Low noise amplifier and low noise amplifier system

Abstract

The invention provides a low-noise amplifier and a low-noise amplifier system. The low-noise amplifier comprises a signal input module, a switching tube module and a load module, the switch tube module is connected with the signal input module and the load module. The load module comprises a load inductor, a load capacitor and an adjustable load resistor which are connected in parallel; wherein the adjustable load resistor is used for adjusting the gain and flatness of the low-noise amplifier; the signal input module is used for providing an input signal for the switching tube module; and the switching tube module is used for outputting an output signal of the low-noise amplifier based on the input signal and the load module. According to the low-noise amplifier, variable gain and variable flatness can be achieved through the adjustable load resistor, the low-noise amplifier can adapt to different modes of different gains and different flatness only by adjusting the resistance value of the adjustable load resistor, and therefore the application scene of the low-noise amplifier can be expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a low noise amplifier and a low noise amplifier system. Background Art

[0002] In the structure of a classic inductive negative feedback common-source common-gate low-noise amplifier with an LCR load, the gain depends on the inductive feedback and the load resistance. In general designs, the inductive feedback affects the input impedance at the same time, so its value is subject to certain constraints. Therefore, in order to achieve the desired gain, it is generally achieved by setting a larger load resistance. However, while this method achieves the desired gain through a fixed load resistance, the flatness cannot be adjusted, which limits the application scenarios of the low-noise amplifier. Summary of the invention

[0003] The object of the present invention is to provide a low noise amplifier and a low noise amplifier system to adapt to different modes with different gains and different flatnesses, so as to expand the application scenarios of the low noise amplifier.

[0004] The present invention provides a low-noise amplifier, which includes: a signal input module, a switch tube module and a load module; the switch tube module is connected to the signal input module and the load module respectively; the load module includes a load inductor, a load capacitor and an adjustable load resistor connected in parallel; wherein the adjustable load resistor is used to adjust the gain and flatness of the low-noise amplifier; the signal input module is used to provide an input signal for the switch tube module; the switch tube module is used to output an output signal of the low-noise amplifier based on the input signal and the load module.

[0005] Furthermore, as the resistance of the adjustable load resistor increases, the gain of the low noise amplifier increases.

[0006] Furthermore, the switch tube module includes: a first switch tube, having a first end, a second end and a third end, the first end of the first switch tube being connected to the signal input end of the switch tube module; a second switch tube, having a first end, a second end and a third end, the first end of the second switch tube being connected to a power supply, the second end of the second switch tube being connected to the output end of the low-noise amplifier, and the third end of the second switch tube being connected to the second end of the first switch tube; a negative feedback inductor, having a first end and a second end, the first end of the negative feedback inductor being connected to the third end of the first switch tube, and the second end of the negative feedback inductor being grounded.

[0007] Furthermore, the gain of the low noise amplifier is determined by the following formula:

[0008] Gain = Rd / (Ls×w0);

[0009] Wherein, Gain represents the gain of the low noise amplifier; Rd represents the resistance value of the adjustable load resistor; Ls represents the inductance value of the negative feedback inductor; and w0 represents the pre-acquired working angular frequency.

[0010] Furthermore, the flatness of a low noise amplifier is positively correlated with its bandwidth; the bandwidth is determined by the following formula:

[0011] BW=w0 / Qall;

[0012] Qall = Rall / (w0 × Ld);

[0013] Among them, Rall is the total load resistance obtained by connecting Rout, Rp and Rd in parallel; Rout represents the output impedance of the low noise amplifier; Rp represents the equivalent parallel resistance of the load inductor; Rd represents the resistance value of the adjustable load resistor; BW represents the bandwidth of the low noise amplifier; w0 represents the pre-acquired working angular frequency; Ld represents the inductance value of the load inductor.

[0014] Furthermore, as the resistance of the adjustable load resistor decreases, the flatness of the low noise amplifier increases.

