CN112653412A - Radio frequency broadband matching circuit - Google Patents
Radio frequency broadband matching circuit Download PDFInfo
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- CN112653412A CN112653412A CN202011504728.XA CN202011504728A CN112653412A CN 112653412 A CN112653412 A CN 112653412A CN 202011504728 A CN202011504728 A CN 202011504728A CN 112653412 A CN112653412 A CN 112653412A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/38—Impedance-matching networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/56—Modifications of input or output impedances, not otherwise provided for
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Abstract
The invention discloses a radio frequency broadband matching circuit which comprises an input matching circuit and an output matching circuit. The input matching circuit consists of a double-section lambda/4 stepped impedance converter and an input impedance imaginary part counteracting circuit; the output matching circuit consists of a three-section lambda/4 step impedance converter and an output impedance imaginary part counteracting circuit. The input matching circuit utilizes a double-section lambda/4 stepped impedance converter with the center frequency of 2.5GHz to realize the matching from the broadband real impedance to the input target impedance of 50 omega. The input impedance imaginary part cancellation circuit adopts an LC type matching network 1, an LC type matching network 2, an LC parallel combination 1 and an LC series combination to cancel the input impedance imaginary part. Similarly, the output matching circuit utilizes a three-section lambda/4 step impedance converter with the center frequency of 2.5GHz to realize the matching from the broadband real impedance to the output target impedance of 50 omega. The output impedance imaginary part cancellation circuit adopts an LC type matching network 3, an LC parallel combination 2 and an inductor to cancel the output impedance imaginary part.
Description
Technical Field
The invention relates to a radio frequency broadband impedance matching circuit, in particular to a broadband low-noise amplifier matching circuit.
Background
The impedance matching circuit is an important component in the process of designing the power amplifier, and the unreasonable impedance matching can cause noise interference and frequency response variation in the circuit, so that the return loss is large, and the maximum power transmission cannot be realized. Therefore, the broadband matching network is the key to the design of the radio frequency power amplifier. However, their function is not limited to impedance matching between the active and the load to achieve ideal power transfer. The function of broadband matching is to realize the transmission of the optimal power in a pass band, reduce the voltage standing wave ratio and reduce the return loss. In order to achieve this, it is common practice to insert a passive network between the active and the load, so that the load impedance matches the source impedance, and maximum power transfer is achieved. The broadband matching method generally includes pi-type network, L-type network, and T-type network. The design of the broadband low-noise matching circuit is realized by adopting an LC type matching network connected to the ground, LC parallel combination and LC series combination to offset the imaginary part of input and output impedance and utilizing a multi-section lambda/4 step impedance transformer with broadband performance to realize the design of the matching circuit from real impedance to target impedance of 50 omega.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a double-section lambda/4 step impedance transformer matched input matching circuit in the frequency range of 2.5GHz in center frequency, 1GHz in bandwidth and 2.0-3.0 GHz in working frequency, so as to realize the matching of 50 omega input impedance. The input impedance imaginary part cancelling circuit can cancel the input impedance imaginary part between the excitation end and the low-noise amplifier. The output matching circuit adopts a three-section lambda/4 step impedance converter for matching, and the matching of output impedance 50 omega is realized. The output impedance imaginary part cancellation circuit can cancel the output impedance imaginary part between the load end and the low noise amplifier. The matching circuit realizes a broadband impedance matching circuit with power gain larger than 17dB, input-output standing wave ratio smaller than 1.3, input-output reflection coefficient smaller than-19 dB and input-output impedance of 50 omega.
