# A 5 Gb/s Optoelectronic Receiver IC in 180 nm CMOS for Short-Distance Optical Interconnects
## 3 Chip Layout and Post Layout Simulation Results
Hence, when compared to prior arts, the proposed CORIC provides competitive performance in terms of the gain-bandwidth tradeoff, despite its implementation in a relatively low-cost 180 nm CMOS process. While most state-of-the-art designs rely on advanced nodes (including 130 nm, 65 nm, or even 40 nm technologies) to achieve high performance, the CORIC demonstrates comparable performance with careful analog front-end architecture and circuit-level optimization--such as the use of a cross-coupled differential TIA and an adaptive equalizer. Namely, it attains comparable or even superior bandwidth and gain characteristics, which not only reduces the fabrication costs, but also enhances the circuit robustness and yield. Figure 9: Simulated eye diagrams of the CORIC for 300 \(\upmu\)A\({}_{\text{pp}}\) input currents at different date rates of (**a**) 1 Gb/s and (**b**) 3 Gb/s, respectively. Moreover, the integration of an on-chip APD and a 3-bit programmable gain control mechanism enables the CORIC to achieve the dynamic range of 60 dB, which is particularly beneficial in scenarios with varying optical input power levels, such as multi-mode fiber \begin{table}
\begin{tabular}{c c c c c c c} \hline \multicolumn{2}{c}{**Parameters**} & [16] & [17] & [18] & [19] & [20] & **This work** \\ \hline \multicolumn{2}{c}{CMOS technology (nm)} & 180 & 130 & 40 & 180 & 65 & 180 \\ \hline \multirow{4}{*}{PD} & \multirow{2}{*}{Type} & Off-chip & Off-chip & Off-chip & Off-chip & Off-chip & On-chip \\  & & (Equiv. PD) & (Equiv. PD) & (Equiv. PD) & (Equiv. PD) & (Equiv. PD) & (APD) & (APD) \\ \cline{2-7}  & \multicolumn{1}{c}{C\({}_{\text{pd}}\) (pF)} & 0.5 & 2 & 0.2 & 0.22 & - & 0.5 \\ \cline{2-7}  & \multicolumn{1}{c}{Responsivity} & \multirow{2}{*}{-} & \multirow{2}{*}{1} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{2.72} \\  & (A/W) & & & & & & \\ \cline{2-7}  & \multicolumn{1}{c}{Wavelength} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{850} & \multirow{2}{*}{850} \\  & (nm) & & & & & & \\ \hline \multicolumn{2}{c}{Input configuration} & \multicolumn{1}{c}{RGC} & AP \(\ddagger\) & Diff. & CS \(\ddagger\) & Diff. & Diff. \\ \hline \multicolumn{2}{c}{Max. TZ gain (dB\(\Omega\))} & 72 & 76.8 & 64 & 54.5 & 60 & 53.2 \\ \hline \multicolumn{2}{c}{Gain control} & No & No & No & No & No & Yes \\ \hline \multicolumn{2}{c}{Bandwidth (GHz)} & 2.4 & 1.6 & 14.5 & 4.3 & 6.0 & 4.83 \\ \hline \multicolumn{2}{c}{Input noise current density} & \multirow{2}{*}{18.12} & \multirow{2}{*}{26.55} & \multirow{2}{*}{22.4} & \multirow{2}{*}{25.3} & \multirow{2}{*}{-} & \multirow{2}{*}{47.9} \\  & (pA/\(\sqrt{\text{Hz}}\)) & & & & & \\ \hline \multicolumn{2}{c}{Dynamic range (dB)} & - & - & - & - & & 60 \\ \hline \multicolumn{2}{c}{Power dissipation per} & \(\lx@sectionsign\) 20.6 & 47.3 & 103 & \(\lx@sectionsign\) 11.5 @ & \(\lx@sectionsign\) 13.7 @ & \multirow{2}{*}{33.7 @ 1.8 V} \\ \multicolumn{2}{c}{channel (mW)} & @@@1.8 V & @@1.8 V & @1.2 V & 1.5 V/3.0 V & 1.2 V & \\ \hline \multicolumn{2}{c}{Chip area (mm\({}^{2}\))} & 0.173 & \(\lx@sectionsign\) 0.00035 & 1.1625 & \(\lx@sectionsign\) 0.0077 & 0.024 & 0.026 \\ \hline \end{tabular} \(\ddagger\) Single-ended, \(\lx@sectionsign\) 7 TA only. RGC (regulated cascode), AP (active inductive peaking), Diff. (differential), CS (common source)  
\end{table} 
Table 1: Performance comparison of the proposed CORIC with the recently published TIAs. Figure 10: Simulated output pulses of the CORIC for different input currents. links or wavelength-division multiplexed systems. The on-chip APD eliminates the need for bulky off-chip photodetectors and their associated packaging and parasitic issues, thereby contributing to both area efficiency and noise reduction. In addition, the gain control allows the CORIC to adapt its amplification level according to input signal strength, ensuring consistent signal quality and preventing saturation under strong inputs while preserving sensitivity for weak signals.