阅读说明：本技术 一种基于等电阻面的微带线e类功率放大器设计方法 (Microstrip line class-E power amplifier design method based on equal resistance surface ) 是由 金科 冒冬琴 于 2019-08-30 设计创作，主要内容包括：本发明公开了一种基于等电阻面的微带线E类功率放大器设计方法,属于基本电子电路的技术领域。该方法包括如下步骤：首先对Kuroda规则进行简化和补充,形成简化的Kuroda规则；在实现集总参数E类功放和微带线E类功放的转换过程中,为保证E类功率放大器的最佳基波阻抗和最佳源阻抗不变,提出“等电阻面”的设计方法；利用“等电阻面”的设计方法,对于E类功放不同的输出匹配电路,可通过确定等电阻面,实现不同输出匹配方式下,E类功放输出电路集总参数和微带线之间的等效转换；利用“等电阻面”的设计方法,对E类功放的输入匹配电路,可通过构建等电阻面,实现输入匹配的谐波抑制功能。(The invention discloses a design method of a microstrip line class-E power amplifier based on an equal resistance surface, and belongs to the technical field of basic electronic circuits. The method comprises the following steps: firstly, simplifying and supplementing a Kuroda rule to form a simplified Kuroda rule; in the process of realizing the conversion of lumped parameter class-E power amplifier and microstrip line class-E power amplifier, in order to ensure the optimal fundamental wave impedance and the optimal source impedance of the class-E power amplifier to be unchanged, a design method of an equal resistance surface is provided; by utilizing the design method of the equal resistance surface, for different output matching circuits of the E-type power amplifier, equivalent conversion between lumped parameters and microstrip lines of the E-type power amplifier output circuit in different output matching modes can be realized by determining the equal resistance surface; by utilizing the design method of the equal resistance surface, the harmonic suppression function of input matching can be realized by constructing the equal resistance surface for the input matching circuit of the E-type power amplifier.)

1. A design method of a microstrip line class-E power amplifier based on an equal resistance surface is characterized in that,

the Kuroda rule is simplified according to the principle that the conversion from the series inductor to the parallel capacitor is realized by respectively connecting unit elements at two ends of the series inductor in series,

determining an equal resistance surface which ensures that the optimal fundamental wave impedance and the optimal source impedance of the class-E power amplifier are not changed,

and determining the position of the unit element inserted in the matching circuit according to the equal resistance surface, and equivalently converting the lumped-parameter E-type power amplifier into a microstrip line E-type power amplifier according to a simplified Kuroda rule.

2. The method for designing an E-class microstrip line power amplifier according to claim 1, wherein the specific method for equivalently converting a lumped-parameter E-class power amplifier into a microstrip line E-class power amplifier according to the simplified Kuroda rule is as follows: the impedance of the unit element is equal to the output impedance of the insertion position, Richard transformation is carried out on the series inductor and the unit elements connected in series at two ends of the series inductor to obtain an equivalent circuit of the unit element parallel capacitor, and then the parallel open circuit is utilized to realize the parallel capacitor to obtain the microstrip line E-type power amplifier.

3. The method according to claim 1, wherein the output impedance at the equal resistance surface is real, and for a matching circuit without the equal resistance surface, a matching element that ensures that the optimal fundamental impedance and the optimal source impedance of the E-class power amplifier are not changed is added to construct the equal resistance surface.

4. The design method of the microstrip line class-E power amplifier based on the equal resistance surface according to claim 2, wherein when Richard transformation is performed on the series inductor and the unit elements connected in series at two ends thereof to obtain an equivalent circuit of the unit element parallel capacitor, the transformed unit element impedance is: z₃＝Z₁+Z_a，Z₃For transformed unit cell impedance, Z₁Is the impedance of a series inductance, Z_aFor the unit element impedance before transformation, the impedance of the parallel capacitor is:

Technical Field

The invention discloses a design method of a microstrip line class-E power amplifier based on an equal resistance surface, and belongs to the technical field of basic electronic circuits.

Background

Since the introduction of class E power amplifiers in 1975, class E power amplifiers have received much attention because the large voltages and currents generated at their drains do not overlap and the theoretical efficiency is 100%. The original class-E power amplifiers all use lumped-parameter elements from a power supply V_dA transistor Q, a parallel output capacitor C, a series resonant circuit, and a residual inductor L_XAnd a load R_LThe composition is shown in FIG. 1 (a).

