POWER AMPLIFIER AND RADIO WAVE TRANSMITTER HAVING THE SAME

• US 20100266066A1
• Filed: 08/22/2008
• Published: 10/21/2010
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Takahashi, Kiyohiko
• Granted Patent: US 8,254,496 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/21136 An input signal of a power amplifier being on/off switched
• CPC Class Codes: H03F 2203/21142 Output signals of a plurality of power amplifiers are parallel combined to a common output
• CPC Class Codes: H03F 2203/21196 the supply voltage of a power amplifier being switchable controlled
• CPC Class Codes: H03F 2203/7215 the gated amplifier being switched on or off by a switch at the input of the amplifier
• CPC Class Codes: H03F 2203/7236 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers by (a ) switch(es)
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• 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: H03G 3/004 Control by varying the supply voltage
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04

Abstract

A power amplifier (10) comprises: an A/D converter (11) for converting, to a time discrete signal, an envelope signal included in a high-frequency modulated signal and including only an amplitude modulated component of the high-frequency modulated signal; a switching amplifier (12) for amplifying the output signal of the A/D converter (11); a low-pass filter (13) for removing high frequency noise from the output signal of the switching amplifier (12); a plurality of high-frequency power amplifiers (15-1 to 15-n) for receiving the output signal of the low-pass filter (13) as a power supply and for amplifying a carrier signal included in the high-frequency modulated signal; and a power controller (14) for adjusting the average power of the output signal of the power amplifier (10) by controlling the total gains of the plurality of high-frequency power amplifiers (15-1 to 15-n).

Claims

1. A power amplifier for amplifying a high-frequency modulated signal, characterized by comprising:

a first processing unit for amplifying an envelope signal included in the high-frequency modulated signal, said envelope signal including only an amplitude modulated component of the high-frequency modulated signal; and

a second processing unit for adjusting an average power of an output signal of said power amplifier,

wherein said first processing unit includes;

an AD converter for converting the envelope signal to a time discrete signal;

a switching amplifier for amplifying an output signal of said AD converter; and

a low-pass filter for removing high-frequency noise from an output signal of said switching amplifier, and

said second processing unit includes;

a plurality of high-frequency power amplifiers supplied with an output signal of said low-pass filter as a power supply for amplifying a carrier signal included in the high-frequency modulated signal; and

a power controller for controlling a total gain of said plurality of high-frequency power amplifiers based on a power control signal independent of the high-frequency modulated signal to adjust an average power of an output signal of said power amplifier.

2. The power amplifier according to claim 1, characterized in that:

said plurality of high-frequency power amplifiers are arranged in parallel,

each of said plurality of high-frequency power amplifiers amplifies the carrier signal by multiplying the carrier signal by the power supply,

said power amplifier further comprises a power combiner circuit for combining output signals of said plurality of high-frequency power amplifiers and for delivering the combined output signal to the outside, and

said power controller conducts on/off control for said plurality of high-frequency power amplifiers to adjust an average power of the output signal of said power amplifier.

3. The power amplifier according to claim 2, further comprising:

a variable gain amplifier positioned antecedent to said AD converter,

wherein said power controller controls the gain of said variable gain amplifier.

4. The power amplifier according to claim 2, further comprising:

a high-frequency variable gain amplifier positioned antecedent to said plurality of high-frequency power amplifiers, wherein said power controller controls the gain of said high-frequency variable gain amplifier.

5. The power amplifier according to claim 2, wherein said envelope signal applied to said AD converter has a substantially constant average power.

6. The power amplifier according to claim 2, wherein said carrier signal is a signal which includes only a phase modulated component of the high-frequency modulated signal.

7. The power amplifier according to claim 2, wherein said carrier signal is a signal which includes a phase modulated component and an amplitude modulated component of the high-frequency modulated signal.

