JPS6341242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the performance of a Rodet line type semiconductor phase shifter that is constructed on a semiconductor substrate and uses an FET as a control element to control the phase of microwaves.

First, a conventional semiconductor phase shifter will be explained.

FIG. 1 shows an example of the structure of a conventional loaded line type semiconductor phase shifter.

In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3 is a main line of a microstrip line configured together with the ground conductor 2, 4 is a branch line, 5 is an FET, and 6 is a
The drain electrode of FET5, 7 is also the source electrode,
8 is a gate electrode, 9 is a through conductor connecting the source electrode 7 and the ground conductor 2, and 10 is a bias circuit consisting of a microstrip line for applying a bias to the gate electrode 8.

Two branch lines 4 are connected to the main line 3 at approximately 1/4 wavelength intervals, and an FET 5 is connected to the other end of the branch line 4.
are connected. The semiconductor phase shifter having such a configuration changes the impedance between the drain and the source with respect to microwaves by changing the bias voltage applied to the gate electrode 8, and FET5
By simultaneously changing the impedance when looking at the side from capacitive to inductive and vice versa, it changes the phase of the microwave propagating through the main line and operates as a phase shifter.

However, the loaded line type conductor phase shifter has 2
If there are differences in the characteristics of the individual FETs, the phase characteristics, loss characteristics, and reflection characteristics of the phase shifter will deteriorate.

Therefore, it is required that the characteristics of the two FETs be the same, but in general, there are variations in characteristics between different FETs even when they are configured on the same semiconductor substrate, so it is difficult to manufacture this type of semiconductor phase shifter. It was becoming a problem. Furthermore, as mentioned above, if it is sufficient to simply have a function of simultaneously switching the impedance viewed from the connection point of the branch line 4 and the main line 3 to the FET 5 side, for example from capacitive to inductive, then
In order to downsize and simplify semiconductor phase shifters, there is a latent demand for reducing the number of bias circuits as much as possible.

In order to solve the above problem, this invention provides one
The drain of the FET is separated, the gate is separated in terms of microwaves, and the structure is common in terms of DC.
In addition, FETs with a common source configuration are used in loaded line semiconductor phase shifters to eliminate deterioration of phase shifter characteristics due to uneven FET characteristics.
The purpose of the present invention is to reduce the number of bias circuits and downsize the circuit, and will be described in detail below.

FIG. 2 is a block diagram of a semiconductor phase shifter showing one embodiment of the present invention, and the FET 11 used here is
divides the drain and gate into two, forming a first drain electrode 12, a second drain electrode 13, a first gate electrode 14, and a second gate electrode 15, respectively, and a common source electrode 16 with a common source. is connected to the ground conductor 2 by a through conductor 9.

Further, the first gate electrode 14 and the second gate electrode 15 are both connected to a capacitor 17, and a bias circuit 18 is further connected to one end of the capacitor 17 to apply a bias voltage to the gate electrode.

Further, the first drain electrode 12 is connected to one branch line 4, and the second drain electrode 13 is connected to the other branch line 4, and one end of these branch lines 4 is connected to the main line 3 with approximately 1/4 wavelength. Connected with intervals.

The semiconductor phase shifter having the above configuration has a bias circuit 18
By changing the bias voltage applied through the , the impedance shown to microwaves between the first drain and source and between the second drain and source changes, and the main line 3 is loaded at approximately 1/4 wavelength intervals. Because the susceptance value changes, the main line 3
The phase of the microwave propagating changes and operates as a phase shifter.

At this time, the capacitor 17 plays a very important role. That is, when a micro beam is incident on the main line 3, the first gate electrode 14 and the second gate electrode 15 are
Microwaves are also coupled. When the combined microwaves interfere with each other, an impedance viewed from the connection point of the branch line 4 and the main line 3 to the FET 11 side is applied to the first gate electrode 14 and the second gate electrode 15. By changing the bias voltage, it becomes difficult to change from the desired capacitive to inductive or vice versa at the same time. Therefore, the capacitor 17 is provided to solve these problems, and the capacitor 17 is provided for each gate electrode 14.
It bypasses the microwaves coupled to the gate electrodes 14 and 15 and shoots them to the ground, and serves to eliminate mutual interference between them. It also serves as a relay point for supplying bias power to each gate electrode 14 and 15 at one point, contributing to miniaturization. are doing.

In the phase shifter configured in this way, FET11
The first drain electrode 12, the first gate electrode 14 and the common source electrode 16, and the second drain electrode 13, and the second gate electrode 15 and the common source electrode 16 are fabricated in extremely close positions. It has ivy characteristics.

Therefore, the impedance shown to microwaves between the first drain electrode 12 and the source electrode 16 and between the second drain electrode 13 and the source electrode 16 becomes equal, and the loaded line type semiconductor transistor manufactured using this FET 11 Phase device is FET
It is possible to prevent performance deterioration due to uneven characteristics of the semiconductor phase shifter, and the semiconductor phase shifter can be downsized due to the simplification of the bias circuit described above.

Although the above description has been made regarding the case in which the main line 3 is arranged linearly, the present invention is not limited to this, and the present invention is not limited to this, but the present invention is also applicable to semiconductors in which the main line 3 between each branch line 4 is bent to reduce the size in the propagation direction. It may also be applied to a phase shifter.

It goes without saying that the semiconductor phase shifter according to the present invention may also be applied to a multi-bit digital semiconductor phase shifter in which the semiconductor phase shifter is cascaded. Furthermore, the capacitor according to the present invention is naturally not limited to overlay, interdigital, or other types.

As described above, in the semiconductor phase shifter according to the present invention, FETs with similar characteristics can be loaded at the ends of two branch lines connected to the main line at approximately 1/4 wavelength intervals, and the capacitors can be connected to the respective gates. Since the bias circuit is connected, it is possible to simplify the bias circuit, and it is possible to realize a semiconductor phase shifter that has good characteristics and is compact and simple, and its industrial value is high.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a conventional loaded line type semiconductor phase shifter, and FIG. 2 is a perspective view showing an embodiment of the present invention. In the figure, 1 is a semiconductor substrate, 2 is a ground conductor, 3 is a main line, 4 is a branch line, 5 is an FET, 6 is a drain electrode, 7 is a source electrode, 8 is a gate electrode, 9 is a through conductor, and 10 is a bias circuit , 11 is FET, 12
13 is a first drain electrode, 13 is a second drain electrode, 14 is a first gate electrode, 15 is a second gate electrode, 16 is a common source electrode, 17 is a capacitor, and 18 is a bias circuit. In addition, in the figure,
Identical or equivalent parts are given the same reference numerals.

Claims (1)

[Claims] 1 In a semiconductor phase shifter in which an FET is connected to a microstrip line constructed on the semiconductor substrate, a main line consisting of a microstrip line is connected to two lines consisting of a microstrip line at approximately 1/4 wavelength intervals. One end of the branch line of the above two branch lines is connected, and the other end of the above two branch lines is connected to the first drain electrode and the second drain electrode of the FET, respectively, and the other end of the above two branch lines is connected to the first drain electrode and the second drain electrode of the FET. On the other hand, the source electrode of the above FET provided in common is grounded,
and a first gate electrode between the first drain electrode and the source electrode of the FET and a second gate electrode between the second drain electrode are connected to one conductor of a capacitor, and the other conductor of the capacitor is In addition to being a grounding conductor, the first
and a semiconductor phase shifter, characterized in that one end of the second gate electrode connection side is connected to a bias circuit.