Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Amplitude control
Reexamination Certificate
2002-12-18
2004-08-31
Le, Dinh T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Amplitude control
C326S087000, C326S081000
Reexamination Certificate
active
06784719
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. P2001-386703, filed on Dec. 19, 2001; 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 level shift circuit converting a signal level between two circuits supplied by different power sources respectively.
2. Description of the Related Art
A level shift circuit
200
shown in
FIG. 1A
is used to convert a signal of amplitude Va received from a circuit
201
to a signal of amplitude Vb supplied to a circuit
204
. The level shift circuit
200
consists of an inverter
202
, and an inverter
203
having an input terminal connected to an output terminal of the inverter
202
. The voltage Va is supplied to the circuit
201
and to the inverter
202
from a power source VCC
1
. The voltage Vb is supplied to the inverter
203
and to the circuit
204
from a power source VCC
2
.
When the voltage of an input signal Vin transmitted from the circuit
201
becomes larger than a threshold voltage Vth(a) of the inverter
202
, the output voltage V
1
of the inverter
202
starts increasing. When the output voltage V
1
of the inverter
202
becomes smaller than a threshold voltage Vth(b) of the inverter
203
, the output signal Vout supplied from an output terminal of the inverter
203
starts increasing. The output signal Vout is supplied to the circuit
204
. However, the threshold voltage Vth(b) of the inverter
203
is different from the threshold voltage Vth(a) of the inverter
202
, because the inverters
202
and
203
are supplied with different voltages Va and Vb. In other words, a trailing edge of the output signal Vout is delayed, because the threshold voltage Vth(b) is different from the threshold voltage Vth(a). As shown in
FIG. 1B
, a low level period TBoff of the output signal Vout is longer than a high level period TBon. In other words, a duty of the output signal Vout is different from a duty of the input signal Vin.
SUMMARY OF THE INVENTION
In a aspect of the present invention, a level shift circuit encompasses a first transmission circuit configured to transmit a leading edge of an input signal, a second transmission circuit configured to transmit a trailing edge of the input signal, and a composite circuit configured to generate an output signal by synthesizing the leading edge and the trailing edge.
REFERENCES:
patent: 5486785 (1996-01-01), Blankenship
patent: 5498980 (1996-03-01), Bowles
patent: 5914624 (1999-06-01), Son
patent: 5952868 (1999-09-01), Gowni et al.
patent: 6025738 (2000-02-01), Masleid
patent: 6163170 (2000-12-01), Takinomi
patent: 6229365 (2001-05-01), Iketani et al.
patent: 6323738 (2001-11-01), Yoshizawa et al.
patent: 6566932 (2003-05-01), Yoon
patent: 8-330939 (1996-12-01), None
Okamoto Ryuta
Takenaka Kyoichi
Yoshizawa Akihiko
Kabushiki Kaisha Toshiba
Le Dinh T.
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