The technical scheme adopted by the invention for solving the technical problems is as follows: the radio frequency broadband matching circuit comprises an input matching circuit between an excitation end and a low-noise amplifier and an output matching circuit between the low-noise amplifier and a load end. The input matching circuit consists of a double-section lambda/4 stepped impedance converter and an input impedance imaginary part counteracting circuit; the output matching circuit consists of a three-section lambda/4 step impedance converter and an output impedance imaginary part counteracting circuit. The input matching circuit utilizes a double-section lambda/4 stepped impedance converter with the center frequency of 2.5GHz and the bandwidth of 1GHz to realize the matching from the broadband real impedance to the input target impedance of 50 omega. The input impedance imaginary part cancellation circuit adopts an LC type matching network 1, an LC type matching network 2, an LC parallel combination 1 and an LC series combination to cancel the input impedance imaginary part. Similarly, the output matching circuit utilizes a three-section lambda/4 stepped impedance converter with the center frequency of 2.5GHz and the bandwidth of 1GHz to realize the matching from the broadband real impedance to the output target impedance of 50 omega. The output impedance imaginary part cancellation circuit adopts an LC type matching network 3, an LC parallel combination 2 and an inductor to cancel the output impedance imaginary part.
The dielectric materials of the multi-section lambda/4 step impedance transformer used in the circuit are all FR4, the thickness of the dielectric material is 1.55mm, the dielectric constant is 4.5, and the tangent loss value is 0.015.
The input matching circuit between the excitation end and the low noise amplifier consists of a two-section lambda/4 step impedance converter and an input impedance imaginary part cancelling circuit. The input matching circuit utilizes a double-section lambda/4 stepped impedance converter with the center frequency of 2.5GHz and the bandwidth of 1GHz to realize the matching from the broadband real impedance to the input target impedance of 50 omega. The input impedance imaginary part cancellation circuit adopts an LC type matching network 1, an LC type matching network 2, an LC parallel combination 1 and an LC series combination to cancel the input impedance imaginary part. According to the series connection, the corresponding impedance point on the Smith circular diagram moves along the equal-resistance circle, the parallel connection enables the corresponding admittance point on the Smith circular diagram to move along the equal-electric-conductance circle, if the inductor is connected, the parameter point moves to the upper semicircle of the Smith circular diagram, if the capacitor is connected, the parameter point moves to the lower semicircle of the Smith circular diagram, whether the inductor or the capacitor needs to be inserted can be judged, and the value of the capacitor or the inductor can be given. The reactive element value of the input impedance imaginary part cancellation circuit is obtained by tuning tool of ADS, and the complicated calculation process is avoided. In addition, according to the formula
The characteristic impedance of the first section lambda/4 converter of the two sections lambda/4 stepped impedance converters is as follows: n is 0, and n is 0,
the characteristic impedance of the second section lambda/4 converter is: n is equal to 1, and n is equal to 1,
according to the characteristic impedance of each section of the lambda/4 converter, the LineCalc is used for calculating the characteristic impedance width of each section of the lambda/4 converter, so that the characteristic impedance of the transmission line is changed in a step mode.
The output matching circuit between the load end and the low noise amplifier is composed of a three-section lambda/4 step impedance converter and an output impedance imaginary part cancelling circuit. The output matching circuit utilizes a three-section lambda/4 stepped impedance converter with the center frequency of 2.5GHz and the bandwidth of 1GHz to realize the matching from the broadband real impedance to the output target impedance of 50 omega. The output impedance imaginary part cancellation circuit adopts an LC type matching network 3, an LC parallel combination 2 and an inductor to cancel the output impedance imaginary part. The reactive element value of the output impedance imaginary part cancellation circuit is obtained by turning tool of ADS, and the complex calculation process is avoided. According to the formula
The characteristic impedance of the first section lambda/4 converter is: n is 0, and n is 0,
the characteristic impedance of the second section lambda/4 converter is: n is equal to 1, and n is equal to 1,
the characteristic impedance of the third section lambda/4 converter is as follows: n is equal to 2, and n is equal to 2,
according to the characteristic impedance of each section of the lambda/4 converter, the LineCalc is used for calculating the characteristic impedance width of each section of the lambda/4 converter, so that the characteristic impedance of the transmission line is changed in a step mode.
