A low-power FSK/spatial modulation transmitter for mm-wave wireless links

Energy-efficient, multi-Gb/s wireless links are of interest for short-range board-to-board links within server chassis/enclosed server platforms. In this paper, we propose to leverage the small physical size/large available bandwidth of mm-wave systems to demonstrate combined frequency and spatial modulation in a mm-wave TX, targeting links operating in slow-varying channels. A pulsed mm-wave digitally-controlled oscillator (DCO) provides low-power FSK capability, while variable pulse trigger delay achieves controlled relative phase between TX elements for low-power space-shift keying (SSK). A two-element 65-nm CMOS TX prototype is packaged with PCB antennas to demonstrate a 2-FSK/4-SSK 3-Gb/s TX up to 60-cm with 21.4 mW power consumption, achieving ~7.1 pJ/bit.