  An ultra-wide-band impulse-radio (UWB-IR) transmitter (TX) for low-energy
biomedical microsystems is presented. High power efficiency is achieved by
modulating an LC tank that always resonates in the steady state during
transmission. A new clipped-sinusoid scheme is proposed for on-off keying
(OOK)-modulation, which is implemented by a voltage clipper circuit with
on-chip biasing generation. The TX is designed to provide a high data-rate
wireless link within the 3-5 GHz band. The chip was fabricated in 130nm CMOS
technology and fully characterized. State-of-the-art power efficiency of 21.3%
was achieved at a data-rate of 230Mbps and energy consumption of 21pJ/b. A
bit-error-rate (BER) of less than 10^-6 was measured at a distance of 1m
without pulse averaging. In addition, simultaneous wireless powering and
VCO-based data transmission are supported. A potential extension to a VCO-free
all-wireless mode to further reduce the power consumption is also discussed.
