Power amplifier and operating method thereof

• US 8,614,601 B2
• Filed: 06/03/2013
• Issued: 12/24/2013
• Est. Priority Date: 05/18/2011
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ota, Ikuma, Inose, Hiroaki, Imai, Shun
• Primary Examiner(s): Choe, Henry
• Application Number:
  US13/908,135
• Publication Number:
  US 20130265111A1
• Time in Patent Office: 204 Days
• Field of Search: 330/51, 330/124.R, 330/295, 330/302, 330/84, 330/126
• US Class Current: 330/51
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2203/7209 the gated amplifier being switched from a first band to a second band
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H04B 1/0458 Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths

Abstract

A power amplifier includes a first amplifier and a second amplifier which include large and small size elements. An RF input signal is amplified by the first and second amplifiers. An output of the first amplifier is connected to an input of a first output matching circuit. An output of the second amplifier is connected to an input of a second output matching circuit. An output of the second output matching circuit is connected to an RF signal output terminal. In a high power state, the RF input signal is amplified by the first amplifier. In a low power state, the RF input signal is amplified by the second amplifier. In amplification with low power and high frequency, reactances of the second output matching circuit are set at predetermined values. In amplification with low power and low frequency, the reactances of the second output matching circuit are set at larger values.

Claims

1. A power amplifier comprising:

an RF signal input terminal;

a first amplifier;

a second amplifier;

a first output matching circuit;

a second output matching circuit; and

an RF signal output terminal;

wherein

the first amplifier includes a first transistor with a large element size to exhibit high power added efficiency in a high power state and a second transistor with a smaller element size than the element size of the first transistor to exhibit high power added efficiency in a low power state;

an input terminal of the first amplifier and an input terminal of the second amplifier are commonly connected to the RF signal input terminal, and an RF input signal that is supplied to the RF signal input terminal is amplified by the first amplifier and the second amplifier;

an output terminal of the first amplifier is connected to an input terminal of the first output matching circuit, and an output terminal of the second amplifier is connected to an input terminal of the second output matching circuit;

an output terminal of the second output matching circuit is connected to the input terminal of the first output matching circuit and an output terminal of the first output matching circuit is connected to the RF signal output terminal;

an inductive reactance is connected between the output terminal of the second output matching circuit and the input terminal of the second output matching circuit, and a capacitive reactance is connected between the input terminal of the second output matching circuit and a ground voltage;

if the power amplifier executes power amplification in the high power state, the RF input signal is amplified by the first amplifier, and a first RF amplified output signal of the first amplifier is output to the RF signal output terminal through the first output matching circuit;

the RF input signal is amplified by the second amplifier if the power amplifier executes power amplification in the low power state and a second RF amplified output signal of the second amplifier is output to the RF signal output terminal through the second output matching circuit and the first output matching circuit;

the inductive reactance and the capacitive reactance of the second output matching circuit are set at respective predetermined values if the power amplifier executes the power amplification in the low power state and the RF input signal having a first frequency is amplified by the second amplifier; and

at least one reactance of the inductive reactance and the capacitive reactance of the second output matching circuit is set at a larger value than the predetermined value if the power amplifier executes the power amplification in the low power state and the RF input signal having a second frequency that is lower than the first frequency is amplified by the second amplifier.

2. The power amplifier according to claim 1, wherein

the capacitive reactance is set at a predetermined capacitance value if the power amplifier executes the power amplification in the low power state and the RF input signal having the first frequency is amplified by the second amplifier;

and

the capacitive reactance is set at a larger capacitance value than the predetermined capacitance value if the power amplifier executes the power amplification in the low power state and the RF input signal having the second frequency is amplified by the second amplifier.

3. The power amplifier according to claim 1, wherein

the inductive reactance is set at a predetermined inductor value if the power amplifier executes the power amplification in the low power state and the RF input signal having the first frequency is amplified by the second amplifier;

and

the inductive reactance is set at a larger inductor value than the predetermined inductor value if the power amplifier executes the power amplification in the low power state and the RF input signal having the second frequency is amplified by the second amplifier.

4. The power amplifier according to claim 1, wherein

the second output matching circuit is supplied with a frequency band select signal;

the inductive reactance and the capacitive reactance of the second output matching circuit are set at the predetermined values if the frequency band select signal is in a first state; and

the one reactance of the second output matching circuit is set at the larger value if the frequency band select signal is in a second state that is different from the first state.

5. The power amplifier according to claim 4, wherein

the second output matching circuit includes a first switch that is supplied with a mode select signal;

the first switch is controlled to be in one of an ON state and an OFF state if the mode select signal indicates the high power state such that an effect of the second output matching circuit to the output terminal of the first amplifier is reduced; and

the first switch is controlled to be in the other of the ON state and the OFF state if the mode select signal indicates the low power state such that the second RF amplified output signal of the second amplifier is supplied to the input terminal of the first output matching circuit through the second output matching circuit including the first switch controlled to be in the other.

