Attenuator with switch function and mobile telephone terminal device using the same

1. A mobile telephone terminal device, characterized in using, for the purpose of switching of a selected band between two bands and for the purpose of gain control in the selected band, an attenuator with switch function which comprises: a first variable resistor ( 41 ) inserted in a first signal line ( 47 ) which connects a first signal input part ( 43 ) with a first signal output part ( 45 ); and a second variable resistor ( 42 ) inserted in a second signal line ( 48 ) which connects a second signal input part ( 44 ) with a second signal output part ( 46 ), said attenuator being characterized in that as the attenuation of each one of said first and said second variable resistors ( 41 ) and ( 42 ) is controlled by means of a gain control voltage, either one of outputs on said first and said second signal lines ( 47 ) and ( 48 ) is blocked and the gain of the remaining output on said first and said second signal lines ( 47 ) and ( 48 ) is controlled linearly and continuously.

2. A mobile telephone terminal device, characterized in using, for the purpose of switching of a selected band between two bands and for the purpose of gain control in the selected band, an attenuator with switch function which comprises: a first variable resistor ( 41 ) inserted in a first signal line ( 47 ) which connects a first signal input part ( 43 ) with a first signal output part ( 45 ); a second variable resistor ( 42 ) inserted in a second signal line ( 48 ) which connects a second signal input part ( 44 ) with a second signal output part ( 46 ); a first and a second reference voltage applying parts ( 51 ) and ( 52 ) which are connected respectively with said first and said second variable resistors ( 41 ) and ( 42 ); and a gain control voltage applying part ( 50 ) which is connected with each one of said first and said second variable resistors ( 41 ) and ( 42 ) via a common gain control line ( 49 ).

3. The mobile telephone terminal device of claim 2 , wherein said first variable resistor ( 41 ) has a structure that a first resistor ( 54 ) is connected at least with the gate of a first field effective transistor ( 53 ), said second variable resistor ( 42 ) has a structure that a second resistor ( 56 ) is connected at least with the gate of a second field effective transistor ( 55 ), the gate of said first field effective transistor ( 53 ) is connected with said gain control voltage applying part ( 50 ) via said first resistor ( 54 ) and said gain control line ( 49 ), the source of said second field effective transistor ( 55 ) is connected with said gain control voltage applying part ( 50 ) via said gain control line ( 49 ), the source of said first field effective transistor ( 53 ) is connected with said first reference voltage applying part ( 51 ), and the gate of said second field effective transistor ( 55 ) is connected with said second reference voltage applying part ( 52 ) via said second resistor ( 56 ).

4. The mobile telephone terminal device of claim 3 , wherein a voltage applied to said second reference voltage applying part ( 52 ) is lower, by a value which is calculated by subtracting a difference between gain control voltages which completely turn off said first and said second field effective transistors ( 53 ) and ( 55 ) from the sum of the threshold voltage of said first field effective transistor ( 53 ) and the threshold voltage of said second field effective transistor ( 55 ), than a voltage applied to said first reference voltage applying part ( 51 ).

5. The mobile telephone terminal device of claim 3 , wherein the values of voltages applied to said first and said second reference voltage applying parts ( 51 ) and ( 52 ) are set such that a gain control voltage which completely turns off said second field effective transistor ( 55 ) will be lower than a gain control voltage which completely turns off said first field effective transistor ( 53 ).

6. The mobile telephone terminal device of claim 3 , wherein the values of voltages applied to said first and said second reference voltage applying parts ( 51 ) and ( 52 ) are set such that only when one of said first and said second field effective transistors ( 53 ) and ( 55 ) is completely off, the other one of said first and said second field effective transistors ( 53 ) and ( 55 ) will perform a gain control operation.

7. The mobile telephone terminal device of claim 2 , wherein a voltage applied to said second reference voltage applying part ( 52 ) is lower than a voltage applied to said first reference voltage applying part ( 51 ).

8. The mobile telephone terminal device of claim 2 , wherein the values of voltages applied to said first and said second reference voltage applying parts ( 51 ) and ( 52 ) are set such that the gain control voltage range over which said first variable resistor ( 41 ) performs a gain control operation will not overlap with the gain control voltage range over which said second variable resistor ( 42 ) performs a gain control operation.

9. The mobile telephone terminal device of claim 2 , wherein the values of voltages applied to said first and said second reference voltage applying parts ( 51 ) and ( 52 ) are set such that the gain control voltage range over which said second variable resistor ( 42 ) performs a gain control operation will be lower than the gain control voltage range over which said first variable resistor ( 41 ) performs a gain control operation.

