CN112702027A - Design of radio frequency circuit - Google Patents

Design of radio frequency circuit Download PDF

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Publication number
CN112702027A
CN112702027A CN202011496827.8A CN202011496827A CN112702027A CN 112702027 A CN112702027 A CN 112702027A CN 202011496827 A CN202011496827 A CN 202011496827A CN 112702027 A CN112702027 A CN 112702027A
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microstrip line
port
series
low
lange coupler
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赛景波
姚成龙
李姝颖
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Beijing University of Technology
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Beijing University of Technology
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/189—High frequency amplifiers, e.g. radio frequency amplifiers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P3/00—Waveguides; Transmission lines of the waveguide type
    • H01P3/02—Waveguides; Transmission lines of the waveguide type with two longitudinal conductors
    • H01P3/08—Microstrips; Strip lines
    • H01P3/081—Microstriplines

Abstract

The invention designs a low-noise broadband amplifying circuit. The circuit comprises an input matching circuit, a Lange coupler, a high-pass filter, a low-noise amplifier and an output matching circuit. The input end of the low-noise amplifier adopts a Lange coupler mode, the characteristic impedance is 50 omega, the coupling degree is 3dB, and the angle is 90 degrees; the high-pass filter adopts the maximum flatness design, the cut-off frequency is 2GHz, the attenuation is 3dB, the pass-band corner frequency is 3GHz, the pass-band attenuation is 0.1dB, and the input and output impedance is 50 omega. The output end of the low-noise amplifier is connected to the load end through the Lange coupler circuit and the output matching circuit.

