A Ka-band broadband low noise amplifier

Abstract

The application discloses a Ka-band broadband low-noise amplifier and belongs to the technical field of electronic communication and integrated circuits. 11 The amplifier comprises an input matching network, a main amplification stage, an inter-stage matching network and a buffer stage which are sequentially connected. 11 The S 11 The -10dB bandwidth reaches 7.5GHz, the noise coefficient ranges from 5.9dB to 6.6dB and is only 0.2dB higher than the lowest noise coefficient; the active transistor of the main amplification stage and the buffer stage is grounded through a large resistance in the substrate by means of a body isolation technology so as to improve the gain of the amplifier, and the highest gain reaches 11.2dB; the drain of the active transistor M2 of the main amplification stage is connected to a power supply voltage VDD through a parallel peak load for improving the gain at low frequencies, and the inter-stage matching network is introduced to improve the -3dB bandwidth and realize a wideband spectrum response, and finally the -3dB bandwidth reaches 7.5GHz.

Description

Technical Field

[0001] This invention relates to a Ka-band broadband low-noise amplifier, belonging to the fields of electronic communication and integrated circuit technology. Background Technology

[0002] Low-noise amplifiers (LNAs) are located at the front end of wireless receiver systems. Their function is to amplify signals with the lowest possible noise while requiring sufficient gain to suppress the impact of noise generated by subsequent circuits. They are crucial modules in various microwave and millimeter-wave communication fields. With the development of communication technology, Sub-5GHz spectrum resources are gradually becoming insufficient to meet the demands of broadband and high-speed communication, leading to the rapid development of millimeter waves above the Ka band in fields such as 5G and radar communication.

[0003] In order for the receiver to operate over the widest possible operating range, the low-noise amplifier needs to have sufficiently wide bandwidth characteristics. Therefore, in Ka-band communication, a broadband low-noise amplifier is required to achieve low-noise amplification of broadband signals. However, achieving noise matching, conjugate matching, and high gain over a wide bandwidth is quite difficult.

[0004] Currently, broadband low-noise amplifiers typically employ common-gate-common-source (CG-CS) amplifiers. Conjugate matching is achieved by adjusting the transconductance, and higher gain is achieved by adjusting the load. However, because the optimal noise source impedance curve required by the amplifier and the conjugate curve of the input impedance change in opposite directions, and they are far apart within the operating frequency band, a good trade-off between noise matching and conjugate matching cannot be achieved, resulting in a relatively high overall noise figure. Using a third-order Chebyshev filter as the input matching network in a common-source amplifier can achieve a wide bandwidth, but its gain drops rapidly at high frequencies. Using an LC trapezoidal filter as the input matching network can achieve a wide gain bandwidth, but its S... 11 The bandwidth is low (<-10dB) and the gain decreases at high frequencies. Summary of the Invention

[0005] To address the trade-offs between input network conjugate matching and noise matching, gain attenuation at high frequencies, and S in current broadband low-noise amplifiers... 11 To address the issue of low bandwidth (<-10dB), this invention provides a Ka-band broadband low-noise amplifier, comprising: an input matching network, a main amplification stage, an inter-stage matching network, and a buffer stage connected in sequence.

[0006] The main amplification stage and the buffer stage are two-stage amplification circuits, each using an active transistor amplifier; the input matching network uses an Arm and Branch structure to match the input S. 11 Impedance curve compression and curling to S 11Within the -10dB circle, the input impedance is matched to 50Ω, and both the conjugate matching and noise matching at the input are matched to 50Ω within the Ka band to improve input bandwidth and reduce noise figure; the interstage matching network uses matching inductor L m To improve the high-frequency gain of the Ka-band broadband low-noise amplifier.

[0007] Optionally, the input matching network includes inductor L1, capacitor C1, inductor L2, and capacitor C2; inductor L1 connected in series with capacitor C1 forms an Arm structure, and inductor L2 connected in parallel with capacitor C2 forms a Branch structure. The Arm structure and the Branch structure are then connected in parallel to the main amplification stage; the self-resonant frequencies of both the Arm structure and the Branch structure are adjusted to the center frequency of the bandwidth, and the value of inductor L1 in the Arm structure is greater than the value of inductor L2 in the Branch structure.

