Ultra-wideband low-noise amplifier based on coupling expansion technology

Abstract

The invention relates to the technical field of communication, in particular to an ultra-wideband low-noise amplifier based on a coupling expansion technology. The ultra-wideband low-noise amplifier comprises a Cascode amplifying circuit, an input coupling inductor pair and an output coupling inductor pair. A drain stray capacitor Cd and a load capacitor CL in a circuit are rapidly charged through negative electromotive force generated by the mutual inductance effect, the charging time is remarkably shortened, the working bandwidth of the amplifier is greatly expanded on the premise that the noise performance is not sacrificed, meanwhile, the requirement for a multi-stage impedance matching network is simplified through the inherent broadband characteristic of the coupling structure, and the cost is reduced. According to the ultra-wideband power divider, ultra-wideband input and output matching is achieved, noise matching is optimized through the noise optimization capacitor Cex, the chip area and the number of peripheral elements are effectively reduced through the multiplexing inductor function, and finally the contradiction among bandwidth, noise, matching and area power consumption is cooperatively solved under the condition of high integration level.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, and in particular to a kind of ultra-wideband low noise amplifier based on coupling expansion technology. BACKGROUND

[0002] Ultra-wideband low noise amplifier is the core front-end module of wireless communication, radar detection and satellite internet communication system, and needs to meet strict requirements such as wide frequency band coverage (usually 3.1-22GHz), low noise factor (NF<3dB), high gain flatness and good impedance matching.

[0003] Current mainstream technical solutions include:

[0004] 1, distributed amplifier: bandwidth is expanded by multiple gain units, but a large number of inductors are needed, resulting in large chip area and high power consumption;

[0005] 2, resistance negative feedback structure: simple to implement, wide bandwidth, but introduces additional thermal noise, which worsens the noise factor;

[0006] 3, parallel peaking technology: LC resonance is used to expand high frequency bandwidth, but the gain flatness is sensitive to process fluctuations, and the design tolerance is small.

[0007] In summary, the existing ultra-wideband low noise amplifier has a difficult-to-coordinate contradiction between bandwidth, noise, impedance matching, area and power consumption, etc. performance indicators, which limits its overall performance and makes it difficult to meet the application requirements of high integration. SUMMARY

[0008] The purpose of the present application is to provide an ultra-wideband low noise amplifier based on coupling expansion technology, which solves the problem of the existing ultra-wideband low noise amplifier having a difficult-to-coordinate contradiction between bandwidth, noise, impedance matching, area and power consumption, etc. performance indicators, which limits its overall performance and makes it difficult to meet the application requirements of high integration.

[0009] To achieve the above purpose, the present application provides an ultra-wideband low noise amplifier based on coupling expansion technology, which comprises a Cascode amplification circuit, an input coupling inductor pair and an output coupling inductor pair. The Cascode amplification circuit is composed of a transistor M1 and a transistor M2 in cascade. The input end of the input coupling inductor pair serves as the input end of the radio frequency signal. The output end of the input coupling inductor pair is connected to the gate of the transistor M1. The input end of the output coupling inductor pair is connected to the drain of the transistor M2. The output end of the output coupling inductor pair serves as the output end of the radio frequency signal.

[0010] The input end of the input coupling inductor pair is connected to the input end matching capacitor C1 and then grounded, the output end of the input coupling inductor pair is provided with a noise optimization capacitor Cex, one end of the noise optimization capacitor Cex away from the input coupling inductor pair is connected to the source of the transistor M1 and grounded, the drain parasitic capacitor Cd exists in the drain node of the transistor M2, and the output end of the output coupling inductor pair is provided with a load capacitor CL.

[0011] The input coupling inductor pair and the output coupling inductor pair are both three-port coupling inductor pair structures with intermediate taps, the input coupling inductor pair is composed of a first inductor L1 and a second inductor L2, and the output coupling inductor pair is composed of a third inductor L3 and a fourth inductor L4.

[0012] The input end of the radio frequency signal and the output end of the radio frequency signal are both provided with a direct current blocking capacitor CB.

