Optical module

1. An optical module comprising:

a semiconductor optical device with a pair of first pads spaced apart in a first direction and with a second pad between the pair of first pads;

a sub-board with a first circuit and a second circuit adjacent in the first direction on a surface thereof, the sub-board having a first back electrode on a back surface thereof to be electrically continuous to and overlap with the first circuit, the sub-board having a second back electrode on the back surface to be electrically continuous to and overlap with the second circuit, the sub-board being next to the semiconductor optical device in a second direction intersecting with the first direction;

a pair of first wires electrically connecting the respective pair of first pads to the first circuit;

a second wire electrically connecting the second pad to the second circuit; and

a first capacitor and a second capacitor, over which the sub-board is placed, the first capacitor and the second capacitor being adjacent to each other in the first direction,

the first capacitor being opposed to and electrically connected to the first back electrode,

the second capacitor being opposed to and electrically connected to the second back electrode,

each of the first circuit and the second circuit having a main region that overlaps with a corresponding one of the first capacitor and the second capacitor,

at least one circuit of the first circuit and the second circuit having an extension region extending from the main region toward another circuit of the first circuit and the second circuit,

at least one of one of the pair of first wires and the second wire being bonded to the extension region.

2. The optical module according to claim 1 , wherein the pair of first wires are bonded to the first circuit at a pair of positions separated from each other in the first direction.

3. The optical module according to claim 2 , wherein the second wire is bonded to the second circuit at a position between the pair of positions in the first direction.

4. The optical module according to claim 1 , wherein

the first circuit has the extension region, and

the one of the pair of first wires is bonded to the extension region of the first circuit.

5. The optical module according to claim 4 , wherein the extension region of the first circuit is farther from the semiconductor optical device than a position where the second wire is bonded to the second circuit.

6. The optical module according to claim 5 , wherein the extension region of the first circuit is farther from the first capacitor than the position where the second wire is bonded to the second circuit.

7. The optical module according to claim 5 , wherein the extension region of the first circuit overlaps with the second capacitor.

8. The optical module according to claim 5 , wherein

each of the first circuit and the second circuit has the extension region, and

the one of the pair of first wires is bonded to the extension region at a position farther from the first capacitor than the position where the second wire is bonded to the extension region.

9. The optical module according to claim 8 , wherein the extension region of the first circuit and the extension region of the second circuit are adjacent to each other in the second direction.

10. The optical module according to claim 9 , wherein the extension region of the second circuit is closer to the semiconductor optical device than the extension region of the first circuit.

11. The optical module according to claim 1 , wherein

at least one of the first circuit and the second circuit includes an interconnect line and a pad and a resistor connected in series between the interconnect line and the pad, and

at least part of the pad is the extension region.