A Wide Dynamic Range Analog-to-Digital Conversion System for GCMS Applications

An analog-to-digital conversion system is described which utilizes three parallel integrators of different sensitivities in front of a 12-bit analog-to-digital converter (ADC) to achieve a wide dynamic range, high linearity, and noise reduction. Gain ranging decisions are made by the hardware using a novel method of checking the ADC serial data output, with a minimal amount of logic circuitry. Applications to gas chromatography mass spectrometry (GCMS) are described.