[0008] At low frequencies, the Arm structure acts like a capacitor, causing S... 11 The impedance curve shifts counterclockwise along the impedance circle at its low-frequency end; the Branch structure acts as an inductor, causing S... 11 The impedance curve rotates counterclockwise along the admittance circle at its low-frequency end.

[0009] At high frequencies, the Arm structure acts as an inductor, making S 11 The high-frequency end of the curve moves clockwise along the impedance circle; the Branch structure acts like a capacitor, causing S... 11 The high-frequency end of the curve rotates clockwise along the admittance circle;

[0010] S 11 With the help of Arm or Branch structures, the curve is compressed and rotated towards the center point of the Smith chart, and S... 11 The curve should fall within the -10dB circle as much as possible.

[0011] Optionally, the main amplification stage includes a gate inductor L. g Active transistor M1, active transistor M2, source inductor L s Load resistance R L and load inductance L L ;

[0012] Active transistors M1 and M2 form a cascode structure; the gate of active transistor M1 is connected to the bias voltage through the inductor L2 of the input matching network, and its source is connected to the source inductor L... s Grounded, and a gate-source capacitance C is connected between the gate and source of the active transistor M1. gs ; through the gate inductor L g Source inductor L s and M1 gate-source capacitance Cgs Achieve conjugate matching of 50Ω at a single frequency point of the center frequency.

[0013] The drain of the active transistor M1 is connected to the source of the active transistor M2; the gate of the active transistor M2 is biased, its source is connected to the drain of the active transistor M1, and its drain is connected to the power supply voltage VDD through a parallel peak load; a drain-source capacitor C is connected between the drain and source of the active transistor M2. ds The parallel peak load includes a load resistor R. L and load inductance L L Through the load resistor R L and load inductance L L A zero is generated to increase the gain at low frequencies.

[0014] Optionally, the buffer stage includes two active transistors M3 and M4; the gate of the active transistor M3 is connected to a resistor R. b A bias voltage is applied, with its drain connected to the power supply voltage VDD and its source connected to the active transistor M4. A gate-source capacitance C is connected between the gate and source of the active transistor M3. gs The active transistor M4 serves as a current source load, with its gate connected to a bias voltage, its source connected to ground, and its drain connected to the source of the active transistor M3; the resistor R b ≥10kΩ;

[0015] In the buffer stage, its output is at the drain of the active transistor M3, serving as the output of the Ka-band broadband low-noise amplifier.

[0016] Optionally, the inter-stage matching network includes an inductor L. m It achieves this by controlling the drain-source capacitance C of the active transistor M2 in the main amplification stage. ds and the gate-source capacitance C of the active transistor M3 in the buffer stage gs Resonance improves the gain and bandwidth of the Ka-band broadband low-noise amplifier at high frequencies.

[0017] Optionally, the active transistors M1 and M2 in the main amplification stage and the active transistors M3 and M4 in the buffer stage are all N-type field-effect transistors in 180nm complementary metal-oxide-semiconductor field-effect transistors, and bulk isolation technology is introduced, with a resistor R connected between their substrate and ground. bulk To increase amplifier gain, the resistor R bulk ≥10kΩ.

[0018] Optionally, the N-type field-effect transistors are all biased at the lowest noise figure current density, 0.15 mA / μm, while their gain is greater than 8 dB.

[0019] Optionally, the Ka-band broadband low-noise amplifier has a -3dB bandwidth of 7.5 GHz, S 11 The bandwidth of <-10dB is 6.7GHz.

[0020] Optionally, the noise figure NF of the Ka-band broadband low-noise amplifier ranges from 5.9 to 6.6 dB within the -3 dB bandwidth.

[0021] This application also provides a wireless receiver, which uses the above-mentioned Ka-band broadband low-noise amplifier to amplify the received signal.

