Transconductance-enhanced low-noise amplifier and radio frequency chip

Abstract

The present invention is suitable for the technical field of wireless communications, and particularly relates to a transconductance-enhanced low-noise amplifier and a radio frequency chip. The transconductance-enhanced low-noise amplifier comprises: an input matching circuit, which comprises a first capacitor and a first inductor, a first end of the first capacitor being connected to a signal input end, a second end thereof being connected to a first end of the first inductor, and a second end of the first inductor being grounded; an output matching circuit, which comprises a second capacitor and a second inductor, a first end of the second capacitor being connected to a signal output end, a second end thereof being connected to a first end of the second inductor, and a second end of the second inductor being connected to a first power supply voltage; an amplifying circuit, which comprises a first MOS transistor and a first resistor, the source electrode of the first MOS transistor being connected to the second end of the first capacitor, the drain electrode thereof being connected to the second end of the second capacitor and the gate electrode thereof being connected to a first end of the first resistor, and a second end of the first resistor being connected to a bias voltage; and a transconductance enhancement circuit, which is used for feeding a signal input into the source electrode of the first MOS transistor into the gate electrode of the first MOS transistor. The present invention improves power gain without addition of a first-stage amplifier.

Description

Transconductance-enhanced low-noise amplifier and RF chip Technical Field

[0001] The present invention is applicable to the field of wireless communication technology, and in particular relates to a low-noise amplifier with enhanced transconductance and a radio frequency chip. Background Art

[0002] A low-noise amplifier (LNA) is an amplifier with a very low noise factor. When using an amplifier to amplify weak signals, the noise of the amplifier itself may interfere with the signal more seriously than the interference of the signal itself. The low-noise amplifier reduces its own noise through a certain structure to improve the signal-to-noise ratio of the signal output, thereby achieving better signal amplification effect.

[0003] The cascode low-noise amplifier (LNA) structure is the most commonly used in various circuits. Currently, to achieve power gain, the cascode LNA requires an additional amplifier stage. This design increases the circuit size and is not conducive to the implementation of microcircuits. Summary of the Invention

[0004] The present invention provides a low-noise amplifier with enhanced transconductance and a radio frequency chip, aiming to solve the problem that the power gain of the existing low-noise amplifier increases the circuit size.

[0005] To solve the above technical problems, in a first aspect, the present invention provides a low-noise amplifier with enhanced transconductance, comprising a signal input terminal, an input matching circuit, an amplifying circuit, a transconductance enhancement circuit, an output matching circuit, and a signal output terminal, wherein:

[0006] The input matching circuit includes a first capacitor and a first inductor, wherein a first end of the first capacitor is connected to the signal input end, a second end of the first capacitor is connected to a first end of the first inductor, and a second end of the first inductor is grounded;

[0007] The output matching circuit includes a second capacitor and a second inductor, wherein a first end of the second capacitor is connected to the signal output end, a second end of the second capacitor is connected to a first end of the second inductor, and a second end of the second inductor is connected to a first power supply voltage;

[0008] The amplifier circuit includes a first MOS transistor and a first resistor, wherein the source of the first MOS transistor is connected to the second end of the first capacitor, the drain of the first MOS transistor is connected to the second end of the second capacitor, the gate of the first MOS transistor is connected to the first end of the first resistor, and the second end of the first resistor is connected to a first bias voltage;

[0009] The transconductance enhancement circuit is used to feed back the signal input to the source of the first MOS transistor to the gate of the first MOS transistor.

[0010] Furthermore, the transconductance enhancement circuit includes a second MOS transistor and a second resistor, the gate of the second MOS transistor is connected to the source of the first MOS transistor as the input end of the transconductance enhancement circuit, the drain of the second MOS transistor is connected to the gate of the first MOS transistor as the output end of the transconductance enhancement circuit, and the source of the second MOS transistor is grounded; the first end of the second resistor is connected to the gate of the second MOS transistor, and the second end of the second resistor is connected to the second bias voltage.

