Wireless communication device and signal detection circuit

1. A wireless communication device comprising:

a wireless communication unit that is configured to:

perform a wireless communication in a first mode using a first frequency band serving as a first communication channel; and

perform the wireless communication in a second mode using a second frequency band including the first communication channel and a second communication channel that is adjacent to the first communication channel;

a detection unit that is configured to:

monitor each of the first frequency band and the second frequency band;

output a first detection signal when an interference signal is detected in the first frequency band; and

output a second detection signal when the interference signal is detected in the second frequency band;

a determination unit that determines whether the interference signal is in the first communication channel or in the second communication channel based on the first detection signal and the second detection signal;

a first filter that filters a radio signal received by the wireless communication unit to output a first component of the radio signal corresponding to the first frequency band; and

a second filter that filters the radio signal to output a second component of the radio signal corresponding to the second frequency band,

wherein the detection unit comprises:

a first detector that is configured to detect the interference signal in the first component output from the first filter; and

a second detector that is configured to detect the interference signal in the second component output from the second filter.

2. The device according to claim 1 , wherein the determination unit determines that the interference signal is in the second communication channel when the first detection signal is not output and the second detection signal is output from the detection unit.

3. A wireless communication device comprising:

a wireless communication unit that is configured to:

perform a wireless communication in a first mode using a first frequency band serving as a first communication channel; and

perform the wireless communication in a second mode using a second frequency band including the first communication channel and a second communication channel that is adjacent to the first communication channel;

an A/D converter that converts a radio signal received by the wireless communication unit into a digital signal; and

a detection unit that monitors the digital signal to detect an interference signal in the first communication channel or the second communication channel,

wherein the detection unit comprises:

a frequency converter that converts a frequency of the digital signal using an oscillation signal having a given oscillation frequency to output a converted signal;

a filter that has a cutoff frequency that equals to the oscillation frequency and filters the converted signal to output a first component of the converted signal corresponding to the first communication channel and a second component of the converted signal corresponding to the second communication channel;

a measurement unit that measures a first intensity of the first component and a second intensity of the second component; and

a determination unit that determines the interference signal based on the first intensity and the second intensity.