JPH0795646B2 - High frequency semiconductor circuit adjustment method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for adjusting a high frequency semiconductor circuit used at high frequencies.

2. Description of the Related Art A microstrip line is generally used as a semiconductor device used in a high frequency band, for example, a signal transmission line such as an amplifier or an oscillator. At this time, in order to match the impedance of the semiconductor element with the impedance of the external circuit, a matching circuit is required in the input / output section of the semiconductor element. Normally, this matching circuit has a configuration in which impedance is adjusted by arranging a stub in parallel with the microstrip main line. For example, consider matching the input side of a semiconductor device. That is, if the characteristic impedance of the microstrip main line is Zo and the impedance on the input side of the semiconductor element is Zs, the impedance Za when looking at the load side (input side of the semiconductor element) at a point A on a certain microstrip main line is expressed by the following equation. Be done.

However, m is the distance from point A to the load.

Further, β = 2π / λ, λ: wavelength.

Next, at this point A, a branch portion is provided on the microstrip line (stubs are installed in parallel), and when this tip portion is opened, from the input side (input side from the external circuit) of this branch point to the load side (semiconductor). Impedance Zc as seen from the input side of the element)
Let Zb be the impedance seen at the branch side at point A That is, Yc = Ya + Yb However, admittance: Y = 1 / Z Therefore, the impedance of the external circuit is usually 50Ω, so if Yc = 1/50, matching is achieved. Also,
The admittance seen from the branch point of the stub is Yb = jYo tanβl, since Yo is open, but Yo = 1 / Zo, 1 is the length of the stub. In Figure 3, l and
The graph which shows the relationship of tan (beta) l is shown. From this graph,
It can be seen that the value of tan βl changes abruptly at the point of l = λ / 4.

FIG. 2 is a plan view showing an impedance adjusting method using a parallel stub in a conventional microstrip line. In this figure, 1 is a microstrip main line, 2 is an island stub, and 3 is a bonding wire. In this circuit, impedance matching is performed by extending the equivalent stub length by connecting the island stub 2 with the bonding wire 3.

Problems to be Solved by the Invention As described above, the parallel stub does not uniformly change the impedance of the circuit by its length, but
It is a function of βl. Therefore, according to the adjustment method of the conventional example as shown in FIG. 2, the length of the stub gradually changes, but in terms of impedance, only uneven values are obtained. Moreover, as can be seen from FIG. 3, as the length of the stub becomes closer to λ / 4, the amount of change in impedance increases, so adjustment at this time becomes extremely difficult.

Means for Solving the Problems The present invention has been made in view of the problems of the conventional method of adjusting a high-frequency semiconductor circuit as described above, and island-shaped parallel arrangements separated from the microstrip main line are provided. The dimension of each stub becomes shorter as the distance from the microstrip main line approaches the length of 1/4 wavelength, and the dimension of each island stub in the lengthwise direction has a constant tan βl ratio. By determining the distance of the island-shaped stub from the microstrip main line, the adjustment range of the impedance matching by the parallel stub is expanded, and the ease of adjustment is improved, so that the impedance matching is more complete, and the semiconductor element The purpose is to improve the characteristics of the entire semiconductor circuit device by fully utilizing the characteristics of the semiconductor circuit device.

Action The present invention has the above-described configuration to widen the adjustment range of impedance matching by the parallel stubs in the microstrip line and improve the ease of adjustment, thereby making impedance matching more complete and sufficiently improving the characteristics of the semiconductor element. The characteristics of the semiconductor circuit device as a whole can be improved by making the best use of it to solve the problems such as the power loss due to impedance mismatch and the reflection caused by it. It is also possible to reduce the size of the device.

Embodiments A method of adjusting a high frequency semiconductor circuit according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a method for adjusting a high frequency semiconductor circuit according to an embodiment of the present invention (1). In FIG. 1, 1 is a microstrip main line on a dielectric substrate, 2 is an island stub, and 3 is a bonding wire, which is used to connect between the microstrip main line and the island stub. As shown in FIG. 1, the island-shaped stub 2 has a smaller dimension in the lengthwise direction with increasing distance from the microstrip main line. Moreover, the length from the microstrip main line is up to λ / 4.
That is, as described above, since the admittance seen from the branch point B of the stub is an open end, Yb = jYo tan βl where Yo = 1 / Zo, 1 is the length of the stub.

