A 400Mb/s 850nm FSO Link based on CMOS Integrated Receiver for Hybrid and Optical Femtocells

The increasing demand for higher data-rates is challenging to satisfy with spectrum- deficient indoor WiFi networks. A novel hybrid WiFi Free-Space Optical (WIFO) system has been proposed to enhance the wireless capacity of indoor WiFi networks. In this thesis, an integrated optical wireless receiver is designed and integrated in 65-nm CMOS technology as a part of the hybrid WIFO network. Signal-to-noise (SNR) at trans- impedance amplifier(TIA) output is increased due to correlated signal addition while noise from different TIA is uncorrelated. A distributed TIA array structure with four Si-PIN photodiodes is introduced to improve SNR by 6dB, each with a capacitance of 1.6pF and sensitivity of 0.4A/W at 850nm wavelength. Simulations suggest an input- referred current noise of 12nA (with 200 MHz integration BW). The receiver and a low cost FSO transmitter using commercial off-the-shelf components, achieve 400 Mb/s data rates at distances beyond 1m. The receiver consumes 80 mW from a 1.2V supply.

Major Advisor: Arun Natarajan
Committee: Alan Wang
Committee: Matthew Johnston
GCR: Leonard Coop