A 1Mb/s 3.2–4.4GHz reconfigurable FM-UWB transmitter in 0.18µm CMOS

This paper presents a 1Mb/s frequency-modulated ultra-wideband (FM-UWB) transmitter for robust non-invasive short range communications. A 51MHz 8-modulo fractional-N PLL with a relaxation VCO is designed to generate a 2-FSK modulated triangular waveform which directly modulates an RF oscillator. The amplitude of the triangular waveform is controlled digitally, determining the RF bandwidth of the UWB spectrum. The center frequency of the RF oscillator is set by a semi-digital quasi-continuous frequency-locked loop (FLL) which enables digital tuning of the UWB frequency band. A 3.2-4.4GHz prototype FM-UWB transmitter is implemented in 0.18μm CMOS, achieving the data rate higher than the reported by at least four times.