Semiconductor device

1. A semiconductor device, comprising:

a plurality of amplifying stages each comprising amplifier circuits; and

secondary circuits,

said all amplifying stages and said secondary circuits being provided over a same semiconductor chip,

wherein the plurality of amplifying stages are respectively formed of field effect transistors placed over a semiconductor substrate of silicon of the semiconductor chip,

wherein the amplifier circuits are disposed on a periphery of a main surface of the semiconductor chip, and

wherein the secondary circuits are placed inside the periphery of the main surface of the semiconductor chip, and

wherein a resistivity of the semiconductor substrate is smaller than 10 mΩ·cm, and wherein the field effect transistors are respectively configured as horizontal type field effect transistors having respective sources of the field effect transistors electrically connected to the semiconductor substrate through semiconductor regions and electrically connected to a fixed potential via an electrode over a back surface of the semiconductor substrate.

2. A semiconductor device of a multiband system, which is capable of coping with high frequency signals lying in a plurality of different frequency bands, said semiconductor device comprising:

a plurality of amplifier circuits which respectively adapt to the high frequency signals lying in the plurality of different frequency bands; and

a plurality of amplifying stages which constitute the plurality of amplifier circuits respectively,

wherein each of the plurality of amplifying stages is provided over one semiconductor chip,

wherein the plurality of amplifying stages are respectively formed of field effect transistors placed over a semiconductor substrate formed of silicon of the semiconductor chip,

wherein the amplifying stages corresponding to a final stage of the plurality of amplifier circuits are placed at sides of the semiconductor chip opposite to each others,

wherein resistivity of the semiconductor substrate is less than 10 mΩ·cm, the field effect transistors are respectively configured as horizontal type field effect transistors, and the sources of the field effect transistors are electrically connected to the semiconductor substrate through semiconductor regions and are electrically connected to a fixed potential via an electrode over the back surface of the semiconductor substrate, and

wherein the semiconductor chip is provided with passive elements for matching circuits, and a bias circuit and a control circuit for the amplifier circuits.

3. A semiconductor device according to claim 2 , wherein the final amplifying stages of the respective amplifier circuits are disposed to be point-symmetric to each other.

4. A semiconductor device according to claim 3 , wherein the plurality of amplifier circuits respectively include three amplifying stages.

5. A semiconductor device comprising:

a semiconductor substrate having a main surface and a back surface opposite to the main surface, said semiconductor substrate being made of silicon, and said semiconductor substrate having resistivity smaller than 10 mΩ·cm;

a first power amplifier circuit and a second power amplifier circuit disposed over the main surface of the semiconductor substrate, each of said first and second power amplifier circuits being comprised of multistage-connected amplifying stages, each of said amplifying stages being comprised of a field effect transistor (FET), and said FET having a gate electrode, a source region and a drain region formed over the main surface of the semiconductor substrate;

a control circuit controlling the first and second power amplifier circuits disposed over the main surface of the semiconductor substrate, said control circuit being disposed between the first and second power amplifier circuits; and

a back electrode formed on the back surface of the semiconductor substrate, said back electrode being electrically connected to the semiconductor substrate and the source region of each of the FETs, and said back electrode is electrically coupled with a reference potential.

6. A semiconductor device according to claim 5 , wherein said main surface of the semiconductor substrate has a first side, a second side, a third side and a fourth side in a plan view;

said first side is opposite to the second side;

said third side is opposite to the fourth side; and

said first and second power amplifier circuits are disposed along the first and second sides respectively.

7. A semiconductor device according to claim 5 , wherein said back electrode is electrically coupled with a reference potential.

8. A semiconductor device according to claim 5 , wherein each of said first and second power amplifier circuits includes three amplifying stages.

9. A semiconductor device for use in a radio communication device, comprising:

a semiconductor substrate having a first main surface and a first back surface opposite to the first main surface, said semiconductor substrate being made of silicon, and said semiconductor substrate having resistivity smaller than 10 mΩ·cm;

a semiconductor layer formed over the first main surface of the semiconductor substrate; said semiconductor layer having a second main surface and a second back surface opposite to the second main surface, said first main surface and second back surface being positioned between the first back surface and second main surface;

a first power amplifier circuit and a second power amplifier circuit disposed over the second main surface of the semiconductor layer, each of said first and second power amplifier circuits being comprised of multistage-connected amplifying stages, each of said amplifying stages being comprised of a field effect transistor (FET), and said FET having a gate electrode, a source region and a drain region formed over the second main surface of the semiconductor layer;

a control circuit controlling the first and second power amplifier circuits disposed over the second main surface of the semiconductor layer, said control circuit being disposed between the first and second power amplifier circuits; and

a back electrode formed on the first back surface of the semiconductor substrate, said back electrode being electrically connected to the semiconductor substrate and the source region of each of the FETs, and said back electrode is electrically coupled with a reference potential.

10. A semiconductor device according to claim 9 , wherein said second main surface of the semiconductor layer has a first side, a second side, a third side and a fourth side in a plan view;

said first side is opposite to the second side;

said third side is opposite to the fourth side; and

said first and second power amplifier circuits are disposed along the first and second sides respectively.

11. A semiconductor device according to claim 9 , wherein said reference potential is a ground potential.

12. A semiconductor device according to claim 9 , wherein said semiconductor layer is an epitaxial layer.

13. A semiconductor device according to claim 9 , wherein resistivity of the semiconductor layer is higher than that of the semiconductor substrate.