[0013] The gate of the transistor M2 is provided with a biasing resistor R1, and one end of the biasing resistor R1 away from the transistor is connected to a biasing voltage end Vcas.

[0014] One end of the first inductor away from the second inductor is connected to a voltage end V6.

[0015] The first inductor L1, the second inductor L2, the third inductor L3 and the fourth inductor L4 are all on-chip planar spiral inductors.

[0016] The ultra-wideband low-noise amplifier based on the coupling expansion technology comprises a Cascode amplification circuit, an input coupling inductor pair and an output coupling inductor pair, the input coupling inductor pair and the output coupling inductor pair are matched by adopting a three-port coupling inductor pair, the mutual inductance effect of the three-port coupling inductor pair generates a negative electromotive force to rapidly charge the drain parasitic capacitor Cd and the load capacitor CL in the circuit, the charging time is significantly reduced, the working bandwidth of the amplifier is greatly expanded without sacrificing the noise performance, meanwhile, the inherent wideband characteristics of the coupling structure simplify the requirement of the multi-stage impedance matching network, the noise matching is optimized by using the noise optimization capacitor Cex, the chip area and the number of peripheral elements are effectively reduced by multiplexing the inductance function, and finally the contradictions among bandwidth, noise, matching and area power consumption are solved under the condition of high integration. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0018] Figure 1 is a model schematic diagram of a three-port coupled inductor pair structure provided by the present application.

[0019] Figure 2 is an equivalent model schematic diagram of a three-port coupled inductor pair structure after decoupling provided by the present application.

[0020] Figure 3 is a circuit structure schematic diagram of an ultra-wideband low-noise amplifier based on coupling expansion technology provided by the present application.

[0021] Figure 4 is an equivalent circuit diagram of an output end of an ultra-wideband low-noise amplifier based on coupling expansion technology after decoupling provided by the present application.

[0022] Figure 5 is an S parameter curve schematic diagram of an ultra-wideband low-noise amplifier based on coupling expansion technology provided by the present application.

[0023] Figure 6 is a noise figure curve schematic diagram of an ultra-wideband low-noise amplifier based on coupling expansion technology provided by the present application. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0025] Please refer to Figures 1 to 6 The present application provides an ultra-wideband low-noise amplifier based on coupling expansion technology, which comprises a Cascode amplification circuit, an input coupled inductor pair and an output coupled inductor pair. The Cascode amplification circuit is composed of a transistor M1 and a transistor M2 in cascade. The input end of the input coupled inductor pair is the input end of the radio frequency signal. The output end of the input coupled inductor pair is connected to the gate of the transistor M1. The input end of the output coupled inductor pair is connected to the drain of the transistor M2. The output end of the output coupled inductor pair is the output end of the radio frequency signal.

[0026] The input terminal of the input coupling inductor pair is connected to the input matching capacitor C1 and then grounded. The output terminal of the input coupling inductor pair is provided with a noise optimization capacitor Cex. The end of the noise optimization capacitor Cex away from the input coupling inductor pair is connected to the source of the transistor M1 and grounded. The drain node of the transistor M2 has a drain parasitic capacitance Cd. The output terminal of the output coupling inductor pair is provided with a load capacitor CL.

[0027] Both the input coupling inductor pair and the output coupling inductor pair are three-port coupling inductor pair structures with a center tap. The input coupling inductor pair is composed of a first inductor L1 and a second inductor L2 coupled together, and the output coupling inductor pair is composed of a third inductor L3 and a fourth inductor L4 coupled together.

[0028] In this embodiment, by employing the input coupling inductor pair and the output coupling inductor pair, which are composed of three-port coupled inductor pairs, the negative electromotive force generated by their mutual inductance effect is used to quickly charge the drain parasitic capacitance Cd and the load capacitance CL in the circuit, significantly reducing the charging time. This greatly expands the operating bandwidth of the amplifier without sacrificing noise performance. At the same time, the inherent broadband characteristics of this coupling structure simplify the requirements of multi-stage impedance matching networks. While achieving ultra-wideband input-output matching (S11 < -10dB), the noise matching is optimized by using the noise optimization capacitor Cex. Furthermore, the chip area and the number of external components are effectively reduced by reusing the inductor function. Ultimately, the contradiction between bandwidth, noise, matching, area, and power consumption is resolved collaboratively under high integration conditions.

