Comms chips

Peregrine Chip Eases D3.1 Transitions

Peregrine Semiconductor Corp. has introduced a single RF switch for DOCSIS 3.1 customer premises equipment (CPE) that will enable MSOs to deploy a set-top, gateway or cable modem that will remain operable regardless of the upstream/downstream spectrum split an MSO upgrades to over time.

The switches also support both DOCSIS 3.0 and 3.1.

Having this part available means an MSO will not have to swap out CPE as it transitions from D3.0 to D3.1, and -- more importantly -- can keep the same unit in place if and when it decides to increase the amount of spectrum it dedicates to the upstream channel, Peregrine's ‎director of marketing, Kinana Hussain, explained to Light Reading.

Cable CPE to date commonly supports only one upstream/downstream band combination, integrating either a low-band filter or a high-band filter. Peregrine's existing PE42722 and its new PE42723 RF switches can be used instead to enable dual upstream/downstream bands to reside in the same product.

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The traditional cable spectrum split dedicates 5MHz to 42MHz for the return path. With the introduction of DOCSIS 3.1, operators can choose to increase their upstream bandwidth allocation from 5-85MHz (often referred to as the mid-split) or 5-204MHz (the high split), as they increase their total amount of spectrum up to 1.7GHz and possibly beyond.

The new PE42723 resides in a package that is 64% the size of its predecessor, and is made with the same silicon on insulator technology, which the company calls UltraCMOS. Hussain claims its UltraCMOS capabilities make Peregrine the only company with an RF switch that has the linearity characteristics that can support dual bands in a DOCSIS environment.

The new part matches the linearity characteristics of its larger predecessor. As the company designed the new IC, Hussain said, "We thought we might have worse performance, but it turned out actually no."

The switch is placed directly at the cable modem (CM) F-connector before the filters and must comply with D3.1 CM spurious emissions requirements of -50 dBmV, requiring the switch harmonic performance to be greater than -115 dBc.

Offered in 12-lead 3 x 3 mm QFN package, volume-production parts, samples and evaluation kits are available now. For 10K-quantity orders, each PE42723 switch is $1.56.

— Brian Santo, Senior Editor, Components, T&M, Light Reading

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