Bandwidth Expansion of a Testing Station Using a 0.3-mm-Pitch LGA Interface for a $25\text{-Gbaud} \times 16- \text{Channel}$ CPO Transceiver

This paper describes the design and transmission characteristics of a bandwidth-expanded testing station using a 0.3-mm-pitch LGA-based electrical pluggable interface for a $\mathbf{25}- \mathbf{Gbaud} \times \mathbf{16}-\mathbf{channel}$ optical transceiver. This testing station employs a core-less building-up multi-layer organic substrate to avoid impedance mismatch at the vias in a core layer. Densely placed electrical connectors are used to shorten the length of electrical transmission lines. This testing station has a 3-dB bandwidth of 17.3 GHz, which is sufficient for 25-Gbaud signal transmission. We also build an optical link by attaching a $\mathbf{28}- \mathbf{Gbaud} \times \mathbf{8}-\mathbf{channel}$ optical transceiver on the testing station to evaluate signal transmission characteristics. When operating the optical link by 28-Gbaud NRZ signals, a measured jitter margin at BER of 10 ⁻¹² is as wide as 0.49 UI. which is 0.12 UI. larger than that of using our previously fabricated testing station.