Anritsu Corporation (President Hirokazu Hashimoto) is releasing two upgrades on January 31, 2017 to strengthen the company’s 32 GBaud PAM4 BER test solutions for its Signal Quality Analyzer MP1800A series.
The newly developed G0375A 32 Gbaud Power PAM4 Converter and G0376A 32 Gbaud PAM4 Decoder with CTLE support the PAM4*1 input tests and BER*2 measurements defined in the next-generation 200GbE/400GbE*3 and CEI-56G*4 standards.
Development Background
Faster communications speeds between servers and network devices are being investigated to help cope with the recent explosive increase in data traffic. The 200GbE/400GbE next-generation Ethernet standard not only uses faster symbol rates and multiple lanes to increase transmission capacity per unit time but also used PAM (pulse amplitude modulation).
Like the NRZ*5 method, evaluation of PAM4 optical communications modules requires a high-amplitude test signal for direct-driving the optical modulator performing the electro-optical conversion. Additionally, evaluation of EA Modulators*6 must take non-linearity of the optical output level into consideration and requires a signal source supporting independent adjustment of the PAM4 signal 3Eye amplitude.
On the other hand, the BER of the 4-level PAM4 signal is measured like the NRZ method by splitting into two binary signals at the PAM4 decoder. Furthermore, confirming the correlation with simulation results requires use of an equalizer circuit such as a Continuous Time Linear Equalizer (CTLE) and BER measurement of a signal corrected for transmission path loss.
Anritsu expects that its signal source for implementing 32 Gbaud*7 PAM4 BER measurements and BER measurement solutions will play a major role in development of next-generation PAM4 communication standards.
Outline of PAM4 Signal Evaluation using G0375A/G0376A and MP1800A Series
The Signal Quality Analyzer MP1800A is a plug-in module type Bit Error Rate Tester; the built-in 32G multichannel PPG and ED modules assure multichannel, high-quality signal generation and high-input-sensitivity measurement.
The newly developed G0375A and G0376A are remote heads for addition to the MP1800A series 32G PPG/ED to extend measurement support for both NRZ and PAM4 measurements using NRZ measuring instruments.
Combining the G0375A with the 28G/32Gbit/s PPG MU183020A converts 32 Gbit/s NRZ signals to PAM4 signals to output a high-amplitude signal of 4.4 Vp-p (differential, max.). Additionally, the 3ch PPG synchronization function for independent control of the PAM4 signal 3Eye amplitudes enables high-reproducibility evaluation of optical modulators without using an external driver amplifier.
With built-in PAM4 decode and CTLE functions, the G0376A supports measurement of PAM4 decoded binary signals using the 28G/32Gbit/s High Sensitivity ED MU183040B. In addition, combination with the CTLE function supports high-efficiency, input-sensitivity performance tests.
[G0375A Features]
- 10 to 32.1 Gbaud rate
- Optical modulator direct driving
- High output amplitude of 4.4 Vp-p max. (differential)
- 3Eye independent level control
- High-quality, low-jitter output waveform
[G0376A Features]
- 10 to 32.1 Gbaud rate
- High input sensitivity of 40 mV typical (per eye, single-end, Eye Height)
- BER measurement after PAM4 Eye opening adjustment using continuously variable CTLE Gain of –12 to 0 dB
- Real-time PAM4 BER Measurement using PAM4 Decoder and 2ch Error Detector
[Target Markets and Applications]
- Target Markets: High-end servers, communications equipment, optical transceivers
- Applications: R&D of high-speed electronic devices, optical devices, optical transceiver modules
[Glossary]
*1 PAM: Pulse Amplitude Modulation
Method for increasing transmission rate using amplitude modulation
*2 BER: Bit Error Rate
Proportion of random data errors in demodulated transferred digital data
*3 200GbE/400GbE
Next-generation Ethernet specification defined by IEEE802.3bs standard supporting transfer of either 200 or 400 gigabits of data per second
*4 CEI (Common Electrical Interface)-56G
Electrical interface standard of 56 Gbit/s per lane defined by Optical Internetworking Forum
*5 NRZ: Non Return to Zero
Method for transferring digital data
*6 EA Modulator: Electroabsorption Modulator
One type of electrical to optical converter used at long-distance optical fiber transmissions
*7 Gbaud: Giga Baud
Unit of modulation rate; defined as a number of modulations per unit time.
