Attenuator unit, step attenuator, and electronic apparatus

• US 6,181,922 B1
• Filed: 01/30/1996
• Issued: 01/30/2001
• Est. Priority Date: 04/11/1995
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Iwai, Kenji, Kobayashi, Kazuhiko
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US08/594,314
• Time in Patent Office: 1,827 Days
• Field of Search: 455/249.1, 455/232.1, 455/234.1, 455/241.1, 455/246.1, 455/251.1, 455/252.1, 455/253.2, 455/116, 455/127, 455/557, 455/558, 526/119, 526/120, 526/112, 526/117, 333/81 R, 333/81 A
• US Class Current: 455/249.1
• CPC Class Codes: H03H 11/245 using field-effect transistor

Abstract

An attenuator unit for attenuating a signal, the unit includes a π-type attenuator having a first resistor and second and third resistors which are arranged on both sides of the first resistor, a first transistor connected in parallel with the first resistor, and a second transistor connected between a joint node of the second resistor and the third resistor and a first voltage level. In the unit, by controlling a gate voltage of the first transistor and a gate voltage of the second transistor, an attenuation value of the attenuator unit is changed.

Claims

1. A step attenuator for attenuating a signal, having a plurality of attenuator units connected in series, at least one of said plurality of attenuator units comprising:

a π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor, said first, second and third resistors respectively having resistance values which control a current flowing in said second transistor to have a current value sufficient to operate said π

-type attenuator;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, an attenuation value of said attenuator unit is changed.

2. The step attenuator as claimed in claim 1, wherein at least one of said plurality of attenuator units further comprises an inverter circuit providing a control signal which controls one of said gate voltage of said first transistor and said gate voltage of said second transistor, said inverter circuit including:

a first depletion-type FET (D-FET);

a fourth resistor connected between a drain of said first D-FET and a first power-supply voltage;

a fifth resistor connected between a source of said first D-FET and a ground; and

a sixth resistor connected between a gate of said first D-FET and said second power-supply voltage;

wherein said control signal supplied to said gate of said first D-FET is inverted, and an inverted control signal is produced from said drain of said first D-FET.

3. A step attenuator for attenuating a signal, having at least one first attenuator unit and at least one second attenuator unit, said first attenuator unit comprising:

a first π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, a first attenuation value of said first attenuator unit is changed; and

said second attenuator unit comprising;

a second π

-type attenuator having a fourth resistor and fifth and sixth resistors which are arranged on both sides of said fourth resistor;

a third transistor connected in parallel with said fourth resistor;

a fourth transistor connected between said fifth resistor and said first voltage level; and

a fifth transistor connected between said sixth resistor and said first voltage level;

wherein;

by controlling a gate voltage of said third transistor, a gate voltage of said fourth transistor, and a gate voltage of said fifth transistor, a second attenuation value of said second attenuator unit is changed; and

said first attenuation value of the first attenuator unit is less than said second attenuation value of said second attenuator unit.

4. The step attenuator as claimed in claim 3, wherein said step attenuator further comprises an inverter circuit providing a control signal which controls at least one of said gate voltage of said first transistor, said gate voltage of said second transistor, said gate voltage of said third transistor, said gate voltage of said fourth transistor, and said gate voltage of said fifth transistor, said inverter circuit including:

a first depletion-type FET (D-FET);

a first resistor connected between a drain of said first D-FET and a first power-supply voltage;

a second resistor connected between a source of said first D-FET and a ground; and

a third resistor connected between a gate of said first D-FET and said second power-supply voltage;

wherein said control signal supplied to said gate of the first D-FET is inverted, and an inverted control signal is produced from said drain of said first D-FET.

5. An amplifier module having a step attenuator attenuating a signal and an amplifier connected to said step attenuator, said step attenuator including a plurality of attenuator units connected in series, at least one of said plurality of attenuator units comprising:

a π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor, said first, second and third resistors respectively having resistance values which control a current flowing in said second transistor to have a current value sufficient to operate said π

-type attenuator;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, an attenuation value of said attenuator unit is changed.

6. An amplifier module having a step attenuator attenuating a signal and an amplifier connected to said step attenuator, said step attenuator including at least one first attenuator unit and at least one second attenuator unit, said first attenuator unit comprising:

a first π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, a first attenuation value of said first attenuator unit is changed; and

said second attenuator unit comprising;

a second π

-type attenuator having a fourth resistor and fifth and sixth resistors which are arranged on both sides of said fourth resistor;

a third transistor connected in parallel with said fourth resistor;

a fourth transistor connected between said fifth resistor and said first voltage level; and

a fifth transistor connected between said sixth resistor and said first voltage level;

wherein;

by controlling a gate voltage of said third transistor, a gate voltage of said fourth transistor, and a gate voltage of said fifth transistor, a second attenuation value of said second attenuator unit is changed; and

said first attenuation value of the first attenuator unit is less than said second attenuation value of said second attenuator unit.