[0022] The beneficial effects of this invention are:

[0023] The input matching network ensures that both conjugate matching and noise matching at the input are matched to 50Ω within the Ka-band, reducing the deviation in conjugate matching and noise matching, thus lowering the noise of the low-noise amplifier and bringing it close to the minimum noise level. This improves the input bandwidth of the low-noise amplifier. Furthermore, the large resistance between the main amplification stage, the inter-stage matching network, and the active transistor substrate and ground enhances the gain and gain bandwidth of the low-noise amplifier. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 The circuit diagram of a Ka-band broadband low-noise amplifier provided by the present invention.

[0026] Figure 2 The input matching network of the Ka-band broadband low-noise amplifier provided by this invention is for S 11 The effect of impedance curves is shown in the diagram.

[0027] Figure 3 The present invention provides an S-band broadband low-noise amplifier for Ka-band. 11 Impedance curves, Smith charts, input impedance, and input reflection coefficient S 11 A graph showing the relationship between frequency and frequency.

[0028] Figure 4 The circuit diagram provided by this invention illustrates the interstage matching of a Ka-band broadband low-noise amplifier.

[0029] Figure 5The graph shows the relationship between the S-parameters and frequency of a Ka-band broadband low-noise amplifier provided by this invention.

[0030] Figure 6 The present invention provides a noise figure NF and a minimum noise figure NF of a Ka-band broadband low-noise amplifier. min A graph showing the relationship between frequency and frequency. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0032] Example 1:

[0033] This embodiment provides a Ka-band broadband low-noise amplifier; see [link / reference]. Figure 1 This broadband low-noise amplifier includes, in sequence, an input matching network, a main amplification stage, an interstage matching network, and a buffer stage. The main amplification stage and the buffer stage are two-stage amplifier circuits, both employing active transistors, with the gates of the active transistors connected to corresponding bias voltages. The input matching network uses an Arm and Branch structure to match the input S... 11 Impedance curve compression and curling to S 11 Within the -10dB circle, the input impedance is matched to 50Ω, and both the conjugate matching and noise matching at the input are matched to 50Ω within the Ka band to improve input bandwidth and reduce noise figure; the interstage matching network uses matching inductor L m To improve the high-frequency gain of the Ka-band broadband low-noise amplifier.

[0034] The active transistors used in the main amplification stage and buffer stage are 180nm N-type field-effect transistors (NMOS) in complementary metal-oxide-semiconductor field-effect transistors (CMOS). The bias voltages of the gate and drain are provided externally, usually through an inductor or a large resistor. The inductor can also be used for matching applications.

[0035] In some preferred embodiments, the N-type field-effect transistors (NMOS) are all biased at a current density with the lowest noise figure, which is 0.15 mA / μm, while having a large gain.

[0036] In some preferred embodiments, bulk isolation technology is introduced, and the substrate of the N-type field-effect transistor can be grounded by connecting a large resistor with a resistance of at least 10kΩ in series, thereby improving the gain of the amplifier.

[0037] The input matching network adopts an LC series-parallel structure based on high-order filters, which can match the input S 11The impedance curve is compressed and curled to a very small area, while the input impedance is matched to 50Ω. The conjugate matching and noise matching at the input are both matched to 50Ω in the Ka band, thereby increasing the input bandwidth and reducing the noise figure.

[0038] Specifically, in the input matching network, an inductor L1 connected in series with a capacitor C1 is used as the Arm structure, and an inductor L2 connected in parallel with a capacitor C2 is used as the Branch structure. The self-resonant frequency (SRF) of both the Arm structure and the Branch structure is adjusted to the center frequency of the bandwidth.

[0039] At low frequencies, the Arm structure acts like a capacitor, causing S... 11 The impedance curve shifts counterclockwise along the impedance circle at the low-frequency end; at high frequencies, the Arm structure acts as an inductor, causing S... 11 The high-frequency end of the curve moves clockwise along the impedance circle.

