JPS642283B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a double-balanced broadband multiplier.

It is well known that a multiplier produces a multiplied output signal having a frequency that is an integer multiple of the input signal frequency. It is also well known that varactor diodes are used to perform frequency multiplication. High frequency voltage Vε ^j 〓 ^t on varactor diode
is applied, the high frequency current i contains harmonic components due to the nonlinearity of the capacitance of the varactor diode, so the high frequency current i is i=I ₁ ε ^j 〓 ^t +I ₂ ε ^j2 〓 ^t +... +Inε ^jn 〓 ^t …… = _∞ 〓 ⁿ⁼¹ Inε ^jn 〓 ^t (1) Given by. Here, n is a subscript representing the nth harmonic, _I1 is the fundamental wave, In(n2) is a parameter giving the current amplitude of the nth harmonic, ω is the angular frequency, and t is time.

FIG. 1 is a theoretical block diagram showing an example of the simplest multiplier constructed according to the prior art. In Fig. 1, 1 is the angular frequency ω ₁ of the input signal
It is a band pass filter or low pass pass filter that allows only the components of the filter to pass through. 2 is the angular frequency nω ₁ (n
2: positive integer) is a bandpass filter for passing only signal components. 3 is a varactor diode or a step recovery diode, which is a multiplication semiconductor element. In a multiplier with such a configuration, it is extremely difficult to match the peripheral circuitry over a wide band with respect to all harmonics generated by the multiplication semiconductor element, and the resulting fractional band is only a few percent at most. There were some drawbacks.
That is, since the multiplier semiconductor element is a variable capacitance type non-linear element, the multiplier necessarily performs multi-frequency operation. In this case, the input/output matching circuit for the semiconductor element is designed to have a narrow band. Particularly at high frequencies, the entire circuit takes on the characteristics of a distributed constant circuit, so it is of course impossible to achieve ideal matching for all harmonics. Furthermore, when trying to widen the band, the input/output matching circuit becomes mismatched with respect to harmonics, and varactor diodes and the like may cause parametric oscillation. For this reason, it is almost impossible to expand the fractional bandwidth by more than a few percent.

Since the multiplier shown in FIG. 1 has narrow band characteristics, an improved type of multiplier is a balanced multiplier. It is well known that broadband characteristics can be easily obtained using a balanced multiplier. FIG. 2 is a principle diagram showing the basic structure of a balanced multiplier constructed according to the prior art. In Figure 2, 4,
5 is a balanced-unbalanced balun, and 6 to 9 are multiplication semiconductor elements. The currents i ₁ to i ₄ flowing through the multiplier semiconductor elements 6 to 9 are respectively i ₁ =I ₀ +I ₁ ε ^j 〓 ^1t +I ₂ ε ^j2 〓 ^1t +I ₃ ε ^j3 〓 ^1t +... = _∞ 〓 ⁿ⁼⁰ Inε ^jn 〓 ^1t (2) i ₂ =I ₀ −I ₁ ε ^j 〓 ^1t +I ₂ ε ^j2 〓 ^1t −I ₃ ε ^j3 〓 ^1t +…… = _∞ 〓 ⁿ⁼⁰ (−1) ⁿ Inε ^jn 〓 ^1t ( 3) i ₃ =I ₀ +I ₁ ε ^j 〓 ^1t +I ₂ ε ^j2 〓 ^1t +I ₃ ε ^j3 〓 ^1t +…… = _∞ 〓 ⁿ⁼⁰ Inε ^jn 〓 ^1t (4) i ₄ =I ₀ −I ₁ ε ^j 〓 ^1t +I ₂ ε ^j2 〓 ^1t −I ₃ ε ^j3 〓 ^1t +... = _∞ 〓 ⁿ⁼⁰ (-1) ⁿ Inε ^jn 〓 ^1t (5) Given by. Here, all the multiplication semiconductor elements 6 to 9 have the same characteristics.