[0015] Furthermore, every time the resistance of the adjustable load resistor doubles, the gain of the low noise amplifier increases by 6 dB.

[0016] Further, the signal input module includes: a gate-terminal capacitor having a first end and a second end, the first end of the gate-terminal capacitor being connected to an external input signal; a gate-terminal inductor having a first end and a second end, the first end of the gate-terminal inductor being connected to the second end of the gate-terminal capacitor, and the second end of the gate-terminal inductor being connected to an output end of the signal input module; a bias current source having a first end and a second end, the first end of the bias current source being connected to a power supply; a mirror switch tube having a first end, a second end and a third end, the second end of the mirror switch tube being connected to the second end of the bias current source, and the third end of the mirror switch tube being grounded; a mirror resistor having a first end and a second end, the first end of the mirror resistor being connected to the second end of the gate-terminal inductor; a mirror capacitor having a first end and a second end, the first end of the mirror capacitor being respectively connected to the first end of the mirror switch tube and the second end of the mirror resistor, and the second end of the mirror capacitor being grounded.

[0017] Furthermore, the first end of the load inductor, the first end of the load capacitor and the first end of the adjustable load resistor are all connected to the power supply; the second end of the load inductor, the second end of the load capacitor and the second end of the adjustable load resistor are all connected to the output end of the low noise amplifier.

[0018] The present invention provides a low noise amplifier system, comprising any one of the above-mentioned low noise amplifiers.

[0019] The low noise amplifier and low noise amplifier system provided by the present invention include: a signal input module, a switch tube module and a load module; the switch tube module is connected to the signal input module and the load module respectively; the load module includes a load inductor, a load capacitor and an adjustable load resistor connected in parallel; wherein the adjustable load resistor is used to adjust the gain and flatness of the low noise amplifier; the signal input module is used to provide an input signal to the switch tube module; the switch tube module is used to output the output signal of the low noise amplifier based on the input signal and the load module. The low noise amplifier can achieve variable gain and variable flatness through the adjustable load resistor R1, and different modes with different gains and different flatness can be adapted by simply adjusting the resistance value of the adjustable load resistor R1, thereby expanding the application scenarios of the low noise amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a low noise amplifier provided by an embodiment of the present invention;

[0022] Figure 2 A circuit diagram of a low noise amplifier provided by an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of a low noise amplifier system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0025] In the related art, when the link needs to adapt to large gain requirements and high flatness requirements under different circumstances, it is difficult to do so. At the same time, fixed load resistance to achieve high gain or broadband performance is easily affected by temperature and process fluctuations, resulting in unsatisfactory performance indicators and insufficient robustness of the structure. Based on this, an embodiment of the present invention provides a low noise amplifier and a low noise amplifier system, which can be applied to applications where the link needs to adapt to different gain and different flatness requirements.

[0026] To facilitate understanding of this embodiment, a low noise amplifier disclosed in an embodiment of the present invention is first introduced. Figure 1 As shown, the low noise amplifier includes: a signal input module 10, a switch tube module 11 and a load module 12; the switch tube module 11 is connected to the signal input module 10 and the load module 12 respectively; the load module 12 includes a load inductor L2, a load capacitor Cd and an adjustable load resistor R1 connected in parallel with each other; wherein the adjustable load resistor R1 is used to adjust the gain and flatness of the low noise amplifier; the signal input module 10 is used to provide an input signal to the switch tube module 11; the switch tube module 11 is used to output the output signal of the low noise amplifier based on the input signal and the load module 12.

