**Acronyms**

*Fiber Optics - From Fundamentals to Industrial Applications*

**84**

of BER, 0, 1.5 × 10<sup>−</sup><sup>6</sup>

at the BER threshold.

results (dots) at BER = 3 × 10<sup>−</sup><sup>5</sup>

threshold is increased to 1.7 × 10<sup>−</sup><sup>4</sup>

BER is shown in **Figure 10(c)**.

**6. Conclusions**

2.5 × 10<sup>−</sup><sup>6</sup>

**Figure 10.**

**Figure 9.**

, and 1.1 × 10<sup>−</sup><sup>5</sup>

. For BER < 2.5 × 10<sup>−</sup><sup>6</sup>

between simulation and experimental results. As BER increases to 2.5 × 10<sup>−</sup><sup>6</sup>

*(b) MER degradation as BER increases; (c) 4096QAM constellation at the BER threshold.*

are shown in **Figure 10(a)**, and the minimum achievable BER is 3 × 10<sup>−</sup><sup>5</sup>

, 5.6 × 10<sup>−</sup><sup>5</sup>

obtained by adjusting the received optical power. Thanks to the additional quantization bits, two-bit digitization has larger tolerance against BER. Its MER performance becomes more resilient against the increasing BER, and the BER

of Channel 4 (worst case) drops to 41 dB, i.e., the minimum CNR requirement of 4096QAM. Therefore, the BER threshold of 32 GSa/s one-bit digitization is

*BER tolerance of 32 GSa/s two-bit delta-sigma digitization: (a) BER and EVM versus received optical power;* 

*BER tolerance of 32 GSa/s one-bit delta-sigma digitization: (a) BER and EVM versus received optical power;* 

*(b) MER degradation as BER increases; (c) 4096QAM constellation at BER threshold.*

4096QAM, but for BERs beyond this threshold, some channels' performance will drop below the DOCSIS 3.1 criteria. **Figure 9(c)** shows the 4096QAM constellation

Similar results for two-bit delta-sigma digitization (Case XII) are shown in **Figure 10**. The experimentally measured EVM and BER of 32 Gbaud DP-16QAM

**Figure 10(b)** shows the MER performance degradation as a function of increasing BER. Simulation results (solid lines) are obtained by flipping a certain number of bits after digitization to emulate various BER values; experimental

In this paper, we proposed and demonstrated delta-sigma digitization and coherent transmission of DOCSIS 3.1 signals for the first time. A low-pass CRFB delta-sigma ADC was designed to digitize 20 × 192-MHz DOCSIS 3.1 channels

, 9.5 × 10<sup>−</sup><sup>5</sup>

were tested, and good consistency is achieved

, 3 × 10<sup>−</sup><sup>4</sup>

. The 4096QAM constellation at the threshold

, all 20 channels have sufficient CNR to support

, MER

.

are

, 5.2 × 10<sup>−</sup><sup>4</sup>