6. The power amplifier according to claim 5, wherein

the first amplifier is controlled to be in an active state and the second amplifier is controlled to be in a non-active state if the power amplifier executes the power amplification in the high power state;

and

the first amplifier is controlled to be in a non-active state and the second amplifier is controlled to be in an active state if the power amplifier executes the power amplification in the low power state.

7. The power amplifier according to claim 6, wherein

the one reactance includes a second switch that is supplied with the frequency band select signal;

if the frequency band select signal is in the first state, the second switch is controlled to be in one of an ON state and an OFF state, and the second switch so controlled is arranged to set the inductive reactance and the capacitive reactance of the second output matching circuit at the respective predetermined values; and

if the frequency band select signal is in the second state, the second switch is controlled to be in the other of the ON state and the OFF state, and the second switch so controlled is arranged to set the one reactance of the second output matching circuit at the larger value.

8. The power amplifier according to claim 7, wherein

the inductive reactance and the first switch are connected in series between the input terminal of the second output matching circuit and the output terminal of the second output matching circuit;

the capacitive reactance includes a first capacitance and a second capacitance; and

one end of the first capacitance and one end of the second capacitance are connected to the input terminal of the second output matching circuit, the other end of the first capacitance is connected to the ground voltage, and the other end of the second capacitance is connected to the ground voltage through the second switch.

9. The power amplifier according to claim 7, wherein

the capacitive reactance includes a first capacitance and a second capacitance;

and

one end of the first capacitance and one end of the second capacitance are connected to the input terminal of the second output matching circuit, the other end of the first capacitance is connected to the ground voltage through the first switch, and the other end of the second capacitance is connected to the ground voltage through the second switch.

10. The power amplifier according to claim 7, wherein

the second output matching circuit includes another capacitance;

the series-connected first switch and the another capacitance are connected in parallel to the inductive reactance between the input terminal of the second output matching circuit and the output terminal of the second output matching circuit;

the first switch is controlled to be in the ON state if the mode select signal indicates the high power state so as to provide a parallel resonance circuit of the other capacitance and the inductive reactance, and the effect of the second output matching circuit to the output terminal of the first amplifier is reduced; and

the first switch is controlled to be in the OFF state if the mode select signal indicates the low power state so as to provide the second RF amplified output signal of the second amplifier to the input terminal of the first output matching circuit through the second output matching circuit including the first switch controlled to be in the OFF state.

11. The power amplifier according to claim 7, wherein

the RF signal input terminal includes a high-band RF signal input terminal and a low-band RF signal input terminal;

the RF signal output terminal includes a high-band RF signal output terminal and a low-band RF signal output terminal;

the first amplifier includes a high-band first amplifier and a low-band first amplifier;

the second amplifier includes a high-band second amplifier and a low-band second amplifier;

the first output matching circuit includes a high-band first output matching circuit and a low-band first output matching circuit;

the second output matching circuit includes a high-band second output matching circuit and a low-band second output matching circuit;

the high-band first amplifier, the high-band second amplifier, the high-band first output matching circuit, and the high-band second output matching circuit are arranged to amplify a high-band RF input signal that is supplied to the high-band RF signal input terminal and to output a high-band RF amplified signal to the high-band RF signal output terminal;

the low-band first amplifier, the low-band second amplifier, the low-band first output matching circuit, and the low-band second output matching circuit are arranged to amplify a low-band RF input signal that is supplied to the low-band RF signal input terminal and to output a low-band RF amplified signal to the low-band RF signal output terminal;

the power amplifier further includes a control circuit that is arranged to receive a band select signal at a common terminal; and

the control circuit is arranged to control the high-band second output matching circuit and the low-band second output matching circuit in response to the band select signal that is received by the common terminal.

12. The power amplifier according to claim 11, wherein

the high-band first amplifier, the high-band second amplifier, the high-band first output matching circuit, and the high-band second output matching circuit are arranged to amplify the high-band RF input signal of a WCDMA system supplied to the high-band RF signal input terminal;

and

the low-band first amplifier, the low-band second amplifier, the low-band first output matching circuit, and the low-band second output matching circuit are arranged to amplify the low-band RF input signal of the WCDMA system supplied to the low-band RF signal input terminal.

13. The power amplifier according to claim 12, wherein

the power amplifier further includes a GSM high-band RF signal input terminal, a GSM low-band RF signal input terminal, a GSM high-band RF signal output terminal, a GSM low-band RF signal output terminal, a GSM high-band amplifier, and a GSM low-band amplifier;

the GSM high-band amplifier is connected between the GSM high-band RF signal input terminal and the GSM high-band RF signal output terminal, and the GSM low-band amplifier is connected between the GSM low-band RF signal input terminal and the GSM low-band RF signal output terminal;

the control circuit is arranged to switch the GSM high-band amplifier and the GSM low-band amplifier between a GMSK operation of GSM system and an EDGE operation of the GSM system in response to a mode switch signal that is received by a first common terminal;

the control circuit is arranged to execute operations of ramp-up and ramp-down at a transmission slot of time division multiple access of the GSM system and an operation of amplitude modulation of EDGE system, of the GSM high-band amplifier and the GSM low-band amplifier, in response to a ramp voltage that is received by a second common terminal; and

the control circuit is arranged to control the high-band second output matching circuit and the low-band second output matching circuit in response to a plurality of band select signals that are received by the first common terminal and the second common terminal.

