Printed circuit board and optical transmission device
View Patent ↗A printed circuit board includes a substrate, a signal output circuit formed on the substrate for outputting a clock signal, a shield for covering the signal output circuit, a power supply wiring for connecting the signal output circuit and a power source, and a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal. The trap filter includes a resonance circuit having one portion of the power supply wiring, an inner-layer wiring of the substrate located below the one portion of the power supply wiring, an inner-layer ground wiring of the substrate located below the inner-layer wiring, and a via hole for connecting the one portion of the power supply wiring and the inner-layer wiring.
1. A printed circuit board, comprising:
a substrate;
a signal output circuit formed on the substrate, for outputting a clock signal;
a shield for covering the signal output circuit;
a power supply wiring for connecting the signal output circuit and a power source; and
a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal;
wherein the trap filter comprises a resonance circuit including:
one portion of the power supply wiring;
an inner-layer wiring of the substrate located below the one portion of the power supply wiring;
an inner-layer ground wiring of the substrate located below the inner-layer wiring; and
a via hole for connecting the one portion of the power supply wiring and the inner-layer wiring.
2. The printed circuit board according to claim 1 ,
wherein the signal output circuit comprises:
an oscillator circuit for oscillating a clock signal; and
an amplifier circuit for amplifying the clock signal oscillated by the oscillator circuit; and
wherein the trap filter is provided to the power supply wiring for each of the oscillator circuit and the amplifier circuit.
3. The printed circuit board according to claim 1 , further comprising a capacitor provided to the power supply wiring.
4. A printed circuit board, comprising:
a substrate;
a signal output circuit formed on the substrate, for outputting a clock signal;
a shield for covering the signal output circuit;
a power supply wiring for connecting the signal output circuit and a power source; and
a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal;
wherein a plurality of the trap filters are provided to the power supply wiring.
5. The printed circuit board according to claim 4 ,
wherein the plurality of the trap filters have a distance between centers of respective via holes thereof set to not more than ¼ a wavelength of the clock signal.
6. The printed circuit board according to claim 4 ,
wherein the plurality of the trap filters have a distance between centers of respective via holes thereof set to not more than 3 mm.
7. The printed circuit board according to claim 4 ,
wherein the plurality of the trap filters have mutually different frequency components to be attenuated.
8. The printed circuit board according to claim 4 ,
wherein the signal output circuit comprises:
an oscillator circuit for oscillating a clock signal; and
an amplifier circuit for amplifying the clock signal oscillated by the oscillator circuit; and
wherein the trap filter is provided to the power supply wiring for each of the oscillator circuit and the amplifier circuit.
9. The printed circuit board according to claim 4 , further comprising a capacitor provided to the power supply wiring.
10. An optical transmission device, comprising:
a substrate;
a signal output circuit formed on the substrate, for outputting a clock signal;
a shield for covering the signal output circuit;
a power supply wiring for connecting the signal output circuit and a power source;
a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal; and
an optical transmission section for receiving the clock signal output by the signal output circuit, modulating an optical signal, and transmitting the optical signal;
wherein the trap filter comprises a resonance circuit including:
one portion of the power supply wiring;
an inner-layer wiring of the substrate located below the one portion of the power supply wiring;
an inner-layer ground wiring of the substrate located below the inner-layer wiring; and
a via hole for connecting the one portion of the power supply wiring and the inner-layer wiring.
11. An optical transmission device, comprising:
a substrate;
a signal output circuit formed on the substrate, for outputting a clock signal;
a shield for covering the signal output circuit;
a power supply wiring for connecting the signal output circuit and a power source;
a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal; and
an optical transmission section for receiving the clock signal output by the signal output circuit, modulating an optical signal, and transmitting the optical signal;
wherein a plurality of the trap filters are provided to the power supply wiring.