When this equation is expressed as impedance, Zb = −jZo cos βl. From this equation and Fig. 3, the parallel stub with open end is λ
It can be seen that it is capacitive up to / 4. And it becomes the same as short-circuiting the terminal when l = λ / 4, and after that, it has an inductive property. By the way, the point of 50Ω on the Smith chart is in the center of the Smith chart, and the point that is inconsistent with this is outside this. Generally, in order to match the impedance on the load side with the impedance of 50Ω on the input side, a parallel stub may be arranged at a position separated from the load by an appropriate length on the input side. That is, the electrical length is changed by separating the load from the load to the input side by an appropriate length, and the concentric circles are rotated on the Smith chart. Then, by adding an appropriate capacity, it is possible to bring it to the center of the Smith chart. Therefore, the stub must first be capacitive. From this, it can be seen that when the open-ended stub is used, the stub length up to λ / 4 is effective. On the contrary, when a short-circuited stub is used, the impedance at the branch point B is represented by Zb = jZo tan βl. Therefore, it can be seen from FIG. 3 that the stub becomes capacitive when λ / 4 <l <(3λ) / 4. Therefore, as shown in an embodiment of claim (1) of the present invention, the shape of the microstrip main line and the island-shaped parallel stubs arranged separately from the microstrip main line is 1 / By adjusting the lengthwise dimension of the island-shaped stub as it approaches the length of four wavelengths, it becomes possible to adjust the high-frequency semiconductor circuit. Further, as described above, the parallel stub does not uniformly change the impedance of the circuit according to its length, but changes it as a function of tan βl. Therefore, the dimension in the lengthwise direction of each island stub is tan.
It can be seen that if the ratio of β1 is determined to be constant, it becomes easier to capture the change numerically during impedance adjustment, and calculation, measurement, evaluation, etc. are greatly simplified.
Therefore, by using the adjusting method of the high-frequency semiconductor circuit according to the present invention described above, the adjustment range of the impedance matching by the parallel stub is expanded, and the ease of adjustment is improved, thereby making the impedance matching more complete,
By fully utilizing the characteristics of the semiconductor element, the characteristics of the entire semiconductor circuit device can be improved.

EFFECTS OF THE INVENTION As described above, according to the present invention, each dimension of the island-shaped parallel stubs arranged separately from the microstrip main line is such that the distance from the microstrip main line is 1/4 wavelength. The length of each island-shaped stub is shortened so that the lengthwise dimension of each island-shaped stub is determined so that the ratio of tan βl is constant. By expanding the adjustment range of impedance matching by parallel stubs on the line and improving the ease of adjustment, impedance matching will be more complete, and the characteristics of semiconductor elements will be fully utilized to improve the characteristics of the entire semiconductor circuit device. Therefore, problems such as power loss due to impedance mismatch and reflection due to it can be solved, and internal adjustment of the impedance matching circuit can be performed. It is possible to reduce the size of the high-frequency semiconductor device, including portions of the surroundings by reduction.

[Brief description of drawings]

FIG. 1 is a plan view showing a method for adjusting a semiconductor circuit according to an embodiment of the present invention, FIG. 2 is a plan view showing a method for adjusting a semiconductor circuit according to a conventional technique, and FIG. 3 is a graph showing a function tan βl. Is. 1 ... Microstrip main line, 2 ... island stub,
3 ... Bonding wire.

Continuation of the front page (56) Reference JP-A-62-269402 (JP, A) JP-A-61-251204 (JP, A) JP-A-58-184801 (JP, A) Actual development Sho-62-203502 (JP , U)

Claims (1)

[Claims] 1. A microwave circuit having a semiconductor element and a microstrip line formed on a dielectric substrate, wherein the length of each of island-shaped parallel stubs arranged separately from the microstrip main line. Direction dimension,
The distance from the microstrip main line is 1/4 wavelength so that the ratio of tan βl (where β = 2π / λ, λ: wavelength, l: distance from microstrip main line to island stub) is constant. A method of adjusting a high-frequency semiconductor circuit, which is characterized in that it becomes shorter as the length approaches.