Semiconductor device

A semiconductor device, comprising:

• first and second power amplifier circuits differing in operating frequency, which respectively comprise a plurality of amplifier circuits configured in a multistage-connected form;
• and
• passive elements for matching circuits employed in the first and second power amplifier circuits and a bias circuit and a control circuit,
• wherein a first to a final stage of the plurality of amplifier circuits of the first and second power amplifier circuits are formed over one silicon semiconductor substrate,
• wherein the plurality of amplifier circuits respectively comprise field effect transistors,
• wherein drain and source electrodes of the field effect transistors are respectively formed over a main surface and a back surface of the semiconductor substrate,
• wherein the respective source electrodes of the plurality of field effect transistors are electrically connected to one another in the back surface of the semiconductor substrate,
• wherein the source electrodes are respectively connected to a fixed potential, and
• wherein resistivity of the semiconductor substrate is equal to or less than about 10 mΩ·cm.

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.

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 are 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, and
• 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 other.

A semiconductor device suitable for mounting in a cellular phone, comprising:

• power amplifier circuits,
• wherein the power amplifier circuits comprise a plurality of amplifier circuits constituted of field effect transistors configured in a multistage-connected form,
• wherein the respective power amplifier circuits are connected to one another via impedance matching circuits comprising passive elements,
• wherein the power amplifier circuits are controlled by a control circuit, and
• wherein the amplifying circuits constituting the power amplifier circuits are formed over a single semiconductor substrate formed of silicon.

A semiconductor device, comprising:

• a first power amplifier circuit formed over a first semiconductor chip and comprising a plurality of amplifier circuits configured in a multistage-connected form;
• and
• a wiring board having the first semiconductor chip paged thereover,
• wherein the first semiconductor chip has a semiconductor substrate formed of silicon,
• wherein the plurality of amplifying circuits comprise field effect transistors formed in the semiconductor substrate, and
• wherein a semiconductor chip including the power amplifier circuits and mounted over the wiring board is present exclusively on the first semiconductor chip.