[0040] Impedance and self-resonant frequency (SRF) of Arm structure:

[0041]

[0042] Where Z is the impedance, j is the imaginary part, ω is the angular frequency, L1 is the inductance, and C1 is the capacitance. This is the Arm self-resonant frequency.

[0043] At low frequencies, the Branch structure acts as an inductor, making S... 11 The impedance curve rotates counterclockwise along the admittance circle at the low-frequency end; at high frequencies, the Branch structure acts like a capacitor, causing S... 11 The high-frequency end of the curve rotates clockwise along the admittance circle.

[0044] Admittance and self-resonant frequency (SRF) of the branch structure:

[0045]

[0046] Where Y is the admittance, j is the imaginary part, ω is the angular frequency, L2 is the inductance, and C2 is the capacitance. This is the Branch self-resonant frequency.

[0047] Figure 2 The input matching network of the Ka-band broadband low-noise amplifier provided by this invention is for S 11 The effect of impedance curves is illustrated. The left figure shows the effect of the Arm structure on S... 11 The effect of impedance curves, the right figure shows the influence of the Branch structure on S 11 The influence of the impedance curve. From Figure 2 As can be seen in S 11With the help of Arm or Branch structures, the curve is compressed and rotated towards the center point of the Smith chart, and S... 11 The curve should fall within the -10dB circle as much as possible.

[0048] The main amplification stage includes a gate inductor L g Active transistor M1, active transistor M2, source inductor L s Load resistance R L and load inductance L L In the main amplification stage, active transistors M1 and M2 form a cascode structure. In the active transistor M1 amplifier of the main amplification stage, its gate is biased through the inductor L2 of the input matching network, and its source is biased through the source inductor L... s Grounded, and a gate-source capacitance C is connected between the gate and source of the active transistor M1. gs Gate inductance L g Source inductor L s and M1 gate-source capacitance C gs To achieve conjugate matching to 50Ω at a single center frequency point, its drain is connected to the source of active transistor M2. In the active transistor M2 amplifier of the main amplification stage, its gate is biased, its source is connected to the drain of active transistor M1, and its drain is connected to a parallel peak load (load resistance R). L and load inductance L L Connected to the power supply voltage VDD, a drain-source capacitor C is connected between the drain and source of the active transistor M2. ds Its load resistance R L and load inductance L L It can generate a zero point, improving the gain at low frequencies.

[0049] Figure 3 The present invention provides an S-band broadband low-noise amplifier for Ka-band. 11 Impedance curves, Smith charts, input impedance, and input reflection coefficient S 11 A graph showing the relationship between frequency and input matching network. As can be seen from the graph, combining the input matching network and the main amplification stage can improve S... 11 The impedance curve is compressed and distorted within the -10dB circle, and in S 11 Two notch filters are introduced on either side of the center frequency of the curve, making S 11 A bandwidth extension of <-10dB is achieved, while simultaneously enabling 50Ω conjugate matching of the input impedance over a wide bandwidth. The real part of the input impedance is 50Ω, and the imaginary part is 0Ω. The inductor L1 in the Arm structure must be greater than the inductor L2 in the Branch structure, thus ensuring the compatibility between the input matching network and the gate inductor L... g and gate-source capacitance Cgs The symmetry also ensures that noise matching can be achieved at approximately 50 ohms over a wide bandwidth, making the noise figure NF of the Ka-band broadband low-noise amplifier close to the minimum noise figure NF. min .

[0050] Noise matching requires matching the impedance of the gate terminal of the active transistor M1 in the main amplification stage to the signal source impedance to the optimal noise source impedance required by M1. The conjugate curves of the optimal noise source impedance and the input impedance change in opposite directions with frequency. To achieve simultaneous noise matching and input impedance matching in the Ka-band, the optimal noise source impedance required by transistor M1 is first adjusted to 50 ohms at the center frequency. Then, a symmetrical noise matching network (L1+C1+L2+C2) is created using Lg, Cgs, and an input matching network, ensuring that the optimal noise source impedance fluctuates around 50 ohms in the Ka-band, thus satisfying both noise matching and input impedance matching.

