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Optical controller simplifies GPON transceiver designs

Posted: 04 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:GPON controller? GPON transceiver? GPON?

DS1865 optical controller from Maxim

Maxim Integrated Products introduces the DS1865, an optical control, calibration and monitor IC. DS1865 integrates GPON power-leveling functionality, a laser bias average-power-control (APC) loop, video amplifier control and SFF-8472 diagnostic and alarm features. The device DS1865 targets BPON and GPON triplexer applications.

The DS1865 optical controller also integrates several analog functions, enabling the device to achieve best-in-class performance. An integrated 13bit ADC includes input scaling, which provides 29dB of dynamic range. The built-in temperature sensor is factory-calibrated and has 50 percent less error than competing solutions. A tracking error lookup table enables compensation for laser-monitor diode error that occurs across temperature. The latter feature further increases the accuracy of the laser power control.

DS1865 includes a 13bit laser-bias DAC to control the video amplifier and a second DAC to control the boost converter for the APD bias. The APD bias can be controlled across a wide temperature range to ensure that the APD operates in the correct gain range. The RF output power of the video amplifier is controlled using the MAX4003 to sense the output RF power, an op amp to make a feedback loop and the DS1865's DAC output to provide a set point for the control loop.

With all this built-in capability, the DS1865 simplifies GPON transceiver design in several ways. The APC loop controls the laser's bias across temperature and aging, thus removing the requirement for a laser-bias LUT. The modulation control DAC and APC loop have eight bits of resolution, and another three levels of scaling: +0dB, -3dB, and -6dB. This scaling ability allows a single register to control the ONU power level. The DS1865 memory map conforms to SFF-8472 specification, making this device simple to use and design in.

DS1865 is available now in a 28-pin 5-by-5mm TQFN housing. It operates from a 2.85-5.5V power supply over a -40C to 95C temperature range. Pricing starts at $1.98 for 10,000-unit quantities. Evaluation kits are also available.

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