| CPC H01S 5/0428 (2013.01) [H01S 5/06825 (2013.01); H01S 5/0683 (2013.01); H04B 10/40 (2013.01); H04B 10/50 (2013.01); H04B 10/503 (2013.01); H04B 10/60 (2013.01); H04B 10/69 (2013.01)] | 8 Claims |
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1. A communication device which is provided on a first terminal side or a second terminal side in an active optical cable configured to perform communication between the first terminal side and the second terminal side by using a laser diode and a photodiode respectively provided on the first terminal side and the second terminal side, the communication device comprising:
a differential input termination resistor configured to terminate a differential input terminals to which a signal to be transmitted to the other party communication device side is input as differential signals, and has a variable resistance value;
a linear laser driver configured to supply a current signal to the laser diode based on a signal to be transmitted to the other party communication device side and output an optical signal from the laser diode;
a transmitted signal detector configured to detect whether or not an input signal for the differential input terminals is an electrical idle;
a linear transimpedance amplifier configured to input a current signal output from a photodiode having received an optical signal having arrived from the other party communication device side, convert the current signal into a voltage signal, and output the voltage signal;
a linear variable gain amplifier configured to amplify and outputs the voltage signal output from the linear transimpedance amplifier;
a linear output driver configured to output the voltage signal output from the linear variable gain amplifier to an output destination device and is able to detect an input termination resistance of the output destination device;
a pulse counter configured to monitor the current signal output from the photodiode or the voltage signal output from the linear transimpedance amplifier, and detect the number of pulses of the current signal or the voltage signal;
a received signal detector configured to monitor the current signal output from the photodiode or the voltage signal output from the linear transimpedance amplifier, and detect whether or not the current signal or the voltage signal is an electrical idle; and
a controller configured to control a transition between an active state in which a signal is able to be transmitted and a sleep state in which power consumption is able to be reduced, based on an electrical idle detection result obtained by the transmitted signal detector, an output destination device input termination resistance detection result obtained by the linear output driver, a pulse number detection result obtained by the pulse counter, and an electrical idle detection result obtained by the received signal detector, and control operations of the differential input termination resistor, the linear laser driver, the linear transimpedance amplifier, the linear variable gain amplifier, and the linear output driver,
wherein the controller
determines a transition from a sleep state to an active state when the transmitted signal detector has detected that the input signal is not an electrical idle or when the number of pulses detected by the pulse counter indicates a transition from the sleep state to the active state,
determines a transition from the active state to the sleep state, based on a fact that the transmitted signal detector has detected that the input signal is an electrical idle or a fact that the received signal detector has detected that the current signal or the voltage signal is an electrical idle,
controls supply of the current signal to the laser diode by the linear laser driver, based on the output destination device input termination resistance detection result obtained by the linear output driver, and whether it is the active state or the sleep state,
controls a resistance value of the differential input termination resistor based on the pulse number detection result obtained by the pulse counter, and
controls operations of the linear transimpedance amplifier, the linear variable gain amplifier, and the linear output driver, based on whether being in the active state or the sleep state.
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