[0011] Furthermore, the transconductance enhancement circuit also includes a third capacitor, a first end of the third capacitor is connected to the source of the first MOS transistor, and a second end of the third capacitor is respectively connected to the gate of the second MOS transistor and the first end of the second resistor.

[0012] Furthermore, the transconductance enhancement circuit also includes a fourth capacitor and a third inductor, a first end of the fourth capacitor is connected to the drain of the second MOS transistor, a second end of the fourth capacitor is connected to the gate of the first MOS transistor, a first end of the third inductor is connected to the first end of the fourth capacitor, and a second end of the third inductor is connected to the second power supply voltage.

[0013] Furthermore, the first inductor is coupled to the third inductor.

[0014] Furthermore, the transconductance enhancement circuit includes a fifth inductor and a sixth capacitor, a first end of the fifth inductor is connected to the first end of the sixth capacitor, a second end of the fifth inductor is grounded, a second end of the sixth capacitor is connected to the gate of the first MOS transistor, and the first inductor is coupled to the fifth inductor.

[0015] Furthermore, the input matching circuit further includes a first input inductor, a second input inductor, a third resistor, a third MOS transistor, a fourth inductor, and a fifth capacitor. The first end of the first input inductor is connected to the signal input terminal, the second end of the first input inductor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the gate of the third MOS transistor, the first end of the third resistor is connected to the second end of the first capacitor, the second end of the third resistor is connected to a third bias voltage, the first end of the second input inductor is connected to the source of the third MOS transistor, the second end of the second input inductor is grounded, the drain of the third MOS transistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the source of the first MOS transistor, the first end of the fourth inductor is connected to the first end of the fifth capacitor, and the second end of the fourth inductor is connected to a third power supply voltage.

[0016] In a second aspect, the present invention further provides a radio frequency chip, comprising the transconductance enhanced low noise amplifier as described above.

[0017] The beneficial effect achieved by the present invention lies in proposing a new low-noise amplifier and radio frequency chip that can achieve transconductance enhancement. Without adding an additional amplifier stage, the low-noise amplifier increases the gate voltage swing by inverting the input signal and feeding it into the MOS tube gate of the common-gate amplifier circuit, thereby effectively enhancing the transconductance of the low-noise amplifier and improving the power gain while maintaining the receiving sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a schematic diagram of a circuit structure of a low-noise amplifier with enhanced transconductance provided by an embodiment of the present invention;

[0019] FIG2 is a schematic diagram of a circuit structure of a low-noise amplifier with transconductance enhancement implemented in an active manner according to an embodiment of the present invention;

[0020] 3 is a schematic diagram of an optimized circuit structure of a low-noise amplifier with transconductance enhancement implemented in an active manner according to an embodiment of the present invention;

[0021] 4 is a schematic diagram of the circuit structure of a low-noise amplifier with enhanced transconductance implemented in a passive manner according to an embodiment of the present invention;

[0022] FIG5 is a schematic diagram of an optimized circuit structure of a low noise amplifier with enhanced transconductance implemented in a passive manner according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1

[0025] Please refer to FIG1 , which is a schematic diagram of a circuit structure of a low noise amplifier 100 with enhanced transconductance according to an embodiment of the present invention. The low noise amplifier 100 with enhanced transconductance includes a signal input terminal RF in , input matching circuit, amplifier circuit, transconductance enhancement circuit, output matching circuit and signal output RF out ,in:

[0026] The input matching circuit includes a first capacitor C1 and a first inductor L1. The first end of the first capacitor C1 is connected to the signal input terminal RF in, the second end of the first capacitor C1 is connected to the first end of the first inductor L1, and the second end of the first inductor L1 is grounded;

[0027] The output matching circuit includes a second capacitor C2 and a second inductor L2. The first end of the second capacitor C2 is connected to the signal output terminal RF out , a second end of the second capacitor C2 is connected to the first end of the second inductor L2, and a second end of the second inductor L2 is used to connect to the first power supply voltage VDD1;

[0028] The amplifier circuit includes a first MOS transistor M1 and a first resistor R1. The source of the first MOS transistor M1 is connected to the second end of the first capacitor C1, the drain of the first MOS transistor M1 is connected to the second end of the second capacitor C2, the gate of the first MOS transistor M1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the first bias voltage V bias1 ;

[0029] The transconductance enhancement circuit is used to feed back the signal input to the source of the first MOS transistor to the gate of the first MOS transistor.

