CN102868367B - Double balanced type frequency tripler - Google Patents

Abstract

The invention provides a double-balanced frequency tripler. The double-balanced frequency tripler at least includes: a 90° first input bridge operating in the fundamental frequency band; ° second input bridge; 4 frequency multiplication circuits respectively connected to one output end of a 90° second input bridge; two -90 ° output bridge; and a combiner connecting the outputs of the two -90° output bridges. The double-balanced frequency tripler of the present invention has the advantages of simple structure, easy integration and low requirements on process capability.

Description

Double balanced frequency tripler

technical field

The invention relates to the technical field of microwave communication, in particular to a double-balanced frequency tripler.

Background technique

The frequency multiplier is a device used to achieve frequency multiplication, multiply the input fundamental frequency to the required harmonic frequency, and make it output the required harmonic power. The introduction of the frequency multiplier can effectively reduce the frequency of the local oscillator (LO), which alleviates the design requirements of the extremely high frequency local oscillator for the millimeter wave system. The extremely high frequency local oscillator has extremely strict requirements on the process and is prone to The frequency is unstable, the linearity is low, the chip consistency is low, and it is difficult to lock the phase directly, so the frequency multiplier can improve the stability of the whole system and reduce the cost.

At present, millimeter-wave frequency triplers mainly use Schottky diodes or heterojunction barrier varactors as nonlinear devices. At the same time, waveguide structures and substrate-integrated waveguide (SIW) structures are used in high-frequency millimeter-wave frequency triplers. It is widely used, the purpose is to use the transmission characteristics of the waveguide cavity to achieve good suppression of the fundamental wave and the second harmonic in the third harmonic. However, this non-planar process structure will greatly affect the miniaturization, high integration and cost reduction of the millimeter wave system.

At present, the frequency tripler based on the planar technology still fails to solve the problem of suppression of all harmonics (including the fundamental wave) except the third harmonic, which directly affects the spectrum purity and triple frequency efficiency of the entire system. Additional complex matching stub circuits or filter networks are used to compensate, which increases the difficulty and cost of circuit design. In recent years, a lot of research has been done on the single-balanced frequency tripler because of its symmetrical structure, simple design method and compact layout area. There are two main topological structures, as shown in Figure 1a and 1b.

A single balanced frequency tripler is realized by a pair of 180°/180° or 90°/90° bridges and a pair of single-terminal frequency multipliers (XN). In general, the phase factors of the input bridge (output phase difference a°) and output bridge (output phase difference b°) determine the output of the Nth harmonic. When satisfied:

N×a ₁ +b×N≈360°×i

The Nth harmonic signal will be linearly superimposed at the output. Among them, N is the frequency multiplier, and i is an integer. According to such theoretical analysis, in the output signal of the 180°/180° bridge, the even harmonic components will cancel each other out, while the odd harmonic components (including the fundamental wave and the third harmonic) will be linearly superimposed at the output end;90 In the output signal of the °/90° bridge, the fundamental components will cancel each other out, while the second harmonic component will be vectorially superimposed at the output end, and the required third harmonic component will be linearly superimposed. It can be seen that no matter which of the two topological structures can realize both the output suppression of the fundamental wave and the output suppression of the even harmonics at the same time, an external matching stub circuit or filter is still required, which will affect The matching characteristics of the nonlinear unit reduce the frequency doubling efficiency of the third harmonic and output the power of the third harmonic.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a double-balanced frequency tripler with good harmonic suppression capability.

In order to achieve the above object and other related objects, the present invention provides a double-balanced frequency tripler, which at least includes:

90° first input bridge, which works in the fundamental frequency band;

Two 90° second input bridges respectively connected to the two output ends of the 90° first input bridge, both of which work in the fundamental frequency band;

4 frequency multiplier circuits connected to the 0° and 90° ends of the two 90° second input bridges at the input terminals;

Two -90° output bridges, the -90° input terminals of the two -90° output bridges are respectively connected to the input terminals to the output of the frequency multiplier circuit at the 0° end of the two 90° second input bridges The 0° input ends of the two -90° output bridges are respectively connected to the output ends of the frequency multiplication circuit whose input ends are connected to the 90° ends of the two 90° second input bridges, and the two The -90° output bridges all work in the third harmonic frequency band; and

A non-inverting combiner connected to the output terminals of the two -90° output bridges;

The electric bridges are all 3db electric bridges.

