOS transistor serves as the load of the NMOS transistor, and the drain of the NMOS transistor also serves as the load of the PMOS transistor. This closed-loop structure allows the two transistors to provide higher transconductance and gain without using external resistors or inductor loads; under the same current limiting conditions, the total transconductance increases due to the joint action of the PMOS and NMOS transistors, thereby improving the overall gain. Compared with the prior art, not only a higher voltage gain is achieved, but also because no additional external load components are required, the occupied area in the integrated circuit can be greatly reduced, while simplifying the circuit design.

[0026] (3) The present invention combines a differential structure with a linear regulator added to the power line. The differential structure processes a pair of opposite signals through two symmetrical branches, thereby improving the linearity and stability of the signal and reducing the influence of external noise. Any fluctuation on the power supply will affect the two symmetrical branches in the same way, resulting in the appearance of unwanted common-mode components in the output signal. To this end, a linear regulator is added to the power supply to provide a stable power supply for the circuit by adjusting the output voltage to a fixed level. The effect of this combination is to enhance the ability to suppress common-mode interference, thereby improving the anti-interference ability and stability of the entire system; compared with the prior art, it further achieves a stronger common-mode interference suppression effect, ensuring higher signal integrity and lower noise levels.

[0027] (4) The present invention combines a PMOS transistor and an NMOS transistor in a cascode configuration. The cascode configuration forms a closed-loop structure, so that the two transistors form a closed-loop structure, thereby enhancing the signal amplification effect. Compared with the method of increasing the size of transistors to improve the gain in the prior art, the structure of the present invention can use small-sized transistors under the same gain requirement, thereby reducing parasitic capacitance and allowing the circuit to operate at a higher frequency without sacrificing performance. This not only improves the performance of the amplifier, but also provides the possibility for its application in high-frequency wireless communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 is a differential structure circuit diagram of a preferred embodiment of the present invention;

[0030] Figure 2 is a simplified circuit diagram of a preferred embodiment of the present invention;

[0031] Figure 3 It is a conventional low noise amplifier circuit diagram of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0034] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0035] Application Overview:

[0036] In the prior art, LNA uses a transistor amplifier stage with a single-ended or differential structure, combined with a load network such as a resistor, inductor or transformer to achieve gain and impedance matching. Combined with a differential structure, it can not only effectively suppress common-mode interference, but also provide good linearity and stability; however, as wireless communication technology develops towards higher frequencies and greater data throughput, higher requirements are also placed on the design of LNA.

[0037] When operating under limited power consumption conditions, the gain of the LNA is directly constrained by the transistor transconductance and the selected load type; in order to obtain higher gain, it is usually necessary to increase the size of the transistor, but this will introduce additional parasitic capacitance, thereby limiting the maximum operating frequency; in addition, although using a resistor as a load is simple, it will lead to a limited output voltage range under high gain requirements, affecting the overall performance of the circuit; inductive loads can avoid the problem of output voltage range and make the output DC operating point unaffected by DC current, but their limited Q value and impedance level impose new restrictions on gain.

[0038] To solve the above problems, the present application provides a radio frequency low noise amplifier based on an inverter structure, by pairing PMOS and NMOS transistors so that the two transistors can serve as each other's load, forming a closed-loop structure to achieve higher gain.

[0039] Example simplified circuit:

[0040] like Figure 2 As shown, a simplified circuit of a low noise amplifier based on an inverter structure includes: a PMOS transistor T P and an NMOS transistor T N ;

[0041] PMOS transistor T P and NMOS crystal T N The tubes are connected to each other through a cascode configuration, forming a closed loop structure;

[0042] PMOS transistor T P The source is connected to the power supply V DD , PMOS transistor T P The gate receives the input signal v1, and the drain is connected to the NMOS transistor T P The drain of the O ;

[0043] NMOS transistor T N The source is grounded, and the NMOS transistor T N The gate receives the input signal v1, and the drain is connected to the drain of the PMOS transistor to take out the output signal v O .

[0044] PMOS and NMOS transistors provide transconductance at the same time. Transconductance refers to the degree of influence of gate voltage changes on drain current and is an important parameter for measuring the amplification capability of transistors. PMOS and NMOS transistors work together to increase the total transconductance, thereby improving the overall gain.

[0045] Transconductance is an important parameter to measure the amplification capability of transistors. It represents the influence of gate voltage change on drain current. Where μ is the carrier mobility, Cox is the oxide layer capacitance per unit area, W, L are the width and length of the transistor, V GS is the gate-source voltage, V th is the threshold voltage.

[0046] The drain of the PMOS transistor serves as the load of the NMOS transistor, and the drain of the NMOS crystal also serves as the load of the PMOS transistor. Each transistor provides a dynamic load for the other, rather than a traditional fixed resistance or inductance load. This mutual load design can achieve higher gain under the same current limiting conditions, and the load effect enhances the signal amplification effect.