Description

Design of radio frequency circuit
Technical Field
The invention relates to a low-noise broadband amplifying circuit.
Background
An ultra-wideband wireless transmission (UWB) system, as one of broadband technology carriers, has the advantages of low cost, low power consumption, low complexity, strong anti-interference, high security, high transmission rate, and the like, and attracts many colleges and universities and research institutes. UWB is mainly applied to the fields of indoor communication, high-speed wireless local area networks, home networks, security detection, position determination, radar, and the like. A Low Noise Amplifier (LNA) is an indispensable and crucial module in a UWB system, and is capable of receiving weak signals in the whole frequency band and ensuring that the signals are amplified under the premise of high signal-to-noise ratio. This requires a low noise amplifier with a wide band input-output matching, a high and flat gain, and low and flat noise. The low noise amplifier, as the first module behind the antenna output, needs to amplify the weak antenna signal for subsequent signal processing. The research on low noise broadband amplifiers is of great importance.
Disclosure of Invention
The invention aims to solve the technical problem of providing a low-noise broadband amplifying circuit with a 1GHz bandwidth, wherein the bandwidth of the circuit is 1GHz, the noise coefficient is less than 1dB, the standing-wave ratio is less than 1.5, and the gain flatness is less than 1.5 dB.
The technical scheme adopted by the invention for solving the technical problems is as follows: the low-noise broadband amplification circuit comprises an input matching circuit module at the front end of a first Lange coupler, the first Lange coupler, a high-pass filter, a low-noise amplifier, a second Lange coupler and an output matching circuit module at the output end of the second Lange coupler. The input matching circuit matches the input impedance of the low noise amplifier to the impedance of the source terminal (50 Ω), and the output matching circuit matches the output impedance of the low noise amplifier to the impedance of the load terminal (50 Ω). The lange coupler divides an input radio frequency signal into two paths at an input end: the power is divided equally, the phase difference is 90 degrees, the signals are amplified through two low-noise amplifiers respectively, and then the signals are synthesized through a Lange coupler at the output end, so that the broadband matching of the signals is realized. The high-pass filter is used for compensating the gain of the high frequency, so that stable power gain is obtained in the frequency, and the gain flatness is guaranteed.
The dielectric material used by all the modules of the invention is RogersRO4350B, the thickness of the dielectric material is 0.508mm, the dielectric constant is 3.66, the tangent loss value is 0.0037, the characteristic impedance of the microstrip line is 50 ohm, and the waveguide wavelength lambdag of 2.5GHz electromagnetic wave in the dielectric is 74.36 mm. The characteristic impedance of the microstrip line in the dielectric material is calculated to be 50 omega when the port widths of the T-shaped microstrip line and the common microstrip line are 1.07mm, so that the port widths of all the T-shaped microstrip line and the common microstrip line are 1.07 mm.
An input matching circuit between the source end and the first Lange coupler is composed of two sections of series microstrip lines, one section of parallel open stub line and one section of T-shaped microstrip line, the matching circuit adopts a T-shaped topological structure, the impedance of the source end is assumed to be 50 ohms, the value of the input end of the Lange coupler on a Smith admittance chart normalized by 50 ohms is a + jb, and the input matching network is used for matching the input impedance of the Lange coupler to 50 ohms. The input matching network includes: first series microstrip line TL1, firstA T-shaped microstrip line Tee1, a first parallel open-circuit microstrip stub TL2 and a second series microstrip line TL 3. From the port of the Lange coupler, firstly, the length of the series microstrip line TL3 is x lambda g, the purpose of the series microstrip line is to perform admittance transformation along a circle with equal reflection coefficient, the normalized admittance of the Lange coupler at the moment can be read from a Schmidt admittance chart, and the length of the TL3 is adjusted to ensure that the normalized admittance value at the moment is at the intersection point of the circle with equal reflection coefficient and an auxiliary circle (an auxiliary matching circle is obtained by rotating an equal resistance circle with a normalized value of 1 by 180 degrees along the counterclockwise direction), and the normalized admittance value at the moment is assumed to be 1+ j f; the first parallel open-circuit microstrip stub TL2 is equivalent to a parallel reactive element such that the impedance point moves along an iso-conductance circle having a value of 1 to the matching point, and the length Y of the second parallel open-circuit stub can be calculated by:
Figure BDA0002842421210000021
λ g is the waveguide wavelength. A third series microstrip line TL1, having a length TL1 of 1/4 × λ g. ,