[0030] In an embodiment of the present invention, the transconductance-enhanced low-noise amplifier 100 in the embodiment of the present invention forms a transconductance enhancement circuit by adding a path at the source end of the MOS tube. The effect of this circuit on the transconductance of the amplifier circuit is represented by a coefficient A. The transconductance enhancement circuit can increase the transconductance Gm by (1+A) while reducing the NF of the device itself by (1+A) while keeping the output impedance of the amplifier unchanged. Specifically, the transconductance enhancement circuit in the transconductance-enhanced low-noise amplifier 100 in the embodiment of the present invention can be implemented based on active, passive, or a combination of active and passive methods. Corresponding to different implementation methods, the embodiment of the present invention also has the following implementation methods:

[0031] Example 2

[0032] A low noise amplifier 100 with transconductance enhancement implemented in an active manner is shown in FIG2 . The transconductance enhancement circuit includes a second MOS transistor M2 and a second resistor R2. The gate of the second MOS transistor M2 is connected to the source of the first MOS transistor M1 as the input of the transconductance enhancement circuit, and the drain of the second MOS transistor M2 is connected to the gate of the first MOS transistor M1 as the output of the transconductance enhancement circuit. The source of the second MOS transistor M2 is grounded. The first end of the second resistor R2 is connected to the gate of the second MOS transistor M2, and the second end of the second resistor R2 is connected to the second bias voltage V bias2 .

[0033] In the active mode, due to the simultaneous stacking of different MOS transistors, a higher DC supply level is required. In the embodiment of the present invention, to improve the DC supply level, the transconductance enhancement circuit further includes a third capacitor C3. A first end of the third capacitor C3 is connected to the source of the first MOS transistor M1, and a second end of the third capacitor C3 is connected to the gate of the second MOS transistor M2 and the first end of the second resistor R2, respectively.

[0034] The transconductance enhancement circuit further includes a fourth capacitor C4 and a third inductor L3. A first end of the fourth capacitor C4 is connected to the drain of the second MOS transistor M2, and a second end of the fourth capacitor C4 is connected to the gate of the first MOS transistor M1. A first end of the third inductor L3 is connected to the first end of the fourth capacitor C4, and a second end of the third inductor L3 is connected to the second power supply voltage VDD2. In this manner, two separate power supply voltages are provided in the circuit to ensure DC supply.

[0035] In this embodiment, the second MOS transistor M2, the second capacitor C2, and the third capacitor C3 together constitute the transconductance enhancement circuit of the transconductance enhanced low noise amplifier 100. The coefficient A is determined by the second MOS transistor M2.

[0036] For example, in order to improve the performance of the transconductance enhanced low noise amplifier 100, in a preferred embodiment, the circuit structure of FIG2 can be optimized. As shown in FIG3, based on FIG2, a first input inductor Lg, a second input inductor Ls, a third resistor R3, a third MOS transistor M3, a fourth inductor L4 and a fifth capacitor C5 are added to the input matching circuit. The first end of the first input inductor Lg is connected to the signal input terminal RF in The second end of the first input inductor Lg is connected to the first end of the first capacitor C1, the second end of the first capacitor C1 is connected to the gate of the third MOS transistor M3, the first end of the third resistor R3 is connected to the second end of the first capacitor C1, and the second end of the third resistor R3 is connected to the third bias voltage V bias3 The first end of the second input inductor Ls is connected to the source of the third MOS transistor M3, the second end of the second input inductor Ls is grounded, the drain of the third MOS transistor M3 is connected to the first end of the fifth capacitor C5, the second end of the fifth capacitor C5 is connected to the source of the first MOS transistor M1, the first end of the fourth inductor L4 is connected to the first end of the fifth capacitor C5, and the second end of the fourth inductor L4 is connected to the third power supply voltage VDD3. In this optimized structure, the first MOS transistor M1, the second MOS transistor M2, and the third MOS transistor M3 collectively constitute the amplification branch of the transconductance-enhanced low-noise amplifier 100.

