CIRCUIT DEVICE

• US 20090244857A1
• Filed: 03/20/2009
• Published: 10/01/2009
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: TANAKA, Takehito
• Granted Patent: US 8,120,925 B2
• Time in Patent Office: Days
• US Class Current: 361/748
• CPC Class Codes: G02F 1/0123 Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
• CPC Class Codes: G02F 1/225 in an optical waveguide structure
• CPC Class Codes: H01P 5/028 between strip lines

Abstract

a circuit device includes a dielectric substrate including a first face and a second face opposite side of the first face; a coplanar line including a first line, a second line and ground electrodes, the first line and the second line being decupled mutually, the ground electrodes formed around the first line and the second line, the first line, the second line and the ground electrodes formed on the first face of the dielectric substrate; a capacitor for connecting the first line and the second line; a termination resistor connecting the second line; a microstrip line formed on the second face of the dielectric substrate; and a conducting portion formed in the dielectric substrate and electrically connecting the first line and the microstrip line.

Claims

1. A circuit device comprising:

a dielectric substrate including a first face and a second face opposite side of the first face;

a coplanar line including a first line, a second line and ground electrodes, the first line and the second line being decupled mutually, the ground electrodes formed around the first line and the second line, the first line, the second line and the ground electrodes formed on the first face of the dielectric substrate;

a capacitor for connecting the first line and the second line;

a termination resistor connecting the second line;

a microstrip line formed on the second face of the dielectric substrate; and

a conducting portion formed in the dielectric substrate and electrically connecting the first line and the microstrip line.

2. The circuit device of claim 1, wherein the first line and the second line have a end portion and a wide portion being wider than the end portion, respectively, the wide portions facing each other at a decoupled portion of the first line and second line.

3. The circuit device of claim 2, wherein the first line and the second line have a tapered portion between the end portion and the wide portion, respectively, the tapered portion having a width continuously changing.

4. The circuit device of claim 3, wherein the wide portion has a line width in accordance with a width of the capacitor.

5. The circuit device of claim 3, wherein the conducting portion is a via hole being formed in the substrate and between the first line and the microstrip line.

6. The circuit device of claim 1, wherein the conducting portion is arranged at a portion of the first line having small electrical influence from the ground electrode.

7. The circuit device of claim 1, further comprising an electrode being electrically connected to the microstrip line via a conductor arranged between the first face and second face, the conductor arranged at different portion of the conducting portion.

8. The circuit device of claim 7, wherein the first line is provided a signal and the electrode is provided a DC bias signal.

9. The circuit device of claim 1, wherein the dielectric substrate has a thickness less or equal approximately 500 μ

m.

10. The circuit device of claim 1, further comprising an optical circuit includes an optical substrate having an electro-optical effect, the optical substrate including a optical wave guide and a progressive wave electrode;

wherein the first line is connected to the progressive wave electrode for terminating the signal and for providing the DC bias signal.

11. The circuit device of claim 10, further comprising a housing accommodating the optical circuit and the dielectric substrate.

12. The circuit device of claim 11, wherein the housing has an air layer to the dielectric substrate side, the air layer having a size being approximately unaffected electrical influence with respect to the dielectric substrate.

13. The circuit device of claim 10, wherein the termination resistor has an impedance amount for matching with the progressive wave electrode.