Abstract-An innovative burst-mode laser transmitter (BM-TX)is presented for gigabit-capable passive optical network (GPON) upstream transmission at 1.25 Gb/s. The laser bias and modulation current each can reach 80 mA with a resolution of 0.1 mA providing a total drive current up to 160 mA. Both currents are generated by 10-bit current steering digital-to-analog converters (DACs), the architecture of which is specially adapted to yield a monotonic current setting at settling times below 12.8 ns. Tests show that fast automatic power control (APC) can stabilize and track the launched optical power with a tolerance of less than 1 dB over a wide temperature range for outdoor operation. The APC only requires a straightforward calibration of the "0" and the "1" level at room temperature. Optical level monitoring on strings of four consecutive "0" bytes and two consecutive "1" bytes at 1.25 Gb/s is demonstrated. APC based on such short strings of data has not been shown before.The circuits have been designed in a 0.35 m SiGe BiCMOS process. Experimental results show that this dc-coupled BM-TX meets the specifications of the recently approved ITU-T Recommendation G.984.2 supporting an intelligent power leveling mechanism (PLM).
Abstract-This paper presents a 1.25-Gb/s burst-mode receiver (BMRx) for upstream transmission over gigabit passive optical networks (G-PONs). The dc-coupled receiver uses a unique arrangement of three limiting amplifiers to convert the bursty input signal to a current mode logic output signal while rejecting the dc offset from a preceding transimpedance amplifier. Peak detectors extract a decision threshold from a sequence of 12 successive nonreturn-tozero (NRZ) 1's and 12 successive NRZ 0's received at the beginning of each packet. Automatic compensation of the remaining offsets of the BMRx is performed digitally via digital-to-analog converters. The chip was designed in a 0.35-m SiGe BiCMOS process. The receiver contains an APD with a gain of 6 and a transimpedance amplifier and shows a sensitivity of 32.8 dBm and a dynamic range of 23.8 dB. A sensitivity penalty of 2.2 dB is incurred when a packet with average optical power of 9 dBm precedes the packet under consideration, the guard time between the packets being 25.6 ns. The BMRx includes activity detection circuitry, capable of quickly detecting average optical levels as low as 35.5 dBm. The performed measurements prove that the receiver meets the G-PON physical media dependent layer specification defined in ITU-T Recommendation G.984.2.
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