SECTION 2-3 - Data Converter AC Errors

Abstract

This chapter details the AC (alternating current) errors associated with data converters. Most of the errors and specifications apply equally to ADCs (analog-to-digital converters) and DACs (digital-to-analog converters), while some are more specific to one or the other. It explains theoretical quantization noise of an ideal N-bit converter. It summarizes the noise in practical ADCs, equivalent input referred noise, and noise-free (flicker-free) code resolution. The chapter explains different ways of characterizing the dynamic performance of data converters such as integral and differential nonlinearity distortion effects that include harmonic distortion, worst harmonic, total harmonic distortion (THD), total harmonic distortion plus noise (THD + N), signal-to-noise-and-distortion ratio (SINAD), signal-to-noise ratio (SNR), and effective number of bits (ENOB). It also explores analog bandwidth, spurious free dynamic range (SFDR), two-tone intermodulation distortion (IMD), second- and third-order intercept points, 1 DB compression point, multitone spurious free dynamic range, wideband CDMA (WCDMA) adjacent channel power ratio (ACPR) and adjacent channel leakage ratio (ADLR), noise power ratio (NPR), noise factor (F), and noise figure (NF) with illustrations. The chapter also briefs about aperture time, aperture delay time, and aperture jitter. It further explains about ADC transient response and overvoltage recovery, ADC sparkle codes, metastable states, and bit error rate (BER). The chapter further discusses DAC dynamic performance, which includes DAC settling time, glitch impulse area, DAC SFDR and SNR, measuring DAC SNR with an analog spectrum analyzer, DAC output spectrum and sin (x)/x frequency roll-off, and oversampling interpolating DACs.