Clock signal supply circuit with odd harmonic leakage...

Details Clock signal supply circuit with odd harmonic leakage... Clock signal supply circuit with odd harmonic leakage...

2002-12-06

2004-08-24

Callahan, Timothy P. (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Clock or pulse waveform generating

C327S295000

Reexamination Certificate

active

06781430

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a supply circuit of a clock signal in, for example, a computer.
2. Description of the Related Art
FIG. 4
shows a conventional clock signal supply circuit
1
. A clock signal outputted from a clock signal generator
35
is supplied to circuit units provided in the inside of a personal computer (called pasokon), such as a CPU
31
, a memory
32
, a video card
33
, and a sound card
34
. The clock signal generator
35
outputs a rectangular wave, and is mounted on a mother board
36
in the personal computer as shown in FIG.
5
.
The CPU
31
or the memory
32
is constructed as an integrated circuit, and is mounted on the mother board
36
. Besides, the video card
33
or the sound card
34
is made of a dedicated card-type board on which an image processing circuit or a sound processing circuit is constructed. Connectors
37
are attached on the mother board
36
, and these cards are mounted to the mother board
36
through the connectors
37
.
A wiring conductor (not shown), which becomes a bus, is formed on the mother board
36
, and the clock signal is supplied to the respective circuit devices through this wiring conductor.
In the conventional structure, the clock signal is transmitted on the mother board and is inputted to the respective circuit devices. The rectangular wave includes many higher harmonics as is generally known, and as shown in
FIG. 6
, the levels of odd harmonics are especially high. Thus, they easily leak out of the personal computer, and there has been a problem that they interfere with other electronic equipment.
SUMMARY OF THE INVENTION
The invention has an object to realize a circuit for preventing odd harmonics of a clock signal from leaking out of an equipment, such as a personal computer, using the clock signal.
To the above problem, a circuit of the invention includes a sine wave oscillator and a circuit operating with an oscillation signal, as a clock signal, outputted from the sine wave oscillator, and is characterized in that a waveform shaping circuit is provided correspondingly to the circuit, the circuit and the waveform shaping circuit are constructed in a same circuit unit, and the oscillation signal is converted into a rectangular wave by the waveform shaping circuit in the circuit unit and is supplied to the circuit.
Besides, a feature is that the circuit unit is an integrated circuit constituting a circuit such as a CPU or a memory.
Besides, a feature is that the circuit unit is a dedicated card-type board constituting a circuit such as a sound processing circuit or an image processing circuit.
Besides, a feature is that the sine wave oscillator is constituted by a PLL synthesizer.


REFERENCES:
patent: 6076171 (2000-06-01), Kawata
patent: 54131973 (1979-10-01), None
patent: 57069258 (1982-04-01), None
patent: 59169222 (1984-09-01), None
patent: 7-86878 (1995-03-01), None

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