10. The mobile telephone terminal device of claim 2 , wherein said first variable resistor ( 41 ) has a structure that a first resistor ( 54 ) is connected at least with the gate of a first field effective transistor ( 53 ); said second variable resistor ( 42 ) has a structure that a second resistor ( 56 ) is connected at least with the gate of a second field effective transistor ( 55 ); the gate of said first field effective transistor ( 53 ) is connected with said gain control voltage applying part ( 50 ) via said first resistor ( 54 ) and said gain control line ( 49 ); the source of said second field effective transistor ( 55 ) is connected with said gain control voltage applying part ( 50 ) via said gain control line ( 49 ); a third resistor ( 57 ) is inserted between the source of said first field effective transistor ( 53 ) and a portion ( 60 ) which is connected with the gate of said second field effective transistor ( 55 ) via said second resistor ( 56 ); a fourth resistor ( 58 ) is inserted between said portion ( 60 ), which is connected with the gate of said second field effective transistor ( 55 ) via said second resistor ( 56 ), and a basic potential portion ( 59 ); and the source of said first field effective transistor ( 53 ) is connected with said first reference voltage applying part ( 51 ).

11. A mobile telephone terminal device, characterized in using, for the purpose of switching of a selected band among at least three bands or more and for the purpose of gain control in the selected band, an attenuator with switch function which comprises: a series circuit of a first and a second variable resistors ( 61 ) and ( 62 ) which are inserted in at least one first signal line ( 71 ) which connects a first signal input part ( 65 ) with a first signal output part ( 68 ); and a third variable resistor ( 63 ) inserted in a second signal line ( 72 ) which connects a second signal input part ( 66 ) with a second signal output part ( 69 ); a fourth variable resistor ( 64 ) inserted in a third signal line ( 73 ) which connects a third signal input part ( 67 ) with a third signal output part ( 70 ), said attenuator being characterized in that as the attenuation of each one of said first, said second, said third and said fourth variable resistors ( 61 ), ( 62 ), ( 63 ) and ( 64 ) is controlled by means of a gain control voltage, the gain of either one of outputs on said first, said second and said third signal lines ( 71 ), ( 72 ) and ( 73 ) is controlled linearly and continuously and the remaining ones of said first, said second and said third signal lines ( 71 ), ( 72 ) and ( 73 ) are blocked.

12. A mobile telephone terminal device, characterized in using, for the purpose of switching of a selected band among at least three bands or more and for the purpose of gain control in the selected band, an attenuator with switch function which comprises: a series circuit of a first and a second variable resistors ( 61 ) and ( 62 ) which are inserted in at least one first signal line ( 71 ) which connects a first signal input part ( 65 ) with a first signal output part ( 68 ); a third variable resistor ( 63 ) inserted in a second signal line ( 72 ) which connects a second signal input part ( 66 ) with a second signal output part ( 69 ); a fourth variable resistor ( 64 ) inserted in a third signal line ( 73 ) which connects a third signal input part ( 67 ) with a third signal output part ( 70 ); and a first, a second, a third and a fourth reference voltage applying parts ( 76 ), ( 77 ), ( 78 ) and ( 79 ) which are connected respectively with said first, said second, said third and said fourth variable resistors ( 61 ), ( 62 ), ( 63 ) and ( 64 ); and a gain control voltage applying part ( 75 ) which is connected with each one of said first, said second, said third and said fourth variable resistors ( 61 ), ( 62 ), ( 63 ) and ( 64 ) via a common gain control line ( 74 ).

13. A mobile telephone terminal device, characterized in comprising: a baseband part ( 101 ), which processes a speech signal and a radio part ( 201 ), which receives the speech signal processed by said baseband part ( 101 ) and communicates with a base station; said radio part ( 201 ) is comprised of a sender part ( 260 ) which generates a send signal to said base station and a receiver part ( 220 ) which receives the send signal from said base station; said sender part ( 260 ) is comprised of an intermediate frequency part ( 230 ), which is formed by a modulator ( 231 ) which modulates an intermediate frequency signal in accordance with the speech signal which is provided from said baseband part ( 101 ), a variable gain intermediate frequency amplifier ( 232 ) which controls the gain of said intermediate frequency signal and a mixer ( 233 ) which performs mixing for frequency conversion from said intermediate frequency signal into a high frequency signal, and a high frequency part ( 270 ) which amplifies said high frequency signal outputted from said intermediate frequency part ( 230 ) and supplies to an antenna ( 300 ); said high frequency part ( 270 ) is comprised of a gain controller with switch function ( 271 ), which switches a selected band between two bands outputted from said intermediate frequency part ( 230 ) and controls the gain of said high frequency signal in the selected band, and two power amplifiers ( 242 ) and ( 252 ) which respectively power-amplify two outputs from said gain controller with switch function ( 271 ); said gain controller with switch function ( 271 ) includes an attenuator with switch function ( 272 ) which switches a selected band between two bands outputted from said intermediate frequency part ( 230 ) and controls the gain of said high frequency signal in the selected band, said mobile telephone terminal device being characterized in that said baseband part ( 101 ) includes a control part ( 120 ); said control part ( 120 ) detects signal information about a receive signal received by said receiver part ( 220 ) and adds a gain control voltage corresponding to this information to said attenuator with switch function ( 272 ) so that an output from either one ( 242 ) of said two power amplifiers is taken over by an output from the other one ( 252 ) of said two power amplifiers; a target value for the output level of the other one ( 252 ) of said two power amplifiers is then set in accordance with the signal information about said receive signal; the output level of the other one ( 252 ) of said two power amplifiers is compared with the target value for the output level of the other one ( 252 ) of said two power amplifiers; a gain control voltage corresponding to the result of the comparison is added to said attenuator with switch function ( 272 ) and said variable gain intermediate frequency amplifier ( 232 ), thereby follow-up controlling the gains of said attenuator with switch function ( 272 ) and said variable gain intermediate frequency amplifier ( 232 ) such that the output level of the other one ( 252 ) of said two power amplifiers will become equal to the target value for the output level of the other one ( 252 ) of said two power amplifiers, and that said attenuator with switch function ( 272 ) is comprised of a first variable resistor ( 41 ), which is inserted in a first signal line ( 47 ) which connects a first signal input part ( 43 ) for said high frequency signal with a first signal output part ( 45 ) and for said high frequency signal; and a second variable resistor ( 42 ) which is inserted in a second signal line ( 48 ) which connects a second signal input part ( 44 ) for said high frequency signal with a second signal output part ( 46 ) for said high frequency signal; the attenuation of each one of said first and said second variable resistors ( 41 ) and ( 42 ) is controlled using a gain control voltage, thereby blocking either one of outputs on said first and said second signal lines ( 47 ) and ( 48 ) while linearly and continuously controlling the remaining one of the outputs on said first and said second signal lines ( 47 ) and ( 48 ); and said attenuator with switch function ( 272 ) accordingly switches to the output from said power amplifier ( 252 ) from the output from said power amplifier ( 242 ) while linearly and continuously controlling the gain of the output from said power amplifier ( 252 ).