[0029] In this technical solution, both the input coupled inductor pair and the output coupled inductor pair are three-port coupled inductor pair structures with center taps. By utilizing the unique characteristics of coupled inductors and performing decoupling equivalent processing on the coupled inductors, the circuit containing mutual inductance is transformed into an equivalent circuit containing only self-inductance (no mutual inductance), allowing Kirchhoff's laws and conventional circuit analysis methods to be directly applied.

[0030] Specifically, such as Figure 1 As shown, the actual structural diagram of the three-port coupled inductor pair structure used in this technical solution is as follows: the two inductors are wound in the same direction and have a center tap (C terminal), forming a three-port device (A terminal, B terminal, C terminal). Due to the existence of mutual inductance M, directly analyzing the impact of this device on the circuit is quite complex.

[0031] To simplify the analysis, the coupled inductors need to be decoupled and equivalently processed. The core of this is based on the law of electromagnetic induction, which transforms a circuit containing mutual inductance into an equivalent circuit containing only self-inductance (no mutual inductance), thus allowing the direct application of conventional circuit analysis methods such as Kirchhoff's laws.

[0032] SeeFigure 2 Figure 1 shows a schematic diagram of a three-port coupled inductor model. Figure 1 Figure 2 shows a decoupled equivalent circuit schematic diagram of the three-port coupled inductor model shown in Figure 1.The derivation process of the equivalent model is as follows:

[0033] For the three-port network shown in Figure 1, the KVL analysis is performed on the ac end and the bc end, respectively: Figure 1

[0034]

[0035] i C (t)=i A (t)+i B (t) (3)

[0036] Substituting formula (3) into formula (1) and formula (2), respectively, we get:

[0037]

[0038] The equivalent decoupled circuit structure from formula (3) and formula (4) is shown in Figure 2. Figure 2

[0039] As can be seen from the decoupled equivalent circuit, at the total branch C end, a negative electromotive force is generated due to the existence of the -M inductor:

[0040]

[0041] The present technical solution utilizes the negative electromotive force generated by the coupled inductor to quickly charge the load capacitor and the drain parasitic capacitor, reduces the capacitor response time, and thus achieves the purpose of expanding the bandwidth.

[0042] Further, the working principle of the present technical solution, especially its bandwidth expansion capability, can be clearly presented by analyzing the output network.

[0043] Referring to Figure 3, which is a decoupled equivalent circuit diagram of the output network part (i.e., L3, L4, Cd, CL) of the present application. Figure 4 The diagram is obtained by performing decoupled equivalent processing on the coupled inductor in Figure 1 and equivalently processing the output coupled inductor pair (L3 / L4) in Figure 1. Figure 3

[0044] In the equivalent circuit:

[0045] The third inductor L3 is equivalently connected in series with an inductor with an inductance value (L3+M) and a negative inductor with a value of -M.

[0046] The fourth inductor L4 is equivalently connected as an inductor with an inductance value (L4+M).

[0047] ​​The cascode amplification circuit is equivalent to a controlled current source (gm·Vgs).

[0048] The working principle of the bandwidth expansion is described from the time domain as follows:

[0049] After power-on, the initial current starts to charge the capacitance in the circuit. In the equivalent circuit Figure 4 , the current flows through the (L4+M) branch, which accelerates the charging of the drain parasitic capacitance Cd. At the same time, it is crucial that the current flowing through the -M negative inductance branch generates a left negative and right positive negative electromotive force Vm. This Vm electromotive force effectively promotes the charging speed of the load capacitance CL.

[0050] Therefore, the charging process of the drain parasitic capacitance Cd and the load capacitance CL is completed simultaneously and quickly, and the total charging time is greatly shortened. In the frequency domain, this effect is manifested as a great expansion of the circuit -3dB bandwidth.