the design method of the lange coupler needs to divide the power of an input signal equally, output two frequency phases with a 90-degree phase difference, and take the characteristic impedance Z0 as 50 omega and the coupling degree (dB):
Figure BDA0002842421210000022
wherein the coupling degree: c ═ Ze-Zo]/[Ze+Zo]The phase angle is as follows: e _ Eff is 90 °, according to the formula:
Figure BDA0002842421210000023
Figure BDA0002842421210000024
the value Ze 120 Ω Zo 20 Ω was calculated, then at a center frequency of 2.5GHz, the dielectric material according to the microstrip line was roger sro4350B, the dielectric material thickness was 0.508mm, the dielectric constant was 3.66, the tangent loss value was 0.0037, the value W0.176015 mm, S0.039598 mm, and L1/4 λ 18.591900mm were calculated for the lange coupler.
The high-pass filter module is designed by adopting a maximum flatness method, the gain difference of a low-noise amplifier is 3dB in a working frequency range according to simulation, when the gain is compensated, the maximum flatness high-pass filter is considered, a cut-off frequency takes a-3 dB point, the gain of the amplifier is compensated to ensure the gain flatness, and the gain flatness is ensured according to | omega/omegacI-1 (cut-off frequency (ω)c) In relation to a graph of attenuation (dB), the order N of the filter is determined, and then a low-pass filter is designed according to the insertion loss method, assuming that the order N of the filter is 2, the source impedance is 1 Ω, and the cutoff frequency ω is set to be ωcA desired power loss ratio can be obtained as 1:
Figure BDA0002842421210000025
input impedance
Figure BDA0002842421210000026
Because of the transmission coefficient
Figure BDA0002842421210000027
So the power loss ratio is expressed as
Figure BDA0002842421210000028
Sorting substitution
Figure BDA0002842421210000029
Then sum with PLRThe comparison yields the final LC value. Then according to a formula of low-pass and high-pass, C is 1/L, and L is 1/C; the inductance of the corresponding position is replaced by the capacitance, and the capacitance is replaced by the inductance.
The output matching network between the output of the lange coupler and the load comprises: the microstrip line structure comprises a third series microstrip line TL4, a second T-shaped microstrip line Tee2, a second parallel open-circuit stub TL5 and a fourth series microstrip line TL 6. Assuming that the normalized admittance at the output end of the lange coupler is i + j × k, the third series microstrip line TL4 makes the admittance value undergo admittance transformation along the circle with equal reflection coefficient, so that the normalized admittance of the low noise amplifier at this time can be read from the smith admittance chart. By adjusting the length of TL4 to make the point fall on equal reflection coefficientAt the intersection of the circle and the auxiliary circle (the auxiliary matching circle is obtained by rotating an equal resistance circle having a normalized value of 1 by 180 ° counterclockwise), taking one of the intersection points as a calculation description, assuming that the normalized admittance value of this intersection point is 1+ j × o at this time, the second parallel open stub TL5 is equivalent to a reactance element so that the impedance point moves to the matching point along the equal electrical conductance circle having a value of 1, and the length L of the second parallel open stub can be calculated by the following equation:
Figure BDA00028424212100000210
λ g is the waveguide wavelength. A fourth series microstrip line TL6, microstrip lines TL6 and TL4 satisfy TL6 ═ 1/4 × λ g.
Drawings
Fig. 1 is a general block diagram of the present invention.
Fig. 2 is a block diagram of an input matching circuit of the present invention.
FIG. 3 is a graph of the S parameter of the input matching circuit of the present invention as a function of frequency
FIG. 4 is a high pass filter block diagram of the present invention
FIG. 5 is a graph of the high pass filter S21 of the present invention as a function of frequency
FIG. 6 is a view of the structure of the Lange coupler of the present invention
FIG. 7 is a graph of the Lange couplers S21, S31, S34 of the present invention as a function of frequency
FIG. 8 is a block diagram of an output matching circuit of the present invention
FIG. 9 is a graph of the variation of S-parameter with frequency of the output matching circuit of the present invention
FIG. 10 is an overall, architectural circuit diagram of the present invention
FIG. 11 is an overall circuit simulation diagram (power gain, noise figure, standing wave ratio) of the present invention
Detailed Description
In fig. 1, a low-noise wide-band amplification circuit includes an input matching circuit, a lange coupler, a high-pass filter circuit, a low-noise amplifier, and an output matching circuit. The output end of the source end input matching circuit is connected with the input end of the first Lange coupler, the output end of the first Lange coupler is connected with the input end of the low-noise amplifier, the output end of the low-noise amplifier is connected with the high-pass filter, the output end of the high-pass filter is connected with the second Lange coupler, the output end of the second Lange coupler is connected with the output matching circuit, and the output end of the matching circuit is connected with the load. The low-noise amplifier used is Qorvo low-noise amplifier QPL9547, the working frequency is 0.1-6GHz, the typical value of the noise coefficient is 0.3dB (1.9GHz), the typical value of the power gain is 19.5dB (1.9GHz), the dielectric material of all the module microstrip lines is RogersRO4350B, the thickness of the dielectric material is 0.508mm, the dielectric constant is 3.66, the tangent loss value is 0.0037, and the characteristic impedance of the microstrip lines is 50 ohms.
