JPH02305202A - Matching circuit - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of a matching circuit in a short time by connecting a varactor diode to an open stab and varying the junction capacitance of the diode. CONSTITUTION:Microstrip open stabs 2, 3 are orthogonal to a microstrip line 1, a capacitor 13, varactor diodes 4a, 4b and voltage sources 5a, 5b are connected between the microstrip open stab 3 and ground. A voltage is applied from voltage sources 5a, 5b to the varactor diodes 4a, 4b so that the output impedance is matched with S11* and the voltage sources 5a, 5b are adjusted while applying microwave characteristic measurement to adjust the impedance. Thus, a troublesome adjustment such as cut-off of the stab or wire bonding is not required.

Description

[Detailed description of the invention] Industrial application field The present invention is a microwave-carved conductor! Regarding the If combiner circuit; 7
, especially MIC and MM using microstrip lines
Regarding IC matching circuits.

(mouth) Conventional technology microphone 1-1 wave integrated circuit (MIC) and monolithic;・
A low-noise microphone (J-wave transformer) is used in a microwave low-noise amplifier, which is an application example of a microwave integrated circuit (MMIC).Normally, matching is achieved with the input and output sides of the transistor to reduce the amplification. The machine is designed to have low noise and high gain.

A matching circuit is used for the second matching.

Conventionally, a matching circuit that measures the microwave characteristic values of a microwave transistor, such as the S parameter and noise parameter, and installs a microstrip open stub in the microstrip line 7 based on these parameters, has become obsolete. ing. In order to provide the open stub mentioned above, it is necessary to know the representative values of the microwave characteristic values, so many microwaves! - It is necessary to measure the transistor, and the average value of the 7 microwave characteristic values is usually used as the representative value, and optimization is performed from this average value to determine the position of the open stub. However, in this matching circuit, the position of the open stub is fixed, so if there are variations in the microwave characteristic values, adjustment can only be made by cutting the open stub.

Therefore, this matching circuit has poor working efficiency, and furthermore, it is very difficult to adjust the integrated circuit so that its performance is maximized. To solve the problem of the matching circuit described above, as shown in Figure 4, a /J\ small land (
8), and run Ij (8>) and land (8) as necessary.
A matching circuit has been proposed in which adjustment is made by bonding a wire between the land (8) and the open stub (9). This matching circuit eliminates the need to cut open stubs 9, and can easily accommodate microwave transistors with varying microwave characteristic values. However, even with the matching circuit shown in FIG. 4, wire bonding work is involved, making it difficult to make adjustments while measuring the performance of the integrated circuit. Moreover, since there are only a finite number of wire bonding methods, it is difficult to adjust the wire bonding methods to maximize the performance of the integrated circuit. Furthermore, once the wires are bonded, it is impossible to remove them.

(c) Problems to be Solved by the Invention As mentioned above, the conventional matching circuit has problems in 1) working efficiency during adjustment, and (11) optimization of microwave characteristics. This problem arises because the microphone 11 wave characteristics of the microwave transistor differ from element to element.

That is, in order to make adjustments, it is necessary to cut the open star and the open stub with something like a razor, or to bond the land and the sink or run 1: and the open stub with a wire. At the time of development, 1Y
It is not possible to make adjustments while measuring the noise characteristics of the iJ MIC, which is extremely inconvenient and also takes time. Furthermore, there is a drawback that once adjusted parts cannot be adjusted again.

Regarding (11), in the conventional technology, the adjustment method is trial and error, and simulation cannot be performed, so it is impossible to make the best use of the performance of the integrated circuit, that is, to perform optimization operations, and all human skill is required. It has the disadvantage of relying on intuition.

(i) In addition to the problems shown in (i), (iN) Conventional matching circuits are used only as matching circuits for M I C + M M I C, and cannot create arbitrary microwave characteristics = 3- j ′, it has the disadvantage that it cannot have the function of a tuner, so to speak.

(d) Means for Solving the Problems The present invention provides a dielectric substrate with a micro strip line and a microphone connected in parallel with the micro strip line. This matching circuit is characterized in that a variable capacitance gayode is connected to the @313 open lambda cube, and a voltage is applied to the variable capacitance diode from an electrification source.

(E) The matching circuit can be adjusted by changing only the voltage applied to the working varactor diode. In other words, the junction capacitance of the variable capacitance diode connected in parallel with the microstrip line (
By changing Cj), the impedance of the matching circuit can be changed, so adjustments can be made in a short time while measuring the performance of the integrated circuit, and the work efficiency is excellent.

Furthermore, if the microwave characteristics of a microwave transistor and the voltage dependence of the capacitance of a varactor diode are known, it is possible to simulate the optimization of a matching circuit in an integrated circuit.

Furthermore, the present invention can be used not only as a MIC+MMIC matching circuit, but also as a tuner that can obtain an arbitrary output impedance.

Kube Example Next, embodiments of the present invention will be described based on the drawings.