[0051] In contrast, in the traditional circuit without the coupling inductance negative electromotive force effect, the initial current cannot quickly charge CL, and the charging process of Cd must be completed before the charging of CL can begin. This series charging process takes a long time, which severely limits the passband of the radio frequency signal.

[0052] Further, a DC blocking capacitance CB is arranged at the input end of the radio frequency signal and the output end of the radio frequency signal.

[0053] In the embodiment, the DC blocking capacitance CB is arranged to isolate the DC signal.

[0054] Further, a bias resistor R1 is arranged at the gate of the transistor M2, one end of the bias resistor R1 away from the transistor is connected to a bias voltage end Vcas, and one end of the first inductor away from the second inductor is connected to a voltage end V6.

[0055] Further, the first inductor L1, the second inductor L2, the third inductor L3, and the fourth inductor L4 are on-chip planar spiral inductors.

[0056] In summary, referring to Figure 5 , the S-parameter simulation results of the ultra-wideband low-noise amplifier based on the coupling expansion technology are shown. It can be seen that the -3dB bandwidth of the amplifier covers an ultra-wide range of 4.5GHz to 24GHz, and the gain flatness is excellent.

[0057] Referring to Figure 6The simulation results of the noise figure (NF) of the ultra-wideband low-noise amplifier based on the coupling expansion technology are shown.

[0058] Therefore, the technical scheme effectively solves the core contradiction in the design of the ultra-wideband low-noise amplifier by introducing the innovative coupling inductance structure and utilizing the negative electromotive force effect generated thereby, and has extremely high practical value and industrial prospect.

[0059] The above only discloses one preferred embodiment of the present application, and of course cannot limit the scope of the rights of the present application, and those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments are implemented, and equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. An ultrawideband low-noise amplifier based on coupling extension technology, characterized in that, It includes a Cascode amplifier circuit, an input coupling inductor pair, and an output coupling inductor pair. The Cascode amplifier circuit is composed of cascaded transistors M1 and M2. The input terminal of the input coupling inductor pair serves as the input terminal of the radio frequency signal. The output terminal of the input coupling inductor pair is connected to the gate of transistor M1. The input terminal of the output coupling inductor pair is connected to the drain of transistor M2. The output terminal of the output coupling inductor pair serves as the output terminal of the radio frequency signal. The input terminal of the input coupling inductor pair is connected to the input matching capacitor C1 and then grounded. The output terminal of the input coupling inductor pair is provided with a noise optimization capacitor Cex. The end of the noise optimization capacitor Cex away from the input coupling inductor pair is connected to the source of the transistor M1 and grounded. The drain node of the transistor M2 has a drain parasitic capacitance Cd. The output terminal of the output coupling inductor pair is provided with a load capacitor CL. Both the input coupling inductor pair and the output coupling inductor pair are three-port coupling inductor pair structures with a center tap. The input coupling inductor pair is composed of a first inductor L1 and a second inductor L2 coupled together, and the output coupling inductor pair is composed of a third inductor L3 and a fourth inductor L4 coupled together.

2. The ultra-wideband low-noise amplifier based on coupling extension technology as described in claim 1, characterized in that, A DC blocking capacitor CB is provided at both the input and output terminals of the radio frequency signal.

3. The ultra-wideband low-noise amplifier based on coupling extension technology as described in claim 2, characterized in that, A bias resistor R1 is provided at the gate of the transistor M2, and the end of the bias resistor R1 away from the transistor is connected to the bias voltage terminal Vcas.

4. The ultra-wideband low-noise amplifier based on coupling extension technology as described in claim 3, characterized in that, The end of the first inductor furthest from the second inductor is connected to the voltage terminal V6.

5. The ultra-wideband low-noise amplifier based on coupling extension technology as described in claim 4, characterized in that, The first inductor L1, the second inductor L2, the third inductor L3 and the fourth inductor L4 are all on-chip planar spiral inductors.

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