In the above embodiment, as shown in fig. 2: the input matching circuit comprises a first series microstrip line TL1, a first T-shaped microstrip line Tee1, a first parallel open-circuit stub TL2 and a second series microstrip line TL 3. The output port of the antenna is connected with a first series microstrip line TL1 of the input matching network, the line length L1 of the TL1 microstrip line is 17.03mm, and the line width W2 is 1.07 mm. The other end of the first series microstrip line TL1 is connected with the left port of a first T-shaped microstrip line Tee1, the port line widths W4, W5 and W6 of the T-shaped microstrip line are 1.07mm, the middle port of the first T-shaped microstrip line is connected with a first parallel open-circuit stub TL2, and the line length L2 of the TL2 microstrip line is equal to the line length L2
Figure BDA0002842421210000031
mm,. lambda.g is the waveguide wavelength, and the line width W5 is 1.07 mm. The right port of the first T-shaped microstrip line is connected with a second series microstrip line TL3, the length L3 of the TL3 microstrip line is 17.82mm, and the line width W6 is 1.07 mm. The other end interface of the second series microstrip line is connected with the input port of the first Lange coupler.
In the above embodiment, as shown in fig. 4, the high-pass filter includes a first parallel inductor L1, a first series capacitor C1, a second parallel inductor L2, a second series capacitor C2, and a third parallel inductor L3. The input port of the low noise amplifier is connected with a first series capacitor C1 and a first parallel inductor L1, the capacitor C1 is 0.95PF, the capacitor L1 is 6.25nH, the other end of the first series capacitor C1 is connected with a second series capacitor C2 and a second parallel inductor L2, the capacitor C2 is 0.95PF, and the capacitor L2 is 1.93 nH. The other end of the second series capacitor C2 is connected to a third shunt inductor L3(L3 ═ 6.25nH) and to the input of the second lange coupler.
In the above embodiment, as shown in fig. 6, the lange coupler is composed of a multi-end microstrip line, and the characteristic impedance Z0 is 50 Ω, and the coupling degree (dB):
Figure BDA0002842421210000032
wherein the coupling degree: c ═ Ze-Zo]/[Ze+Zo]The phase angle is as follows: e _ Eff is 90 degrees, according to calculation, even mode characteristic impedance Ze is 120 omega, odd mode characteristic impedance Zo is 20 omega, then at the center frequency of 2.5GHz, according to dielectric material RogersRO4350B of microstrip line, the thickness of the dielectric material is 0.508mm, the dielectric constant is 3.66, the tangent loss value is 0.0037, the W of the Lange coupler is 0.176015mm, S is 0.039598mm, L is 1/4 lambda is 18.591900mm, the input end of the first Lange coupler is connected with the output end of the input matching circuit, the isolation end is connected with 50 omega resistor to the ground, the first low noise amplifier is directly connected with the ground, and the second low noise amplifier is connected with the input end of the first Lange coupler. The input end of the second Lange coupler is connected with the output end of the high-pass filter after the first low-noise amplifier; the isolation end is connected with the output end of the high-pass filter behind the second low-noise amplifier; a 50 omega resistor is directly connected with the ground; the coupling end is connected with the input end of the output matching network.
In the above embodiment, as shown in fig. 8: the output matching circuit consists of a third series microstrip line TL4, a second T-shaped microstrip line Tee2, a second parallel open-circuit stub TL5 and a fourth series microstrip line TL 6. The output port (coupling end) of the second coupler is connected with one port of a third series microstrip line TL4 of the output matching network, the line length L4 of the TL4 microstrip line is 16.96mm, and the line width W7 is 1.07 mm. The other end of the third series microstrip line TL4 is connected with the left port of a second T-shaped microstrip line Tee2, the line widths W10, W11 and W12 of the ports of the T-shaped microstrip lines are 1.07mm, the middle port of the second T-shaped microstrip line is connected with a second parallel open-circuit stub TL5, and the line length L5 of the TL5 microstrip line is equal to the line length L5
Figure BDA0002842421210000041
λ g is the waveguide wavelength and the linewidth W8 is 1.07 mm. Second T-shaped microstrip lineThe right port of the microstrip line is connected with a fourth series microstrip line TL6, the line length L6 of the TL6 microstrip line is 17.88mm, and the line width W9 is 1.07 mm. The other end of the fourth series microstrip TL6 terminates the load.
In the above specific embodiment, as shown in fig. 11, the low noise amplifier circuit obtained through design and simulation has a gain flatness of < 1dB and a power gain varying in a range of 15.9dB to 15.2dB within a bandwidth of 1GHz at an operating frequency of 2GHz to 3 GHz. The standing-wave ratio is less than 1.5. The noise is less than 0.5 dB.

