A quad small form-factor pluggable 28Gbps optical transceiver design scheme is proposed. It is capable of transmitting 50Gbps of data up to a distance of 40km using modulation signals with four level pulse-amplitude. The proposed scheme is designed using a combination of electro-absorption modulated laser, transmitter optical sub-assembly, low-cost positive-intrinsic-native photodiode, and receiver optical sub-assembly to achieve standard performance and low cost. Moreover, hardware and firmware design schemes to implement the optical transceiver are presented. The results confirm the effectiveness of the proposed scheme and the performance of the manufactured optical transceiver, thereby confirming its applicability to real industrial sites.