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 block diagram of an output matching circuit of the present invention.
Fig. 4 is a block diagram of an input impedance imaginary part cancellation circuit of the present invention.
Fig. 5 is a block diagram of the output impedance imaginary part cancellation circuit of the present invention.
Fig. 6 is an overall circuit diagram of the present invention.
Fig. 7 is a circuit diagram of the imaginary part cancellation of the input impedance of the present invention.
Fig. 8 is a circuit diagram of the imaginary part cancellation of the output impedance of the present invention.
Fig. 9 is a circuit diagram of 3 combination method of the present invention.
Fig. 10 is a graph of input and output impedance versus frequency for a low noise amplifier and data plots.
Fig. 11 is a graph of input and output reflection coefficient versus frequency for a low noise amplifier and a data plot.
Fig. 12 is a graph of the input-output standing wave ratio of a low noise amplifier versus frequency and data.
Fig. 13 is a graph of noise figure versus frequency for a low noise amplifier and a data plot.
Fig. 14 is a graph of the stability factor of a low noise amplifier versus frequency and data.
Fig. 15 is a graph of power gain versus frequency for a low noise amplifier and a data plot.
FIG. 16 is a graph and data plot of imaginary input-output impedance cancellation as a function of frequency for the present invention.
FIG. 17 is a graph and data plot of the input and output impedance of the present invention as a function of frequency.
FIG. 18 is a graph of input and output reflectance versus frequency for the present invention.
FIG. 19 is a graph and data plot of the I/O standing wave ratio versus frequency for the present invention.
FIG. 20 is a graph of noise figure versus frequency and a data plot in accordance with the present invention.
FIG. 21 is a graph of stability factor versus frequency and a data plot in accordance with the present invention.
Fig. 22 is a graph of power gain versus frequency and data for the present invention.
Detailed Description
In fig. 1, an overall rf broadband matching circuit includes two matching modes, i.e., an input matching circuit and an output matching circuit. The input end of the input matching circuit is connected with the excitation end, the output end of the input matching circuit is connected with the input end of the low-noise amplifier, the output end of the low-noise amplifier is connected with the input end of the output matching circuit, and the output end of the output matching circuit is connected with the load end. In fig. 2, the input matching circuit is composed of a two-section λ/4 ladder impedance transformer and an input impedance imaginary part cancellation circuit. As the matching circuit is not easy to be overlarge in size, the final multi-section lambda/4 stepped impedance converter adopts a double-section lambda/4 stepped impedance converter to realize the matching of the input impedance of 50 omega. In fig. 3, the output matching circuit is composed of a three-section λ/4 ladder impedance transformer and an output impedance imaginary part cancellation circuit. Considering that the size of the matching circuit is not too large easily, the final multi-section lambda/4 step impedance converter adopts a three-section lambda/4 step impedance converter to realize the matching of the input impedance of 50 omega. In fig. 4, the input impedance imaginary part canceling circuit cancels the input impedance imaginary part by using an LC type matching network 1, an LC type matching network 2, an LC parallel combination 1, and an LC series combination. The tuning tool of ADS can obtain reactance element values for the input impedance imaginary part cancellation circuit, i.e., C1 ═ 1pF, L1 ═ 1.17nH, C2 ═ 1pF, L2 ═ 0.93nH, C3 ═ 1.95087pF, L3 ═ 1.38nH, C4 ═ 0.93pF, and L4 ═ 1 nH. According to the formula
And linecac tool, the characteristic impedance n of the first section lambda/4 transformer is 0,
the width W1 is 139.577 mil; the characteristic impedance n of the second section lambda/4 transformer is 1,
the width W2 is 167.527mil, so that the characteristic impedance of the transmission line changes in a step manner. In fig. 5, the output impedance imaginary part canceling circuitAn LC type matching network 3, an LC parallel combination 2 and an inductor are adopted to offset the imaginary part of the output impedance. Among them, the tuning tool of ADS can obtain reactance element values for canceling the imaginary part circuit of the output impedance, i.e., C5 ═ 1pF, L5 ═ 0.97nH, C6 ═ 0.15pF, L6 ═ 3.4084512nH, and L7 ═ 0.69 nH. According to the formula
And linecac tool, the characteristic impedance n of the first section lambda/4 transformer is 0,
the width W1 is 175.235 mil; the characteristic impedance of the second section lambda/4 converter is: n is equal to 1, and n is equal to 1,
the width W2 is 153.133 mil; the characteristic impedance of the third section lambda/4 converter is as follows: n is equal to 2, and n is equal to 2,
the width W3 is 133.133mil, so that the characteristic impedance of the transmission line changes in a step manner. The dielectric materials of the lambda/4 step impedance transformers used in the input matching circuit and the output matching circuit are all FR4, the thickness of the dielectric material is 1.55mm, the dielectric constant is 4.5, and the tangent loss value is 0.015.
