A digitally programmable ring oscillator in the UWB range

Abstract

The increasing interest in impulse radio UWB communication links focuses the research interest on building blocks optimized for these specific systems. In this context, this paper proposes a ring oscillator for an impulse radio UWB transmitter. A multiloop ring oscillator is considered because it holds the potential of both high oscillation frequency and fast switch-on time. The novelty of the proposed inverter cell is found in the possibility to adjust the oscillation frequency digitally, rather than with an analog voltage. This leads to larger tuning range and less sensitivity to control noise. The digitally controlled oscillator is designed in 0.13μm CMOS technology and according to simulations the tuning range is from 4 GHz to 12.5 GHz. The power consumption is below 8 mW

A low-power digitally programmable impulse radio ultra wideband transmitter with pulse shape control

“…A widely tunable oscillator structure, similar to that presented in [5], is used and modified to obtain an integrated mixing element for IR-UWB radios. This configuration avoids the need of a filter to shape the pulse spectrum or of a full mixer to up-convert the pulse, and can be easily power cycled since the oscillator does not need to be run continuously.…”

“…The pulse generator produces a programmable Gaussian pulse at clocked intervals when the data signal is high. The pulse is upconverted by a modified programmable multi-loop ring oscillator [5]. A VGA then compensates for the frequency dependency of the pulse amplitude, and finally, a driver feeds the antenna, overcoming typical QFN package parasitics.…”