Gray-code input DAC architecture for clean signal generation

Abstract

This paper describes digital-to-analog converter (DAC) architectures for clean signal generation used in such as arbitrary waveform generators (AWGs) as well as graphic displays; the clean signal is applied to analog/mixed-signal/RF devices for testing. We propose here three types of Gray-code input DAC architectures (current-steering, charge-mode and voltage-mode DACs) for glitch reduction. They use current/voltage switch matrixes realized by double-pole double-throw (dpdt) switches. For a binary-weighted DAC, glitches which are trigged by switching during conversion in a DAC system are serious problems in some applications. Gray code (reflected binary code) is a binary numeral system where two successive values differ in only one bit and conversion between binary-code and Gray-code can be easily realized by XOR circuits. SPICE simulation has been performed to prove their feasibility and ability of glitch reduction.