[0037] Example 3

[0038] A low-noise amplifier 100 with transconductance enhancement implemented in a passive manner is shown in FIG4 . The transconductance enhancement circuit includes a fifth inductor L5 and a sixth capacitor C6. A first end of the fifth inductor L5 is connected to a first end of the sixth capacitor C6, a second end of the fifth inductor L5 is grounded, a second end of the sixth capacitor C6 is connected to the gate of the first MOS transistor M1, and the first inductor L1 is coupled to the fifth inductor L5.

[0039] The coupling coefficient between the first inductor L1 and the fifth inductor L5 is k. In this embodiment, the coefficient A is determined by the coupling coefficient k.

[0040] Similarly, in order to improve the performance of the transconductance enhanced low noise amplifier 100, in a preferred embodiment, the circuit structure of FIG4 can be optimized. As shown in FIG5, based on FIG4, a first input inductor Lg, a second input inductor Ls, a third resistor R3, a third MOS transistor M3, a fourth inductor L4 and a fifth capacitor C5 are added to the input matching circuit. The first end of the first input inductor Lg is connected to the signal input terminal RF in The second end of the first input inductor Lg is connected to the first end of the first capacitor C1, the second end of the first capacitor C1 is connected to the gate of the third MOS transistor M3, the first end of the third resistor R3 is connected to the second end of the first capacitor C1, and the second end of the third resistor R3 is connected to the third bias voltage V bias3 The first end of the second input inductor Ls is connected to the source of the third MOS transistor M3, the second end of the second input inductor Ls is grounded, the drain of the third MOS transistor M3 is connected to the first end of the fifth capacitor C5, the second end of the fifth capacitor C5 is connected to the source of the first MOS transistor M1, the first end of the fourth inductor L4 is connected to the first end of the fifth capacitor C5, and the second end of the fourth inductor L4 is connected to the third power supply voltage VDD3. In this optimized structure, the first MOS transistor M1, the second MOS transistor M2, and the third MOS transistor M3 collectively constitute the amplification branch of the transconductance-enhanced low-noise amplifier 100.

[0041] In the circuit structure shown in FIG5 , since multiple inductors are provided, different inter-stage matching and output matching can be flexibly configured as needed during implementation, thereby achieving multi-stage matching.

[0042] Example 4

[0043] The circuit structure of the transconductance enhanced low noise amplifier 100 implemented based on the active-passive combination is the same as that of the second embodiment, as shown in FIG2 . The specific implementation of the active-passive combination is to couple the first inductor L1 with the third inductor L3 based on the second embodiment.

[0044] The coupling coefficient between the first inductor L1 and the third inductor L3 is k.

[0045] In this embodiment, the coefficient A is determined by the second MOS transistor M2 and the coupling coefficient k.

[0046] Through the above implementation, the embodiment of the present invention provides a larger output voltage swing while keeping the output impedance of the amplifier circuit unchanged, thereby improving the gain.

[0047] The beneficial effect achieved by the present invention lies in proposing a new low-noise amplifier and radio frequency chip that can achieve transconductance enhancement. Without adding an additional amplifier stage, the low-noise amplifier increases the gate voltage swing by inverting the input signal and feeding it into the MOS tube gate of the common-gate amplifier circuit, thereby effectively enhancing the transconductance of the low-noise amplifier and improving the power gain while maintaining the receiving sensitivity.

[0048] Example 5

[0049] An embodiment of the present invention further provides a radio frequency chip including a low-noise amplifier with enhanced transconductance as described in the above embodiment. The radio frequency chip using the low-noise amplifier with enhanced transconductance can effectively enhance the transconductance of the low-noise amplifier without adding an additional amplifier stage, thereby improving power gain while maintaining receiver sensitivity.