When an input signal having an angular frequency ω ₁ is applied to the unbalanced side of the balanced-unbalanced balun 4, an output current i _put is obtained from the unbalanced side of the balanced-unbalanced balun 5. The output current i _put is i _put = i ₁ + i ₂ + i ₃ + i ₄ = 4 (I ₀ + I ₂ ε ^j2 〓 ^1t + I ₄ ε ^j4 〓 ^1t +...) = 4 _∞ 〓 ⁿ⁼⁰ I ₂ nε ^j2n 〓 ^1t (6), and even-order harmonic components are output.

Although FIG. 3 has the same configuration as FIG. 2, the connection polarity of the multiplication semiconductor elements 6 to 9 is different. Third
In the figure, the output current i _put is i _put = i ₁ + i ₂ − i ₃ − _{i 4} = 4 (I ₁ ε ^j 〓 ^1t + I ₃ ε ^j3 〓 ^1t +...) = 4 _∞ 〓 ⁿ⁼⁰ I _{2o+ 1} ε ^j(2n+1) 〓 ^1t (7), and odd harmonic components are output.

Therefore, in designing a balanced multiplier, it is sufficient to consider only the even harmonic components or the odd harmonic components. Therefore, it is possible to design a balanced multiplier with a wide band. However, conventional balanced-unbalanced baluns have been constructed using lumped transformers using ferrite cores as shown in Figure 4, so it is difficult to widen the frequency characteristics, and the maximum frequency However, the disadvantage was that it was limited to 3GHz at most.

The purpose of the present invention is to provide a wideband multiplier using a microwave balun that can be used in a high frequency range of 3 GHz or higher by eliminating the maximum frequency limit of the balanced multiplier constructed in the prior art. be.

To achieve the above object, a double-balanced broadband multiplier according to the present invention includes a pair of first and second three-wire coplanar λ/4 type microwave baluns and a plurality of diodes. . A three-wire coplanar λ/4 type microwave balun is constructed by forming a metal conductor layer on the same plane formed of a dielectric material. a pair of first and second three
The linear coplanar λ/4 type microwave baluns are used to perform balanced-unbalanced conversion on the input and output sides of the multiplier, respectively, and the unbalanced ends are connected to the input and output, respectively. A plurality of diodes for performing multiplication are bridge-connected between the balanced ends of the pair of first and second three-wire coplanar λ/4 type microwave baluns. The unbalanced ends of the outer strip conductors of the first and second three-wire coplanar λ/4 type microwave baluns are connected to an outer conductor line having a common ground potential, and are arranged centrally as described above. The strip-shaped conductors are connected to the input line and the output line, respectively.

The double-balanced broadband multiplier according to the present invention will be explained in more detail below with reference to the drawings.

FIG. 5 is a plan view of a layout showing an embodiment of a double-balanced broadband multiplier according to the present invention. Further, FIG. 6 is an external view of the double-balanced broadband multiplier shown in FIG. 5. In FIG. 5, a microwave signal applied to an input terminal 10 is applied to multiplier diodes 6 to 9 via a first three-wire coplanar λ/4 type microwave balun 12. The harmonics generated by diodes 6 to 9 are the second three
Linear coplanar type λ/4 type microwave balun 13
appears at the output terminal 11 via. In FIG. 5, diodes 6 to 9 are bridge-connected to obtain even harmonics. Therefore, input terminal 1
An input signal with an angular frequency ω ₁ applied to 0 is
An output signal having an angular frequency of 2nω ₁ appears at the output terminal 11. In order to obtain odd harmonics, a connection transformation similar to that seen between FIGS. 2 and 3 may be performed.

The first and second three-wire coplanar λ/4 type microwave baluns 12 and 13 each have an electrical equivalent length of λ/4 between the balanced end and the unbalanced end, and are mounted on a dielectric substrate. It is constructed using microwave integrated circuit technology.

