Micromachine switch

Details Micromachine switch Micromachine switch

2001-07-09

2003-09-23

Enad, Elvin (Department: 2832)

Electricity: circuit makers and breakers

Electrostrictive or electrostatic

C200S245000, C361S234000, C216S013000

Reexamination Certificate

active

06624367

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a micromachine switch used in a milliwave circuit and microwave circuit.
BACKGROUND ART
Switch devices such as a PIN diode switch, HEMT switch, micromachine switch, and the like are used in a milliwave circuit and microwave circuit. Of these switches, the micromachine switch is characterized in that the loss is smaller than that of the other devices, and a compact high-integrated switch can be easily realized.
As a conventional micromachine switch, for example, a switch is described in Japanese Patent Laid-Open No. 9-17300 (U.S. Pat. No. 5,578,976).
FIG. 13
is a plan view showing the structure of this micromachine switch.
FIG. 14
is a sectional view taken along the line XIV-XIV′ of the micromachine switch shown in FIG.
13
.
As shown in
FIGS. 13 and 14
, signal lines
102
a
and
102
b
, lower electrode
111
, post
112
, and control lines
116
a
and
116
b
are formed on a dielectric substrate
104
. A GND plate
105
is formed on the lower surface of the dielectric substrate
104
.
The signal lines
102
a
and
102
b
are disposed apart from each other at a gap G. The signal lines
102
a
and
102
b
are lines for flowing high-frequency electromagnetic energy.
The lower electrode
111
is formed apart from the signal lines
102
and
102
b
including the gap G. The lower electrode
111
has a rectangular shape as a whole.
The control lines
116
a
and
116
b
are connected to side surfaces of the lower electrode
111
on the signal line
102
a
side and on the signal line
102
b
side, respectively. The control lines
116
a
and
116
b
are parallel to the signal lines
102
a
and
102
b
, respectively. A voltage for controlling the operation of a micromachine switch
101
is selectively applied from the control lines
116
a
and
116
b
to the lower electrode
111
.
The post
112
a
is formed apart from the lower electrode
111
on an extension line from the gap G to the lower electrode
111
.
The base portion of an arm
113
is fixed on the upper surface of the post
112
. The arm
113
extends from the upper surface of the post
112
to a portion above the gap G via a portion above the lower electrode
111
. The arm
113
is made of an insulating member.
An upper electrode
114
is formed on the upper surface of the arm
113
. The upper electrode
114
extends from a portion above the post
112
to a portion above the lower electrode
111
. A capacitor structure is formed by the upper electrode
114
and lower electrode
111
.
A contact
115
is formed on the distal end portion of the lower surface of the arm
113
. The contact
115
extends from a portion above an end portion of the signal line
102
a
to a portion above an end portion of the signal line
102
b
via the gap G.
When no voltage is applied to the lower electrode
111
, the contact
115
and signal lines
102
a
and
102
b
are apart from each other. Accordingly, a little high-frequency electromagnetic energy is transmitted from the signal line
102
a
to the signal line
102
b.
On the other hand, when a voltage is applied to the lower electrode
111
, an electrostatic force for attracting the upper electrode
114
to the lower electrode
111
is generated. This force makes the arm
113
curve, and the contact
115
is displaced downward. When the contact
115
is brought into contact with the signal lines
102
a
and
102
b
, the high-frequency electromagnetic energy is transmitted from the signal line
102
a
to the signal line
102
b.
When the control lines
116
a
and
116
b
are disposed on the same side as that of the signal lines
102
a
and
102
b
, respectively, the high-frequency electromagnetic energy flowing in the signal lines
102
a
and
102
b
leaks out into the control lines
116
a
and
116
b
. That is, the conventional micromachine switch
101
has a large energy loss. An increase in frequency of the energy makes this problem conspicuous.
When the distance between the signal lines
102
a
and
102
b
and the control lines
116
a
and
116
b
increases, the coupling amount of high-frequency electromagnetic energy becomes small. To reduce the energy loss, therefore, the lower electrode
111
continuous with the control lines
116
a
and
116
b
may be apart from the signal lines
102
a
and
102
b.
However, the distance between the lower electrode
111
and signal lines
102
a
and
102
b
cannot be made large by the following reasons.
First, a decrease in length of a portion of the arm
113
placed above a space from the upper portion of the post
112
to the lower electrode
111
requires a large voltage to drive the micromachine switch
101
. Therefore, to drive the micromachine switch
101
using a low voltage of 40V or less, a distance between the post
112
and lower electrode
111
need be made long.
In addition, if the length of the portion of the arm
113
from the upper electrode
114
to the contact
115
becomes long, the weight of the contact
115
makes the arm
113
curve. Thus, since a distance between the upper electrode
114
and contact
115
cannot be set long, the distance between the lower electrode
111
and the signal lines
102
a
and
102
b
must be inevitably shortened.
The present invention has been made to solve the above problem, and has as its object to reduce the loss of energy flowing in the signal line opened/closed by the micromachine switch.
DISCLOSURE OF INVENTION
In order to achieve the above object, a micromachine switch of the present invention is characterized by comprising at least two signal lines disposed apart from each other at a gap on a substrate and each having a fixed contact, a movable contact arranged above the fixed contacts via the gap and attached to an arm to connect the signal lines to each other in a high-frequency manner by the operation of the arm, an electrode disposed apart from the gap and each of the signal lines to receive a control signal to drive the arm, and a control line for connecting the control signal from a control terminal to the electrode, wherein the control line and the control terminal are disposed farther away from each of the signal lines than a position of the electrode.
In this case, in one structure of the control line, the portion of the control line, which is connected to the electrode, is formed obliquely with respect to one of the signal lines disposed on the same side as that of the control line. Alternatively, the control line is so formed as to extend from the electrode as a start point in a direction apart from one of the signal lines disposed on the same side as that of the control line.
In another structure, the control line includes a parallel portion which has one end connected to the electrode and is formed parallel to one of the signal lines disposed on the same side as that of the control line, and an inclined portion formed obliquely with respect to the one of the signal lines disposed on the same side as that of the control line, and connected to the other end of the parallel portion. Alternatively, the control line includes a parallel portion which has one end connected to the electrode and is formed parallel to one of the signal lines disposed on the same side as that of the control line, and an inclined portion connected to the other end of the parallel portion and extending from the other end of the parallel portion as a start point in a direction apart from the one of the signal lines disposed on the same side as that of the control line.
In this case, a length of the parallel portion of the control line is preferably not more than a ⅛ wavelength of a high-frequency signal flowing the signal lines.
In still another structure, the control line is connected to one of side surfaces of the electrode, which opposes the gap.
By forming the control line as described above, as a whole, the distance between the signal line and control line becomes larger than that in a case in which the control line is formed to be parallel to the signal line. In addition, when the control line having a predetermined length is to be formed, t

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