[0027] The inductance value of the above-mentioned load inductor L2 and the capacitance value of the load capacitor Cd can be set according to actual needs; the above-mentioned adjustable load resistor R1 can be designed as a multi-level adjustable resistor, and a suitable resistance value can be selected according to actual needs; the above-mentioned gain represents the power amplification factor of the low-noise amplifier; the above-mentioned flatness can be understood as the value of the "dramatic increase" and "rapid decrease" of the gain within a given bandwidth range, measured in decibels (dB); in actual implementation, the gain and flatness of the low-noise amplifier can be adjusted by adjusting the resistance value of the adjustable load resistor R1. For example, by increasing the resistance value of the adjustable load resistor R1, the gain of the low-noise amplifier can be increased; by reducing the resistance value of the adjustable load resistor R1, the flatness of the low-noise amplifier can be improved, etc.; the signal input module can receive external input, and provide an input signal to the switch tube module by filtering the external input; the switch tube module usually includes a power switch tube, such as a MOS tube, etc., and the switch tube module can output the output signal corresponding to the low-noise amplifier through the load module according to the received input signal.

[0028] The above-mentioned low-noise amplifier can achieve variable gain and variable flatness through the adjustable load resistor R1. Different modes with different gains and different flatness can be adapted by simply adjusting the resistance value of the adjustable load resistor R1, thereby expanding the application scenarios of the low-noise amplifier.

[0029] Furthermore, as the resistance of the adjustable load resistor R1 increases, the gain of the low noise amplifier increases. In this embodiment, when the gain of the low noise amplifier needs to be increased, it can be achieved by increasing the resistance of the adjustable load resistor R1; similarly, when the gain of the low noise amplifier needs to be reduced, it can be achieved by reducing the resistance of the adjustable load resistor R1.

[0030] Further, such as Figure 2A circuit diagram of a low noise amplifier is shown, wherein the switch tube module comprises: a first switch tube M1, having a first end, a second end and a third end, wherein the first end of the first switch tube M1 is connected to the signal input end of the switch tube module; a second switch tube M2, having a first end, a second end and a third end, wherein the first end of the second switch tube M2 is connected to the power supply VDD, the second end of the second switch tube M2 is connected to the output end of the low noise amplifier, and the third end of the second switch tube M2 is connected to the second end of the first switch tube M1; a negative feedback inductor L1, having a first end and a second end, wherein the first end of the negative feedback inductor L1 is connected to the third end of the first switch tube M1, and the second end of the negative feedback inductor L1 is grounded.

[0031] In this embodiment, the first switch tube M1 and the second switch tube M2 can be implemented by MOS tubes, then the first end of the first switch tube M1 and the first end of the second switch tube M2 both refer to the gate of the MOS tube, the second end of the first switch tube M1 and the second end of the second switch tube M2 both refer to the drain of the MOS tube, and the third end of the first switch tube M1 and the third end of the second switch tube M2 both refer to the source of the MOS tube; the inductance value of the negative feedback inductor L1 can be set according to actual needs; in actual implementation, the input signal provided by the signal input module can be received through the first end of the first switch tube M1; the second switch tube M2 can provide a higher input impedance and a certain reverse isolation, and the negative feedback inductor L1 can provide input impedance, for example, it can provide an input impedance of 50ohm.

[0032] Furthermore, the gain of the low noise amplifier is determined by the following formula:

[0033] Gain = Rd / (Ls×w0);

[0034] Wherein, Gain represents the gain of the low noise amplifier; Rd represents the resistance value of the adjustable load resistor R1; Ls represents the inductance value of the negative feedback inductor L1; and w0 represents the pre-acquired working angular frequency.

