Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Having specific delay in producing output waveform
Reexamination Certificate
1999-06-29
2001-10-30
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Having specific delay in producing output waveform
C327S284000
Reexamination Certificate
active
06310503
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic circuit, and more particularly to a circuit having a constant delay time regardless of the variation in a driving voltage.
2. Description of the Prior Art
Generally, a certain time is required when an electronic signal is transmitted, which is typically the time that the signal is delayed.
FIG. 1
is a circuit diagram of a conventional delay circuit. As shown in this drawing, the conventional delay circuit comprises an inverter
10
for inverting an input signal IN, a capacitor
11
connected to an output terminal of the inverter
10
in parallel and an inverter
12
for inverting the output signal from the inverter
10
so as to generate a delayed signal OUT.
The delay circuit of
FIG. 1
is adapted to delay the input signal IN using a RC delay according to the turn-on resistance of an electric wire and a capacitance of the capacitor
11
wherein the delay time is determined mainly by the capacitance thereof.
If a voltage applied to the capacitor
11
is varied, an amount of current flowing through the output terminal of the inverter
10
and the capacitor
11
is varied, too. Accordingly, the time for charging the capacitor
11
becomes diverse resulting in a variation in the delay time. Typically, the current is proportional to a square of driving voltage and the capacitance to the driving voltage. Thus, the driving voltage should be maintained constantly to keep the delay time fixed, which is difficult in actuality. As a result, there is a need for a delay circuit which can have a constant delay time regardless of the variation in the driving voltage.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in prior arts and to provide a circuit having a constant delay time regardless of variation of a driving voltage.
To accomplish the above mentioned object, the present invention provides a circuit having a constant delay time comprising: an electric wire for transmitting a driving signal from a driver; a capacitor connected between said electric wire and ground, and for delaying transmission of said driving signal; and a current source connected to said electric wire and capacitor in parallel, and for keeping an amount of an electric current applied to said capacitor constant when a signal applied to said capacitor is varied.
The present invention further provides a circuit having a constant delay time comprising: an electric wire for transmitting a signal; a capacitor connected to said electric wire in parallel and for delaying the transmission of said signal; a current controlling transistor connected to said capacitor in parallel, and coupled between said electric wire and the ground; and a reference voltage generator at its output terminal connected to a gate of said current controlling transistor, and for varying an amount of an electric current flowing through said current controlling transistor when a level of a voltage applied to said capacitor is changed, thereby keeping an amount of an electric current flowing through said capacitor constant.
The present invention further provides a circuit having a constant delay time comprising: an inverter for inverting an input signal to generate an output signal; an electric wire for transmitting said output signal; a capacitor connected between said electric wire and a terminal of the source voltage, and for delaying the transmission of said output signal; a first current controlling transistor connected to said capacitor in parallel, and connected between said electric wire and a terminal of the voltage source; first switching means connected to a gate of said first current controlling transistor, and operated in response to a first control signal which is enabled when a level of a voltage applied to said capacitor varies, whereas it is disabled to turn off said first current controlling transistor when that of the voltage goes constant; and a first reference voltage generator at its output terminal connected to said first switching means, and for varying an amount of an electric current flowing through said first current controlling transistor when a level of a voltage applied to said capacitor is changed, thereby keeping an amount of an electric current flowing through said capacitor constant.
The present invention further provides a circuit having a constant delay time comprising: an inverter for inverting an input signal to generate an output signal; an electric wire for transmitting said output signal; a capacitor connected between said electric wire and the ground, and for delaying the transmission of said output signal; a first current controlling transistor connected to said capacitor in parallel, and connected between said electric wire and the ground; first switching means connected to a gate of said first current controlling transistor, and for increasing an amount of the electric current flowing through said first current controlling transistor when a voltage applied to said capacitor is increased, thereby causing the amount of the electric current flowing through said capacitor to be kept constant; a second current controlling transistor connected between said electric wire and a terminal of the source voltage; and second switching means connected to a gate of said second current controlling transistor, and for decreasing an amount of the electric current flowing through said second current controlling transistor when a voltage applied to said capacitor is decreased, thereby causing the amount of the electric current flowing through said capacitor to be kept constant.
REFERENCES:
patent: 5397967 (1995-03-01), Carobolante et al.
patent: 5617051 (1997-04-01), Bingham
patent: 5748542 (1998-05-01), Zheng et al.
patent: 8-83487 (1996-03-01), None
Hong Hyun Sung
Kim Hack Soo
Kim Saeng Hwan
Cox Cassandra
Crompton Seager & Tufte LLC
Hyundai Electronics Industries Co,. Ltd.
Tran Toan
LandOfFree
Delay circuit having a constant delay time does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Delay circuit having a constant delay time, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Delay circuit having a constant delay time will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2585236