Wave transmission lines and networks – Coupling networks – Delay lines including a lumped parameter
Reexamination Certificate
1998-12-28
2001-06-26
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Delay lines including a lumped parameter
C333S164000
Reexamination Certificate
active
06252474
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor phase shifter used in a phased array radar or the like.
2. Description of the Related Art
In a first prior art semiconductor phase shifter (See: Robert V. Garver, “Broad-Band Diode Phase Shifters”, IEEE Trans. of Microwave Theory and Techniques, Vol. MTT-20, No. 5, pp. 314-323, May 1972), a T-type high-pass filter and a T-type low-pass filter are switched by arranging switches. This will be explained later in detail.
In the first prior art semiconductor phase shifter, however, since two control biases are required, so that the two switches and are required, a large insertion loss is created.
In a second prior art semiconductor phase shifter (see: JP-A-1-202007), only one control bias is provided. This also will be explained later in detail.
In the second prior art semiconductor phase shifter, however, even if the frequency of propagation signals is shifted a little from the desired frequency, the phase shift deviates, so that the semiconductor phase shifter is narrowband.
SUMMARY OF INVENTION
It is an object of the present invention to provide a semiconductor phase shifter capable of reducing the insertion loss and obtaining a wide bandwidth of operation as well as an increased return loss.
According to the present invention, in a semiconductor phase shifter, a high-pass signal path and a low-pass signal path are connected in parallel between an input terminal and an output terminal. The high-pass signal path is constructed by first and second transmission lines connected to the input and output terminals and having an effective length of &lgr;/4, where &lgr; is a wave length of propagating signals, at least one first field effect transistor connected between the first and second transmission lines, and at least two third transmission lines each connected to the first field effect transistor and to a ground terminal. The low-pass signal path is constructed by fourth and fifth transmission lines connected to the input and output terminals and having an effective length of &lgr;/4, at least one sixth transmission line connected between the fourth and fifth transmission lines, and at least two second field effect transistors each connected to the sixth transmission line and to the ground terminal. Each of the third and sixth transmission lines serves as an inductor.
REFERENCES:
patent: 3718873 (1973-02-01), Garver
patent: 4733203 (1988-03-01), Ayasli
patent: 5317290 (1994-05-01), Jacomb-Hood
patent: 208307 (1986-09-01), None
patent: 1-202007 (1989-08-01), None
Robert V. Garver, “Broad-Band Diode Phase Shifter”, IEEE Trans. on Microwave Theory and Techniques, vol. MTT-20, No. 5, pp. 314-323, May 1972.
Lee Benny
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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