RangeXtender2

PAM4/NRZ module products based on the RangeXtender 2 reference design and SoC can extend the reach of 5G, edge, cloud fronthaul and backhaul networks to 40 km. By significantly increasing the range of existing fiber transmission paths, RangeXtender 2 enables a reduction of up to 25 percent in total cost of ownership for 5G network connectivity deployments.

The RangeXtender 2 provides dual-signal PAM4 and NRZ modulation to extend optical network distances while ensuring full data integrity. Capable of speed-switching between PAM4 and NRZ modes, a single SoC can support multiple lines of module products (including PAM4, NRZ and DWDM) and is tunable to address a variety of network requirements globally. This flexible ecosystem approach will help expand access use cases such as 5G fronthaul/backhaul networks and cable operator networks, enabling multiple system operators (MSOs) to scale their existing networks from 10G to 25G DWDM and deliver more digital services to consumers.

At the heart of the RangeXtender 2 module is a new SoC featuring a world-class PAM4 modulation engine. The new SoC extends the reach of 5G fronthaul/backhaul networks by cutting data frequency in half while maintaining full signal quality and maintaining legacy compatibility through NRZ mode for the host-side interface. The new SoC also integrates Point2’s proprietary EDC engine, which combines two lanes of bidirectional clock-and-data recovery (CDR) and EDC with a CDR/retimer. This approach minimizes distortion caused by dispersion, reduces bit-error rates and simplifies integration into today’s SFP28 module products.

The RangeXtender 2 module converts electrical NRZ modulation to optical PAM-4 modulation, which has half the data frequency (12.5 Gbaud) compared to NRZ (25 Gbaud). This half-rate optical PAM4 mode is more immune to optical dispersion and can reduce module cost by enabling developers to use existing 10G components. The analog EDC filter flawlessly compensates for directly modulated laser (DML) chirp dispersion, reducing transmitter optical subassembly (TOSA) cost. RangeXtender 2 also features a linear receiver optical subassembly (ROSA) that enables multiple module suppliers to deliver a range of PAM4 and NRZ solutions.

The new SoC offers two different modes of operation: 25 Gbps NRZ-EDC mode and 25 Gbps NRZ (25 Gbaud)-to-PAM4 (12.5 Gbaud) mode. While the NRZ-to-PAM4 mode offers the benefit of using 10 Gbps TOSA/ROSA for 25 Gbps transmission and longer reach (up to 40 km), the NRZ-EDC mode provides more link budget margins (10 dB) than the NRZ-to-PAM4 mode. Module manufacturers can decide which mode they will use, depending on the distance and link budget requirements of their interconnect solutions.

The RangeXtender 2 module reference design currently supports 25 Gbps solutions with a roadmap to deliver up to 100 Gbps for future access networks.

RangeXtender 2 Reference Design and SoC Key Features

• Capable of speed-switching between PAM4 and NRZ modulation, enabling a single SoC to support multiple product lines
• Extends the reach in C-band up to 40 km in PAM4 mode and converts electrical NRZ modulation to optical PAM4 modulation
• Supports NRZ mode for the electrical (host) side for legacy compatibility with a world-class EDC engine that extends the reach up to 30 km
• Enables compensation for real-time asymmetric PAM4 signals through on-the-fly calibration
• Data rate: 24.43 Gbps~28 Gbps (with support for ePRI and CPRI)
• NRZ EDC mode: RX sensitivity < Psig = -22 dBm at BER 5E-5, up to C-band, 30 km, I-temp
• PAM-4 mode: RX sensitivity < Psig = -18d Bm at BER 5E-5, up to C-band, 40 km, I-temp
• Bypass mode optimized for low data rate applications
• Pdiss ~640 mW/bi-directional lanes
• Programmable output amplitude control with level adjustment (PAM4 mode)
• POD: 3.8 mm x 3.8 mm (1.0 mm max. height)