[0047] Due to the higher gain, smaller transistors can be used to achieve the same gain requirement; smaller transistors reduce parasitic capacitance, allowing the circuit to operate at higher frequencies without sacrificing performance.

[0048] For a radio frequency low noise amplifier, its gain A v It can be estimated by the formula: A v =g m R L , where R L is the load resistance or equivalent impedance.

[0049] Example differential structure circuit:

[0050] Furthermore, if Figure 1 The low noise amplifier based on the inverter structure and the differential structure includes: two NMOS transistors M1a, M1b and two PMOS transistors M2a, M2b, and two bias current sources I B1 , I B2 ;

[0051] The sources of the NMOS transistors M1a and M1b are connected to the ground, and the gates of the NMOS transistors M1a and M1b receive input signals respectively. and The drains of NMOS transistors M1a and M1b are connected to the drains of PMOS transistors M2a and M2b to extract the output signal. and

[0052] The source of PMOS transistors M2a and M2b are connected to V DD The gates of the PMOS transistors M2a and M2b are connected to the gates of the NMOS transistors M1a and M1b; the drains of the PMOS transistors M2a and M2b are connected to the drains of the NMOS transistors M1a and M1b to take out the output signal. and

[0053] Among them, the bias current source I B1 Provides bias current for NMOS transistors M1a and M1b; bias current source I B2 Provides bias current for PMOS transistors M2a, M2b.

[0054] The drains of the PMOS and NMOS transistors are interconnected to form a closed-loop structure. The output of each transistor is directly connected to the gate of the other transistor, thereby achieving higher gain without using external load components. In addition, M1a, M2a and M1b, M2b form a pair of complementary signal paths, which together constitute a differential pair and construct a differential structure. The differential structure processes a pair of opposite signals through two symmetrical branches, thereby improving the linearity and stability of the signal and reducing the influence of external noise. Since any common-mode signal will be offset by the two symmetrical branches, the differential structure can effectively suppress common-mode interference.

[0055] The performance of the LNA can be measured by calculating the noise figure, which is Where k is the Boltzmann constant, T is the absolute temperature, and R s is the source resistance.

[0056] Furthermore, since any fluctuation on the power supply will affect the two symmetrical branches in the same way, resulting in unwanted common-mode components in the output signal, a linear regulator is added to the power supply to enhance the suppression of common-mode interference; a linear regulator is a DC power converter that provides a stable power supply to the circuit by adjusting the output voltage to a fixed level.

[0057] Embodiment 1

[0058] A low noise amplifier based on an inverter structure and a differential structure includes: two NMOS transistors M1a, M1b and two PMOS transistors M2a, M2b, and two bias current sources I B1 , I B2 ;

[0059] The sources of the NMOS transistors M1a and M1b are connected to the ground, and the gates of the NMOS transistors M1a and M1b receive input signals respectively. and The drains of NMOS transistors M1a and M1b are connected to the drains of PMOS transistors M2a and M2b to extract the output signal. and

[0060] The source of PMOS transistors M2a and M2b are connected to V DD The gates of the PMOS transistors M2a and M2b are connected to the gates of the NMOS transistors M1a and M1b; the drains of the PMOS transistors M2a and M2b are connected to the drains of the NMOS transistors M1a and M1b to take out the output signal. and

[0061] Among them, the bias current source I B1Provides bias current for NMOS transistors M1a and M1b; bias current source I B2 Provides bias current for PMOS transistors M2a, M2b.

[0062] M1a, M2a and M1b, M2b form a pair of complementary signal paths, together forming a differential pair;

[0063] Add a linear regulator to the power supply.

[0064] Set the power consumption level to 75mW.

[0065] Embodiment 2

[0066] A low noise amplifier based on an inverter structure and a differential structure, the same points as those of the first embodiment are not repeated here, and the difference from the first embodiment is that the power consumption level is set to 50mW.

[0067] Embodiment 3

[0068] A low noise amplifier based on an inverter structure and a differential structure, the same points as those of the first embodiment are not described in detail, and the difference from the first embodiment is that the power consumption level is set to 100mW.

[0069] Comparative Example 1

[0070] like Figure 3 As shown, a conventional low noise amplifier comprises:

[0071] Input signal V in ,V in+ The gate electrodes of the two NMOS transistors are connected to the ground through a common source and common gate configuration.

[0072] The drain of each NMOS transistor is connected to the power supply V through an LC resonant network consisting of an inductor and a capacitor. DD LC resonant network is used to provide a high Q load, thus achieving high gain at a specific frequency;

[0073] The gates of the two NMOS transistors are controlled by bias voltage VB2, respectively, and the gate of the NMOS transistor in the common source and common gate configuration is controlled by bias voltage VB1;

[0074] The output signal is taken from the drain of each NMOS transistor and output after passing through the LC resonant network;

[0075] Set the power consumption level to 75mW.

