High-Speed SiGe BiCMOS Detector Enabling a 28 Gbps Quasi-Coherent Optical Receiver

This brief presents a high-speed detector targeting quasi-coherent optical receivers operating up to 28 Gbps data rates. The circuit consists of a balanced rectifier based on diode-connected heterojunction bipolar transistors (HBTs) together with tailored input and output filtering networks. The rectifier is buffered by a linear DC-coupled single-ended to differential amplifier providing a
$50\,\Omega $
output interface. The design was fabricated in a commercial 130 nm SiGe BiCMOS technology with f textsubscript t/f textsubscript max of 250/340 GHz, and was tested on a quasi-coherent receiver setup. Optical receiver sensitivity better than −28 dBm and −26 dBm (FEC-limited BER of 1E-3) is demonstrated, respectively, at 25 and 28 Gbps data rates. To the best of the author’s knowledge, the reported circuit represents the fastest envelope detector published to date.