[0051] The buffer stage includes two active transistors M3 and M4. In the active transistor M3 of the buffer stage, its gate is connected to a large resistor R. b A bias voltage is applied, with its drain connected to the power supply voltage VDD and its source connected to the active transistor M4. A gate-source capacitance C is connected between the gate and source of the active transistor M3. gs In the buffer stage, the active transistor M4 serves as a current source load, with its gate connected to a bias voltage, its source connected to ground, and its drain connected to the source of the active transistor M3. In this buffer stage, the output terminal is at the drain of the active transistor M3, serving as the output terminal of the Ka-band broadband low-noise amplifier. Resistor R... b ≥10kΩ.

[0052] Figure 4 This invention provides a circuit schematic for interstage matching in a Ka-band broadband low-noise amplifier. The interstage matching network includes an inductor L. m It achieves this by controlling the drain-source capacitance C of the active transistor M2 in the main amplification stage. ds and the gate-source capacitance C of the active transistor M3 in the buffer stage gs Resonance improves the gain and bandwidth of the Ka-band broadband low-noise amplifier at high frequencies.

[0053] Figure 5 The graph shows the S-parameters versus frequency of a Ka-band broadband low-noise amplifier provided by this invention. It can be seen that the -3dB bandwidth is 7.5GHz (29.1-36.6GHz), and the S-parameters... 11 The <-10dB bandwidth is 6.7GHz (28.3-35GHz), and within the -3dB bandwidth range, S22 Less than -10dB, S 12 Less than -20dB.

[0054] Figure 6 The present invention provides a noise figure NF and a minimum noise figure NF of a Ka-band broadband low-noise amplifier. min The graph shows the relationship between frequency and noise figure. As can be seen from the graph, within the -3dB bandwidth, the noise figure NF ranges from 5.9 to 6.6dB, only slightly lower than the lowest noise figure NF. min 0.2dB higher.

[0055] In summary, this invention addresses the trade-offs between conjugate matching and noise matching in the input network of a broadband low-noise amplifier, the gain attenuation problem at high frequencies, and S... 11 To address the issue of low bandwidth (<-10dB), a Ka-band broadband low-noise amplifier is provided, which improves S-band bandwidth through the Arm and Branch structures of the input matching network. 11 To improve bandwidth, reduce the deviation between noise figure and minimum noise figure, improve bandwidth by -3dB through volume isolation technology, parallel peak load and interstage matching network, and achieve broadband spectrum response.

[0056] Some steps in the embodiments of the present invention can be implemented using software, and the corresponding software program can be stored in a readable storage medium, such as an optical disc or a hard disk.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Ka-band wideband low noise amplifier, characterized by, The Ka-band broadband low-noise amplifier includes, in sequence, an input matching network, a main amplification stage, an inter-stage matching network, and a buffer stage. The main amplification stage and the buffer stage are two-stage amplification circuits, each using an active transistor amplifier; the input matching network uses an Arm and Branch structure to connect S... 11 Impedance curve compression and curling to Within a 10dB circle, the input impedance is simultaneously matched to 50Ω, and both the conjugate matching and noise matching at the input are matched to 50Ω within the Ka band to improve input bandwidth and reduce noise figure; the interstage matching network uses matching inductor L m To improve the high-frequency gain of the Ka-band broadband low-noise amplifier; The input matching network includes inductor L1, capacitor C1, inductor L2, and capacitor C2; inductor L1 connected in series with capacitor C1 forms an Arm structure, and inductor L2 connected in parallel with capacitor C2 forms a Branch structure. The Arm structure and the Branch structure are then connected in parallel to the main amplification stage; the self-resonant frequencies of both the Arm structure and the Branch structure are adjusted to the center frequency of the bandwidth, and the value of inductor L1 in the Arm structure is greater than the value of inductor L2 in the Branch structure. At low frequencies, the Arm structure acts like a capacitor, causing S... 11 The impedance curve shifts counterclockwise along the impedance circle at its low-frequency end; the Branch structure acts as an inductor, causing S... 11 The impedance curve rotates counterclockwise along the admittance circle at its low-frequency end. At high frequencies, the Arm structure behaves like an inductance, making S 11 The impedance curve moves clockwise along the impedance circle at the high frequency end; the Branch structure behaves like a capacitance, making S 11 The impedance curve rotates clockwise along the admittance circle at the high frequency end; S 11 The impedance curves are compressed and rotated towards the center point of the Smith chart with the help of the Arm structure or the Branch structure and make the S 11 impedance curves fall within the 10 dB circle.