Preferably, the 90° first input bridge has the same structure as the 90° second input bridge.

Preferably, the 90° first input bridge includes a 3dB Lange coupler.

Preferably, the frequency multiplier circuit adopts a MOSFET single-tube circuit operating in the class C power amplifier region.

Preferably, the 90° first input bridge includes a 3dB Lange coupler.

Preferably, the combiner includes a Wilkinson power divider.

As mentioned above, the advantages of the double-balanced frequency tripler of the present invention include: all components and parts can be realized by planar circuit technology, the structure is simple, and it is easy to integrate; Harmonic suppression characteristics.

Description of drawings

1a and 1b are schematic diagrams showing the topological structure of a single balanced frequency tripler in the prior art.

FIG. 2 is a schematic diagram of the topology of the double-balanced frequency tripler of the present invention.

FIG. 3 is a schematic structural diagram of a 90° 3dB input bridge of the double-balanced frequency tripler of the present invention.

FIG. 4 is a schematic structural diagram of a frequency multiplication circuit of a double-balanced frequency tripler according to the present invention.

FIG. 5 is a schematic structural diagram of a -90° 3dB output bridge of the double-balanced frequency tripler of the present invention.

FIG. 6 is a schematic structural diagram of a combiner of a double-balanced frequency tripler according to the present invention.

Detailed ways

The implementation of the present invention will be illustrated by specific specific examples below, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

See Figures 2 through 6. It should be noted that the structures, proportions, sizes, etc. shown in the drawings attached to this specification are only used to match the content disclosed in the specification, for those who are familiar with this technology to understand and read, and are not used to limit the implementation of the present invention. Limiting conditions, so there is no technical substantive meaning, any modification of structure, change of proportional relationship or adjustment of size, without affecting the effect and purpose of the present invention, should still fall within the scope of the present invention. The disclosed technical content must be within the scope covered. At the same time, terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit this specification. The practicable scope of the invention and the change or adjustment of its relative relationship shall also be regarded as the practicable scope of the present invention without any substantial change in the technical content.

As shown in FIG. 2, the present invention provides a double-balanced frequency tripler. The double-balanced frequency tripler at least includes: three 3dB input 90° electric bridges, working in the fundamental frequency band, respectively bridge 1, bridge 2 and bridge 3; four symmetrical frequency multiplier circuits; two 3dB output- The 90° electric bridge, which works in the third harmonic frequency band, is respectively bridge 4 and bridge 5; and the combiner at the final output end, which works in the third harmonic frequency band.

The input end of the double-balanced frequency tripler is the input end of bridge 1; the 0° output end of bridge 1 is connected to the input end of bridge 2; the 90° output end of bridge 1 is connected to the input end of bridge 3; The 0° output end and the 90° output end are respectively connected to the input ends of the frequency multiplication circuit 1 and the frequency multiplication circuit 2; the 0° output end and the 90° output end of the bridge 3 are respectively connected to the inputs of the frequency multiplication circuit 3 and the frequency multiplication circuit 4 The output terminals of the frequency multiplication circuit 1 and the frequency multiplication circuit 2 are respectively connected with the -90° input terminal and the 0° input terminal of the bridge 4; the output terminals of the frequency multiplication circuit 3 and the frequency multiplication circuit 4 are respectively connected with the - The 90° input terminal is connected to the 0° input terminal; the output terminals of bridge 4 and bridge 5 are respectively connected to the two input terminals of the combiner, and the output terminal of the combiner is the output terminal of the frequency tripler. Adopting the double-balanced frequency tripler of the present invention can realize higher fundamental wave and even-order harmonic output suppression, and at the same time, the variation of the suppression ratio with the process deviation is small, and the whole frequency tripler has the advantages of miniaturization and easy integration and low cost.

