On the Spectral Tones in a Digital-Analog Converter Due to Mismatch and Flicker Noise

Abstract

Spurious-free dynamic range (SFDR) is one of the most important design metrics for a high-performance digital-analog converter (DAC). SFDR is limited by both dynamic (switching) and static (mismatch) nonlinearities. A good design needs to ensure that the spurious spectral tones caused by the static mismatches do not limit the performance. Aggressively scaling device sizes have also aggravated the problem of flicker noise, which gets modulated by the signal and presents itself as spectral tones. Typically, time domain statistical simulations are needed to guarantee system performance in presence of these nonidealities. In this work, we present a theoretical approach to compute these spectral tones.

A 6-bit, 500-MS/s current-steering DAC in SiGe BiCMOS technology and considerations for SFDR performance

“…Unwanted spurious signals generated by the DAC degrade the bit error rate of wideband communication systems and the effectiveness of wideband EW systems [1,2].…”

“…The degradation of the SFDR performance can be attributed to static and dynamic non-linearity [1,4]. Static non-linearity arises from the mismatch between transistors, while dynamic non-linearity can be attributed to switching characteristics and finite output impedance of the current source cells [1].…”