Analog-to-digital converters (ADCs) are an indispensible component in the electronic processing chain of modern computer-ized instruments, such as Fourier transform infrared (FT-IR) spectrophotometers. In an FT-IR spectrometer, the interferogram of a broadband source covers a wide dynamic range, on the order of 106:1. This is a very demanding application for a high-speed ADC. Since FT-IR spectroscopy carries the promise of achieving high accuracy, all possible sources of systematic errors must be examined in order to validate that promise'. We will show that linearity errors in the ADC can result in a distortion of the transformed spectrum. This distortion can lead to significant systematic inaccuracies in FT-IR spectrophotometry.