Transmitter power varying device having a bypass line for a power amplifier

• US 5,909,643 A
• Filed: 09/26/1996
• Issued: 06/01/1999
• Est. Priority Date: 11/24/1995
• Status: Expired due to Term

• Current Assignee: Collabo Innovations, Inc. (Wi-LAN Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Aihara, Yuukichi
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US08/722,856
• Time in Patent Office: 978 Days
• Field of Search: 455/127, 455/343, 455/91, 455/86, 455/116, 330/51
• US Class Current: 455/127.3
• CPC Class Codes: H03F 2203/7239 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers and shunting lines by one or more switch(es)
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

A transmitter section of a mobile telephone set of a cellular telephone system includes a high-frequency signal oscillator, a modulator, a variable gain amplifier, a power amplifier, an antenna duplexer, and an antenna. Two high-frequency signal changeover switches are respectively provided upstream and downstream of the power amplifier. In transmitting a signal at a low output power, the power amplifier is turned off and the two changeover switches cause a high-frequency signal to go through a bypass line, that is, bypass the power amplifier. Thus, transmitter power control with a wide dynamic range can be attained while the power consumption is greatly reduced.

Claims

1. A transmitter power varying device comprising:

a variable gain amplifier for amplifying a transmission signal with a variable gain;

a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna;

a bypass line provided parallel with the power amplifier; and

first and second high-frequency signal changeover switches respectively provided upstream and downstream of the power amplifier and the bypass line, for causing the transmission signal to go through the bypass line while bypassing the power amplifier in response to an output power of the transmission signal being reduced below a first threshold value;

wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.

2. The transmitter power varying device according to claim 1, wherein the power amplifier is made off while it is bypassed.

3. The transmitter power varying device according to claim 1, wherein the first and second high-frequency signal changeover switches cause the transmission signal to go through the power amplifier in response to the output power of the transmission signal being increased above a second threshold value that is larger than the first threshold value, to provide a hysteretic output control characteristic.

4. The transmitter power varying device according to claim 1, further comprising an isolator that is provided in the bypass line.

5. The transmitter power varying device according to claim 1, further comprising a resistive attenuator that is provided in the bypass line.

6. The transmitter power varying device according to claim 4, further comprising a circulator that is connected to an output side of the isolator and to an output side of the power amplifier via the second high-frequency signal changeover switch, wherein the second high-frequency signal changeover switch is so constructed as to selectively connect the output side of the isolator to the output side of the power amplifier or a ground side via the circulator.

7. The transmitter power varying device according to claim 1, further comprising, upstream of the first high-frequency signal changeover switch, a cascade connection of a high-frequency signal oscillator, a modulator, and a variable gain amplifier.

8. The transmitter power varying device according to claim 1, further comprising, upstream of the first high-frequency signal changeover switch, a cascade connection of an IF signal oscillator, an IF signal modulator, an IF band variable gain amplifier, an up-converter mixer, and a RF amplifier.

9. The transmitter power varying device according to claim 1, further comprising upstream of the first high-frequency signal changeover switch, a cascade connection of an IF signal oscillator, an IF signal modulator, an IF band variable gain amplifier, an up-converter mixer, and a RF band variable gain amplifier.

10. The transmitter power varying device according to claim 1, wherein each of the first and second high-frequency signal changeover switches is a single-pole double-throw switch.

11. The transmitter power varying device according to claim 1, wherein each of the first and second high-frequency signal changeover switches is a pair of single-pole single-throw switches.

12. The transmitter power varying device according to claim 1, wherein each of the first and second high-frequency signal changeover switches is a pair of on/off switches.

13. The transmitter power varying device according to claim 1, further comprising a bandpass filter that is provided in the bypass line.

14. The transmitter power varying device according to claim 1, further comprising an isolator that is provided downstream of the second high-frequency signal changeover switch.

15. A transmitter power varying device comprising:

a variable gain amplifier for amplifying a transmission signal with a variable gain;

a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna;

a quarter-wavelength line provided parallel with the power amplifier; and

a high-frequency signal changeover switch provided upstream or downstream of the power amplifier and the quarter-wavelength line, for causing the transmission signal to go through the quarter-wavelength line while bypassing the power amplifier in response to an output power of the transmission signal being reduced below a threshold value;

wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.

16. A transmitter power varying device comprising:

a variable gain amplifier for amplifying a transmission signal with a variable gain;

a power amplifier for amplifying the transmission signal which is to be transmitted from an antenna;

a bypass line provided parallel with the power amplifier;

first and second high-frequency signal changeover switches respectively provided upstream and downstream of the power amplifier and the bypass line, for causing the transmission signal to go through the bypass line while bypassing the power amplifier, reducing a power of the transmission signal below a first threshold value;

an isolator provided in the bypass line; and

a circulator that is connected to an output side of the isolator and to an output side of the power amplifier via the second high-frequency signal changeover switch, wherein the second high-frequency signal changeover switch is so constructed as to selectively connect the output side of the isolator to the output side of the power amplifier or a ground side via the circulator;

wherein the gain of the variable gain amplifier is increased to compensate for a gain reduction due to bypassing of the power amplifier.