[0050] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0051] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0052] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only a preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms and equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A low-noise amplifier with enhanced transconductance, characterized in that: It includes a signal input terminal, an input matching circuit, an amplifying circuit, a transconductance enhancement circuit, an output matching circuit and a signal output terminal, wherein: The input matching circuit includes a first capacitor and a first inductor, wherein a first end of the first capacitor is connected to the signal input end, a second end of the first capacitor is connected to a first end of the first inductor, and a second end of the first inductor is grounded; The output matching circuit includes a second capacitor and a second inductor, wherein a first end of the second capacitor is connected to the signal output end, a second end of the second capacitor is connected to a first end of the second inductor, and a second end of the second inductor is connected to a first power supply voltage; The amplifier circuit includes a first MOS transistor and a first resistor, wherein the source of the first MOS transistor is connected to the second end of the first capacitor, the drain of the first MOS transistor is connected to the second end of the second capacitor, the gate of the first MOS transistor is connected to the first end of the first resistor, and the second end of the first resistor is used to connect to a first bias voltage; The transconductance enhancement circuit is used to feed back the signal input to the source of the first MOS transistor to the gate of the first MOS transistor.

2. The low noise amplifier with enhanced transconductance according to claim 1, wherein: The transconductance enhancement circuit includes a second MOS transistor and a second resistor. The gate of the second MOS transistor is connected to the source of the first MOS transistor as the input end of the transconductance enhancement circuit, the drain of the second MOS transistor is connected to the gate of the first MOS transistor as the output end of the transconductance enhancement circuit, and the source of the second MOS transistor is grounded; the first end of the second resistor is connected to the gate of the second MOS transistor, and the second end of the second resistor is connected to a second bias voltage.

3. The low noise amplifier with enhanced transconductance according to claim 2, wherein: The transconductance enhancement circuit further includes a third capacitor, a first end of the third capacitor is connected to the source of the first MOS transistor, and a second end of the third capacitor is respectively connected to the gate of the second MOS transistor and the first end of the second resistor.

4. The low noise amplifier with enhanced transconductance according to claim 2, wherein: The transconductance enhancement circuit also includes a fourth capacitor and a third inductor, wherein a first end of the fourth capacitor is connected to the drain of the second MOS transistor, a second end of the fourth capacitor is connected to the gate of the first MOS transistor, a first end of the third inductor is connected to the first end of the fourth capacitor, and a second end of the third inductor is connected to the second power supply voltage.

5. The low noise amplifier with enhanced transconductance according to claim 4, wherein: The first inductor is coupled to the third inductor.

6. The low noise amplifier with enhanced transconductance according to claim 1, wherein: The transconductance enhancement circuit includes a fifth inductor and a sixth capacitor, wherein a first end of the fifth inductor is connected to a first end of the sixth capacitor, a second end of the fifth inductor is grounded, a second end of the sixth capacitor is connected to the gate of the first MOS transistor, and the first inductor is coupled to the fifth inductor.

7. The low noise amplifier with enhanced transconductance according to claim 1, wherein: The input matching circuit also includes a first input inductor, a second input inductor, a third resistor, a third MOS transistor, a fourth inductor, and a fifth capacitor. The first end of the first input inductor is connected to the signal input end, the second end of the first input inductor is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the gate of the third MOS transistor, the first end of the third resistor is connected to the second end of the first capacitor, the second end of the third resistor is connected to a third bias voltage, the first end of the second input inductor is connected to the source of the third MOS transistor, the second end of the second input inductor is grounded, the drain of the third MOS transistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the source of the first MOS transistor, the first end of the fourth inductor is connected to the first end of the fifth capacitor, and the second end of the fourth inductor is connected to a third power supply voltage.

8. A radio frequency chip, characterized in that: The radio frequency chip includes the transconductance-enhanced low-noise amplifier according to any one of claims 1 to 7.

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