14. A mobile telephone terminal device, characterized in comprising: a baseband part ( 101 ), which processes a speech signal and a radio part ( 201 ), which receives the speech signal processed by said baseband part ( 101 ) and communicates with a base station; said radio part ( 201 ) is comprised of a sender part ( 260 ) which generates a send signal to said base station and a receiver part ( 220 ) which receives the send signal from said base station; said sender part ( 260 ) is comprised of an intermediate frequency part ( 230 ), which is formed by a modulator ( 231 ) which modulates an intermediate frequency signal in accordance with the speech signal which is provided from said baseband part ( 101 ), a variable gain intermediate frequency amplifier ( 232 ) which controls the gain of said intermediate frequency signal and a mixer ( 233 ) which performs mixing for frequency conversion from said intermediate frequency signal into a high frequency signal, and a high frequency part ( 270 ) which amplifies said high frequency signal outputted from said intermediate frequency part ( 230 ) and supplies to an antenna ( 300 ); said high frequency part ( 270 ) is comprised of a gain controller with switch function ( 271 ), which switches a selected band between two bands outputted from said intermediate frequency part ( 230 ) and controls the gain of said high frequency signal in the selected band, and two power amplifiers ( 242 ) and ( 252 ) which respectively power-amplify two outputs from said gain controller with switch function ( 271 ); said gain controller with switch function ( 271 ) includes an attenuator with switch function ( 272 ) which switches a selected band between two bands outputted from said intermediate frequency-part ( 230 ) and controls the gain of said high frequency signal in the selected band, said mobile telephone terminal device being characterized in that said baseband part ( 101 ) includes a control part ( 120 ); said control part ( 120 ) detects signal information about a receive signal received by said receiver part ( 220 ) and adds a gain control voltage corresponding to this information to said attenuator with switch function ( 272 ) so that an output from either one ( 242 ) of said two power amplifiers is taken over by an output from the other one ( 252 ) of said two power amplifiers; a target value for the output level of the other one ( 252 ) of said two power amplifiers is then set in accordance with the signal information about said receive signal; the output level of the other one ( 252 ) of said two power amplifiers is compared with the target value for the output level of the other one ( 252 ) of said two power amplifiers; a gain control voltage corresponding to the result of the comparison is added to said attenuator with switch function ( 272 ) and said variable gain intermediate frequency amplifier ( 232 ), thereby follow-up controlling the gains of said attenuator with switch function ( 272 ) and said variable gain intermediate frequency amplifier ( 232 ) such that the output level of the other one ( 252 ) of said two power amplifiers will become equal to the target value for the output level of the other one ( 252 ) of said two power amplifiers, and that said attenuator with switch function ( 272 ) is comprised of: a first variable resistor ( 41 ) which is inserted in a first signal line ( 47 ) which connects a first signal input part ( 43 ) for said high frequency signal with a first signal output part ( 45 ) and for said high frequency signal; a second variable resistor ( 42 ) which is inserted in a second signal line ( 48 ) which connects a second signal input part ( 44 ) for said high frequency signal with a second signal output part ( 46 ) for said high frequency signal; a first and a second reference voltage applying parts ( 51 ) and ( 52 ) which are connected respectively with said first and said second variable resistors ( 41 ) and ( 42 ); and a gain control voltage applying part ( 50 ) which is connected with each one of said first and said second variable resistors ( 41 ) and ( 42 ) via a common gain control line ( 49 ).