[0076] Comparative Example 2

[0077] A traditional low noise amplifier, the same as the comparative example 1 is not repeated here, and the difference from the comparative example 1 is that the power consumption level is set to 50mW.

[0078] Comparative Example 3

[0079] A traditional low noise amplifier, the same as the comparative example 1 is not repeated here, and the difference from the comparative example 1 is that the power consumption level is set to 100mW.

[0080] Experimental Example 1

[0081] This experimental example selects embodiments 1 to 3 and comparative examples 1 to 3 to conduct electrical experiments to test the voltage gain, area occupied in the integrated circuit and maximum frequency of different amplifiers;

[0082] Table 1 Electrical test results

[0083]

[0084]

[0085] Under the same power consumption conditions, the LNA based on the inverter structure exhibits a higher voltage gain. In the design based on the inverter structure, the PMOS and NMOS transistors act as each other's dynamic load. This closed-loop structure allows the two transistors to provide higher transconductance and gain without using external resistors or inductors. In addition, since no additional external load components are required, under the same current limit conditions, the total transconductance is increased, thereby improving the overall gain.

[0086] The LNA based on the inverter structure occupies a significantly smaller area. Traditional LNA requires additional inductors and capacitors to achieve impedance matching and high-frequency gain. These passive components occupy a large chip area. The LNA based on the inverter structure uses PMOS and NMOS transistors as loads for each other, which simplifies the circuit design and reduces the dependence on external components, thus significantly reducing the occupied area.

[0087] LNA based on inverter structure supports higher operating frequency. Traditional LNA uses large-size transistors to improve gain, but this also introduces more parasitic capacitance, limiting the maximum operating frequency. In contrast, LNA based on inverter structure can use smaller transistors under the same gain requirements, reducing the impact of parasitic capacitance, so that the circuit can operate at a higher frequency without sacrificing performance. In addition, the dynamic load effect enhances the amplification effect of the signal, further increasing the operating frequency.

[0088] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A radio frequency low noise amplifier based on an inverter structure, comprising: A PMOS transistor T P and an NMOS transistor T N , It is characterized by: The PMOS transistor T P The source is connected to the power supply V DD , the PMOS transistor T P The gate of the PMOS transistor T receives the input signal v1. P The drain of the NMOS transistor T P The output signal v is taken from the drain connection O ; The NMOS transistor T N The source is grounded, and the NMOS transistor T N The gate receives the input signal v1.

2. The RF low noise amplifier based on the inverter structure according to claim 1, characterized in that: The PMOS transistor T P and the NMOS crystal T N The tubes are connected to each other through a cascode configuration to form a closed loop structure.

3. The RF low noise amplifier based on the inverter structure according to claim 1, characterized in that: The PMOS transistor and the NMOS transistor simultaneously provide transconductance.

4. The RF low noise amplifier based on the inverter structure according to claim 1, characterized in that: The drain of the PMOS transistor serves as a load for the NMOS transistor, and the drain of the NMOS transistor also serves as a load for the PMOS transistor, and each transistor provides a dynamic load for the other.

5. A low noise amplifier based on an inverter structure and a differential structure, according to any one of claims 1 to 4, characterized in that: Two NMOS transistors M1a, M1b and two PMOS transistors M2a, M2b, and two bias current sources I B1 , I B2 ; The sources of the NMOS transistors M1a and M1b are connected to the ground, and the gates of the NMOS transistors M1a and M1b receive input signals respectively. and The sources of the PMOS transistors M2a, M2b are connected to V DD , the gates of the PMOS transistors M2a and M2b are connected to the gates of the NMOS transistors M1a and M1b; The drains of the PMOS transistors M2a and M2b are connected to the drains of the NMOS transistors M1a and M1b to extract the output signal and 6. A low noise amplifier based on an inverter structure and a differential structure according to claim 5, characterized in that: Bias current source I B1 Provides bias current for NMOS transistors M1a and M1b; bias current source I B2 Provides bias current for PMOS transistors M2a, M2b.

7. The low noise amplifier based on the inverter structure and the differential structure according to claim 5, characterized in that: M1a, M2a and M1b, M2b form a pair of complementary signal paths and together constitute a differential pair.

8. The RF low noise amplifier based on an inverter structure according to claim 1, characterized in that: For the RF low noise amplifier gain A v It can be estimated by the formula: A v =g m R L , where R L is the load resistance or equivalent impedance.

9. The RF low noise amplifier based on the inverter structure according to claim 1, characterized in that: The performance of a RF low noise amplifier is measured by calculating the noise figure, which is Where k is the Boltzmann constant, T is the absolute temperature, and R s is the source resistance.

10. The low noise amplifier based on the inverter structure and the differential structure according to claim 5, characterized in that: Add a linear regulator to the power supply.

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