A CMOS Fully Integrated 4 × 4 VLC-Compliant Receiver Array With 2.5 Gb/s per Channel

Abstract

This article presents a fully integrated 4\times4 receiver (Rx) array implemented in Austria Micro Systems (AMS) 0.35- \mu \text{m} CMOS technology for high-data rate (DR) visible-light-communication (VLC) indoor applications. Each Rx channel is composed of a digitally stabilized transimpedance amplifier (TIA), a programmable equalizer, an automatic gain-control (AGC) circuit, a programmable-gain output buffer (OB), and a dual offset-cancellation network (OCN). The Rx dB \Omega maximum gain with -28 dBm 1-dB input compression power. A gain control range of 50-60 dB is achieved using a Gilbert-type linear variable-gain-amplifier (VGA). A parasitic-bipolar-junction-transistor (BJT)-based exponential function is employed to achieve dB-linear VGA control and an AGC constant settling time. Each of the 16 Rx channels delivers up to 3-Gb/s on-off-keying (OOK) DR with a VLC-compliant bit-error-rate (BER < 10{-{3}} ) over a 3-m link distance with an input OOK sensitivity of -24 dBm from a 5-GHz bandwidth (BW) laser diode (LD) at 680-nm wavelength. Extended dual-multiple-input-multiple-output (MIMO) testing to a full 16-channel MIMO scenario would deliver 40-Gb/s total capacity based on the measured BER margin at 2.5-Gb/s DR. The Rx total area is 4.1\times4.1 mm, and each channel consumes around 230 mW from a 3.3-V dc supply.