The working process of the present invention is as follows: the radio frequency signal enters the double-balanced frequency tripler through the input end of the bridge 1; the output end of the bridge 1 is divided into two-way signals of 0° phase and 90° phase of equal amplitude; the 0° phase The signal of 0° phase enters the input end of bridge 2, and the signal of 90° phase enters the input end of bridge 3; at the output end of bridge 2, the signal of 0° phase is divided into two signals of 0° phase and 90° phase of equal amplitude; At the output end of bridge 3, the 90° phase signal is divided into two signals of equal amplitude 90° phase and 180° phase; the 0° phase signal at the output end of bridge 2 enters the frequency multiplier circuit 1; the 90° phase signal at the output end of bridge 2 The signal enters the frequency multiplication circuit 2; the 90° phase signal at the output end of the bridge 3 enters the frequency multiplication circuit 3; the 180° phase signal at the output end of the bridge 3 enters the frequency multiplication circuit 4; after the nonlinear change of the frequency multiplication circuit, the output of the frequency multiplication circuit 1 terminal outputs the fundamental wave/second harmonic/third harmonic signal with relative phases of 0°/0°/0° respectively, and the output terminal of frequency multiplier circuit 2 outputs fundamental wave signals with relative phases of 90°/180°/270° respectively. wave/second harmonic/third harmonic signal, the output terminal of frequency multiplication circuit 3 outputs fundamental wave/second harmonic/third harmonic signal with relative phases of 90°/180°/270° respectively, frequency multiplication circuit 4 The output terminal of the output terminal outputs the fundamental wave/second harmonic/third harmonic signal with relative phases of 180°/0°/180° respectively; the fundamental wave/second harmonic/third harmonic signal output by the frequency multiplier circuit 1 The relative phases of the output terminals of 4 are 270°/270°/270° respectively, and the relative phases of the fundamental/second harmonic/third harmonic signals output by the frequency multiplication circuit 2 at the output terminals of bridge 4 are 90°/180° respectively /270 °, like this, at the output terminal of bridge 4, the fundamental wave signals cancel each other, the second harmonic vector superposition, the relative phase is 225 °, the third harmonic linear superposition, the relative phase is 270 °; The relative phases of wave/second harmonic/third harmonic signal at the output end of bridge 5 are 90°/180°/270° respectively, and the fundamental wave/second harmonic/third harmonic signal output by frequency multiplier circuit 4 is at the bridge The relative phases of the output terminals of 5 are 180°/0°/180° respectively. In this way, the fundamental wave signals at the output terminals of bridge 4 cancel each other out, the second harmonic vector is superimposed, the relative phase is 45°, and the third harmonic is linearly superimposed, The relative phase is 180°; the equal-amplitude and reverse second-harmonic signals are linearly canceled at the output end of combiner 1, and the equal-amplitude quadrature third-harmonic signals are vector-added at the output end of combiner 1, so that The required third harmonic component is obtained at the radio frequency output terminal, and the fundamental wave and the second harmonic component are symmetrically canceled at the radio frequency output terminal, and the rejection ratio is improved; since the working frequency band of bridge 4 and bridge 5 is in the third harmonic , at the input ends of bridge 4 and bridge 5, most components of the fundamental wave and the second harmonic are returned to the frequency multiplier circuit with reflection, which improves the efficiency of the third harmonic output.

The implementation of the components included in the double-balanced frequency tripler is described below:

1) 90° 3dB input bridge in the fundamental working frequency band

Because the Lange coupler has a small area and a relatively wide operating bandwidth, the Lange coupler is selected as the 90° 3dB input bridge of the fundamental operating frequency band, as shown in Figure 3, where 11 is the input end, and 12 It is 0° coupled end, 13 is 90° coupled end, and 14 is isolated end.