[0035] The above-mentioned working angular frequency is the frequency point where the gain drops by 3dB in the amplitude-frequency characteristic curve, and is an important parameter that marks the frequency response of the low-noise amplifier. It can be seen from the above formula that the gain of the low-noise amplifier has nothing to do with the gm (transconductance) of the first switch tube M1, but is only related to the adjustable load resistance R1 and the negative feedback inductor L1; the negative feedback inductor L1 generally cannot be made into a variable inductor, mainly considering that it will bring two problems: one is that the area is too large, and the other is that it will affect the input impedance; therefore, the gain can only be changed by changing Rd, thereby increasing the robustness of the circuit. For example, at high temperatures, the gain of the low-noise amplifier decreases, and at low temperatures, the gain of the low-noise amplifier increases. In the prior art, the means to reduce the fluctuation of the high and low temperature gain is generally: through the IPTAT current (current that is positively correlated with temperature) of the positive feedback coefficient, in A large current is provided at high temperature, and a small current is provided at low temperature to change the gm of the first switch tube M1 (generally, the amplifier gain can be simplified as: Gain = gm*Rd), thereby changing the gain of the low noise amplifier. However, in this embodiment, the gain of the low noise amplifier with an inductive negative feedback common source and common gate structure is independent of the gm of the first switch tube M1. Therefore, the IPTAT current at high and low temperatures does not work. At this time, the resistance value of the adjustable load resistor R1 can be increased at high temperatures and reduced at low temperatures to achieve the effect of reducing the gain fluctuation caused by high and low temperatures. In actual applications, the corresponding relationship between the temperature change amount and the resistance adjustment amount of the adjustable load resistor R1 can be pre-configured, and the resistance value of the adjustable load resistor R1 can be adjusted according to the corresponding relationship and the actual temperature change amount.

[0036] Furthermore, the flatness of the low noise amplifier is positively correlated with the bandwidth, that is, the larger the bandwidth, the better the flatness; the bandwidth is determined by the following formula:

[0037] BW=w0 / Qall;

[0038] Qall = Rall / (w0 × Ld);

[0039] Among them, Rall is the total load resistance obtained by connecting Rout, Rp and Rd in parallel; Rout represents the output impedance of the low noise amplifier; Rp represents the equivalent parallel resistance of the load inductor L2; Rd represents the resistance value of the adjustable load resistor R1; BW represents the bandwidth of the low noise amplifier; w0 represents the pre-acquired working angular frequency; Ld represents the inductance value of the load inductor L2.

[0040] It can be seen from the above formula that flatness depends on the inductance Ld of the load inductance L2 and the total load Q value Qall, and the total load Q value Qall is proportional to the total load resistance Rall. Generally, the load inductance L2 will be constrained by the working frequency band. Therefore, the flatness indicator is also strongly related to the resistance value Rd of the adjustable load resistor R1. Generally, the above Rout and Rp are both large. Therefore, the total load resistance Rall mainly depends on Rd. Therefore, the purpose of adjusting the flatness can be achieved by adjusting the resistance value Rd of the adjustable load resistor R1 to adjust the bandwidth of the low noise amplifier.

[0041] Furthermore, as the resistance of the adjustable load resistor R1 decreases, the flatness of the low noise amplifier increases. As can be seen from the above formula, in this embodiment, when the flatness of the low noise amplifier needs to be improved, it can be achieved by reducing the resistance of the adjustable load resistor R1. Similarly, when the flatness of the low noise amplifier needs to be reduced, it can be achieved by increasing the resistance of the adjustable load resistor R1.

[0042] Furthermore, the adjustable resistor can be made adjustable in multiple gears. Since Rout and Rp are both large, the total load resistance Rall is approximately equal to the resistance Rd of the adjustable load resistor R1. For every doubling of the resistance Rd of the adjustable load resistor R1, the gain of the low noise amplifier increases by 6dB. If the resistance Rd of the adjustable load resistor R1 is reduced by half, the flatness can be doubled.

[0043] Further, such as Figure 2 As shown, the signal input module includes:

[0044] The gate-terminal capacitor C1 has a first end and a second end. The first end of the gate-terminal capacitor C1 is connected to an external input signal. The capacitance of the gate-terminal capacitor C1 can be set according to actual needs.

[0045] The gate-terminal inductor Lg has a first end and a second end. The first end of the gate-terminal inductor Lg is connected to the second end of the gate-terminal capacitor C1, and the second end of the gate-terminal inductor Lg is connected to the output end of the signal input module. The inductance value of the gate-terminal inductor Lg can be set according to actual needs. The second end of the gate-terminal inductor Lg is connected to the first end of the first switch tube M1.