In the above embodiment, fig. 6 shows an overall circuit structure. As shown in fig. 7, in the input impedance imaginary part canceling circuit, the LC-type matching network 1 includes a capacitor C1 connected to ground and an inductor L1 connected in series, where C1 and L1 constitute a low pass filter. The LC-type matching network 2 comprises a capacitor C2 connected to ground and an inductor L2 connected in series, wherein C2 and L2 form a low-pass filter. LC parallel combination 1 includes an inductance L3 connected to ground and a capacitance C3 connected to ground. The LC series combination includes a capacitor C4 and an inductor L4 connected to ground. As shown in fig. 8, in the output matching circuit, the LC-type matching network 3 includes a capacitor C5 connected to ground and a series inductor L5, where C5 and L5 constitute a low pass filter. LC parallel combination 2 includes an inductance L6 connected to ground and a capacitance C6 connected to ground. The path of fig. 9(a) shows an LC type matching network, the path of fig. 9(b) shows an LC parallel combination, and the path of fig. 9(c) shows an LC series combination.
In the above specific embodiment, the low noise amplifier is subjected to ADS simulation under the conditions that the operating frequency is 2.0GHz-3.0GHz, the bandwidth is 1GHz, and the input/output resistance is 50 Ω, so as to obtain a graph 10, where the real part of the input impedance is 31.366+ j 1.301-32.014-j 10.023 Ω, the real part does not reach 50 Ω of matching, and the imaginary part fluctuates between-10 Ω and 10 Ω. Similarly, the output impedance is 38.837-j 20.614-54.790-j 26.332 Ω, the real part does not reach the target matching 50 Ω, and the imaginary part is wide, so that the imaginary part needs to be further cancelled and the target impedance needs to be matched with 50 Ω. As shown in FIG. 11, the input reflection coefficient S (1, 1) is-12.069 to-12.878, the output reflection coefficient is-11.800 to-12.121, the return loss is large, and further reduction of the loss is required. As shown in FIG. 12, the input standing wave ratio is 1.592-1.664, the output standing wave ratio is 1.659-1.692, which are both larger than 1.5, and the standing wave ratio needs to be further reduced. As shown in fig. 13, at 2.5GHz, the noise reaches a maximum of 0.512dB, and the low noise amplifier itself has low noise, on the basis of which the matching flexibility is increased. As shown in FIG. 14, the stability factor is 1.347-1.429, the low noise amplifier is stable, and the matching ease is increased. As shown in FIG. 15, the power gain of the low noise amplifier is 17.142 ~ 20.186.
In the above embodiment, as shown in FIG. 16, the imaginary part of the input impedance is reduced to a range of-7 to 7 and the imaginary part of the output impedance is reduced to a range of-10 to 7 by the input and output impedance imaginary part cancellation circuit.