In FIG. 6, the layout shown in FIG. 5 is constructed on a dielectric substrate and mounted on a support 16.
The unbalanced ends 14 of the outer strip conductors of the first and second three-wire coplanar λ/4 type microwave baluns 12 and 13 are connected to the common ground potential conductor of the support 16 by side bonding or through-hole technology. It's connected. Outer conductor case 15 of support body 16
A dielectric substrate is mounted inside the dielectric substrate, and a gap is provided at the bottom of the dielectric substrate to reduce the influence on the multiplier of the support 16.

Next, the operation of the three-wire coplanar λ/4 type microwave balun will be explained in detail. FIG. 7 is a diagram showing a balun for performing balanced-unbalanced conversion. In FIG. 7, a microwave signal is input from the left end of the central strip conductor 301. At the right end whose equivalent electrical length is λ/4 away from the input end, there is a central strip conductor 30.
1 and an outer band-shaped conductor 302 are connected. Since the right end is separated from the left end by λ/4, the right end is in an open state and no current flows. At the left end of the outer strip conductor 302, a current having the same amplitude and opposite phase as the left end of the central strip conductor 301 flows. Similarly, no current flows at the right end of the outer strip conductor 303, and a current flows at the left end with the same amplitude and opposite phase as the left end of the central strip conductor 301. Thus, the unbalanced mode at the left end of the balun is converted to the balanced mode at the right end. The transmission line is
Since it is a TEM mode electromagnetic wave, the factor that determines the frequency characteristics is the equivalent line length of the balun, which of course must be selected to λ/4 according to the frequency used.

As explained above, the double-balanced broadband multiplier constructed according to the present invention has broadband characteristics. Moreover, the double-balanced wideband multiplier according to the present invention can be constructed even in high frequency ranges that cannot be achieved with prior art multipliers constructed using lumped transformers with ferrite cores. There is a big advantage.

[Brief explanation of the drawing]

Figure 1 is a basic block diagram of the simplest multiplier constructed according to the prior art, and Figure 2 is a diagram using a lumped constant balanced-unbalanced balun using a ferrite core transformer, constructed according to the prior art. The principle block diagram of a double-balanced multiplier with an even-order harmonic output is shown in Fig. 3. The principle block diagram of a double balanced multiplier with harmonic output. Figure 4 shows the appearance and equivalent circuit of the ferrite core transformer used in the balanced-unbalanced balun in Figures 2 and 3. FIG. FIG. 5 is a plan view showing the layout of an embodiment of the double-balanced broadband multiplier according to the present invention, FIG. 6 is an external view of the double-balanced broadband multiplier shown in FIG. 5, and FIG. FIG. 3 is a principle diagram for explaining the operation of a three-wire coplanar λ/4 type microwave balun used in the double-balanced broadband multiplier shown in the figure. 1, 2... wave generator, 4, 5... transformer, 3, 6-9
...Diode, 12, 13...3-wire coplanar type λ/4 type microwave balun, 16...Support, 1
0, 11...terminal, 15...outer conductor case of support body,
14...Unbalanced common ground potential end of three-wire coplanar λ/4 type microwave balun, 101, 102,
201, 202...Leads of ferrite core type lumped constant transformer, 301-303...Band-shaped conductor of balun.

Claims (1)

[Claims] 1. In a multiplier for obtaining a multiplied output having a frequency that is an integer multiple of the input signal frequency, a pair of first and second three-wire coplanar elements are formed of a metal conductor layer on the same plane formed of a dielectric material. Shape λ/
4-type microwave balun and each balanced end of the plurality of band-shaped conductors of the first and second three-wire coplanar type λ/4-type microwave baluns are arranged and connected to form a bridge circuit. a plurality of diodes, and among the plurality of strip conductors, unbalanced ends of the strip conductors placed on the outside are connected to external conductor lines, and unbalanced ends of the strip conductors placed in the center are respectively inputted. A double-balanced wideband multiplier characterized in that it is configured to be used as a terminal and an output terminal.