[0046] The bias current source IB has a first end and a second end, and the first end of the bias current source IB is connected to the power supply VDD; the current provided by the bias current source IB can vary with temperature, for example, the bias current source IB can provide a current that is proportional to the temperature.

[0047] The mirror switch tube Mb has a first end, a second end and a third end. The second end of the mirror switch tube Mb is connected to the second end of the bias current source IB, and the third end of the mirror switch tube Mb is grounded. In this embodiment, the mirror switch tube Mb can be a MOS tube. The first end of the mirror switch tube Mb is the gate of the MOS tube, the second end of the mirror switch tube Mb is the drain of the MOS tube, and the third end of the mirror switch tube Mb is the source of the MOS tube.

[0048] The mirror resistor Rb has a first end and a second end, and the first end of the mirror resistor Rb is connected to the second end of the gate-end inductor Lg; the resistance value of the mirror resistor Rb can be set according to actual needs.

[0049] The mirror capacitor Cb has a first end and a second end. The first end of the mirror capacitor Cb is respectively connected to the first end of the mirror switch tube Mb and the second end of the mirror resistor Rb. The second end of the mirror capacitor Cb is grounded. The resistance value of the mirror capacitor Cb can be set according to actual needs.

[0050] like Figure 2 As shown, the bias current of the first switch tube M1 is established by the mirror switch tube Mb and the bias current source IB, and the mirror resistor Rb and the mirror capacitor Cb can isolate the signal path from the bias current source IB and the mirror switch tube Mb; wherein the signal path corresponds to Figure 2 The path formed by the gate-end capacitor C1, the gate-end inductor Lg, the first switch tube M1, the second switch tube M2, the negative feedback inductor L1 and the load model, and the gate-end inductor Lg make the imaginary part of the input impedance zero.

[0051] Further, such as Figure 2 As shown, the first end of the load inductor L2, the first end of the load capacitor Cd and the first end of the adjustable load resistor R1 are all connected to the power supply VDD; the second end of the load inductor L2, the second end of the load capacitor Cd and the second end of the adjustable load resistor R1 are all connected to the output end of the low noise amplifier. Among them, the load inductor L2 and the load capacitor Cd resonate in the working frequency band, which can suppress out-of-band signals to a certain extent. The adjustable load resistor R1 is a resistor matrix, and the resistance value can be adjusted within a certain range.

[0052] For the above-mentioned low noise amplifier, when the link requires high gain, high gain can be achieved by increasing the resistance Rd of the adjustable load resistor R1; when the link flatness index requirement is high, the resistance Rd of the adjustable load resistor R1 can be reduced to increase the bandwidth and thus improve the flatness. When the temperature or process fluctuates, the influence of the temperature or process fluctuation on the gain or flatness can also be reduced by adjusting the resistance Rd of the adjustable load resistor R1.

[0053] The above-mentioned low noise amplifier realizes variable gain and variable flatness through the adjustable load resistor R1. Compared with the prior art method of realizing high gain through a fixed large resistor or realizing wide flatness through a low Q resistor, this solution can adapt to different modes of high gain or wide flatness by adjusting the resistance value Rd of the adjustable load resistor R1. At the same time, when affected by temperature or process fluctuations, the performance deviation caused by the influence can also be offset by adjusting the resistance value Rd of the adjustable load resistor R1, thereby improving robustness and having a wider range of applications.

[0054] The embodiment of the present invention also discloses a low noise amplifier system, such as Figure 3 As shown, the low noise amplifier system 30 includes any one of the above-mentioned low noise amplifiers 100 .

