A monolithically integrated 20-Gb/s 850-nm optical receiver realized in 28-nm CMOS technology

The demand for high-bandwidth interconnects in applications such as data centers and high-performance computing has led to the widespread adoption of optical interconnect solutions. To further enhance the market acceptance of these applications, cost reduction is essential. For this, we realized an avalanche photodetector (APD) that relies on the vertical N+/P-well Si junction for photodetection. It achieves the responsivity of 0.28 A/W and the bandwidth of 5.9 GHz for 0 dBm incident optical power. We implemented a monolithically integrated optical receiver that contains APD, under-damped trans-impedance amplifier, and output buffers using 28-nm standard CMOS technology without any process modification and design rule violation. The fabricated optical receiver successfully operates up to 20 Gb/s. Details of the monolithic optical receiver performance as well as the limiting factors that need to be overcome for further performance improvement will be discussed in the presentation.