First, FIG. 1 shows a matching circuit that can be connected to a microwave transistor of an integrated circuit. In the figure, (1) is a microstrip line, <2) and (3) is a microstrip line.
Lip open stub, (4a) (4b) are varactor diodes, (5a) (Sb) are varactor diodes (4
a) A voltage source that applies voltage to (4b). The microstrip open stub (2>(3) is perpendicular to the microstrip line (1), and one capacitor (13) is connected between the microstrip open stub (3>) and the ground.
, 7<rank diodes (4a) (4b) and voltage source<
5a)<5b) are connected. Note that a -1 capacitor, a varactor diode, and a voltage source may also be connected to the microstrip open stub (2).In addition, in this embodiment, the microwave transistor and the bias circuit for applying voltage to the transistor are not shown. It is omitted.

The equivalent circuit of the varactor diode 1° (4a) (4b) is represented by a series connection of a junction table: t(Cj) (6) and a series resistor (Rs) (7), as shown in FIG. As shown in FIG. 3, the dependence of the junction capacitance of the varactor diodes (4a) (4b) on the bias voltage changes almost linearly by lowering the reverse bias.

The microwave characteristics of the matching circuit using the characteristics of the varactor diodes (4a) and (ab) described above are shown below.

Figure 5 is a Smith diagram, and the 10 mark (10) in the diagram is a micro? , * is the reflection coefficient (So) of the l-lansistor at a frequency of 12 GHz. Therefore, the conjugate value S I+ of S n shown by the moss x mark (11) that matches S u
Also the output impedance in Figure 1. It is necessary to come. In this example, varactor diode (4g) (4b
It is known that the junction capacitance (Cj) of This result can be found in the area surrounded by A, B, C, and D in Figure 5. Therefore, the varactor diode (4a) < 4b) is set so that the output impedance matches 811*. voltage source (5a) (
It is sufficient to apply a voltage from 5b). With this method, you can measure the microphone [voltage while measuring the 7-wave characteristics]. By adjusting (5g>(5b)C), impedance can be adjusted, and troublesome adjustments such as cutting a stub or pounding a wire are not necessary.

In addition, since a capacitor <13) of about 100 pF that does not depend on the applied voltage is inserted between the varactor diodes (4a) (4b) and the open stub 3), no direct current flows into the microstrip line 1). There is no need to worry about it flowing into
The combined capacitance of the capacitor (13) and the junction capacitance (Cj) is only the junction stand 1t (Cj) because the capacitor (13) is so large that it can be ignored.

- As mentioned above, the circuit of the present invention is particularly effective when the microwave characteristics of the microwave transistor vary; for example, in FIG. However, within the range surrounded by ABCD, the performance of the integrated circuit can be optimized by changing only the voltage applied to the varactor diodes (4a) (4b).1, that is, 1 The single matching circuit pattern can be used with any microwave transistor, and its adjustment method is extremely easy.

Next, another embodiment will be explained using FIG. 6.

This matching circuit consists of three varactor diodes (14a) (
14b) (14c), and a microstrip open stub (12) is connected to the microstrip line 11).

A -7 densifier (13), a varactor diode (14a)<14b) (14c), and a voltage source (15a) (15b) (15c) are connected to the open stub (12), respectively. Note that a plurality of varactor diodes may be arranged in parallel in order to increase the value of the capacitance connected to the open stub (12).

By using the above configuration, the output impedance can be obtained over the entire Habo-Smith diagram except for areas where the reflection coefficient is close to 1. Therefore, it is possible to construct a matching circuit with a tuner function that can minimize the noise figure of a low-noise microwave transistor.

Furthermore, in this matching circuit, the voltage 'IFA (15a)<15
b) From (15c), by fixing the applied voltage, it is possible to give any impedance with good reproducibility, and it is possible to obtain multiple reproducibility values that are necessary when measuring estimated parameters of low-noise microwave transistors. Can create good impedance.

(g) Effects of the Invention As described above, the present invention connects a varactor diode to an open stub and makes the junction capacitance of this diode variable, thereby making it easy to adjust the matching circuit in a short time. or -] It is possible to optimize the microwave characteristics of the matching circuit.

Furthermore, the present invention can also be used as a tuner used to measure the noise figure of a phychrowave transistor with low noise.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a matching circuit according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a varactor diode, FIG. 3 is a diagram showing the bias dependence of the junction capacitance of a varactor diode, and FIG. Diagram showing a conventional matching circuit, No. 5V3! J is a diagram showing an adjustable impedance region according to one embodiment of the present invention, and FIG. 6 is a diagram showing a matching circuit according to another embodiment of the present invention. (1)(11>(16)...Microphone D strip line, (2)(3)(9>(12)..."Microstrip open stub, (4a)(4b)(14a)(14b
) (14c) - Varactor diode, C3a) (5b)
(15a)<15b) (15c) - N pressure source, (6) -.
・Junction capacitance, (7)...Series resistance, 8〉...Adjustment land, (10)...S of microwave transistor
u, (11)... Conjugate value S of S n' (10)
11*, (13)... Capacitor.

Claims (1)

[Claims] 1. In a matching circuit including a microstrip line and a microstrip open stub connected in parallel with the microstrip line on a dielectric substrate, a variable capacitance diode is connected to the open stub, and a voltage source is connected to the variable capacitance diode. A matching circuit characterized in that a voltage is applied.