Avago Technologies Fiber IP (singapore) Pte. Ltd

Mauro Cerisola

Michela Franz

A method and apparatus for use in an optical receiver are provided for monitoring the received optical power in the optical receiver over wide range of optical power levels with high accuracy. An adjustable resistor circuit of the apparatus has a first resistor and one or more second resistors that may be switched into and out of parallel with the first resistor to vary the resistance of the adjustable resistor circuit. A controller of the optical receiver controls the switching of the one or more second resistors into and out of parallel with the first resistor. Varying the resistance of the adjustable resistor circuit in this manner causes the value of the analog voltage signal representing the received optical power to be varied prior to being input to the ADC of the controller. In this way, the amplitude of the analog voltage signal is reduced when it is at the high end of the received power range so as not to exceed the input range of the ADC of the controller IC. When the amplitude of the analog voltage signal is at the lower end of the input range of the ADC, the amplitude of the analog voltage signal is not reduced. In this way, a wide range of received power is monitored with high accuracy.

Apparatus and method for monitoring received optical power in an optical receiver over a wide range of received power with high accuracy

The power of a digital signal such as an optical data stream is set via digital-to-analog converter having a reference input for connection to a DC reference signal. The pilot tone is injected into the reference input of the digital-to-analog converter. In the place of a dual amplitude control (modulation current and pilot tone), the disclosed arrangement only requires a single control, thereby reducing cost, power consumption, microcontroller input/output activity, area occupation (PCB real estate) and failure rate.

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Turin, Italy

Mauro Cerisola