TRANSMISSION CIRCUIT AND COMMUNICATION DEVICE

• US 20120099675A1
• Filed: 04/01/2010
• Published: 04/26/2012
• Est. Priority Date: 07/02/2009
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Miyazaki, Takahito, Kitamura, Ryo
• Granted Patent: US 8,565,344 B2
• Time in Patent Office: Days
• US Class Current: 375/300
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• 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 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

Provided is a transmission circuit which allows smooth switching of the operation mode when switching the operation mode of the transmission circuit. A power amplifier 14 includes: a first input terminal to which a direct-current voltage or a voltage in accordance with an amplitude signal M is supplied; a second input terminal to which an output signal from a first variable gain amplifier 171 or an output signal from a second variable gain amplifier 172 is inputted; and a third input terminal to which an output signal from a first bias circuit 15 or an output signal from a second bias circuit 16 is inputted. A control section 11 switches the operation mode of the transmission circuit so that at least one of the first input terminal, the second input terminal, and the third input terminal of the power amplifier is prevented from being in a no input state.

Claims

1. A transmission circuit for outputting a transmission signal, comprising:

a control section for determining whether to switch an operation mode of the transmission circuit to a quadrature modulation scheme or a polar modulation scheme, based on power information, and outputting a vector signal which includes I and Q signals when the operation mode of the transmission circuit is the quadrature modulation scheme, and outputting an amplitude signal and a phase signal when the operation mode of the transmission circuit is the polar modulation scheme;

an amplitude phase modulation section for amplitude-phase modulating the vector signal outputted by the control section;

a first variable gain amplifier for amplifying an output signal from the amplitude phase modulation section with a first gain;

a regulator for outputting a voltage in accordance with the amplitude signal outputted by the control section;

a phase modulation section for phase-modulating the phase signal outputted by the control section;

a second variable gain amplifier for amplifying an output signal from the phase modulation section with a second gain;

a power amplifier for receiving a predetermined direct-current voltage supplied thereto and amplifying an output signal from the first variable gain amplifier using the supplied predetermined direct-current voltage when the operation mode of the transmission circuit is the quadrature modulation scheme, and for receiving the voltage in accordance with the amplitude signal supplied thereto by the regulator and amplifying an output signal from the second variable gain amplifier using the supplied voltage when the operation mode of the transmission circuit is the polar modulation scheme; and

a bias circuit for outputting a bias control signal to the power amplifier, wherein

the power amplifier comprises;

a first input terminal to which the direct-current voltage or the voltage in accordance with the amplitude signal is supplied;

a second input terminal to which the output signal from the first variable gain amplifier or the output signal from the second variable gain amplifier is inputted; and

a third input terminal to which the bias control signal is inputted, and

the control section controls switching of the operation mode of the transmission circuit so that at least one of the first input terminal and the second input terminal is prevented from being in a no input state.

2. The transmission circuit according to claim 1, wherein

the bias circuit is configured of;

a first bias circuit for outputting a first bias control signal to the power amplifier when the operation mode of the transmission circuit is the quadrature modulation scheme; and

a second bias circuit for outputting a second bias control to the power amplifier when the operation mode of the transmission circuit is the polar modulation scheme, wherein

the control section controls the switching of the operation mode of the transmission circuit so that at least one of the first input terminal, the second input terminal, and the third input terminal is prevented from being in the no input state.

3. The transmission circuit according to claim 1, wherein the regulator supplies the power amplifier with the predetermined direct-current voltage when the operation mode of the transmission circuit is the quadrature modulation scheme, and supplies the power amplifier with the voltage in accordance with the amplitude signal outputted by the control section when the operation mode of the transmission circuit is the polar modulation scheme.

4. The transmission circuit according to claim 1, further comprising a third variable gain amplifier for amplifying, with a third gain, the amplitude signal outputted by the control section.

5. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a first delay adjustment circuit for delaying switching of the direct-current voltage to be supplied to the power amplifier a first delay time; and

a second delay adjustment circuit for delaying switching of the direct-current voltage supplied to drive the regulator a second delay time, wherein

the control section adjusts the first delay time and the second delay time so that one of the direct-current voltage and the voltage in accordance with the amplitude signal is surely supplied to the first input terminal of the power amplifier.

6. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a third delay adjustment circuit for delaying switching of an operation of the first variable gain amplifier a third delay time; and

a fourth delay adjustment circuit for delaying switching of an operation of the second variable gain amplifier a fourth delay time, wherein

the control section adjusts the third delay time and the fourth delay time so that one of the output signal from the first variable gain amplifier and the output signal from the second variable gain amplifier is surely inputted to the second input terminal of the power amplifier.

7. The transmission circuit according to claim 2, wherein

the transmission circuit further comprises:

a fifth delay adjustment circuit for delaying switching of an operation of the first bias circuit a fifth delay time; and

a sixth delay adjustment circuit for delaying switching an operation of the second bias circuit a sixth delay time, wherein

the control section adjusts the fifth delay time and the sixth delay time so that one of the first bias control signal and the second bias control signal is surely inputted to the third input terminal of the power amplifier.

