Transmitting circuit, communication device, communication method, and program

Abstract

To prevent the deterioration of radio characteristics in transmission.SOLUTION: A frequency conversion unit 21 converts a baseband signal into a first radio frequency signal for a data transmission period. The frequency conversion unit 21 converts a baseband signal into a second radio frequency signal for a non-data-transmission period. An amplifier 22 includes a GaN device and amplifies the first radio frequency signal or the second radio frequency signal. A band pass filter 23 passes a signal within a predetermined pass band. The first radio frequency signal is a signal in a band within a pass band of the band pass filter 23 and the second radio frequency signal is a signal in a band outside the pass band of the band pass filter 23.SELECTED DRAWING: Figure 1

Claims

1. A frequency conversion unit receives a first oscillation signal and a second oscillation signal having a different frequency from the first oscillation signal as inputs, and uses the input first oscillation signal or the second oscillation signal to convert a baseband signal into a radio frequency signal. An amplifier that amplifies the radio frequency signal, including a gallium nitride device as an amplifying element, The system includes a band-pass filter that receives the radio frequency signal amplified by the amplifier and allows signals within a predetermined passband to pass through. The frequency conversion unit receives the first oscillation signal during the period when data is transmitted wirelessly, and the second oscillation signal during the period when data is not transmitted wirelessly. The frequency conversion unit converts the baseband signal to a first radio frequency signal when the first oscillation signal is input, and converts the baseband signal to a second radio frequency signal when the second oscillation signal is input. A transmitting circuit in which the first radio frequency signal is a signal within the passband of the band-pass filter, and the second radio frequency signal is a signal outside the passband of the band-pass filter.

2. The transmission circuit according to claim 1, wherein the band-pass filter allows the first radio frequency signal to pass towards the antenna and totally reflects the second radio frequency signal.

3. The transmitting circuit according to claim 2, wherein the transmitting circuit is a transmitting circuit used in time-division duplex wireless communication, and the period during which the data is not transmitted wirelessly is the period during which the data is received via the antenna in time-division duplex wireless communication.

4. The first radio frequency signal is a signal within the passband of the band-pass filter and a signal within the amplification band of the amplifier. The transmitting circuit according to any one of claims 1 to 3, wherein the second radio frequency signal is a signal in a band outside the passband of the band-pass filter and a signal outside the amplification band of the amplifier.

5. The transmitting circuit according to claim 4, wherein the amplifier amplifies a second radio frequency signal in a saturated state.

6. The transmission circuit according to any one of claims 1 to 3, wherein the frequency conversion unit includes a changeover switch that switches and outputs the first oscillation signal or the second oscillation signal, and a mixer that mixes the first oscillation signal or the second oscillation signal output from the changeover switch with the baseband signal.

7. The transmitting circuit according to any one of claims 1 to 3, wherein the drain current of the gallium nitride device of the amplifier is constant during the period when the data is transmitted and during the period when the data is not transmitted.

8. The transmitting circuit according to any one of claims 1 to 3, further comprising another amplifier, which includes a device different from the gallium nitride device as an amplifying element, in the preceding stage of the aforementioned amplifier.

9. A communication device, A baseband unit that generates a transmit baseband signal and performs signal processing on a received baseband signal, A first oscillator that outputs a first oscillation signal, A second oscillator that outputs a second oscillation signal having a frequency different from that of the first oscillation signal, A transmitting circuit that converts the aforementioned baseband signal into a radio frequency signal, An antenna that transmits the aforementioned transmission radio frequency signal and receives the received radio frequency signal, The system includes a receiving circuit that converts the received radio frequency signal into the received baseband signal, The aforementioned transmitting circuit is A frequency conversion unit that selectively inputs the first oscillation signal and the second oscillation signal, and uses the input first oscillation signal or the second oscillation signal to convert the transmit baseband signal into a transmit radio frequency signal, An amplifier that amplifies the transmitted radio frequency signal, including a gallium nitride device as an amplifying element, The transmitted radio frequency signal amplified by the amplifier is input, and the system has a band-pass filter that allows signals within a predetermined passband to pass through. The frequency conversion unit receives the first oscillation signal during the period when data is transmitted wirelessly, and the second oscillation signal during the period when data is not transmitted wirelessly. The frequency conversion unit converts the transmit baseband signal to a first transmit radio frequency signal when the first oscillation signal is input, and converts the transmit baseband signal to a second transmit radio frequency signal when the second oscillation signal is input. A communication device in which the first transmitted radio frequency signal is a signal within the passband of the band-pass filter, and the second transmitted radio frequency signal is a signal outside the passband of the band-pass filter.

10. The communication device according to claim 9, wherein the band-pass filter allows the first transmitted radio frequency signal to pass toward the antenna and totally reflects the second transmitted radio frequency signal.

11. The communication device is a communication device used in time-division duplex wireless communication, the period during which the data is transmitted wirelessly is the period during which the transmitting circuit transmits the first transmitting radio frequency signal via the antenna, and the period during which the data is not transmitted wirelessly is the period during which the receiving circuit is supplied with the receiving radio frequency signal from the antenna, according to claim 9 or 10.

12. The frequency conversion unit includes a selector switch that switches between outputting the first oscillation signal or the second oscillation signal, and a first mixer that mixes the first oscillation signal or the second oscillation signal output from the selector switch with the transmit baseband signal. The communication device according to claim 9 or 10, wherein the receiving circuit includes a third amplifier for amplifying the received radio frequency signal and a second mixer for mixing the received radio frequency signal amplified by the third amplifier with the first oscillation signal.

13. During the period when data is transmitted wirelessly, a first oscillation signal is used to convert the baseband signal into a first radio frequency signal which is a signal within the passband of a band-pass filter. The first radio frequency signal is amplified by an amplifier including a gallium nitride device as an amplifying element. The first radio frequency signal amplified by the amplifier is input to the band-pass filter, and the first radio communication signal that has passed through the band-pass filter is output toward the antenna. During periods when data is not transmitted wirelessly, a second oscillation signal with a frequency different from that of the first oscillation signal is used to convert the baseband signal into a second radio frequency signal which is a signal outside the passband of the band-pass filter. The second radio frequency signal is amplified by the amplifier. A communication method comprising inputting a second radio frequency signal amplified by the amplifier into the band-pass filter, and causing the second radio communication signal to undergo total reflection in the band-pass filter.

14. During the period when data is transmitted wirelessly, a first oscillation signal is used to convert the baseband signal into a first radio frequency signal which is a signal within the passband of a band-pass filter. The first radio frequency signal is amplified by an amplifier including a gallium nitride device as an amplifying element. The first radio frequency signal amplified by the amplifier is input to the band-pass filter, and the first radio communication signal that has passed through the band-pass filter is output toward the antenna. During periods when data is not transmitted wirelessly, a second oscillation signal with a frequency different from that of the first oscillation signal is used to convert the baseband signal into a second radio frequency signal which is a signal outside the passband of the band-pass filter. The second radio frequency signal is amplified by the amplifier. A program that causes a processor to input a second radio frequency signal amplified by the amplifier into the band-pass filter and to perform a process of totally reflecting the second radio communication signal in the band-pass filter.

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