Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Charge transfer device
Reexamination Certificate
1999-09-20
2002-08-20
Loke, Steven (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Charge transfer device
C257S239000, C257S214000, C257S912000
Reexamination Certificate
active
06437378
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Patent Application No. 98-39100, filed Sep. 21, 1998, the entire disclosure of which is hereby incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to the field of integrated circuits in general, and more particularly to charge coupled devices.
BACKGROUND OF THE INVENTION
Solid state image pickup devices, such as Charge Coupled Devices (CCDs), can be relatively small, light weight, and consume less power than other image pickup type devices such as an electron gun. Therefore, it is known to use CCDs in broadcasting, domestic video cameras, monitoring camera systems, digital still cameras, and the like.
The CCD shown in
FIG. 1
is arranged in the form of a charge coupled array that includes a horizontal transfer section
10
. The horizontal transfer section
10
includes transfer gate electrodes
12
formed on an integrated circuit substrate such as a semiconductor substrate
11
. An output gate electrode
13
is disposed adjacent to the last one of the transfer gate electrodes
12
on the semiconductor substrate
11
. An n type impurity region
14
is formed in the semiconductor substrate
11
adjacent to the output gate electrode
13
. The n type impurity region
14
is a floating diffusion region.
A reset gate electrode
16
is disposed between the floating diffusion region
14
and an n type impurity region
15
. The n type impurity region
15
is formed in the surface region of the semiconductor substrate
11
adjacent to the reset gate electrode
16
. The floating diffusion region
14
, the n type impurity region
15
and the reset gate electrode
16
form a Field Effect Transistor (FET)
20
.
In operation, the potential at the floating diffusion region
14
is reset to the voltage level VOD by application the reset signal &phgr;R. Signal charges are transferred from the array by the horizontal transfer section
10
and converted from signal charges into signal voltages in accordance with the respective variation of the input potential from the reset voltage level. In particular, clock signals &phgr;H applied at the output gate electrode
13
cause electrons (charge signals) to enter the floating diffusion region
14
. The electrons are stored in the floating diffusion region
14
in accordance with the capacitance associated with the floating diffusion region
14
.
The presence of the charge signals in the floating diffusion region
14
may
10
cause the voltage level thereon to be lowered compared with the initial reset voltage level which is provided by the reset signal &phgr;R. The output circuit
30
detects the lowering of the potential of the floating diffusion region
14
and outputs a corresponding voltage level. The voltage level at the floating diffusion region is reset by the application of the reset signal &phgr;R before reading the next charge signals.
It is known to use CCDs in situations having relatively low levels of illumination, wherein respective weak signal charges may need to be converted into signal voltages for output. Unfortunately, as the area occupied by the CCDs decreases, the capacitance of the floating diffusion region
14
may make it difficult to provide adequate signal voltages in situations involving low level illumination. Accordingly, there is a need to allow improved CCDs and methods of transferring charge signals in CCDs.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to allow improved charge coupled devices and methods of transferring charge signals from charge coupled devices.
It is another object of the present invention to allow charge coupled devices having increased sensitivity.
These, and other objects of the present invention, may be achieved by charge coupled devices that include an integrated circuit substrate and a transfer circuit, in the integrated circuit substrate, that transfers charge signals in the charge coupled device to provide transferred charge signals. An amplifier, in the integrated circuit substrate and electrically coupled to the transfer circuit, amplifies the transferred charge signals to generate amplified charge signals.
According to the present invention, the amplifier can provide improved sensitivity by amplifying the transferred charge signals. The amplified charge signals can be amplified by a gain factor (&bgr;) of the amplifier. The sensitivity of the charge coupled device may also be increased by reducing the associated capacitance.
In another aspect of the present invention, the charge coupled device includes an output circuit, electrically coupled to the amplifier, that outputs the amplified charge signals from the charge coupled device.
In another aspect of the present invention, the charge coupled device includes a reset circuit, electrically coupled to the amplifier, that resets a level of the amplified charge signals in response to a reset signal applied to the reset circuit.
In one embodiment, the reset circuit is a field effect transistor that includes a drain region electrically coupled to a reset voltage level and a gate region electrically coupled to a reset signal line. A source region is electrically coupled to the amplifier and the n type semiconductor source region electrically couples the amplifier to the reset voltage level in response to a reset signal applied to the reset signal line.
REFERENCES:
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patent: 3943543 (1976-03-01), Caywood
patent: 4097885 (1978-06-01), Walsh
patent: 4148132 (1979-04-01), Bower
patent: 4831425 (1989-05-01), Pals et al.
patent: 5097305 (1992-03-01), Mead et al.
patent: 5202907 (1993-04-01), Yonemoto
patent: 5270559 (1993-12-01), Yariv et al.
patent: 5369293 (1994-11-01), Slob
patent: 5483090 (1996-01-01), Kitamura et al.
patent: 5498887 (1996-03-01), Ohki et al.
patent: 5563429 (1996-10-01), Isogai
patent: 5942774 (1999-08-01), Isogai et al.
patent: 5990471 (1999-11-01), Watanabe
patent: 10-50977 (1998-02-01), None
Loke Steven
Myers Bigel & Sibley & Sajovec
Nadav Ori
Samsung Electronics Co,. Ltd.
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