Design and Device Mismatch Analysis of CSS–UWB Pulse Generator

Abstract

This paper presents the design of a Chirp Spread Spectrum (CSS), ultra-wideband (UWB), pulse generator (PG) and device mismatch impact on its performance. The proposed CSS-PG is built using a differential ring oscillator (RO) controlled by a ramp generator, allowing varying linearly the pulse frequency with time over the CSS pulse duration. Device mismatches and random variations during integrated circuit manufacturing are the most critical imperfections in high precision differential UWB voltage controlled RO circuit. These mismatches lead to behavioral variations of the PG. The proposed CSS-UWB-PG is designed and analyzed using CMOS 0.18[Formula: see text][Formula: see text]m technology. The CSS-PG presents an output swing of 266[Formula: see text]mV Vpp for 20[Formula: see text]nsec and consumes 1.72[Formula: see text]mW for a PRF of 10[Formula: see text]MHz. The simulated PSD covers the UWB low band from 3[Formula: see text]GHz to 5[Formula: see text]GHz and complies with the FCC regulations. For [Formula: see text] mismatch, the simulation results show a maximum relative accuracy on oscillation frequency and phase noise of 3.43% and 6.9%, respectively. Monte Carlo and process simulation are performed to study the impact of the random parameter variation on this CSS-PG. Theses simulations show the robustness of the proposed design as the PG PSD is still inside the FCC-UWB mask and its bandwidth is greater than 500[Formula: see text]MHz.