M. Hossain and W. T. Beyene, "Toward 224-Gb/s Electrical Signaling—Modulation, Equalization, and Channel Options," in IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 11, no. 3, pp. 451-461, March 2021
- Fabulous introduction, they summarized the issues perfectly and mention "constructive use of ISI [5, 11]" which sounds very interesting.
- ceramic vs organic material packages. Ceramic can have dramatically lower loss packages and reduce reflections from vias but organic packages (most common today) can be much larger.
- "The ceramic substrate shows a loss of about −3 dB, and the organic package loss exceeds −14 dB at frequency of 56 GHz. The ceramic substrate has the advantage of minimizing via reflection, while organic substrate, to support bigger package size, requires a larger core via that increases reflection"
- "Although for simplicity ADCs are often modeled as an effective number of bits (ENOBs), it does not appropriately reflect link performance."
- " Currently, up to 35–37-dB loss compensation is demonstrated in the literature based on ADC-DSP-based solutions." , I assume that they are discussing 112G links. They should have really had a reference here.
- CNRZ suffers from skew issues but CNRZ+ADC is great since the skew isn't a big deal. Any gain mismatch can be easily compensated for in the ADC.
- "Based on the simulation results, multiwire encoding can compensate up to 40 dB of channel loss and with aggressive FEC and equalization, it can be further extended to 45 dB."
- "multiwire encoding performs significantly better when implemented in digital domain and capable of compensating up to 45 dBs of loss. Obviously, this performance improvement comes at the cost of increased power consumption. Specifically, we need 6 ADCs to decode 5 bits, compared with PAM-4 that requires only one ADC per pair of wire but with higher resolution. One important limitation for multiwire encoding is the spectrum inefficiency compared with PAM-4. Given that we can only send 5 bits over six wires compared with 6 bits over six wires in PAM-4, we need to increase data rate by 20%"
- Discrete Multitone (DMT) Modulation
- Mentioned that this is an option but is not backwards compatable.
Papers to read:
[5] A. K. M. D. Hossain, Aurangozeb, M. Mohammad and M. Hossain, "A 35 mW 10 Gb/s ADC-DSP less direct digital sequence detector and equalizer in 65 nm CMOS", Proc. IEEE Symp. VLSI Circuits (VLSI-Circuits), pp. 1-2, Jun. 2016.
[11] W. T. Beyene and A. Amirkhany, "Controlled intersymbol interference design techniques of conventional interconnect systems for data rates beyond 20 Gbps", IEEE Trans. Adv. Packag., vol. 31, no. 4, pp. 731-740, Nov. 2008.
[DMT] B. Nowrouzian, Luqing Wang and W. Agha, "An overview of discrete multitone modulation/demodulation systems in xDSL applications," Conference Record of Thirty-Fifth Asilomar Conference on Signals, Systems and Computers (Cat.No.01CH37256), Pacific Grove, CA, USA, 2001, pp. 31-35 vol.1
