MARCH 19, 2010 -- Opnext Inc. (NASDAQ:OPXT) says it has developed a low-power quad CMOS analog-to-digital converter (ADC), designed for use in a 127-Gbps polarization-multiplexed quadrature phase-shift keying (PM-QPSK) modulation scheme. Opnext verified the digital signal processing (DSP) and forward error correction (FEC) algorithms on its real-time 100G coherent platform, which it used in a trial with AT&T announced earlier this month.
Opnext says the ADC will be integrated with the DSP and FEC into a single PM-QPSK receiver chip using a standard CMOS process. This approach will eliminate “numerous” high-speed interconnects between the ADC, DSP, and the FEC, says Opnext. The chip includes continuous digital background self-calibration and synchronization that eliminates the need for external calibration signals as well.
The receiver is therefore immune to process, voltage, and temperature variations, allowing reliable performance over a broad range of operating conditions, Opnext asserts. The ADC will use a BGA package, enabling volume SMT manufacturing, consistent with Opnext’s current 32-Gbps mux.
"Opnext previously announced the mux and last week it demonstrated its DSP prototype," said Karen Liu, principal analyst, Ovum. "With this ADC, Opnext will have control of all the critical chips for its MSA transponder: A reliable merchant supply of the transponder is essential for the 100G market to move quickly toward a robust supply chain."
Mobius Semiconductor is a privately held company in Irvine, CA, that specializes in high-performance mixed-signal products. Its DSP-assisted mixed-signal calibration techniques are used in a family of multi-gigasample data converters.
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