8. The transmission circuit according to claim 2, wherein

the control section comprises:

a signal generation section for generating the vector signal when the operation mode of the transmission circuit is the quadrature modulation scheme, and generating the amplitude signal and the phase signal when the operation mode of the transmission circuit is the polar modulation scheme;

a bias control section for controlling the operation mode of the transmission circuit so that, when switching the operation mode of the transmission circuit, at least one of the following conditions is satisfied;

at least one of the direct-current voltage and the voltage in accordance with the amplitude signal is surely supplied to the first input terminal of the power amplifier;

at least one of the output signal from the first variable gain amplifier and the output signal from the second variable gain amplifier is surely inputted to the second input terminal of the power amplifier; and

at least one of the first bias control signal and the second bias control signal is surely inputted to the third input terminal of the power amplifier;

a mode switching determination section for determining whether to switch the operation mode to the quadrature modulation scheme or the polar modulation scheme, based on the power information; and

a mode switching control section for controlling the signal generation section and the bias control section, in accordance with determination by the mode switching determination section.

9. The transmission circuit according to claim 8, wherein the mode switching determination section determines whether to switch the operation mode of the transmission circuit to the quadrature modulation scheme or the polar modulation scheme, based on the power information and a lookup table defining the operation mode.

10. The transmission circuit according to claim 8, wherein the mode switching determination section determines that the transmission circuit is to be caused to operate in the quadrature modulation scheme if the power information is smaller than a predetermined threshold value, and determines that the transmission circuit is to be caused to operate in the polar modulation scheme if the power information is equal to or greater than the predetermined threshold value.

11. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a distributer for distributing the transmission signal outputted from the power amplifier; and

a detector for detecting an output power of the distributer and outputting a voltage value in proportion to the output power when switching the operation mode of the transmission circuit, wherein

the control section further comprises;

a comparison section for comparing a voltage value detected by the detector before the operation mode of the transmission circuit is switched and a voltage value detected by the detector after the operation mode of the transmission circuit is switched, and outputting a difference therebetween; and

a gain control section for controlling at least one of the first gain and the second gain, based on the difference outputted by the comparison section and the power information so that an output power of the power amplifier converges to a target output power level.

12. The transmission circuit according to claim 2, wherein

the transmission circuit further comprises:

a distributer for distributing the transmission signal outputted from the power amplifier; and

a detector for detecting an output power of the distributer and outputting a voltage value in proportion to the output power when switching the operation mode of the transmission circuit, wherein

the control section further comprises;

a comparison section for comparing a voltage value detected by the detector before the operation mode of the transmission circuit is switched and a voltage value detected by the detector after the operation mode of the transmission circuit is switched, and outputting a difference therebetween; and

a gain control section for controlling at least one of the first gain, the second gain, and the third gain, based on the difference outputted by the comparison section and the power information so that an output power of the power amplifier converges to a target output power level.

13. The transmission circuit according to claim 11, wherein, when the operation mode of the transmission circuit is switched, the control section converges the output power of the power amplifier to the target output power level within predetermined time periods before and after a boundary between symbols.

14. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a first DC power generation section for supplying the direct-current voltage to the first input terminal of the power amplifier when the operation mode of the transmission circuit is the quadrature modulation scheme; and

a second DC power generation section for supplying a direct-current voltage that drives the regulator when the operation mode of the transmission circuit is the polar modulation scheme.

15. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a third DC power generation section for supplying a direct-current voltage that drives the first variable gain amplifier when the operation mode of the transmission circuit is the quadrature modulation scheme, and

a fourth DC power generation section for supplying a direct-current voltage that drives the second variable gain amplifier when the operation mode of the transmission circuit is the polar modulation scheme.

16. The transmission circuit according to claim 2, wherein

the transmission circuit further comprises:

a fifth DC power supply generation section for supplying a direct-current voltage that drives the first bias circuit when the operation mode of the transmission circuit is the quadrature modulation scheme, and

a sixth DC power supply generation section for supplying a direct-current voltage that drives the second bias circuit when the operation mode of the transmission circuit is the polar modulation scheme.

17. The transmission circuit according to claim 1, wherein

the transmission circuit further comprises:

a first DAC connected to digital-to-analog convert the I signal outputted by the control section to output a resultant signal to the amplitude phase modulation section when switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, and connected to digital-to-analog convert the amplitude signal outputted by the control section to output a resultant signal to the regulator when switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme;

a second DAC connected to digital-to-analog convert the Q signal outputted by the control section to output a resultant data to the amplitude phase modulation section when switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, and connected to digital-to-analog convert the phase signal outputted by the control section to output a resultant signal to the phase modulation section when switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme; and

a DC power supply generation section for supplying a direct-current voltage to the regulator when switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, so that the first input terminal of the power amplifier is prevented from being in the no input state, and supplying a direct-current voltage to the amplitude phase modulation section when switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme, so that the second input terminal of the power amplifier is prevented from being in the no input state.

