Monolithically Integrated Coherent Receiver
The presented chip is a monolithically integrated coherent receiver designed to support high symbol rates (up to 64 GBd) necessary for inter- and intra-datacenter fiber-optic links. It represents a significant technological advancement as the first monolithic, single polarization coherent ePIC receiver operating at 64 GBd.
The chip was fabricated using a 0.25 µm ePIC SiGe BiCMOS technology, which enables the co-integration of high-speed electronics and photonics on a single silicon die. This technology combines high-performance lateral Ge photodetectors (with a responsivity of 0.7 A/W) and SiGe bipolar transistors (fT = 190 GHz).
The integrated circuit features a highly compact total footprint of and incorporates several key components: on-chip grating couplers (GCs), a 90° hybrid (realized as a multimode interferometric structure), photodiodes (PDs), and transimpedance amplifiers (TIAs). The TIAs employ a fully-differential shunt-feedback architecture and operate in limiting mode, achieving a fixed transimpedance gain of 7.7 kΩ. Crucially, the interconnects between the PDs and the TIAs are very short, measuring as low as 60 µm.
The measured opto-electrical 3 dB bandwidth of the receiver for the in-phase and quadrature channels is 34 GHz. The chip operates with a low total power dissipation of 416 mW. The device successfully achieved real-time data transmission of 64 GBd-QPSK, corresponding to 128 Gb/s, with a Bit Error Ratio (BER) of 3.74e-5, which is below the Forward Error Correction (FEC) limit.
Area: 2.56mm x 1.16 mm
Technology: 250nm SiGe:C BiCMOS IHP (H4 EPIC)
Reference
C. Kress, S. Gudyriev, J. C. Scheyt et al., "64 GBd Monolithically Integrated Coherent QPSK Single Polarization Receiver in 0.25 μm SiGe-Photonic Technology," 2018 Optical Fiber Communications Conference and Exposition (OFC), San Diego, CA, USA, 2018, pp. 1-3.
S. Gudyriev, C. Kress, J. C. Scheytt et al., "Coherent ePIC Receiver for 64 GBaud QPSK in 0.25 μm Photonic BiCMOS Technology," in Journal of Lightwave Technology, vol. 37, no. 1, pp. 103-109, 1 Jan.1, 2019.
Weltrekord am Heinz Nixdorf Institut der Universität Paderborn