2. The Ka-band wideband low noise amplifier of claim 1, wherein, The main amplification stage comprises a gate inductance L g , an active transistor M1, an active transistor M2, a source inductance L s , a load resistance R L and a load inductance L L ; Active transistors M1 and M2 form a cascode structure; the gate of active transistor M1 is connected to the bias voltage through the inductor L2 of the input matching network, and its source is connected to the source inductor L... s Grounded, and a gate-source capacitance C is connected between the gate and source of the active transistor M1. gs ; through the gate inductor L g Source inductor L s and M1 gate-source capacitance C gs Achieve conjugate matching of 50Ω at a single frequency point of the center frequency. The drain of the active transistor M1 is connected to the source of the active transistor M2; the gate of the active transistor M2 is biased, its source is connected to the drain of the active transistor M1, and its drain is connected to the power supply voltage VDD through a parallel peak load; a drain-source capacitor C is connected between the drain and source of the active transistor M2. ds The parallel peak load includes a load resistor R. L and load inductance L L Through the load resistor R L and load inductance L L A zero is generated to increase the gain at low frequencies.

3. The Ka-band wideband low noise amplifier of claim 2, wherein, The buffer stage includes two active transistors M3 and M4; the gate of the active transistor M3 is connected to a resistor R. b A bias voltage is applied, with its drain connected to the power supply voltage VDD and its source connected to the active transistor M4. A gate-source capacitance C is connected between the gate and source of the active transistor M3. gs The active transistor M4 serves as a current source load, with its gate connected to a bias voltage, its source connected to ground, and its drain connected to the source of the active transistor M3; the resistor R b ≥10kΩ; In the buffer stage, its output is at the drain of the active transistor M3, serving as the output of the Ka-band broadband low-noise amplifier.

4. The Ka-band wideband low noise amplifier of claim 3, wherein, The inter-stage matching network comprises an inductor L m by resonating the drain-source capacitance C ds of the active transistor M2 of the main amplification stage and the gate-source capacitance C gs of the active transistor M3 of the buffer stage, improving the gain and bandwidth of the Ka-band broadband low-noise amplifier at high frequencies.

5. The Ka-band wideband low noise amplifier of claim 4, wherein, The active transistors M1 and M2 in the main amplification stage and the active transistors M3 and M4 in the buffer stage are all N-type field-effect transistors in 180nm complementary metal-oxide field-effect transistors, and bulk isolation technology is introduced, with a resistor R connected between their substrate and ground. bulk To increase amplifier gain, the resistor R bulk ≥10kΩ.

6. The Ka-band wideband low noise amplifier of claim 5, wherein, The N-type field-effect transistors are all biased at the lowest noise figure current density of 0.15 mA / μm, while their gain is greater than 8 dB.

7. The Ka-band wideband low noise amplifier of claim 6, wherein, The Ka-band broadband low noise amplifier of 3 dB bandwidth is 7.5 GHz.

8. The Ka-band wideband low noise amplifier of claim 7, wherein, The Ka-band broadband low noise amplifier of the present application has 3dB bandwidth range, the noise figure NF ranges from 5.9 6.6dB.

9. A wireless receiver, characterized by The wireless receiver uses a Ka-band broadband low-noise amplifier as described in any one of claims 1-8 to amplify the received signal.

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