Claims (8)

1. A low-noise broadband amplification circuit, characterized in that: the overall circuit comprises an input matching circuit, a Lange coupler, a high-pass filter, a low-noise amplifier and an output matching circuit. The working center frequency of the low-noise broadband amplifying circuit is 2.5GHz, the bandwidth is 1GHz, and the impedance of a source end and a load end is 50 omega. The source end and the load end use a series transmission line and a parallel open stub as an impedance matching circuit. The source end is connected with the input matching circuit, the output end of the input matching circuit is connected with the first Lange coupler, the output end of the first Lange coupler is connected with the low-noise amplifier, the output end of the low-noise amplifier is connected with the high-pass filter, the output end of the high-pass filter is connected with the input end of the second Lange coupler, the output end of the second Lange coupler is connected with the output matching circuit, and the other end of the output matching circuit is connected with the load.
2. A low noise wide band amplifier circuit as defined in claim 1, wherein: the input matching network consists of a first series microstrip line TL1, a first T-shaped microstrip line Tee1, a first parallel open-circuit stub TL2 and a second series microstrip line TL 3. The source end is connected with the first series microstrip line TL1 of the input matching network. The other end of the first series microstrip line TL1 is connected to the left port of the first T-shaped microstrip line Tee 1. The middle port of the first T-shaped microstrip line Tee1 is connected to the first parallel open stub TL 2. The right port of the first T-shaped microstrip line Tee1 is connected with the second series microstrip line TL3, and the other end interface of the second series microstrip line TL3 is connected with the input port of the first lange coupler.
3. A low noise wide band amplifier circuit as defined in claim 1, wherein: an input port (upper left port) of the first lange coupler module is connected with the second series microstrip line TL 3; an isolation port (a left lower port) of the first Lange coupler is connected with a 50 omega resistor, and the other end of the resistor is grounded; a through port (upper right port) of the first Lange coupler is connected with a first low-noise amplifier, and the other end of the first low-noise amplifier is connected with the input end of a first high-pass filter; the coupling port (lower right port) of the first Lange coupler is connected with the second low-noise amplifier, and the other end of the second low-noise amplifier is connected with the input end of the second high-pass filter.
4. A low noise wide band amplifier circuit as defined in claim 1, wherein: the first high-pass filter is composed of a first parallel inductor L1, a first series capacitor C1, a second parallel inductor L2, a second series capacitor C2 and a third parallel inductor L3. The left side of the input end of the first high-pass filter is connected with the output end of a first low-noise amplifier LNA1, the other port of the first high-pass filter is connected with a first parallel inductor L1 and a first series capacitor C1, the other end of the first parallel inductor L1 is connected with the ground, the other end of the first series capacitor C1 is connected with a second parallel inductor L2 and a second series capacitor C2, the other end of the second parallel inductor L2 is connected with the ground, and the other end of the second series capacitor C2 is connected with the input ends of a third parallel inductor L3 and a second Lange coupler. The other end of the third shunt inductor L3 is grounded.
5. A low noise wide band amplifier circuit as defined in claim 1, wherein: the second high-pass filter is composed of a fourth shunt inductor L4, a third series capacitor C3, a fifth shunt inductor L5, a fourth series capacitor C4 and a sixth shunt inductor L6. The left side of the input end of the second high-pass filter is connected with the output end of a second low-noise amplifier LNA2, the other port of the second high-pass filter is connected with a fourth parallel inductor L4 and a third series capacitor C3, the other end of the fourth parallel inductor L4 is connected with the ground, the other end of the third series capacitor C3 is connected with a fifth parallel inductor L5 and a fourth series capacitor C4, the other end of the fifth parallel inductor L5 is connected with the ground, and the other end of the fourth series capacitor C4 is connected with a sixth parallel inductor L6 and the isolation end of the second Lange coupler. The other end of the sixth shunt inductor L6 is grounded.
6. A low noise wide band amplifier circuit as defined in claim 1, wherein: the input port (upper left port) of the second lange coupler module is connected to a second series capacitance C2; the isolation port (lower left port) of the second lange coupler is connected to a fourth series capacitor C4; a through port (upper right port) of the second Lange coupler is connected with a 50 omega grounding resistor; the coupling port (lower right port) of the second lange coupler is connected to the third series microstrip line TL4 of the output matching network.
7. A low noise wide band amplifier circuit as defined in claim 1, wherein: the output matching network consists of a third series microstrip line TL4, a second T-shaped microstrip line Tee2, a second parallel open-circuit stub TL5 and a fourth series microstrip line TL 6. The output end of the second lange coupler is connected with the third series microstrip line TL 4. The other end of the third series microstrip line TL4 is connected to the left port of the second T-shaped microstrip line Tee 2. The middle port of the second T-shaped microstrip line Tee2 is connected to the second parallel stub TL 5. The right port of the second T-shaped microstrip line Tee2 is connected with a fourth series microstrip line TL6, and the other end of the fourth series microstrip line TL6 is connected with a load port.
8. A low noise wide band amplifier circuit as defined in claim 1, wherein: the materials of the Lange coupler module and the input and output matching circuit module are both RogersRO4350B, the dielectric constant of the Lange coupler module is 3.66, and the tangent loss value of the Lange coupler module is 0.0037; the Qorvo low noise amplifier QPL9547 used by the low noise amplifier has an operating frequency of 0.1-6GHz, a typical noise figure value of 0.3dB (1.9GHz) and a typical power gain value of 19.5dB (1.9GHz).
CN202011496827.8A 2020-12-17 2020-12-17 Design of radio frequency circuit Pending CN112702027A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5467063A (en) * 1993-09-21 1995-11-14 Hughes Aircraft Company Adjustable microwave power divider
CN111245452A (en) * 2020-01-13 2020-06-05 北京工业大学 Radio frequency circuit
US20220158594A1 (en) * 2019-09-23 2022-05-19 University College Dublin, National University Of Ireland Power amplifiers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5467063A (en) * 1993-09-21 1995-11-14 Hughes Aircraft Company Adjustable microwave power divider
US20220158594A1 (en) * 2019-09-23 2022-05-19 University College Dublin, National University Of Ireland Power amplifiers
CN111245452A (en) * 2020-01-13 2020-06-05 北京工业大学 Radio frequency circuit

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