Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2003-04-10
2004-10-26
Cao, Phat X. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S130000
Reexamination Certificate
active
06809387
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2003-32308, filed on Feb. 10, 2003, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power switching device.
2. Related Background Art
MIS (Metal Insulated Semiconductor) transistors, such as power MOSFETs and IGBTs (Insulated Gate Bipolar Transistors) are used in various electronic apparatuses such as power supplies and inverters.
FIG. 9
is a circuit diagram of a conventional DC—DC converter. A DC—DC converter
500
includes a power MOSFET Q
1
(hereafter also referred to as transistor Q
1
) connected between an input IN and an output OUT. The transistor Q
1
is driven by a driver DR
1
, which is controlled at a high frequency by a control circuit IC
1
.
The DC—DC converter
500
further includes an inductor L, a capacitor C
in
, and a capacitor C
out
. The inductor L, the capacitor C
in
and the capacitor C
out
convert an input voltage V
in
to an output voltage V
out
by switching on or off the transistor Q
1
.
The DC—DC converter
500
further includes a diode DI and a power MOSFET Q
2
(hereafter also referred to as transistor Q
2
). The diode DI and the transistor Q
2
complement an output current of the DC—DC converter when the transistor Q
1
is switched from ON to OFF. When the transistor Q
1
is ON, therefore, the transistor Q
2
is OFF. When the transistor Q
1
is switched from ON to OFF, the transistor Q
2
is switched from OFF to ON. In other words, the DC—DC converter
500
is a DC—DC converter of synchronous commutation type. The transistor Q
2
is driven by a driver DR
2
, which is controlled by a control circuit IC
1
.
In the conventional transistor Q
1
, all cells are driven by using one gate electrode. The transistor Q
1
, has a large number of cells connected in parallel to each other in order to let a large current flow from the input to the output. Gate electrodes are provided respectively on these cells, and aluminum wiring is connected to gate electrodes. The aluminum wiring is connected to a bonding pad (not illustrated). By applying a voltage to the aluminum wiring via the bonding pad, the potential at the gate electrodes of all cells is changed. As a result, all cells are switched on or off. This means that the area of an activated cell region (hereafter referred to as activated region) depends upon the chip size and it is fixed.
For increasing the switching speed of the transistor Q
1
, it is effective to decrease the resistance or inductance of the aluminum wiring. In the conventional technique, the width of aluminum wiring is made wider in fabrication, or a plurality of pieces of aluminum wiring have been fabricated, in order to reduce the resistance or inductance of aluminum wiring.
In the case where the resistance of the aluminum wiring is reduced, however, the driver DR
1
, must let flow a large current. Therefore, the burden imposed on the driver DR
1
, increases. In addition, in this case, a large current flows through the bonding wire to the gate electrode. Therefore, it becomes necessary to consider the resistance and inductance of the bonding wire.
Therefore, a power switching device capable of conducting switching at a high speed is desired.
SUMMARY OF THE INVENTION
A power switching device comprises a semiconductor substrate; a plurality of cells, each of which switches a current from a power supply to a load on the basis of a potential at a gate electrode, said cells being arranged on said semiconductor substrate to form a cell array; and a plurality of drivers connected to the gate electrode, said plurality of drivers being distributively arranged in said cell array or being distributively arranged peripheral said cell array.
A power switching device comprises a switching circuit including a semiconductor substrate, a plurality of cells, each of which switches a current from a power supply to a load on the basis of a potential at a gate electrode, said cells being arranged on said semiconductor substrate to form a cell array, and a plurality of drivers connected to the gate electrode, said a plurality of drivers being distributively arranged in said cell array or being distributively arranged peripheral said cell array; a control circuit to control said plurality of drivers; and a detection circuit to detect a current that flows through said switching circuit, said detection circuit feeding back a result of the detection to said control circuit.
A power switching device comprises a switching circuit including a semiconductor substrate, a plurality of cells, each of which switches a current from a power supply to a load on the basis of a potential at a gate electrode, said cells being arranged on said semiconductor substrate to form a cell array, and a plurality of drivers connected to the gate electrode, said a plurality of drivers being distributively arranged in said cell array or being distributively arranged peripheral said cell array; and a control circuit to control said plurality of drivers on the basis of an operation frequency of said switching circuit.
REFERENCES:
patent: 5693966 (1997-12-01), Anazawa et al.
patent: 6653697 (2003-11-01), Hidaka et al.
patent: 6-216315 (1994-08-01), None
patent: 8-204183 (1996-08-01), None
patent: 8-274182 (1996-10-01), None
patent: 2002-16486 (2002-01-01), None
Cao Phat X.
Kabushiki Kaisha Toshiba
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