Resistive Feedback Influence on Ring Oscillator Performance for IR-UWB Pulse Generator in 0.13 m CMOS technology

A CMOS standard three-stage ring oscillator is examined in UMC 0.13 m technologies. As the ring oscillator is a part of IR-UWB (Impulse Radio Ultra Wide Band) pulse generator, its oscillating frequency determines the central frequency of the pulse spectrum and has significant effect on spectrum fitting within UWB FCC mask. The influence of inverter feedback resistors on the ring oscillator frequency and the peak-to-peak amplitude are investigated. Furthermore, as the ring oscillator usually drives a buffer in pulse generator/transmitter chain, dependence of its Figures of Merit on the buffer resistive feedback is presented in the paper.