In the above specific embodiment, through the ADS simulation, as shown in fig. 17, the input impedance Zin1 is 49.265+ j 4.098 Ω to 51.573+ j 1.326 Ω, the real part fluctuates in the range of-2 to 2 above and below 50 Ω, and the imaginary part fluctuates in the range of-2 to 7 above and below, so that the matching of the target impedance 50 Ω and the cancellation of the imaginary part are realized. Similarly, the output impedance Zin2 is 42.043-j 9.964-54.893-j 3.041 omega, the real part fluctuates within the range of-10 around 50 omega, and the imaginary part fluctuates within the range of-10-4 around 0 omega, so that the target impedance 50 omega matching and the imaginary part cancellation are realized. As shown in FIG. 18, the input reflection coefficient S (1, 1) is-22.768 to-41.422, and the output reflection coefficient S (1, 1) is-22.768 to-41.422The coefficient is-17.219 to-29.136, and the return loss is obviously reduced. As shown in FIG. 19, the input standing wave ratio VSWR1 is 1.017-1.157, the output standing wave ratio VSWR2 is 1.072-1.319, and the reduction from more than 1.5 to less than 1.3 is realized. As shown in fig. 20, the noise figure is increased by 0.848-0.512 to 0.336dB, and the noise figure is still lower than 1. As shown in fig. 21, according to
|S11|2<1-|s11s22|，|S22|2<1-|s12s21L. Wherein D ═ s11s22-s12s21K is the stability discrimination coefficient, K>The 1 is a stable state, and the matching circuit system is in a stable state. As shown in FIG. 22, the power gain S (2, 1) is 17.279-20.456 dB, which is larger than 17 dB.
Claims (5)
1. A radio frequency broadband matching circuit, characterized by: the input matching circuit uses a multi-section lambda/4 ladder impedance transformer to match the input real impedance. Considering that the size of the matching circuit is not too large easily, the final multi-section lambda/4 stepped impedance converter adopts a double-section lambda/4 stepped impedance converter to realize the matching of the input impedance of 50 omega.
2. A radio frequency broadband matching circuit, characterized by: the input impedance imaginary part cancellation circuit adopts an LC type matching network 1, an LC type matching network 2, an LC parallel combination 1 and an LC series combination to cancel the input impedance imaginary part. The LC matching network 1 and the LC type matching network 2 are both low-pass filters, so that out-of-band low-frequency signals are filtered, and interference caused by out-of-band frequencies is reduced. In addition, the LC series combination is inserted into the impedance matching network in parallel, the bandwidth can be increased, and the impedance expression of the series LC:
the expression indicates that the LC series circuit behaves capacitively when the frequency is low and inductively when the frequency is high.
3. A radio frequency broadband matching circuit, characterized by: the output matching circuit adopts a multi-section lambda/4 step impedance converter to match the output real impedance. Considering that the size of the matching circuit is not too large easily, the final multi-section lambda/4 step impedance converter adopts a three-section lambda/4 step impedance converter to realize the matching of the output impedance of 50 omega.
4. A radio frequency broadband matching circuit, characterized by: the output impedance imaginary part cancellation circuit adopts an LC type matching network 3, an LC parallel combination 2 and an inductor to cancel the output impedance imaginary part. The LC type matching network 3 is a low pass filter, which filters out low frequency signals outside the band and reduces interference caused by frequency outside the band.
5. A radio frequency broadband matching circuit, characterized by: the dielectric materials of the multi-section lambda/4 step impedance transformers used in the input matching circuit and the output matching circuit are all FR4, the thickness of the dielectric material is 1.55mm, the dielectric constant is 4.5, and the tangent loss value is 0.015.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117236265A (en) * | 2023-11-14 | 2023-12-15 | 成都四威功率电子科技有限公司 | Self-adaptive impedance matching method for broadband power amplifier based on real frequency method |
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| CN117236265B (en) * | 2023-11-14 | 2024-02-23 | 成都四威功率电子科技有限公司 | Self-adaptive impedance matching method for broadband power amplifier based on real frequency method |
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Application publication date: 20210413 |