In the MHz frequency range, the practical maximum working efficiency of the E-type power amplifier can reach 96%. However, in GHz or higher frequency band, the design of class E power amplifier is limited by lumped parameter element and is not easy to be realized because of the existence of frequency resonance point and high frequency parasitic parameter in lumped parameter element, and the circuit can work in higher frequency band by adopting microstrip line instead of lumped parameter element and is easy to be debugged. Fig. 2 is a common microstrip line load network, and theoretically, the class E power amplifier load network requires infinite impedance for all harmonics, however, practical engineering studies show that higher efficiency can be achieved by properly matching the impedance of the second and third harmonics. Fig. 2 can realize suppression of the second, third, fourth, and fifth harmonics by designing 1/4 wavelengths of the electrical lengths of the four-section lines to be the second, third, fourth, and fifth harmonics, respectively.

At present, a general design method for realizing a microstrip line class E power amplifier is as follows: in the traditional lumped parameter class-E power amplifier circuit, according to the microwave transmission line theory, a series high-impedance line is adopted to approximately replace a series inductor, and a parallel low-impedance open line replaces a parallel capacitor. A significant drawback of this method is that because it can only achieve approximate replacement of the series high-impedance line and the series inductance, it cannot ensure that the optimal fundamental impedance and the optimal source impedance of the class E power amplifier are unchanged, i.e. accurate equivalence of the lumped parameter element and the microstrip line cannot be achieved.

Disclosure of Invention

The invention aims to provide a design method of a microstrip line E-type power amplifier based on an equal resistance surface, which aims to overcome the defects of the prior art, realizes the accurate equivalence of a lumped parameter element and a microstrip line by determining or constructing the equal resistance surface, and solves the technical problem that the microstrip line E-type power amplifier cannot be accurately designed.

The invention adopts the following technical scheme for realizing the aim of the invention:

the invention simplifies and supplements the Kuroda rule commonly used in the radio frequency filter to form the simplified Kuroda rule, and the conversion from the series inductor to the parallel capacitor can be realized by adding unit elements at two ends of the distributed inductor.

For class-E power amplifiers, microstrip line implementation can be divided into two parts, namely an input matching circuit and an output matching circuit, and output matching is usually performed from 50 omega standard impedance to load impedance R_LWhich involves only the conversion between real impedances, as shown in fig. 1 (b). Input matching often involves the conversion of a complex impedance to a standard impedance of 50 Ω, i.e., the conversion of a complex to real impedance. The design method of the equal resistance surface can realize the accurate equivalence of the lumped parameter element and the microstrip line by determining or constructing the equal resistance surface in the class E power amplifier and selecting the position as the insertion position of the unit element on the premise of ensuring that the optimal fundamental wave impedance and the optimal source impedance of the class E power amplifier are not changed.

By adopting the technical scheme, the invention has the following beneficial effects:

(1) the accurate equivalence of lumped parameter E-type power amplification and microstrip line E-type power amplification can be realized under the condition of ensuring that the optimal fundamental wave impedance and the optimal source impedance of the E-type power amplification are not changed.

(2) For E-class power amplifiers adopting different output matching modes, the design of a microstrip line E-class power amplifier can be realized by determining an equal resistance surface.

(3) For an input matching circuit of the class-E power amplifier, the design of the input end microstrip line class-E power amplifier can be realized by using the method, and meanwhile, the design of an input end harmonic suppression function, namely the design of an input end filtering function, can be realized.

Drawings

Fig. 1(a) is a circuit diagram of a conventional lumped-parameter class-E power amplifier, and fig. 1(b) is a circuit diagram of the conventional lumped-parameter class-E power amplifier after being inserted into an output impedance matching network.

Fig. 2 is a microstrip line load network commonly used for class E power amplifiers.

Fig. 3 is an equivalent circuit of a simplified Kuroda-rule series inductor with unit cells connected in series across the inductor.

Fig. 4(a) is an output circuit diagram in the LCLC matching system, fig. 4(b) is an output circuit diagram after a unit element is inserted into the circuit shown in fig. 4(a), fig. 4(c) is a schematic diagram showing a conversion result of a series inductance, and fig. 4(d) is a microstrip line circuit diagram in the LCLC matching system.