18. The transmission circuit according to claim 5, wherein

for switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme, given that the first delay time is t₁ and the second delay time is t₂, the first delay time t₁ and the second delay time t₂ are set so as to satisfy a relationship of a following equation:

t₁+min (d₁)>

t₂+max (d₂),

where min (d₁) denotes a minimal value of a delay time d₁ which occurs in a path from the control section to the first input terminal of the power amplifier, exclusive of the first delay time t₁, and max (d₂) denotes a maximal value of a delay time d₂ which occurs in a path from the control section to the first input terminal of the power amplifier via the regulator, exclusive of the second delay time t₂.

19. The transmission circuit according to claim 5, wherein

for switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, the first delay time t₁ and the second delay time t₂ are set so as to satisfy a relationship of a following equation:

t₁+max (d₁)<

t₂+min (d₂),

where max (d₁) denotes a maximal value of a delay time d₁ which occurs in a path from the control section to the first input terminal of the power amplifier, exclusive of the first delay time t₁, and min (d₂) denotes a minimal value of a delay time d₂ which occurs in a path from the control section to the first input terminal of the power amplifier via the regulator, exclusive of the second delay time t₂.

20. The transmission circuit according to claim 6, wherein

for switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme, given that the third delay time is t₃ and the fourth delay time is t₄, the third delay time t₃ and the fourth delay time t₄ are set so as to satisfy a relationship of a following equation:

t₃+min (d₃)>

t₄+max (d₄),

where min (d₃) denotes a minimal value of a delay time d₃ which occurs in a path from the control section to the second input terminal via the amplitude phase modulation section and the first variable gain amplifier, exclusive of the third delay time t₃, and max (d₄) denotes a maximal value of delay time d₄ which occurs in a path from the control section to the second input terminal via the phase modulation section and the second variable gain amplifier, exclusive of the third delay time t₃.

21. The transmission circuit according to claim 6, wherein

for switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, the third delay time t₃ and the fourth delay time t₄ are set so as to satisfy a relationship of a following equation:

t₃+max (d₃)<

t₄+min (d₄),

where max (d₃) denotes a maximal value of a delay time d₃ which occurs in a path from the control section to the second input terminal via the amplitude phase modulation section and the first variable gain amplifier, exclusive of the third delay time t₃, and min (d₄) denotes a minimal value of the delay time d₄ which occurs in a path from the control section to the second input terminal via the phase modulation section and the second variable gain amplifier, exclusive of the fourth delay time t₄.

22. The transmission circuit according to claim 7, wherein

for switching the operation mode of the transmission circuit from the quadrature modulation scheme to the polar modulation scheme, given that the fifth delay time is t₅ and the sixth delay time is t₆, the fifth delay time t₅ and the sixth delay time t₆ are set so as to satisfy a relationship of a following equation:

t₅+min (d₅)>

t₆+max (d₆),

where min (d₅) denotes a minimal value of a delay time d₅ which occurs in a path from the control section to the third input terminal via the first bias circuit, exclusive of the fifth delay time t₅, and max (d₆) denotes a maximal value of a delay time d₆ which occurs in a path from the control section to the third input terminal via the second bias circuit, exclusive of the sixth delay time t₆.

23. The transmission circuit according to claim 7, wherein

for switching the operation mode of the transmission circuit from the polar modulation scheme to the quadrature modulation scheme, the fifth delay time t₅ and the sixth delay time t₆ are set so as to satisfy a relationship of a following equation:

t₅+max (d₅)<

t₆+min (d₆),

where max (d₅) denotes a maximal value of a delay time d₅ which occurs in a path from the control section to the third input terminal via the first bias circuit, exclusive of the fifth delay time t₅, and min (d₆) denotes a minimal value of a delay time d₆ which occurs in a path from the control section to the third input terminal via the second bias circuit, exclusive of the sixth delay time t₆.

25. A communication device comprising:

a transmission circuit for generating a transmission signal; and

an antenna for outputting the transmission signal generated by the transmission circuit, wherein

the transmission circuit is the transmission circuit according to claim 1.

26. The transmission circuit according to claim 25, further comprising:

a reception circuit for processing a reception signal received from the antenna; and

an antenna duplexer for outputting the transmission signal generated by the transmission circuit to the antenna and outputting the reception signal received from the antenna to the reception circuit.

24. A transmission circuit for outputting a transmission signal, comprising:

a control section for switching between a first operation mode and a second operation mode, based on power information; and

a power amplifier for amplifying a signal inputted from a second input terminal, based on a signal inputted from a first input terminal, wherein

at least one of the signal inputted to the first input terminal of the power amplifier and the signal inputted to the second input terminal of the power amplifier is switched in accordance with an operation mode of the transmission circuit, and

the control section controls switching of the operation mode of the transmission circuit so that at least one of the first input terminal or the second input terminal is prevented from being in a no input state.