Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By amplitude
Reexamination Certificate
1998-12-14
2001-02-27
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By amplitude
C327S053000
Reexamination Certificate
active
06194919
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device, and in particular, to a sense amplifier.
2. Background of Related Art
A main amplifier generally uses a voltage sensing method or a current sensing one. The voltage sensing method will now be described.
A signal, amplified by a sense amplifier, is transmitted from a bit line to a data sense amplifier by column selection. Since the sense amplifier is connected in common in a single cell array block, a long wiring length is needed, which makes it difficult to transmit signals at high speed. There is a need to develop a high-sensitivity data sense amplifier that reduces the parasitic capacitance and resistance through such wiring.
FIG. 1
is a circuit diagram of a related art main amplifier using a voltage sensing method. As shown in
FIG. 1
, a main amplifier using the voltage sensing method includes a first-stage amplifying part
11
, a first enabling part
13
that drives the first-stage amplifying part
11
, a second-stage amplifying part
15
and a second enabling part
17
that drives second-stage amplifying part
15
.
The first-stage amplifying part
11
has first and second differential amplifiers
11
a
and
11
b
, and the second amplifying part
15
has third and fourth differential amplifiers
15
a
and
15
b
. The first and second enabling parts
13
and
17
each are a metal oxide semiconductor (MOS) transistor. In the related art main amplifier using the voltage sensing method, the first-stage amplifying part
11
is driven by the first enabling part
13
to amplify an applied signal. The amplified signal is transmitted to second-stage amplifying part
15
to be amplified a second time. The differential amplifier is also called a data bus sense amplifier, and consists of a current mirror with four transistors.
Transistors Q
1
, Q
2
, Q
3
and Q
4
constitute the first differential amplifier
11
a
, and transistors Q
5
, Q
6
, Q
7
and Q
8
form the second differential amplifier
11
b
. Transistors Q
9
, Q
10
, Q
11
, and Q
12
and transistors Q
13
, Q
14
, Q
15
, and Q
16
respectively constitute the third differential amplifier
15
a
and the fourth differential amplifier
15
b
. One of a data bus DB and a data bus {overscore (DB)}, which are precharged “high” during a data read, transitions “low” from output data of a bit-line sense amplifier (not shown), and the other one maintains a “high” level. A low-level signal is applied to an input terminal of the transistor Q
1
, and a high-level signal is input to an input terminal of the transistor Q
2
. A low-level signal is applied to an input terminal of the transistor Q
5
, and a high-level signal is input to the transistor Q
6
. If a driving signal is input to first enabling part
13
, the MOS transistor is turned on. The signal, amplified once by the first differential amplifier
11
a
, is transmitted to the third and fourth differential amplifiers
15
a
and
15
b
of the second-stage amplifying part
15
. Similarly, the signal, amplified once by the second differential amplifier
11
b
, is sent to the third and fourth differential amplifiers
15
a
and
15
b
of the second-stage amplifying part
15
.
As shown in
FIG. 1
, the signal, amplified by the first differential amplifier
11
a
, is simultaneously applied to a gate of the transistor Q
9
of the second-stage amplifying part
15
and a gate of the transistor Q
13
. The signal, amplified by the second differential amplifier
11
b
, is concurrently applied to a gate of the transistors Q
10
and Q
14
of the second-stage amplifying part
15
. The third and fourth differential amplifiers
15
a
and
15
b
amplify the first amplified signal and produce the same through an output buffer (not shown).
FIG. 2
is a circuit diagram of a related art main amplifier using the current sensing method. The related art main amplifier using the current sensing method includes a current/voltage converter
21
and a differential amplifying part
23
amplifying a signal converted into a voltage.
The current/voltage converter
21
converts a current into a voltage and is constituted by a current mirror having four transistors M
1
, M
2
, M
3
and M
4
. A signal, output from a bit-line amplifier (not shown), is input to a source of the transistor M
2
and a drain of the transistor M
4
. Biases
1
,
2
and
3
are applied to the transistors M
1
, M
2
and M
3
so that each transistor is actuated in the saturation region.
In the related art current amplifier using the current sensing method, the applied current signal is applied not to the gate of one of the transistors M
1
, M
2
and M
3
but to the transistor M
4
actuated in the linear region. Therefore, the voltage equivalent to the current is produced from a gate of the transistor M
4
. The voltage, output from the gate of the transistor M
4
, is transmitted to differential amplifying part
23
and then amplified, before being output through the output buffer (not shown).
FIG. 3
graphically shows the result of simulation of the related art main amplifier of the voltage sensing method. As shown in
FIG. 3
, as an input signal and an enabling signal are applied to the main amplifier, the main amplifier is enabled to amplify the signal. It takes about 2.7 nanoseconds (ns) until the main amplifier produces an output signal.
As described above, the related art main amplifiers have various problems. In the main amplifier using the voltage sensing method, the signal produced from the bit-line amplifier (the input signal of the main amplifier) is applied to each gate of the transistors of the differential amplifying parts, which causes a transmission delay. The transmission delay is a severe problem for a highly-integrated semiconductor device because of the large parasitic capacitance. The amplification speed of the related art main amplifier of voltage sensing method is lower than that of current sensing method. In the related art current main amplifier, since biases
1
,
2
and
3
are applied so that each transistor is actuated in the saturation region, the main amplifier of the current sensing method varies with a power supply voltage level. When the power supply voltage is low and a transmission line is long, significant time can be required to convert the current into a voltage. Such delay can be a problem for a highly-integrated semiconductor device.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a main amplifier that substantially obviates one or more of the problems caused by limitations and disadvantages of the related art.
Another object of the present invention is to provide a sense amplifier that overcomes variation in an applied signal caused by a low power supply voltage.
Another object of the present invention is to provide a current sense amplifier that prevents a signal transmission delay.
Another object of the present invention is to provide a main current sense amplifier that overcomes a decrease of an applied signal, which results from a low power supply voltage through current amplification, and prevents a signal transmission delay to ensure high-speed data generation in a highly-integrated semiconductor device by the corresponding parasitic capacitance.
To achieve at least these objects and other advantages in a whole or in parts and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a main amplifier including a current amplifying part and a current/voltage converting part each performing current amplification with respect to a signal applied from a first data bus and a second data bus, and converting the amplified signal current into a voltage and a voltage amplifying part amplifying the voltage from the current amplifying part and current/voltage converting part to produce an amplified output.
To further achieve the above objects in a whole or in parts and according to another aspect of the present invention, a main amplifier is provided that includes a first current amplifier circuit that amplifies
Fleshner & Kim LLP
Hyundai Electronics Industries Co,. Ltd.
Nguyen Linh M
Tran Toan
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