Patent ID: 7881608

Claim:
A transceiver module comprising: a photodiode configured to receive an optical signal generated by a laser and convert the optical signal into an electrical signal; a first amplifier coupled to the photodiode for amplifying the electrical signal; a filter coupled to the first amplifier for reducing a bandwidth of the electrical signal; a second amplifier coupled to the filter; permanent jitter measurement circuitry coupled to the second amplifier and configured to receive the electrical signal, the jitter measurement circuitry configured to produce a jitter measurement value based on the received electrical signal, the jitter measurement value providing an indication of an amount of jitter that is in the optical signal, wherein the jitter measurement circuitry comprises a frequency detector that produces the jitter measurement value, wherein the frequency detector comprises a phase-locked loop (PLL), the PLL comprising a phase comparator, a loop filter and a voltage controlled oscillator (VCO), the phase comparator obtaining a phase difference between the electrical signal received by the jitter measurement circuitry and a clock signal of the VCO, the loop filter receiving the phase difference and producing a control voltage signal that is used by the VCO to adjust a frequency of the VCO clock signal, the control voltage signal corresponding to the jitter measurement value; average amplitude measurement circuitry coupled to the first amplifier; an analog-to-digital-converter coupled to the amplitude measurement circuitry for converting analog amplitude measurement signals to digital amplitude measurement signals; and a processor coupled to the analog-to-digital-converter and to the permanent jitter measurement circuitry, the processor determining whether to adjust bias of the laser based on the digital amplitude measurement signals, the processor receiving the jitter measurement value and correlating the jitter measurement value to an amount of jitter contained in the optical signal.