ADC precision requirement for digital ultra-wideband receivers with sublinear front-ends: a power and performance perspective

Abstract

This paper presents the power and performance analysis of a digital, direct sequence ultra-wideband (DS-UWB) receiver operating in the 3 to 4 GHz band. The signal to noise and distortion ratio (SNDR) and bit error rate (BER) were evaluated with varying degrees of front-end linearity and analog to digital converter (ADC) accuracy. The analysis and simulation results indicate two or more ADC bits are required for reliable data reception in the presence of strong interference and intermodulation distortion. In addition to BER performance, power consumption of different hardware configurations is also evaluated to form the cost function for evaluating design choices. The combined power and performance analysis indicates that starting with one-bit ADC resolutions, a substantial gain in reliability can be attained by increasing ADC resolution to two-bits or more. When the ADC resolution improves beyond three bits, front-end linearization achieves similar BER improvements to increasing the ADC accuracy, at a fraction of the power cost. As a result, linear front-end designs become significant only when high precision ADCs are utilized.