MT-074 TUTORIAL

Differential Drivers for Precision ADCs
DIFFERENTIAL INPUT ADC CHARACTERISTICS
Many high performance ADCs are now being designed with differential inputs. A fully differential ADC design offers the advantages of good common-mode rejection, reduction in second-order distortion products, and simplified dc trim algorithms. Although they can be driven single-ended, a fully differential driver usually optimizes overall performance.
One of the most common ways to drive a differential input ADC is with a transformer. However, there are many applications where the ADCs cannot be driven with transformers because the frequency response must extend to dc. In these cases, differential drivers are required. This tutorial focuses on driving high resolution 16- to 18-bit ADCs with sampling rates up to 10 MSPS. The bandwidth of the input signals is generally limited to a few MHz. Tutorial MT-075 discusses differential amplifiers suitable for driving higher speed ADCs.