[0055] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0056] In addition, each functional unit in the embodiments provided in the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0057] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low noise amplifier, characterized in that: The low noise amplifier comprises: a signal input module, a switch module and a load module; the switch module is connected to the signal input module and the load module respectively; the load module comprises a load inductor, a load capacitor and an adjustable load resistor connected in parallel with each other; wherein the adjustable load resistor is used to adjust the gain and flatness of the low noise amplifier; The signal input module is used to provide an input signal to the switch tube module; The switch tube module is used to output the output signal of the low noise amplifier based on the input signal and the load module.

2. The low noise amplifier according to claim 1, characterized in that: As the resistance of the adjustable load resistor increases, the gain of the low noise amplifier increases.

3. The low noise amplifier according to claim 1, characterized in that: The switch tube module comprises: A first switch tube, having a first end, a second end and a third end, wherein the first end of the first switch tube is connected to the signal input end of the switch tube module; a second switch tube, having a first end, a second end and a third end, wherein the first end of the second switch tube is connected to a power supply, the second end of the second switch tube is connected to the output end of the low noise amplifier, and the third end of the second switch tube is connected to the second end of the first switch tube; The negative feedback inductor has a first end and a second end, the first end of the negative feedback inductor is connected to the third end of the first switch tube, and the second end of the negative feedback inductor is grounded.

4. The low noise amplifier according to claim 3, characterized in that: The gain of the low noise amplifier is determined by the following formula: Gain = Rd / (Ls×w0); Wherein, Gain represents the gain of the low noise amplifier; Rd represents the resistance of the adjustable load resistor; Ls represents the inductance of the negative feedback inductor; and w0 represents the pre-acquired working angular frequency.

5. The low noise amplifier according to claim 1, characterized in that: The flatness of the low noise amplifier is positively correlated with the bandwidth; the bandwidth is determined by the following formula: BW = w0 / Qall; Qall = Rall / (w0 × Ld); Among them, Rall is the total load resistance obtained by connecting Rout, Rp and Rd in parallel; Rout represents the output impedance of the low noise amplifier; Rp represents the equivalent parallel resistance of the load inductor; Rd represents the resistance value of the adjustable load resistor; BW represents the bandwidth of the low noise amplifier; w0 represents the pre-acquired working angular frequency; Ld represents the inductance value of the load inductor.

6. The low noise amplifier according to claim 1, characterized in that: As the resistance of the adjustable load resistor decreases, the flatness of the low noise amplifier increases.

7. The low noise amplifier according to claim 1, characterized in that: Every time the resistance of the adjustable load resistor doubles, the gain of the low noise amplifier increases by 6dB.

8. The low noise amplifier according to claim 1, characterized in that: The signal input module comprises: A gate terminal capacitor having a first end and a second end, wherein the first end of the gate terminal capacitor is connected to an external input signal; A gate-end inductor having a first end and a second end, wherein the first end of the gate-end inductor is connected to the second end of the gate-end capacitor, and the second end of the gate-end inductor is connected to the output end of the signal input module; A bias current source having a first end and a second end, wherein the first end of the bias current source is connected to a power supply; A mirror switch tube, having a first end, a second end and a third end, wherein the second end of the mirror switch tube is connected to the second end of the bias current source, and the third end of the mirror switch tube is grounded; A mirror resistor having a first end and a second end, wherein the first end of the mirror resistor is connected to the second end of the gate-end inductor; The mirror capacitor has a first end and a second end, the first end of the mirror capacitor is respectively connected to the first end of the mirror switch tube and the second end of the mirror resistor, and the second end of the mirror capacitor is grounded.

9. The low noise amplifier according to claim 1, characterized in that: The first end of the load inductor, the first end of the load capacitor and the first end of the adjustable load resistor are all connected to a power supply; The second end of the load inductor, the second end of the load capacitor and the second end of the adjustable load resistor are all connected to the output end of the low noise amplifier.

10. A low noise amplifier system, characterized in that: A low noise amplifier comprising the low noise amplifier according to any one of claims 1 to 9.

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