2) Frequency multiplication circuit

In this example, the frequency multiplier circuit adopts a MOSFET single-tube circuit working in the class C power amplifier area, which can generate various high-order harmonic components, as shown in Figure 4, where matching circuit 1 and matching circuit 2 are the input and output terminals respectively end equipment to obtain greater harmonic output power and output efficiency.

3) -90° 3dB output bridge in the third harmonic working frequency band

Because the Lange coupler has a small area and a relatively wide operating bandwidth, the Lange coupler is selected as the -90° 3dB output bridge of the fundamental wave operating frequency band, as shown in Figure 5, wherein 21 is the output terminal, 22 is a 0° coupling input end, 23 is a -90° coupling input end, and 24 is an isolation end.

4) The third harmonic working frequency band combiner

A Wilkinson power divider is used as the combiner in this example, as shown in Figure 6, where In1 and In2 are the input terminals, and Out is the output terminal of the combiner.

In summary, the double-balanced frequency tripler proposed by the present invention has the advantages compared with the prior art in that:

1. In the present invention, utilize bridge 4 and bridge 5 to have larger echo reflection coefficient in the fundamental frequency band, have realized the repeated utilization of fundamental wave reflection back frequency multiplication circuit, have improved the efficiency of third harmonic output; utilize double balance The characteristics of the formula, the fundamental wave components are linearly canceled at the output ports of bridge 4 and bridge 5 respectively, which realizes the suppression of the fundamental wave components at the output end, and at the same time, the suppression of the fundamental wave components by the process deviation is reduced due to the use of a double-balanced structure Impact.

2. In the present invention, utilize bridge 4 and bridge 5 to have larger echo reflection coefficient in the fundamental frequency band, have realized the repeated utilization of second harmonic reflection back frequency multiplication circuit, have improved the efficiency of third harmonic output; Utilize The characteristics of double balance, the second harmonic component is reversed and equal in amplitude at the output ports of bridge 4 and bridge 5, and finally linearly canceled at the output port of the combiner; without using off-chip filters or additional matching circuits , while achieving the suppression of the fundamental wave and the second harmonic.

3. In the present invention, all components and devices can be realized by planar circuit technology, and no additional waveguide or SIW structure is needed to suppress low-frequency components such as fundamental wave or second harmonic wave, realizing miniaturization, easy integration and low cost of the circuit change.

Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (6)

1. A double-balanced frequency tripler, characterized in that, said double-balanced frequency tripler at least includes: 90° first input bridge, which works in the fundamental frequency band; Two 90° second input bridges respectively connected to the two output ends of the 90° first input bridge, both of which work in the fundamental frequency band; 4 frequency multiplier circuits connected to the 0° and 90° ends of the two 90° second input bridges at the input terminals; Two -90° output bridges, the -90° input terminals of the two -90° output bridges are respectively connected to the input terminals to the output of the frequency multiplier circuit at the 0° end of the two 90° second input bridges The 0° input ends of the two -90° output bridges are respectively connected to the output ends of the frequency multiplication circuit whose input ends are connected to the 90° ends of the two 90° second input bridges, and the two The -90° output bridges all work in the third harmonic frequency band; and A non-inverting combiner connected to the output terminals of the two -90° output bridges; The electric bridges are all 3db electric bridges. 2 . The double-balanced frequency tripler according to claim 1 , wherein the structure of the 90° first input bridge is the same as that of the 90° second input bridge. 3. The double-balanced frequency tripler according to claim 1 or 2, characterized in that: the 90° first input bridge comprises a 3dB Lange coupler. 4. The double-balanced frequency tripler according to claim 1, characterized in that: the frequency multiplier circuit adopts a MOSFET single-tube circuit operating in the class C power amplifier region. 5. The double-balanced frequency tripler according to claim 1, wherein the -90° output bridge comprises a 3dB Lange coupler. 6. The double-balanced frequency tripler according to claim 1, wherein the combiner comprises a Wilkinson power divider.