Fig. 5(a) is a Smith chart diagram of the pi matching system, fig. 5(b) is a circuit diagram of the pi input matching, fig. 5(c) is an input circuit diagram after the unit element is inserted into the circuit shown in fig. 5(b), fig. 5(d) is a microstrip line circuit diagram of the pi matching system, and fig. 5(e) is a microstrip line network of the final input terminal.

Detailed Description

The technical scheme of the invention is explained in detail in the following with reference to the attached drawings.

Fig. 3 shows a simplified Kuroda rule, where S ═ jtan (θ) is Richard transform, and θ has a value range of 0 ° to 90 °, and only 45 ° is described here as an example. Z_a、Z₃Is a unit cell characteristic impedance, Z_L、Y_cRespectively the reactance of the series inductance and the parallel capacitance.

According to the simplified Kuroda rule, it is shown that the conversion of a series inductor to a parallel capacitor can be achieved by adding a unit cell across the inductor.

For output matching of class-E power amplifiers, it is often necessary to achieve a standard impedance of 50 Ω to a load impedance R_LThe common matching modes include pi-type matching, T-type matching, LCLC matching, and the like, in addition to the simplest LC matching mode. Generally, except for a certain Q value of the LC type matching circuit, the Q value of the circuit under other matching modes is adjustable, namely the bandwidth of the circuit is adjustable. Here, the design method of the "equal resistance surface" is described by taking the LCLC type matching method as an example, and the other output matching methods can be converted by the similar method.

Fig. 4(a) shows a schematic diagram of an output circuit in an LCLC type matching mode, because three series inductors are present in the circuit, three unit elements are required to implement the conversion from the series inductor to the parallel capacitor.

The design method of the equal resistance surface is that the optimal fundamental wave impedance output by the class E power amplifier can be ensured to be unchanged by determining or constructing the equal resistance surface in the lumped circuit and inserting the unit element with the same resistance value into the position.

Theoretically, unit elements can be inserted into the left and right sides of the three series inductors in fig. 4(a) to realize the conversion from the series inductor to the parallel capacitor. However, according to the design method of the equal resistance surface, only by inserting the unit element into the equal resistance surface, the optimal fundamental wave impedance of the class E power amplifier output can be ensured to be unchanged, that is, only by inserting the unit element at the position 1 and the position 2 in fig. 4(a), the design requirement can be met. Wherein the output resistance at position 1 is R₁The output resistance at position 2 is R₂So that the impedance is inserted as R at the position 1₁Position 2 with two inserted resistances R₂As shown in fig. 4 (b).

Wherein:

Z_a＝Z_b＝R₂(1)，

Z_c＝R₁(2)，

the conversion result of the series inductance is shown in fig. 4(c), and on the basis, all parallel capacitances in fig. 4(c) can be realized by parallel open-circuit lines by using Richard transformation, and finally, a microstrip line load network is shown in fig. 4 (d).

Wherein:

Z₂＝Z_a+ωL_x＝18.952 (4)，

Z₃＝Z_b+ωL₁＝21.931 (5)，

Z₅＝Z_c+ωL₂＝52.889 (7)，

fig. 5 shows a schematic diagram of a microstrip line implementation of the input matching network.

Taking the switch tube CGH40010F of CREE as an example, the optimal source impedance is 3.19-j4.76 at the frequency of 2.5GHz, and the standard impedance needs to be matched to 50 Ω. The conventional LC matching method does not have an equal resistance surface, but if a matching element is further added, an equal resistance surface is constructed to form a pi-type matching method, fig. 5(a) is a Smith chart diagram of the pi-type matching method, and a circuit diagram is shown in fig. 5 (b).

In this matching scheme, as shown in fig. 5(b), a unit element can be inserted into the series inductor L only at position 1 by the "equal resistance surface" design method. The characteristic impedance of the inserted unit element is R₁I.e. Z_a＝R₁As shown in fig. 5 (c). By using the simplified Kuroda rule, the conversion result from the series inductance to the parallel capacitance is shown in fig. 5(d), and the microstrip line network at the final input end is shown in fig. 5(e), which has the input harmonic suppression and input matching functions.

Wherein:

Z₂＝Z_a+ωL＝30.509 (10)，

it will be understood that equivalents and modifications of the invention as described herein may occur to those skilled in the art, and that such modifications and alterations are intended to fall within the scope of the appended claims.