ClariPhy samples a 200 Gigabit coherent DSP-ASIC

ClariPhy Communications has announced it is sampling the CL20010, a coherent merchant chip capable of 100 and 200 Gigabit transmission speeds. 

The CL20010 is the first of ClariPhy's LightSpeed-II family of coherent digital signal processing ASICs (DSP-ASICs), manufactured using a 28nm CMOS process. "We believe it is the first 28nm standard product, and leaps ahead of the current generation [DSP-ASIC] devices," says Paul Voois, co-founder and chief strategy officer at ClariPhy.

Paul Voois

ClariPhy has been shipping its 40 Gigabit coherent CL4010 LightSpeed chip since September 2011. Customers using the device include optical module makers Oclaro, NEC and JDSU. "We continue to go into new deployments but it is true that the 40 Gig market is not growing like the 100 Gig market," says Voois. 

With the CL20010, Clariphy now joins NTT Electronics (NEL) as a merchant supplier of high-speed coherent silicon. Clariphy has said that the LightSpeed-II devices will address metro, long-haul and submarine.

No longer do the integrators need to buy a separate transmit multiplexer chip

Using an advanced 28nm CMOS process enables greater on-chip integration. The CL20010 includes the transmit and receive DSPs, soft-decision forward error correction, and mixed signal analogue-to-digital and digital-to-analogue converters. "No longer do the integrators need to buy a separate transmit multiplexer chip," says Voois. 

The LightSpeed-II silicon also features an on-chip Optical Transport Network (OTN) framer/ mapper and a general-purpose processor. The general purpose processor enables the chip to be more network aware - for example, the state of a link - and support software-defined networking (SDN) in the WAN.  

The LightSpeed-II ICs support three modulation schemes - polarisation-multiplexed, bipolar phase-shift keying (PM-BPSK), quadrature phase-shift keying (PM-QPSK) and 16-quadrature amplitude modulation (PM-16-QAM). Using PM-16-QAM, the CL20010 can support 200 Gigabit  traffic. "I believe that is also a first for merchant silicon," says Voois. 

Having an on-chip framer enables the transmission of two 100 Gigabit clients signals as a 200 Gigabit OTN signal. In turn, combining two CL20010 devices enables a 400 Gig flexible-grid super-channel to be transmitted.  The on-chip transmit DSP enables the CL20010 to support flexible grid, with the dual carrier 400 Gigabit super-channel occupying 75GHz rather than 100GHz. The CL20010 can achieve a reach of 3,500km at 100 Gig, and over 600km at 200 and 400 Gig.

ClariPhy has not announced the power consumption of its chips but says that it is also targeting the metro pluggable market. Given that a CFP coherent module consumes up to 32W and that the optics alone consume 12W, a LightSpeed-II metro DSP-ASIC will likely consume 18-20W.      

Merchant market 

Many of the leading optical transport equipment makers, such as Alcatel-Lucent, Ciena, Cisco Systems, Huawei and Infinera, use their own coherent DSP-ASICs. More recently, Acacia Communications announced a CFP 100 Gig coherent pluggable module that uses its internally developed DSP-ASIC.    

Some of the OEMs will continue to develop internal technology but even they can't cover all possible applications  

ClariPhy says that despite the bulk of the 100 Gigabit coherent ports shipped use internally developed designs, there are signs that the market is moving towards adopting merchant silicon. "It doesn't happen all at once," says Voois. "Some of the OEMs will continue to develop internal technology but even they can't cover all possible applications."  

He cites coherent silicon for metro networks as an example. Equipment makers are focussed on DSP-ASIC designs that satisfy the most demanding, ultra-long-haul network applications. But such high-performance, high-power chips are not suited for the more cost-conscious, low-power and compact metro requirements.        

"Our committed customer base includes a nice spectrum of applications and integration types: OEMs and module vendors; metro, long haul and submarine," says Voois. 

General availability of the CL20010 is expected later this year. The company will also be demonstrating the device at OFC 2014.