8. The power amplifier according to claim 1, characterized in that:

said plurality of high-frequency power amplifiers are arranged in series,

said power amplifier further comprises;

high-frequency switches each having one input terminal and two output terminals, disposed between respective ones of said plurality of high-frequency power amplifiers, each said high-frequency switch having the input terminal connected to said high-frequency power amplifier preceding thereto, and a first output terminal connected to said high-frequency power amplifier subsequent thereto; and

a matching circuit connected to second output terminals of said high-frequency switches for delivering an output signal to the outside,

said high-frequency power amplifier at the first stage multiplies the carrier signal by the power supply for amplification, and delivers the output signal to said high-frequency switch subsequent thereto,

said high-frequency power amplifiers except for those at the first stage and the final stage amplify an output signal of said high-frequency switch antecedent thereto, and deliver an output signal to said high-frequency switch subsequent thereto,

said high-frequency power amplifier at the final stage amplifies an output signal of said high-frequency switch antecedent thereto and delivers the output signal to the outside, and

said power controller conducts switching control for said high-frequency switches to adjust the average power of the output signal of said power amplifier.

9. The power amplifier according to claim 8, further comprising a variable gain amplifier positioned antecedent to said AD converter,

wherein said power controller controls the gain of said variable gain amplifier.

10. The power amplifier according to claim 8, further comprising a high-frequency variable gain amplifier positioned antecedent to said plurality of high-frequency power amplifiers,

wherein said power controller controls the gain of said high-frequency variable gain amplifier.

11. The power amplifier according to claim 8, wherein said envelope signal applied to said AD converter has a substantially constant average power.

12. The power amplifier according to claim 8, wherein said carrier signal is a signal which includes only a phase modulated component of the high-frequency modulated signal.

13. The power amplifier according to claim 8, wherein said carrier signal is a signal which includes a phase modulated component and an amplitude modulated component of the high-frequency modulated signal.

14. A radio wave transmitter comprising a power amplifier according to claim 2, characterized by further comprising:

a digital baseband circuit for generating the power control signal, an I-signal, and a Q-signal; and

a polar coordinate conversion circuit for generating the envelope signal and the carrier signal based on the I-signal and the Q-signal delivered from said digital baseband circuit,

wherein said AD converter receives the envelope signal delivered from said polar coordinate conversion circuit,

said plurality of high-frequency power amplifiers receive the carrier signal delivered from said polar coordinate conversion circuit, and

said power controller receives the power control signal delivered from said digital baseband circuit, and conducts on/off control for said plurality of high-frequency power amplifiers based on the power control signal to adjust the average power of the output signal of said power amplifier.

15. A radio wave transmitter comprising the power amplifier according to claim 8, characterized by further comprising:

a digital baseband circuit for generating the power control signal, an I-signal, and a Q-signal; and

a polar coordinate conversion circuit for generating the envelope signal and the carrier signal based on the I-signal and the Q-signal delivered from said digital baseband circuit,

wherein said AD converter receives the envelope signal delivered from said polar coordinate conversion circuit,

a high-frequency power amplifier at a first stage among said plurality of high-frequency power amplifiers receives the carrier signal delivered from said polar coordinate conversion circuit, and

said power controller receives the power control signal delivered from said digital baseband circuit, and conducts switching control for said high frequency switches based on the power control signal to adjust the average power of the output signal of said power amplifier.

16. The power amplifier according to claim 3, wherein said envelope signal applied to said AD converter has a substantially constant average power.

17. The power amplifier according to claim 4, wherein said envelope signal applied to said AD converter has a substantially constant average power.

18. The power amplifier according to claim 3, wherein said carrier signal is a signal which includes only a phase modulated component of the high-frequency modulated signal.

19. The power amplifier according to claim 4, wherein said carrier signal is a signal which includes only a phase modulated component of the high-frequency modulated signal.

20. The power amplifier according to claim 5, wherein said carrier signal is a signal which includes only a phase modulated component of the high-frequency modulated signal.