Output circuit of high-frequency transmitter

1. A transmitting and receiving device, comprising:

a transmission circuit that transmits transmission data by FM-modulating a carrier wave of the transmission data, the transmission circuit including:

a modulation pattern generator that generates modulation pattern data,

a current-controlled oscillator that changes a cycle of a frequency modulation signal according to the modulation pattern data, and

a modulation circuit that generates a communication signal by modifying an amplitude of the frequency modulation signal according to the transmission data;

an FM demodulation circuit that generates a demodulation signal by FM-demodulating a received signal;

a first filter circuit that changes a pass-band for letting the received signal pass through according to the demodulation signal; and

a parallel resonance circuit that adjusts a resonance frequency to a first carrier frequency of the communication signal according to the modulation pattern data, and adjusts the resonance frequency to a second carrier frequency of the received signal according to the frequency demodulation data,

wherein the transmitting and receiving device performs a power supply line communication through the power supply line in which a signal is transmitted and received among the plurality of transmitting and receiving devices.

2. The transmitting and receiving device according to claim 1 , further comprising:

a second filter having a wider frequency pass-band than the first filter circuit;

wherein, the FM demodulation circuit receives the signal through the second filter circuit and to generate the demodulation signal by FM-demodulating the signal received through the second filter circuit.

3. The transmitting and receiving device according to claim 1 ,

wherein, one of transmitting and receiving devices transmits the signal with a carrier wave having a frequency substantially the same as the frequency of the carrier wave of the signal received from the other transmitting and receiving device.

4. The transmitting and receiving device according to claim 3 ,

wherein, the power supply line is branched in a power supply route and a route for transmitting and receiving the signal.

5. The transmitting and receiving device according to claim 4 , wherein

the first filter circuit changes the pass-band for passing through the signal according to a given frequency for starting transmission of the signal, and

the resonance circuit changes the resonant frequency according to the given frequency for starting transmission of the signal.

6. The transmitting and receiving device according to claim 5 ,

wherein the transmission circuit includes a third filter circuit changes a cut off frequency according to a frequency of a carrier wave.

7. A method for power supply line communication, the method comprising:

transmitting a signal by FM-demodulating a carrier wave;

generating modulation pattern data;

changing a cycle of a frequency modulation signal according to the modulation pattern data;

generating a communication signal by modifying an amplitude of the frequency modulation signal according to the transmission data;

generating a demodulation signal by FM-demodulating a received signal;

changing a pass-band for letting the received signal pass through according to the demodulation signal;

adjusting a resonance frequency to a first carrier frequency of the communication signal according to the modulation pattern data; and

adjusting the resonance frequency to a second carrier frequency of the received signal according to the frequency demodulation data; and

transmitting and receiving a signal among a plurality of transmitting and receiving devices via a power supply line.