7. A transmitter module having a transmission circuit for producing a transmission signal, a step attenuator attenuating said transmission signal and an amplifier amplifying said transmission signal transmitted from said step attenuator, said step attenuator including a plurality of attenuator units connected in series, at least one of said plurality of attenuator units comprising:

a π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor, said first, second and third resistors respectively having resistance values which control a current flowing in said second transistor to have a current value sufficient to operate said π

-type attenuator;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, an attenuation value of said attenuator unit is changed.

8. A transmitter module having a transmission circuit for producing a transmission signal, a step attenuator attenuating said transmission signal and an amplifier amplifying said transmission signal transmitted from said step attenuator, said step attenuator including at least one first attenuator unit and at least one second attenuator unit, said first attenuator unit comprising:

a first π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, a first attenuation value of said first attenuator unit is changed; and

said second attenuator unit comprising;

a second π

-type attenuator having a fourth resistor and fifth and sixth resistors which are arranged on both sides of said fourth resistor;

a third transistor connected in parallel with said fourth resistor;

a fourth transistor connected between said fifth resistor and said first voltage level; and

a fifth transistor connected between said sixth resistor and said first voltage level;

wherein;

by controlling a gate voltage of said third transistor, a gate voltage of said fourth transistor, and a gate voltage of said fifth transistor, a second attenuation value of said second attenuator unit is changed; and

said first attenuation value of said first attenuator unit is less than said second attenuation value of said second attenuator unit.

9. A receiver module having a step attenuator attenuating a received signal, a reception amplifier, and a reception circuit receiving an amplified received signal, said step attenuator including a plurality of attenuator units connected in series, at least one of said plurality of attenuator units comprising:

a π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor, said first, second and third resistors respectively having resistance values which control a current flowing in said second transistor to have a current value sufficient to operate said π

-type attenuator;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, an attenuation value of said attenuator unit is changed.

10. A receiver module having a step attenuator attenuating a received signal, a reception amplifier, and a reception circuit receiving an amplified received signal, said step attenuator including at least one first attenuator unit and at least one second attenuator unit, said first attenuator unit comprising:

a first π

-type attenuator having a first resistor and second and third resistors which are arranged on both sides of said first resistor;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, a first attenuation value of said first attenuator unit is changed; and

said second attenuator unit comprising;

a second π

-type attenuator having a fourth resistor and fifth and sixth resistors which are arranged on both sides of said fourth resistor;

a third transistor connected in parallel with said fourth resistor;

a fourth transistor connected between said fifth resistor and said first voltage level; and

a fifth transistor connected between said sixth resistor and said first voltage level;

wherein;

by controlling a gate voltage of said third transistor, a gate voltage of said fourth transistor, and a gate voltage of said fifth transistor, a second attenuation value of said second attenuator unit is changed; and

said first attenuation value of said first attenuator unit is less than said second attenuation value of said second attenuator unit.

11. A wireless card including a data processing part for processing data, a modulation-and-demodulation part, a high-frequency part having a transmission circuit and a reception circuit and at least one step attenuator, and an antenna, said wireless card being provided to a data processing apparatus to communicate said data with another apparatus, said step attenuator including a plurality of attenuator units connected in series, at least one of said plurality of attenuator units comprising:

a π

-type attenuator having a first resistor and second and third resistors arranged on both sides of said first resistor, said first, second and third resistors respectively having resistance values which control a current flowing in said second transistor to have a current value sufficient to operate said π

-type attenuator;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, an attenuation value of said attenuator unit is changed.

12. A wireless card including a data processing part for processing data, a modulation-and-demodulation part, a high-frequency part having a transmission circuit and a reception circuit and at least one step attenuator, and an antenna, said wireless card being provided to a data processing apparatus to communicate said data with another apparatus, said step attenuator including at least one first attenuator unit and at least one second attenuator unit, said first attenuator unit comprising:

a first π

-type attenuator having a first resistor and second and third resistors arranged on both sides of said first resistor;

a first transistor connected in parallel with said first resistor; and

a second transistor connected between a joint node of said second resistor and said third resistor and a first voltage level;

wherein by controlling a gate voltage of said first transistor and a gate voltage of said second transistor, a first attenuation value of said first attenuator unit is changed; and

said second attenuator unit comprising;

a second π

-type attenuator having a fourth resistor and fifth and sixth resistors arranged on both sides of said fourth resistor;

a third transistor connected in parallel with said fourth resistor;

a fourth transistor connected between said fifth resistor and said first voltage level; and

a fifth transistor connected between said sixth resistor and said first voltage level;

wherein;

by controlling a gate voltage of said third transistor, a gate voltage of said fourth transistor, and a gate voltage of said fifth transistor, a second attenuation value of said second attenuator unit is changed; and

said first attenuation value of said first attenuator unit is less than said second attenuation value of said second attenuator unit.