14. An operating method of a power amplifier including an RF signal input terminal, a first amplifier, a second amplifier, a first output matching circuit, a second output matching circuit, and an RF signal output terminal, wherein

the first amplifier includes a first transistor with a large element size to exhibit high power added efficiency in a high power state and a second transistor with a smaller element size than the element size of the first transistor to exhibit high power added efficiency in a low power state;

an input terminal of the first amplifier and an input terminal of the second amplifier are commonly connected to the RF signal input terminal, and an RF input signal that is supplied to the RF signal input terminal is amplified by the first amplifier and the second amplifier;

an output terminal of the first amplifier is connected to an input terminal of the first output matching circuit and an output terminal of the second amplifier is connected to an input terminal of the second output matching circuit;

an output terminal of the second output matching circuit is connected to the input terminal of the first output matching circuit and an output terminal of the first output matching circuit is connected to the RF signal output terminal;

an inductive reactance is connected between the output terminal of the second output matching circuit and the input terminal of the second output matching circuit, and a capacitive reactance is connected between the input terminal of the second output matching circuit and a ground voltage;

the RF input signal is amplified by the first amplifier if the power amplifier executes power amplification in the high power state, and a first RF amplified output signal of the first amplifier is output to the RF signal output terminal through the first output matching circuit;

the RF input signal is amplified by the second amplifier if the power amplifier executes power amplification in the low power state, and a second RF amplified output signal of the second amplifier is output to the RF signal output terminal through the second output matching circuit and the first output matching circuit;

the inductive reactance and the capacitive reactance of the second output matching circuit are set at respective predetermined values if the power amplifier executes the power amplification in the low power state and the RF input signal having a first frequency is amplified by the second amplifier, and

at least one reactance of the inductive reactance and the capacitive reactance of the second output matching circuit is set at a larger value than the predetermined value if the power amplifier executes the power amplification in the low power state and the RF input signal having a second frequency that is lower than the first frequency is amplified by the second amplifier.

15. The operating method of the power amplifier according to claim 14, wherein

the capacitive reactance is set at a predetermined capacitance value if the power amplifier executes the power amplification in the low power state and the RF input signal having the first frequency is amplified by the second amplifier;

and

the capacitive reactance is set at a larger capacitance value than the predetermined capacitance value if the power amplifier executes the power amplification in the low power state and the RF input signal having the second frequency is amplified by the second amplifier.

16. The operating method of the power amplifier according to claim 14, wherein

the inductive reactance is set at a predetermined inductor value if the power amplifier executes the power amplification in the low power state and the RF input signal having the first frequency is amplified by the second amplifier;

and

the inductive reactance is set at a larger inductor value than the predetermined inductor value if the power amplifier executes the power amplification in the low power state and the RF input signal having the second frequency is amplified by the second amplifier.

17. The operating method of the power amplifier according to claim 14, wherein

the second output matching circuit is supplied with a frequency band select signal;

the inductive reactance and the capacitive reactance of the second output matching circuit are set at the predetermined values if the frequency band select signal is in a first state; and

the one reactance of the second output matching circuit is set at the larger value if the frequency band select signal is in a second state that is different from the first state.

18. The operating method of the power amplifier according to claim 17, wherein

the second output matching circuit includes a first switch that is supplied with a mode select signal;

the first switch is controlled to be in one of an ON state and an OFF state if the mode select signal indicates the high power state such that an effect of the second output matching circuit to the output terminal of the first amplifier is reduced; and

the first switch is controlled to be in the other of the ON state and the OFF state if the mode select signal indicates the low power state such that the second RF amplified output signal of the second amplifier is supplied to the input terminal of the first output matching circuit through the second output matching circuit including the first switch controlled to be in the other.

19. The operating method of the power amplifier according to claim 18, wherein

the first amplifier is controlled to be in an active state and the second amplifier is controlled to be in a non-active state if the power amplifier executes the power amplification in the high power state;

and

the first amplifier is controlled to be in a non-active state and the second amplifier is controlled to be in an active state if the power amplifier executes the power amplification in the low power state.

20. The operating method of the power amplifier according to claim 19, wherein

the one reactance includes a second switch that is supplied with the frequency band select signal;

the second switch is controlled to be in one of an ON state and an OFF state if the frequency band select signal is in the first state, and the second switch controlled to be in the one of the ON state and the OFF state sets the inductive reactance and the capacitive reactance of the second output matching circuit at the respective predetermined values; and

the second switch is controlled to be in the other of the ON state and the OFF state if the frequency band select signal is in the second state, and the second switch controlled to be in the other of the ON state and the OFF state sets the one reactance of the second output matching circuit at the larger value.